summaryrefslogtreecommitdiff
blob: 691a7560e8b889f493e7c7cc24d2604eb30b870b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
# Copyright 1999-2010 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

from __future__ import print_function

import gc
import logging
import re
import sys
import textwrap
from itertools import chain

import portage
from portage import os
from portage import digraph
from portage.const import PORTAGE_PACKAGE_ATOM
from portage.dbapi import dbapi
from portage.dbapi.dep_expand import dep_expand
from portage.dep import Atom
from portage.output import bold, blue, colorize, create_color_func, darkblue, \
	darkgreen, green, nc_len, red, teal, turquoise, yellow
bad = create_color_func("BAD")
from portage.package.ebuild.getmaskingstatus import \
	_getmaskingstatus, _MaskReason
from portage.sets import SETPREFIX
from portage.sets.base import InternalPackageSet
from portage.util import cmp_sort_key, writemsg, writemsg_stdout
from portage.util import writemsg_level

from _emerge.AtomArg import AtomArg
from _emerge.Blocker import Blocker
from _emerge.BlockerCache import BlockerCache
from _emerge.BlockerDepPriority import BlockerDepPriority
from _emerge.changelog import calc_changelog
from _emerge.countdown import countdown
from _emerge.create_world_atom import create_world_atom
from _emerge.Dependency import Dependency
from _emerge.DependencyArg import DependencyArg
from _emerge.DepPriority import DepPriority
from _emerge.DepPriorityNormalRange import DepPriorityNormalRange
from _emerge.DepPrioritySatisfiedRange import DepPrioritySatisfiedRange
from _emerge.FakeVartree import FakeVartree
from _emerge._find_deep_system_runtime_deps import _find_deep_system_runtime_deps
from _emerge.format_size import format_size
from _emerge.is_valid_package_atom import is_valid_package_atom
from _emerge.Package import Package
from _emerge.PackageArg import PackageArg
from _emerge.PackageCounters import PackageCounters
from _emerge.PackageVirtualDbapi import PackageVirtualDbapi
from _emerge.RepoDisplay import RepoDisplay
from _emerge.RootConfig import RootConfig
from _emerge.search import search
from _emerge.SetArg import SetArg
from _emerge.show_invalid_depstring_notice import show_invalid_depstring_notice
from _emerge.UnmergeDepPriority import UnmergeDepPriority

if sys.hexversion >= 0x3000000:
	basestring = str
	long = int

class _frozen_depgraph_config(object):

	def __init__(self, settings, trees, myopts, spinner):
		self.settings = settings
		self.target_root = settings["ROOT"]
		self.myopts = myopts
		self.edebug = 0
		if settings.get("PORTAGE_DEBUG", "") == "1":
			self.edebug = 1
		self.spinner = spinner
		if "_test_" in myopts and "/" not in trees:
			self._running_root = trees[self.target_root]["root_config"]
		else:
			self._running_root = trees["/"]["root_config"]
		self._opts_no_restart = frozenset(["--buildpkgonly",
			"--fetchonly", "--fetch-all-uri", "--pretend"])
		self.pkgsettings = {}
		self.trees = {}
		self._trees_orig = trees
		self.roots = {}
		# All Package instances
		self._pkg_cache = {}
		self._highest_license_masked = {}
		for myroot in trees:
			self.trees[myroot] = {}
			# Create a RootConfig instance that references
			# the FakeVartree instead of the real one.
			self.roots[myroot] = RootConfig(
				trees[myroot]["vartree"].settings,
				self.trees[myroot],
				trees[myroot]["root_config"].setconfig)
			for tree in ("porttree", "bintree"):
				self.trees[myroot][tree] = trees[myroot][tree]
			self.trees[myroot]["vartree"] = \
				FakeVartree(trees[myroot]["root_config"],
					pkg_cache=self._pkg_cache)
			self.pkgsettings[myroot] = portage.config(
				clone=self.trees[myroot]["vartree"].settings)

		self._required_set_names = set(["world"])

		self.excluded_pkgs = InternalPackageSet(allow_wildcard=True)
		for x in ' '.join(myopts.get("--exclude", [])).split():
			try:
				x = Atom(x, allow_wildcard=True)
			except portage.exception.InvalidAtom:
				x = Atom("*/" + x, allow_wildcard=True)
			self.excluded_pkgs.add(x)


class _dynamic_depgraph_config(object):

	def __init__(self, depgraph, myparams, allow_backtracking,
		runtime_pkg_mask, needed_user_config_changes, needed_use_config_changes):
		self.myparams = myparams.copy()
		self._vdb_loaded = False
		self._allow_backtracking = allow_backtracking
		# Maps slot atom to package for each Package added to the graph.
		self._slot_pkg_map = {}
		# Maps nodes to the reasons they were selected for reinstallation.
		self._reinstall_nodes = {}
		self.mydbapi = {}
		# Contains a filtered view of preferred packages that are selected
		# from available repositories.
		self._filtered_trees = {}
		# Contains installed packages and new packages that have been added
		# to the graph.
		self._graph_trees = {}
		# Caches visible packages returned from _select_package, for use in
		# depgraph._iter_atoms_for_pkg() SLOT logic.
		self._visible_pkgs = {}
		#contains the args created by select_files
		self._initial_arg_list = []
		self.digraph = portage.digraph()
		# contains all sets added to the graph
		self._sets = {}
		# contains atoms given as arguments
		self._sets["args"] = InternalPackageSet()
		# contains all atoms from all sets added to the graph, including
		# atoms given as arguments
		self._set_atoms = InternalPackageSet()
		self._atom_arg_map = {}
		# contains all nodes pulled in by self._set_atoms
		self._set_nodes = set()
		# Contains only Blocker -> Uninstall edges
		self._blocker_uninstalls = digraph()
		# Contains only Package -> Blocker edges
		self._blocker_parents = digraph()
		# Contains only irrelevant Package -> Blocker edges
		self._irrelevant_blockers = digraph()
		# Contains only unsolvable Package -> Blocker edges
		self._unsolvable_blockers = digraph()
		# Contains all Blocker -> Blocked Package edges
		self._blocked_pkgs = digraph()
		# Contains world packages that have been protected from
		# uninstallation but may not have been added to the graph
		# if the graph is not complete yet.
		self._blocked_world_pkgs = {}
		# Contains packages whose dependencies have been traversed.
		# This use used to check if we have accounted for blockers
		# relevant to a package.
		self._traversed_pkg_deps = set()
		self._slot_collision_info = {}
		# Slot collision nodes are not allowed to block other packages since
		# blocker validation is only able to account for one package per slot.
		self._slot_collision_nodes = set()
		self._parent_atoms = {}
		self._slot_conflict_parent_atoms = set()
		self._serialized_tasks_cache = None
		self._scheduler_graph = None
		self._displayed_list = None
		self._pprovided_args = []
		self._missing_args = []
		self._masked_installed = set()
		self._masked_license_updates = set()
		self._unsatisfied_deps_for_display = []
		self._unsatisfied_blockers_for_display = None
		self._circular_deps_for_display = None
		self._dep_stack = []
		self._dep_disjunctive_stack = []
		self._unsatisfied_deps = []
		self._initially_unsatisfied_deps = []
		self._ignored_deps = []
		self._highest_pkg_cache = {}
		if runtime_pkg_mask is None:
			runtime_pkg_mask = {}
		else:
			runtime_pkg_mask = dict((k, v.copy()) for (k, v) in \
				runtime_pkg_mask.items())

		if needed_user_config_changes is None:
			self._needed_user_config_changes = {}
		else:
			self._needed_user_config_changes = \
				dict((k.copy(), v.copy()) for (k, v) in \
					needed_user_config_changes.items())

		if needed_use_config_changes is None:
			self._needed_use_config_changes = {}
		else:
			self._needed_use_config_changes = \
				dict((k.copy(), (v[0].copy(), v[1].copy())) for (k, v) in \
					needed_use_config_changes.items())

		self._autounmask = depgraph._frozen_config.myopts.get('--autounmask', 'n') == True

		self._runtime_pkg_mask = runtime_pkg_mask
		self._need_restart = False

		for myroot in depgraph._frozen_config.trees:
			self._slot_pkg_map[myroot] = {}
			vardb = depgraph._frozen_config.trees[myroot]["vartree"].dbapi
			# This dbapi instance will model the state that the vdb will
			# have after new packages have been installed.
			fakedb = PackageVirtualDbapi(vardb.settings)

			self.mydbapi[myroot] = fakedb
			def graph_tree():
				pass
			graph_tree.dbapi = fakedb
			self._graph_trees[myroot] = {}
			self._filtered_trees[myroot] = {}
			# Substitute the graph tree for the vartree in dep_check() since we
			# want atom selections to be consistent with package selections
			# have already been made.
			self._graph_trees[myroot]["porttree"]   = graph_tree
			self._graph_trees[myroot]["vartree"]    = graph_tree
			def filtered_tree():
				pass
			filtered_tree.dbapi = _dep_check_composite_db(depgraph, myroot)
			self._filtered_trees[myroot]["porttree"] = filtered_tree
			self._visible_pkgs[myroot] = PackageVirtualDbapi(vardb.settings)

			# Passing in graph_tree as the vartree here could lead to better
			# atom selections in some cases by causing atoms for packages that
			# have been added to the graph to be preferred over other choices.
			# However, it can trigger atom selections that result in
			# unresolvable direct circular dependencies. For example, this
			# happens with gwydion-dylan which depends on either itself or
			# gwydion-dylan-bin. In case gwydion-dylan is not yet installed,
			# gwydion-dylan-bin needs to be selected in order to avoid a
			# an unresolvable direct circular dependency.
			#
			# To solve the problem described above, pass in "graph_db" so that
			# packages that have been added to the graph are distinguishable
			# from other available packages and installed packages. Also, pass
			# the parent package into self._select_atoms() calls so that
			# unresolvable direct circular dependencies can be detected and
			# avoided when possible.
			self._filtered_trees[myroot]["graph_db"] = graph_tree.dbapi
			self._filtered_trees[myroot]["vartree"] = \
				depgraph._frozen_config.trees[myroot]["vartree"]

			dbs = []
			portdb = depgraph._frozen_config.trees[myroot]["porttree"].dbapi
			bindb  = depgraph._frozen_config.trees[myroot]["bintree"].dbapi
			vardb  = depgraph._frozen_config.trees[myroot]["vartree"].dbapi
			#               (db, pkg_type, built, installed, db_keys)
			if "--usepkgonly" not in depgraph._frozen_config.myopts:
				db_keys = list(portdb._aux_cache_keys)
				dbs.append((portdb, "ebuild", False, False, db_keys))
			if "--usepkg" in depgraph._frozen_config.myopts:
				db_keys = list(bindb._aux_cache_keys)
				dbs.append((bindb,  "binary", True, False, db_keys))
			db_keys = list(depgraph._frozen_config._trees_orig[myroot
				]["vartree"].dbapi._aux_cache_keys)
			dbs.append((vardb, "installed", True, True, db_keys))
			self._filtered_trees[myroot]["dbs"] = dbs

class depgraph(object):

	pkg_tree_map = RootConfig.pkg_tree_map

	_dep_keys = ["DEPEND", "RDEPEND", "PDEPEND"]
	
	def __init__(self, settings, trees, myopts, myparams, spinner,
		frozen_config=None, runtime_pkg_mask=None, needed_user_config_changes=None, \
			needed_use_config_changes=None, allow_backtracking=False):
		if frozen_config is None:
			frozen_config = _frozen_depgraph_config(settings, trees,
			myopts, spinner)
		self._frozen_config = frozen_config
		self._dynamic_config = _dynamic_depgraph_config(self, myparams,
			allow_backtracking, runtime_pkg_mask, needed_user_config_changes, needed_use_config_changes)

		self._select_atoms = self._select_atoms_highest_available
		self._select_package = self._select_pkg_highest_available

	def _load_vdb(self):
		"""
		Load installed package metadata if appropriate. This used to be called
		from the constructor, but that wasn't very nice since this procedure
		is slow and it generates spinner output. So, now it's called on-demand
		by various methods when necessary.
		"""

		if self._dynamic_config._vdb_loaded:
			return

		for myroot in self._frozen_config.trees:

			preload_installed_pkgs = \
				"--nodeps" not in self._frozen_config.myopts and \
				"--buildpkgonly" not in self._frozen_config.myopts

			fake_vartree = self._frozen_config.trees[myroot]["vartree"]
			if not fake_vartree.dbapi:
				# This needs to be called for the first depgraph, but not for
				# backtracking depgraphs that share the same frozen_config.
				fake_vartree.sync()

			if preload_installed_pkgs:
				vardb = fake_vartree.dbapi
				fakedb = self._dynamic_config._graph_trees[
					myroot]["vartree"].dbapi

				for pkg in vardb:
					self._spinner_update()
					# This triggers metadata updates via FakeVartree.
					vardb.aux_get(pkg.cpv, [])
					fakedb.cpv_inject(pkg)

				# Now that the vardb state is cached in our FakeVartree,
				# we won't be needing the real vartree cache for awhile.
				# To make some room on the heap, clear the vardbapi
				# caches.
				self._frozen_config._trees_orig[myroot
					]["vartree"].dbapi._clear_cache()
				gc.collect()

		self._dynamic_config._vdb_loaded = True

	def _spinner_update(self):
		if self._frozen_config.spinner:
			self._frozen_config.spinner.update()

	def _show_missed_update(self):

		if '--quiet' in self._frozen_config.myopts and \
			'--debug' not in self._frozen_config.myopts:
			return

		# In order to minimize noise, show only the highest
		# missed update from each SLOT.
		missed_updates = {}
		for pkg, mask_reasons in \
			self._dynamic_config._runtime_pkg_mask.items():
			if pkg.installed:
				# Exclude installed here since we only
				# want to show available updates.
				continue
			k = (pkg.root, pkg.slot_atom)
			if k in missed_updates:
				other_pkg, mask_type, parent_atoms = missed_updates[k]
				if other_pkg > pkg:
					continue
			for mask_type, parent_atoms in mask_reasons.items():
				if not parent_atoms:
					continue
				missed_updates[k] = (pkg, mask_type, parent_atoms)
				break

		if not missed_updates:
			return

		missed_update_types = {}
		for pkg, mask_type, parent_atoms in missed_updates.values():
			missed_update_types.setdefault(mask_type,
				[]).append((pkg, parent_atoms))

		self._show_missed_update_slot_conflicts(
			missed_update_types.get("slot conflict"))

		self._show_missed_update_unsatisfied_dep(
			missed_update_types.get("missing dependency"))

	def _show_missed_update_unsatisfied_dep(self, missed_updates):

		if not missed_updates:
			return

		write = sys.stderr.write
		backtrack_masked = []

		for pkg, parent_atoms in missed_updates:

			try:
				for parent, root, atom in parent_atoms:
					self._show_unsatisfied_dep(root, atom, myparent=parent,
						check_backtrack=True)
			except self._backtrack_mask:
				# This is displayed below in abbreviated form.
				backtrack_masked.append((pkg, parent_atoms))
				continue

			write("\n!!! The following update has been skipped " + \
				"due to unsatisfied dependencies:\n\n")

			write(str(pkg.slot_atom))
			if pkg.root != '/':
				write(" for %s" % (pkg.root,))
			write("\n")

			for parent, root, atom in parent_atoms:
				self._show_unsatisfied_dep(root, atom, myparent=parent)
				write("\n")

		if backtrack_masked:
			# These are shown in abbreviated form, in order to avoid terminal
			# flooding from mask messages as reported in bug #285832.
			write("\n!!! The following update(s) have been skipped " + \
				"due to unsatisfied dependencies\n" + \
				"!!! triggered by backtracking:\n\n")
			for pkg, parent_atoms in backtrack_masked:
				write(str(pkg.slot_atom))
				if pkg.root != '/':
					write(" for %s" % (pkg.root,))
				write("\n")

		sys.stderr.flush()

	def _show_missed_update_slot_conflicts(self, missed_updates):

		if not missed_updates:
			return

		msg = []
		msg.append("\n!!! One or more updates have been skipped due to " + \
			"a dependency conflict:\n\n")

		indent = "  "
		for pkg, parent_atoms in missed_updates:
			msg.append(str(pkg.slot_atom))
			if pkg.root != '/':
				msg.append(" for %s" % (pkg.root,))
			msg.append("\n\n")

			for parent, atom in parent_atoms:
				msg.append(indent)
				msg.append(str(pkg))

				msg.append(" conflicts with\n")
				msg.append(2*indent)
				if isinstance(parent,
					(PackageArg, AtomArg)):
					# For PackageArg and AtomArg types, it's
					# redundant to display the atom attribute.
					msg.append(str(parent))
				else:
					# Display the specific atom from SetArg or
					# Package types.
					msg.append("%s required by %s" % (atom, parent))
				msg.append("\n")
			msg.append("\n")

		sys.stderr.write("".join(msg))
		sys.stderr.flush()

	def _show_slot_collision_notice(self):
		"""Show an informational message advising the user to mask one of the
		the packages. In some cases it may be possible to resolve this
		automatically, but support for backtracking (removal nodes that have
		already been selected) will be required in order to handle all possible
		cases.
		"""

		if not self._dynamic_config._slot_collision_info:
			return

		self._show_merge_list()

		msg = []
		msg.append("\n!!! Multiple package instances within a single " + \
			"package slot have been pulled\n")
		msg.append("!!! into the dependency graph, resulting" + \
			" in a slot conflict:\n\n")
		indent = "  "
		# Max number of parents shown, to avoid flooding the display.
		max_parents = 3
		explanation_columns = 70
		explanations = 0
		for (slot_atom, root), slot_nodes \
			in self._dynamic_config._slot_collision_info.items():
			msg.append(str(slot_atom))
			if root != '/':
				msg.append(" for %s" % (root,))
			msg.append("\n\n")

			for node in slot_nodes:
				msg.append(indent)
				msg.append(str(node))
				parent_atoms = self._dynamic_config._parent_atoms.get(node)
				if parent_atoms:
					pruned_list = set()
					for pkg, atom in parent_atoms:
						num_matched_slot_atoms = 0
						atom_set = InternalPackageSet(initial_atoms=(atom,))
						for other_node in slot_nodes:
							if other_node == node:
								continue
							if atom_set.findAtomForPackage(other_node):
								num_matched_slot_atoms += 1
						if num_matched_slot_atoms < len(slot_nodes) - 1:
							pruned_list.add((pkg, atom))
							if len(pruned_list) >= max_parents:
								break

					# If this package was pulled in by conflict atoms then
					# show those alone since those are the most interesting.
					if not pruned_list:
						# When generating the pruned list, prefer instances
						# of DependencyArg over instances of Package.
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							parent, atom = parent_atom
							if isinstance(parent, DependencyArg):
								pruned_list.add(parent_atom)
						# Prefer Packages instances that themselves have been
						# pulled into collision slots.
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							parent, atom = parent_atom
							if isinstance(parent, Package) and \
								(parent.slot_atom, parent.root) \
								in self._dynamic_config._slot_collision_info:
								pruned_list.add(parent_atom)
						for parent_atom in parent_atoms:
							if len(pruned_list) >= max_parents:
								break
							pruned_list.add(parent_atom)
					omitted_parents = len(parent_atoms) - len(pruned_list)
					parent_atoms = pruned_list
					msg.append(" pulled in by\n")
					for parent_atom in parent_atoms:
						parent, atom = parent_atom
						msg.append(2*indent)
						if isinstance(parent,
							(PackageArg, AtomArg)):
							# For PackageArg and AtomArg types, it's
							# redundant to display the atom attribute.
							msg.append(str(parent))
						else:
							# Display the specific atom from SetArg or
							# Package types.
							msg.append("%s required by %s" % (atom.unevaluated_atom, parent))
						msg.append("\n")
					if omitted_parents:
						msg.append(2*indent)
						msg.append("(and %d more)\n" % omitted_parents)
				else:
					msg.append(" (no parents)\n")
				msg.append("\n")
			explanation = self._slot_conflict_explanation(slot_nodes)
			if explanation:
				explanations += 1
				msg.append(indent + "Explanation:\n\n")
				for line in textwrap.wrap(explanation, explanation_columns):
					msg.append(2*indent + line + "\n")
				msg.append("\n")
		msg.append("\n")
		sys.stderr.write("".join(msg))
		sys.stderr.flush()

		explanations_for_all = explanations == len(self._dynamic_config._slot_collision_info)

		if explanations_for_all or "--quiet" in self._frozen_config.myopts:
			return

		msg = []
		msg.append("It may be possible to solve this problem ")
		msg.append("by using package.mask to prevent one of ")
		msg.append("those packages from being selected. ")
		msg.append("However, it is also possible that conflicting ")
		msg.append("dependencies exist such that they are impossible to ")
		msg.append("satisfy simultaneously.  If such a conflict exists in ")
		msg.append("the dependencies of two different packages, then those ")
		msg.append("packages can not be installed simultaneously.")
		backtrack_opt = self._frozen_config.myopts.get('--backtrack')
		if not self._dynamic_config._allow_backtracking and \
			(backtrack_opt is None or \
			(backtrack_opt > 0 and backtrack_opt < 30)):
			msg.append(" You may want to try a larger value of the ")
			msg.append("--backtrack option, such as --backtrack=30, ")
			msg.append("in order to see if that will solve this conflict ")
			msg.append("automatically.")

		for line in textwrap.wrap(''.join(msg), 70):
			writemsg(line + '\n', noiselevel=-1)
		writemsg('\n', noiselevel=-1)

		msg = []
		msg.append("For more information, see MASKED PACKAGES ")
		msg.append("section in the emerge man page or refer ")
		msg.append("to the Gentoo Handbook.")
		for line in textwrap.wrap(''.join(msg), 70):
			writemsg(line + '\n', noiselevel=-1)
		writemsg('\n', noiselevel=-1)

	def _slot_conflict_explanation(self, slot_nodes):
		"""
		When a slot conflict occurs due to USE deps, there are a few
		different cases to consider:

		1) New USE are correctly set but --newuse wasn't requested so an
		   installed package with incorrect USE happened to get pulled
		   into graph before the new one.

		2) New USE are incorrectly set but an installed package has correct
		   USE so it got pulled into the graph, and a new instance also got
		   pulled in due to --newuse or an upgrade.

		3) Multiple USE deps exist that can't be satisfied simultaneously,
		   and multiple package instances got pulled into the same slot to
		   satisfy the conflicting deps.

		Currently, explanations and suggested courses of action are generated
		for cases 1 and 2. Case 3 is too complex to give a useful suggestion.
		"""

		if len(slot_nodes) != 2:
			# Suggestions are only implemented for
			# conflicts between two packages.
			return None

		all_conflict_atoms = self._dynamic_config._slot_conflict_parent_atoms
		matched_node = None
		matched_atoms = None
		unmatched_node = None
		for node in slot_nodes:
			parent_atoms = self._dynamic_config._parent_atoms.get(node)
			if not parent_atoms:
				# Normally, there are always parent atoms. If there are
				# none then something unexpected is happening and there's
				# currently no suggestion for this case.
				return None
			conflict_atoms = all_conflict_atoms.intersection(parent_atoms)
			for parent_atom in conflict_atoms:
				parent, atom = parent_atom
				if not atom.use:
					# Suggestions are currently only implemented for cases
					# in which all conflict atoms have USE deps.
					return None
			if conflict_atoms:
				if matched_node is not None:
					# If conflict atoms match multiple nodes
					# then there's no suggestion.
					return None
				matched_node = node
				matched_atoms = conflict_atoms
			else:
				if unmatched_node is not None:
					# Neither node is matched by conflict atoms, and
					# there is no suggestion for this case.
					return None
				unmatched_node = node

		if matched_node is None or unmatched_node is None:
			# This shouldn't happen.
			return None

		if unmatched_node.installed and not matched_node.installed and \
			unmatched_node.cpv == matched_node.cpv:
			# If the conflicting packages are the same version then
			# --newuse should be all that's needed. If they are different
			# versions then there's some other problem.
			return "New USE are correctly set, but --newuse wasn't" + \
				" requested, so an installed package with incorrect USE " + \
				"happened to get pulled into the dependency graph. " + \
				"In order to solve " + \
				"this, either specify the --newuse option or explicitly " + \
				" reinstall '%s'." % matched_node.slot_atom

		if matched_node.installed and not unmatched_node.installed:
			atoms = sorted(set(atom for parent, atom in matched_atoms))
			explanation = ("New USE for '%s' are incorrectly set. " + \
				"In order to solve this, adjust USE to satisfy '%s'") % \
				(matched_node.slot_atom, atoms[0])
			if len(atoms) > 1:
				for atom in atoms[1:-1]:
					explanation += ", '%s'" % (atom,)
				if len(atoms) > 2:
					explanation += ","
				explanation += " and '%s'" % (atoms[-1],)
			explanation += "."
			return explanation

		return None

	def _process_slot_conflicts(self):
		"""
		Process slot conflict data to identify specific atoms which
		lead to conflict. These atoms only match a subset of the
		packages that have been pulled into a given slot.
		"""
		for (slot_atom, root), slot_nodes \
			in self._dynamic_config._slot_collision_info.items():

			all_parent_atoms = set()
			for pkg in slot_nodes:
				parent_atoms = self._dynamic_config._parent_atoms.get(pkg)
				if not parent_atoms:
					continue
				all_parent_atoms.update(parent_atoms)

			for pkg in slot_nodes:
				parent_atoms = self._dynamic_config._parent_atoms.get(pkg)
				if parent_atoms is None:
					parent_atoms = set()
					self._dynamic_config._parent_atoms[pkg] = parent_atoms
				for parent_atom in all_parent_atoms:
					if parent_atom in parent_atoms:
						continue
					# Use package set for matching since it will match via
					# PROVIDE when necessary, while match_from_list does not.
					parent, atom = parent_atom
					atom_set = InternalPackageSet(
						initial_atoms=(atom,))
					if atom_set.findAtomForPackage(pkg):
						parent_atoms.add(parent_atom)
					else:
						self._dynamic_config._slot_conflict_parent_atoms.add(parent_atom)

	def _reinstall_for_flags(self, forced_flags,
		orig_use, orig_iuse, cur_use, cur_iuse):
		"""Return a set of flags that trigger reinstallation, or None if there
		are no such flags."""
		if "--newuse" in self._frozen_config.myopts or \
			"--binpkg-respect-use" in self._frozen_config.myopts:
			flags = set(orig_iuse.symmetric_difference(
				cur_iuse).difference(forced_flags))
			flags.update(orig_iuse.intersection(orig_use).symmetric_difference(
				cur_iuse.intersection(cur_use)))
			if flags:
				return flags
		elif "changed-use" == self._frozen_config.myopts.get("--reinstall"):
			flags = orig_iuse.intersection(orig_use).symmetric_difference(
				cur_iuse.intersection(cur_use))
			if flags:
				return flags
		return None

	def _create_graph(self, allow_unsatisfied=False):
		dep_stack = self._dynamic_config._dep_stack
		dep_disjunctive_stack = self._dynamic_config._dep_disjunctive_stack
		while dep_stack or dep_disjunctive_stack:
			self._spinner_update()
			while dep_stack:
				dep = dep_stack.pop()
				if isinstance(dep, Package):
					if not self._add_pkg_deps(dep,
						allow_unsatisfied=allow_unsatisfied):
						return 0
					continue
				if not self._add_dep(dep, allow_unsatisfied=allow_unsatisfied):
					return 0
			if dep_disjunctive_stack:
				if not self._pop_disjunction(allow_unsatisfied):
					return 0
		return 1

	def _add_dep(self, dep, allow_unsatisfied=False):
		debug = "--debug" in self._frozen_config.myopts
		buildpkgonly = "--buildpkgonly" in self._frozen_config.myopts
		nodeps = "--nodeps" in self._frozen_config.myopts
		empty = "empty" in self._dynamic_config.myparams
		deep = self._dynamic_config.myparams.get("deep", 0)
		recurse = empty or deep is True or dep.depth <= deep
		if dep.blocker:
			if not buildpkgonly and \
				not nodeps and \
				dep.parent not in self._dynamic_config._slot_collision_nodes:
				if dep.parent.onlydeps:
					# It's safe to ignore blockers if the
					# parent is an --onlydeps node.
					return 1
				# The blocker applies to the root where
				# the parent is or will be installed.
				blocker = Blocker(atom=dep.atom,
					eapi=dep.parent.metadata["EAPI"],
					priority=dep.priority, root=dep.parent.root)
				self._dynamic_config._blocker_parents.add(blocker, dep.parent)
			return 1

		if dep.child is None:
			dep_pkg, existing_node = self._select_package(dep.root, dep.atom,
				onlydeps=dep.onlydeps)
		else:
			# The caller has selected a specific package
			# via self._minimize_packages().
			dep_pkg = dep.child
			existing_node = self._dynamic_config._slot_pkg_map[
				dep.root].get(dep_pkg.slot_atom)
			if existing_node is not dep_pkg:
				existing_node = None 

		if not dep_pkg:
			if dep.priority.optional:
				# This could be an unecessary build-time dep
				# pulled in by --with-bdeps=y.
				return 1
			if allow_unsatisfied:
				self._dynamic_config._unsatisfied_deps.append(dep)
				return 1
			self._dynamic_config._unsatisfied_deps_for_display.append(
				((dep.root, dep.atom), {"myparent":dep.parent}))

			# The parent node should not already be in
			# runtime_pkg_mask, since that would trigger an
			# infinite backtracking loop.
			if self._dynamic_config._allow_backtracking:
				if dep.parent in self._dynamic_config._runtime_pkg_mask:
					if "--debug" in self._frozen_config.myopts:
						writemsg(
							"!!! backtracking loop detected: %s %s\n" % \
							(dep.parent,
							self._dynamic_config._runtime_pkg_mask[
							dep.parent]), noiselevel=-1)
				else:
					# Do not backtrack if only USE have to be changed in
					# order to satisfy the dependency.
					dep_pkg, existing_node = \
						self._select_package(dep.root, dep.atom.without_use,
							onlydeps=dep.onlydeps)
					if dep_pkg is None:
						self._dynamic_config._runtime_pkg_mask.setdefault(
							dep.parent, {})["missing dependency"] = \
								set([(dep.parent, dep.root, dep.atom)])
						self._dynamic_config._need_restart = True
						if "--debug" in self._frozen_config.myopts:
							msg = []
							msg.append("")
							msg.append("")
							msg.append("backtracking due to unsatisfied dep:")
							msg.append("    parent: %s" % dep.parent)
							msg.append("  priority: %s" % dep.priority)
							msg.append("      root: %s" % dep.root)
							msg.append("      atom: %s" % dep.atom)
							msg.append("")
							writemsg_level("".join("%s\n" % l for l in msg),
								noiselevel=-1, level=logging.DEBUG)

			return 0
		# In some cases, dep_check will return deps that shouldn't
		# be proccessed any further, so they are identified and
		# discarded here. Try to discard as few as possible since
		# discarded dependencies reduce the amount of information
		# available for optimization of merge order.
		if dep.priority.satisfied and \
			dep.priority.satisfied.visible and \
			not dep_pkg.installed and \
			not (existing_node or recurse):
			myarg = None
			if dep.root == self._frozen_config.target_root:
				try:
					myarg = next(self._iter_atoms_for_pkg(dep_pkg))
				except StopIteration:
					pass
				except portage.exception.InvalidDependString:
					if not dep_pkg.installed:
						# This shouldn't happen since the package
						# should have been masked.
						raise
			if not myarg:
				# Existing child selection may not be valid unless
				# it's added to the graph immediately, since "complete"
				# mode may select a different child later.
				dep.child = None
				self._dynamic_config._ignored_deps.append(dep)
				return 1

		if not self._add_pkg(dep_pkg, dep):
			return 0
		return 1

	def _add_pkg(self, pkg, dep):
		myparent = None
		priority = None
		depth = 0
		if dep is None:
			dep = Dependency()
		else:
			myparent = dep.parent
			priority = dep.priority
			depth = dep.depth
		if priority is None:
			priority = DepPriority()
		"""
		Fills the digraph with nodes comprised of packages to merge.
		mybigkey is the package spec of the package to merge.
		myparent is the package depending on mybigkey ( or None )
		addme = Should we add this package to the digraph or are we just looking at it's deps?
			Think --onlydeps, we need to ignore packages in that case.
		#stuff to add:
		#SLOT-aware emerge
		#IUSE-aware emerge -> USE DEP aware depgraph
		#"no downgrade" emerge
		"""
		# Ensure that the dependencies of the same package
		# are never processed more than once.
		previously_added = pkg in self._dynamic_config.digraph

		# select the correct /var database that we'll be checking against
		vardbapi = self._frozen_config.trees[pkg.root]["vartree"].dbapi
		pkgsettings = self._frozen_config.pkgsettings[pkg.root]

		arg_atoms = None
		if True:
			try:
				arg_atoms = list(self._iter_atoms_for_pkg(pkg))
			except portage.exception.InvalidDependString as e:
				if not pkg.installed:
					show_invalid_depstring_notice(
						pkg, pkg.metadata["PROVIDE"], str(e))
					return 0
				del e

		if not pkg.onlydeps:
			if not pkg.installed and \
				"empty" not in self._dynamic_config.myparams and \
				vardbapi.match(pkg.slot_atom):
				# Increase the priority of dependencies on packages that
				# are being rebuilt. This optimizes merge order so that
				# dependencies are rebuilt/updated as soon as possible,
				# which is needed especially when emerge is called by
				# revdep-rebuild since dependencies may be affected by ABI
				# breakage that has rendered them useless. Don't adjust
				# priority here when in "empty" mode since all packages
				# are being merged in that case.
				priority.rebuild = True

			existing_node = self._dynamic_config._slot_pkg_map[pkg.root].get(pkg.slot_atom)
			slot_collision = False
			if existing_node:
				existing_node_matches = pkg.cpv == existing_node.cpv
				if existing_node_matches and \
					pkg != existing_node and \
					dep.atom is not None:
					# Use package set for matching since it will match via
					# PROVIDE when necessary, while match_from_list does not.
					atom_set = InternalPackageSet(initial_atoms=[dep.atom])
					if not atom_set.findAtomForPackage(existing_node):
						existing_node_matches = False
				if existing_node_matches:
					# The existing node can be reused.
					if arg_atoms:
						for parent_atom in arg_atoms:
							parent, atom = parent_atom
							self._dynamic_config.digraph.add(existing_node, parent,
								priority=priority)
							self._add_parent_atom(existing_node, parent_atom)
					# If a direct circular dependency is not an unsatisfied
					# buildtime dependency then drop it here since otherwise
					# it can skew the merge order calculation in an unwanted
					# way.
					if existing_node != myparent or \
						(priority.buildtime and not priority.satisfied):
						self._dynamic_config.digraph.addnode(existing_node, myparent,
							priority=priority)
						if dep.atom is not None and dep.parent is not None:
							self._add_parent_atom(existing_node,
								(dep.parent, dep.atom))
					return 1
				else:
					# A slot conflict has occurred. 
					# The existing node should not already be in
					# runtime_pkg_mask, since that would trigger an
					# infinite backtracking loop.
					if self._dynamic_config._allow_backtracking and \
						existing_node in \
						self._dynamic_config._runtime_pkg_mask:
						if "--debug" in self._frozen_config.myopts:
							writemsg(
								"!!! backtracking loop detected: %s %s\n" % \
								(existing_node,
								self._dynamic_config._runtime_pkg_mask[
								existing_node]), noiselevel=-1)
					elif self._dynamic_config._allow_backtracking and \
						not self._accept_blocker_conflicts():
						self._add_slot_conflict(pkg)
						if dep.atom is not None and dep.parent is not None:
							self._add_parent_atom(pkg, (dep.parent, dep.atom))
						if arg_atoms:
							for parent_atom in arg_atoms:
								parent, atom = parent_atom
								self._add_parent_atom(pkg, parent_atom)
						self._process_slot_conflicts()

						parent_atoms = \
							self._dynamic_config._parent_atoms.get(pkg, set())
						if parent_atoms:
							conflict_atoms = self._dynamic_config._slot_conflict_parent_atoms.intersection(parent_atoms)
							if conflict_atoms:
								parent_atoms = conflict_atoms
						if pkg >= existing_node:
							# We only care about the parent atoms
							# when they trigger a downgrade.
							parent_atoms = set()

						self._dynamic_config._runtime_pkg_mask.setdefault(
							existing_node, {})["slot conflict"] = parent_atoms
						self._dynamic_config._need_restart = True
						if "--debug" in self._frozen_config.myopts:
							msg = []
							msg.append("")
							msg.append("")
							msg.append("backtracking due to slot conflict:")
							msg.append("   package: %s" % existing_node)
							msg.append("      slot: %s" % existing_node.slot_atom)
							msg.append("   parents: %s" % \
								[(str(parent), atom) \
								for parent, atom in parent_atoms])
							msg.append("")
							writemsg_level("".join("%s\n" % l for l in msg),
								noiselevel=-1, level=logging.DEBUG)
						return 0

					# A slot collision has occurred.  Sometimes this coincides
					# with unresolvable blockers, so the slot collision will be
					# shown later if there are no unresolvable blockers.
					self._add_slot_conflict(pkg)
					slot_collision = True

			if slot_collision:
				# Now add this node to the graph so that self.display()
				# can show use flags and --tree portage.output.  This node is
				# only being partially added to the graph.  It must not be
				# allowed to interfere with the other nodes that have been
				# added.  Do not overwrite data for existing nodes in
				# self._dynamic_config.mydbapi since that data will be used for blocker
				# validation.
				# Even though the graph is now invalid, continue to process
				# dependencies so that things like --fetchonly can still
				# function despite collisions.
				pass
			elif not previously_added:
				self._dynamic_config._slot_pkg_map[pkg.root][pkg.slot_atom] = pkg
				self._dynamic_config.mydbapi[pkg.root].cpv_inject(pkg)
				self._dynamic_config._filtered_trees[pkg.root]["porttree"].dbapi._clear_cache()
				self._dynamic_config._highest_pkg_cache.clear()
				self._check_masks(pkg)

			if not pkg.installed:
				# Allow this package to satisfy old-style virtuals in case it
				# doesn't already. Any pre-existing providers will be preferred
				# over this one.
				try:
					pkgsettings.setinst(pkg.cpv, pkg.metadata)
					# For consistency, also update the global virtuals.
					settings = self._frozen_config.roots[pkg.root].settings
					settings.unlock()
					settings.setinst(pkg.cpv, pkg.metadata)
					settings.lock()
				except portage.exception.InvalidDependString as e:
					show_invalid_depstring_notice(
						pkg, pkg.metadata["PROVIDE"], str(e))
					del e
					return 0

		if arg_atoms:
			self._dynamic_config._set_nodes.add(pkg)

		# Do this even when addme is False (--onlydeps) so that the
		# parent/child relationship is always known in case
		# self._show_slot_collision_notice() needs to be called later.
		self._dynamic_config.digraph.add(pkg, myparent, priority=priority)
		if dep.atom is not None and dep.parent is not None:
			self._add_parent_atom(pkg, (dep.parent, dep.atom))

		if arg_atoms:
			for parent_atom in arg_atoms:
				parent, atom = parent_atom
				self._dynamic_config.digraph.add(pkg, parent, priority=priority)
				self._add_parent_atom(pkg, parent_atom)

		""" This section determines whether we go deeper into dependencies or not.
		    We want to go deeper on a few occasions:
		    Installing package A, we need to make sure package A's deps are met.
		    emerge --deep <pkgspec>; we need to recursively check dependencies of pkgspec
		    If we are in --nodeps (no recursion) mode, we obviously only check 1 level of dependencies.
		"""
		if arg_atoms:
			depth = 0
		pkg.depth = depth
		deep = self._dynamic_config.myparams.get("deep", 0)
		empty = "empty" in self._dynamic_config.myparams
		recurse = empty or deep is True or depth + 1 <= deep
		dep_stack = self._dynamic_config._dep_stack
		if "recurse" not in self._dynamic_config.myparams:
			return 1
		elif pkg.installed and not recurse:
			dep_stack = self._dynamic_config._ignored_deps

		self._spinner_update()

		if not previously_added:
			dep_stack.append(pkg)
		return 1

	def _check_masks(self, pkg):

		slot_key = (pkg.root, pkg.slot_atom)

		# Check for upgrades in the same slot that are
		# masked due to a LICENSE change in a newer
		# version that is not masked for any other reason.
		other_pkg = self._frozen_config._highest_license_masked.get(slot_key)
		if other_pkg is not None and pkg < other_pkg:
			self._dynamic_config._masked_license_updates.add(other_pkg)

	def _add_parent_atom(self, pkg, parent_atom):
		parent_atoms = self._dynamic_config._parent_atoms.get(pkg)
		if parent_atoms is None:
			parent_atoms = set()
			self._dynamic_config._parent_atoms[pkg] = parent_atoms
		parent_atoms.add(parent_atom)

	def _add_slot_conflict(self, pkg):
		self._dynamic_config._slot_collision_nodes.add(pkg)
		slot_key = (pkg.slot_atom, pkg.root)
		slot_nodes = self._dynamic_config._slot_collision_info.get(slot_key)
		if slot_nodes is None:
			slot_nodes = set()
			slot_nodes.add(self._dynamic_config._slot_pkg_map[pkg.root][pkg.slot_atom])
			self._dynamic_config._slot_collision_info[slot_key] = slot_nodes
		slot_nodes.add(pkg)

	def _add_pkg_deps(self, pkg, allow_unsatisfied=False):

		mytype = pkg.type_name
		myroot = pkg.root
		mykey = pkg.cpv
		metadata = pkg.metadata
		myuse = self._pkg_use_enabled(pkg)
		jbigkey = pkg
		depth = pkg.depth + 1
		removal_action = "remove" in self._dynamic_config.myparams

		edepend={}
		depkeys = ["DEPEND","RDEPEND","PDEPEND"]
		for k in depkeys:
			edepend[k] = metadata[k]

		if not pkg.built and \
			"--buildpkgonly" in self._frozen_config.myopts and \
			"deep" not in self._dynamic_config.myparams and \
			"empty" not in self._dynamic_config.myparams:
			edepend["RDEPEND"] = ""
			edepend["PDEPEND"] = ""
		bdeps_optional = False

		if pkg.built and not removal_action:
			if self._frozen_config.myopts.get("--with-bdeps", "n") == "y":
				# Pull in build time deps as requested, but marked them as
				# "optional" since they are not strictly required. This allows
				# more freedom in the merge order calculation for solving
				# circular dependencies. Don't convert to PDEPEND since that
				# could make --with-bdeps=y less effective if it is used to
				# adjust merge order to prevent built_with_use() calls from
				# failing.
				bdeps_optional = True
			else:
				# built packages do not have build time dependencies.
				edepend["DEPEND"] = ""

		if removal_action and self._frozen_config.myopts.get("--with-bdeps", "y") == "n":
			edepend["DEPEND"] = ""

		if removal_action:
			bdeps_root = myroot
		else:
			bdeps_root = "/"
			root_deps = self._frozen_config.myopts.get("--root-deps")
			if root_deps is not None:
				if root_deps is True:
					bdeps_root = myroot
				elif root_deps == "rdeps":
					edepend["DEPEND"] = ""

		deps = (
			(bdeps_root, edepend["DEPEND"],
				self._priority(buildtime=(not bdeps_optional),
				optional=bdeps_optional),
				pkg.built),
			(myroot, edepend["RDEPEND"],
				self._priority(runtime=True),
				False),
			(myroot, edepend["PDEPEND"],
				self._priority(runtime_post=True),
				False)
		)

		debug = "--debug" in self._frozen_config.myopts
		strict = mytype != "installed"
		try:
			if not strict:
				portage.dep._dep_check_strict = False

			for dep_root, dep_string, dep_priority, ignore_blockers in deps:
				if not dep_string:
					continue
				if debug:
					writemsg_level("\nParent:    %s\n" % (pkg,),
						noiselevel=-1, level=logging.DEBUG)
					writemsg_level("Depstring: %s\n" % (dep_string,),
						noiselevel=-1, level=logging.DEBUG)
					writemsg_level("Priority:  %s\n" % (dep_priority,),
						noiselevel=-1, level=logging.DEBUG)

				try:

					dep_string = portage.dep.paren_normalize(
						portage.dep.use_reduce(
						portage.dep.paren_reduce(dep_string),
						uselist=self._pkg_use_enabled(pkg)))

					dep_string = list(self._queue_disjunctive_deps(
						pkg, dep_root, dep_priority, dep_string))

				except portage.exception.InvalidDependString as e:
					if pkg.installed:
						del e
						continue
					show_invalid_depstring_notice(pkg, dep_string, str(e))
					return 0

				if not dep_string:
					continue

				dep_string = portage.dep.paren_enclose(dep_string)

				if not self._add_pkg_dep_string(
					pkg, dep_root, dep_priority, dep_string,
					allow_unsatisfied, ignore_blockers=ignore_blockers):
					return 0

		except portage.exception.AmbiguousPackageName as e:
			pkgs = e.args[0]
			portage.writemsg("\n\n!!! An atom in the dependencies " + \
				"is not fully-qualified. Multiple matches:\n\n", noiselevel=-1)
			for cpv in pkgs:
				portage.writemsg("    %s\n" % cpv, noiselevel=-1)
			portage.writemsg("\n", noiselevel=-1)
			if mytype == "binary":
				portage.writemsg(
					"!!! This binary package cannot be installed: '%s'\n" % \
					mykey, noiselevel=-1)
			elif mytype == "ebuild":
				portdb = self._frozen_config.roots[myroot].trees["porttree"].dbapi
				myebuild, mylocation = portdb.findname2(mykey)
				portage.writemsg("!!! This ebuild cannot be installed: " + \
					"'%s'\n" % myebuild, noiselevel=-1)
			portage.writemsg("!!! Please notify the package maintainer " + \
				"that atoms must be fully-qualified.\n", noiselevel=-1)
			return 0
		finally:
			portage.dep._dep_check_strict = True
		self._dynamic_config._traversed_pkg_deps.add(pkg)
		return 1

	def _add_pkg_dep_string(self, pkg, dep_root, dep_priority, dep_string,
		allow_unsatisfied, ignore_blockers=False):
		depth = pkg.depth + 1
		debug = "--debug" in self._frozen_config.myopts
		strict = pkg.type_name != "installed"

		if debug:
			writemsg_level("\nParent:    %s\n" % (pkg,),
				noiselevel=-1, level=logging.DEBUG)
			writemsg_level("Depstring: %s\n" % (dep_string,),
				noiselevel=-1, level=logging.DEBUG)
			writemsg_level("Priority:  %s\n" % (dep_priority,),
				noiselevel=-1, level=logging.DEBUG)

		try:
			selected_atoms = self._select_atoms(dep_root,
				dep_string, myuse=self._pkg_use_enabled(pkg), parent=pkg,
				strict=strict, priority=dep_priority)
		except portage.exception.InvalidDependString as e:
			show_invalid_depstring_notice(pkg, dep_string, str(e))
			del e
			if pkg.installed:
				return 1
			return 0

		if debug:
			writemsg_level("Candidates: %s\n" % \
				([str(x) for x in selected_atoms[pkg]],),
				noiselevel=-1, level=logging.DEBUG)

		root_config = self._frozen_config.roots[dep_root]
		vardb = root_config.trees["vartree"].dbapi

		for atom, child in self._minimize_children(
			pkg, dep_priority, root_config, selected_atoms[pkg]):

			if ignore_blockers and atom.blocker:
				# For --with-bdeps, ignore build-time only blockers
				# that originate from built packages.
				continue

			mypriority = dep_priority.copy()
			if not atom.blocker:
				inst_pkgs = vardb.match_pkgs(atom)
				if inst_pkgs:
					for inst_pkg in inst_pkgs:
						if self._pkg_visibility_check(inst_pkg):
							# highest visible
							mypriority.satisfied = inst_pkg
							break
					if not mypriority.satisfied:
						# none visible, so use highest
						mypriority.satisfied = inst_pkgs[0]

			if not self._add_dep(Dependency(atom=atom,
				blocker=atom.blocker, child=child, depth=depth, parent=pkg,
				priority=mypriority, root=dep_root),
				allow_unsatisfied=allow_unsatisfied):
				return 0

		selected_atoms.pop(pkg)

		# Add selected indirect virtual deps to the graph. This
		# takes advantage of circular dependency avoidance that's done
		# by dep_zapdeps. We preserve actual parent/child relationships
		# here in order to avoid distorting the dependency graph like
		# <=portage-2.1.6.x did.
		for virt_pkg, atoms in selected_atoms.items():

			if debug:
				writemsg_level("Candidates: %s: %s\n" % \
					(virt_pkg.cpv, [str(x) for x in atoms]),
					noiselevel=-1, level=logging.DEBUG)

			# Just assume depth + 1 here for now, though it's not entirely
			# accurate since multilple levels of indirect virtual deps may
			# have been traversed. The _add_pkg call will reset the depth to
			# 0 if this package happens to match an argument.
			if not self._add_pkg(virt_pkg,
				Dependency(atom=Atom('=' + virt_pkg.cpv),
				depth=(depth + 1), parent=pkg, priority=dep_priority.copy(),
				root=dep_root)):
				return 0

			for atom, child in self._minimize_children(
				pkg, self._priority(runtime=True), root_config, atoms):
				# This is a GLEP 37 virtual, so its deps are all runtime.
				mypriority = self._priority(runtime=True)
				if not atom.blocker:
					inst_pkgs = vardb.match_pkgs(atom)
					if inst_pkgs:
						for inst_pkg in inst_pkgs:
							if self._pkg_visibility_check(inst_pkg):
								# highest visible
								mypriority.satisfied = inst_pkg
								break
						if not mypriority.satisfied:
							# none visible, so use highest
							mypriority.satisfied = inst_pkgs[0]

				if not self._add_dep(Dependency(atom=atom,
					blocker=atom.blocker, child=child, depth=virt_pkg.depth,
					parent=virt_pkg, priority=mypriority, root=dep_root),
					allow_unsatisfied=allow_unsatisfied):
					return 0

		if debug:
			writemsg_level("Exiting... %s\n" % (pkg,),
				noiselevel=-1, level=logging.DEBUG)

		return 1

	def _minimize_children(self, parent, priority, root_config, atoms):
		"""
		Selects packages to satisfy the given atoms, and minimizes the
		number of selected packages. This serves to identify and eliminate
		redundant package selections when multiple atoms happen to specify
		a version range.
		"""

		atom_pkg_map = {}

		for atom in atoms:
			if atom.blocker:
				yield (atom, None)
				continue
			dep_pkg, existing_node = self._select_package(
				root_config.root, atom)
			if dep_pkg is None:
				yield (atom, None)
				continue
			atom_pkg_map[atom] = dep_pkg

		if len(atom_pkg_map) < 2:
			for item in atom_pkg_map.items():
				yield item
			return

		cp_pkg_map = {}
		pkg_atom_map = {}
		for atom, pkg in atom_pkg_map.items():
			pkg_atom_map.setdefault(pkg, set()).add(atom)
			cp_pkg_map.setdefault(pkg.cp, set()).add(pkg)

		for cp, pkgs in cp_pkg_map.items():
			if len(pkgs) < 2:
				for pkg in pkgs:
					for atom in pkg_atom_map[pkg]:
						yield (atom, pkg)
				continue

			# Use a digraph to identify and eliminate any
			# redundant package selections.
			atom_pkg_graph = digraph()
			cp_atoms = set()
			for pkg1 in pkgs:
				for atom in pkg_atom_map[pkg1]:
					cp_atoms.add(atom)
					atom_pkg_graph.add(pkg1, atom)
					atom_set = InternalPackageSet(initial_atoms=(atom,))
					for pkg2 in pkgs:
						if pkg2 is pkg1:
							continue
						if atom_set.findAtomForPackage(pkg2):
							atom_pkg_graph.add(pkg2, atom)

			for pkg in pkgs:
				eliminate_pkg = True
				for atom in atom_pkg_graph.parent_nodes(pkg):
					if len(atom_pkg_graph.child_nodes(atom)) < 2:
						eliminate_pkg = False
						break
				if eliminate_pkg:
					atom_pkg_graph.remove(pkg)

			# Yield < and <= atoms first, since those are more likely to
			# cause slot conflicts, and we want those atoms to be displayed
			# in the resulting slot conflict message (see bug #291142).
			less_than = []
			not_less_than = []
			for atom in cp_atoms:
				if atom.operator in ('<', '<='):
					less_than.append(atom)
				else:
					not_less_than.append(atom)

			for atom in chain(less_than, not_less_than):
				child_pkgs = atom_pkg_graph.child_nodes(atom)
				yield (atom, child_pkgs[0])

	def _queue_disjunctive_deps(self, pkg, dep_root, dep_priority, dep_struct):
		"""
		Queue disjunctive (virtual and ||) deps in self._dynamic_config._dep_disjunctive_stack.
		Yields non-disjunctive deps. Raises InvalidDependString when 
		necessary.
		"""
		i = 0
		while i < len(dep_struct):
			x = dep_struct[i]
			if isinstance(x, list):
				for y in self._queue_disjunctive_deps(
					pkg, dep_root, dep_priority, x):
					yield y
			elif x == "||":
				self._queue_disjunction(pkg, dep_root, dep_priority,
					[ x, dep_struct[ i + 1 ] ] )
				i += 1
			else:
				try:
					x = portage.dep.Atom(x)
				except portage.exception.InvalidAtom:
					if not pkg.installed:
						raise portage.exception.InvalidDependString(
							"invalid atom: '%s'" % x)
				else:
					# Note: Eventually this will check for PROPERTIES=virtual
					# or whatever other metadata gets implemented for this
					# purpose.
					if x.cp.startswith('virtual/'):
						self._queue_disjunction( pkg, dep_root,
							dep_priority, [ str(x) ] )
					else:
						yield str(x)
			i += 1

	def _queue_disjunction(self, pkg, dep_root, dep_priority, dep_struct):
		self._dynamic_config._dep_disjunctive_stack.append(
			(pkg, dep_root, dep_priority, dep_struct))

	def _pop_disjunction(self, allow_unsatisfied):
		"""
		Pop one disjunctive dep from self._dynamic_config._dep_disjunctive_stack, and use it to
		populate self._dynamic_config._dep_stack.
		"""
		pkg, dep_root, dep_priority, dep_struct = \
			self._dynamic_config._dep_disjunctive_stack.pop()
		dep_string = portage.dep.paren_enclose(dep_struct)
		if not self._add_pkg_dep_string(
			pkg, dep_root, dep_priority, dep_string, allow_unsatisfied):
			return 0
		return 1

	def _priority(self, **kwargs):
		if "remove" in self._dynamic_config.myparams:
			priority_constructor = UnmergeDepPriority
		else:
			priority_constructor = DepPriority
		return priority_constructor(**kwargs)

	def _dep_expand(self, root_config, atom_without_category):
		"""
		@param root_config: a root config instance
		@type root_config: RootConfig
		@param atom_without_category: an atom without a category component
		@type atom_without_category: String
		@rtype: list
		@returns: a list of atoms containing categories (possibly empty)
		"""
		null_cp = portage.dep_getkey(insert_category_into_atom(
			atom_without_category, "null"))
		cat, atom_pn = portage.catsplit(null_cp)

		dbs = self._dynamic_config._filtered_trees[root_config.root]["dbs"]
		categories = set()
		for db, pkg_type, built, installed, db_keys in dbs:
			for cat in db.categories:
				if db.cp_list("%s/%s" % (cat, atom_pn)):
					categories.add(cat)

		deps = []
		for cat in categories:
			deps.append(Atom(insert_category_into_atom(
				atom_without_category, cat)))
		return deps

	def _have_new_virt(self, root, atom_cp):
		ret = False
		for db, pkg_type, built, installed, db_keys in \
			self._dynamic_config._filtered_trees[root]["dbs"]:
			if db.cp_list(atom_cp):
				ret = True
				break
		return ret

	def _iter_atoms_for_pkg(self, pkg):
		# TODO: add multiple $ROOT support
		if pkg.root != self._frozen_config.target_root:
			return
		atom_arg_map = self._dynamic_config._atom_arg_map
		root_config = self._frozen_config.roots[pkg.root]
		for atom in self._dynamic_config._set_atoms.iterAtomsForPackage(pkg):
			if atom.cp != pkg.cp and \
				self._have_new_virt(pkg.root, atom.cp):
				continue
			visible_pkgs = \
				self._dynamic_config._visible_pkgs[pkg.root].match_pkgs(atom)
			visible_pkgs.reverse() # descending order
			higher_slot = None
			for visible_pkg in visible_pkgs:
				if visible_pkg.cp != atom.cp:
					continue
				if pkg >= visible_pkg:
					# This is descending order, and we're not
					# interested in any versions <= pkg given.
					break
				if pkg.slot_atom != visible_pkg.slot_atom:
					higher_slot = visible_pkg
					break
			if higher_slot is not None:
				continue
			for arg in atom_arg_map[(atom, pkg.root)]:
				if isinstance(arg, PackageArg) and \
					arg.package != pkg:
					continue
				yield arg, atom

	def select_files(self, myfiles):
		"""Given a list of .tbz2s, .ebuilds sets, and deps, populate
		self._dynamic_config._initial_arg_list and call self._resolve to create the 
		appropriate depgraph and return a favorite list."""
		self._load_vdb()
		debug = "--debug" in self._frozen_config.myopts
		root_config = self._frozen_config.roots[self._frozen_config.target_root]
		sets = root_config.sets
		getSetAtoms = root_config.setconfig.getSetAtoms
		myfavorites=[]
		myroot = self._frozen_config.target_root
		dbs = self._dynamic_config._filtered_trees[myroot]["dbs"]
		vardb = self._frozen_config.trees[myroot]["vartree"].dbapi
		real_vardb = self._frozen_config._trees_orig[myroot]["vartree"].dbapi
		portdb = self._frozen_config.trees[myroot]["porttree"].dbapi
		bindb = self._frozen_config.trees[myroot]["bintree"].dbapi
		pkgsettings = self._frozen_config.pkgsettings[myroot]
		args = []
		onlydeps = "--onlydeps" in self._frozen_config.myopts
		lookup_owners = []
		for x in myfiles:
			ext = os.path.splitext(x)[1]
			if ext==".tbz2":
				if not os.path.exists(x):
					if os.path.exists(
						os.path.join(pkgsettings["PKGDIR"], "All", x)):
						x = os.path.join(pkgsettings["PKGDIR"], "All", x)
					elif os.path.exists(
						os.path.join(pkgsettings["PKGDIR"], x)):
						x = os.path.join(pkgsettings["PKGDIR"], x)
					else:
						print("\n\n!!! Binary package '"+str(x)+"' does not exist.")
						print("!!! Please ensure the tbz2 exists as specified.\n")
						return 0, myfavorites
				mytbz2=portage.xpak.tbz2(x)
				mykey=mytbz2.getelements("CATEGORY")[0]+"/"+os.path.splitext(os.path.basename(x))[0]
				if os.path.realpath(x) != \
					os.path.realpath(self._frozen_config.trees[myroot]["bintree"].getname(mykey)):
					print(colorize("BAD", "\n*** You need to adjust PKGDIR to emerge this package.\n"))
					return 0, myfavorites

				pkg = self._pkg(mykey, "binary", root_config,
					onlydeps=onlydeps)
				args.append(PackageArg(arg=x, package=pkg,
					root_config=root_config))
			elif ext==".ebuild":
				ebuild_path = portage.util.normalize_path(os.path.abspath(x))
				pkgdir = os.path.dirname(ebuild_path)
				tree_root = os.path.dirname(os.path.dirname(pkgdir))
				cp = pkgdir[len(tree_root)+1:]
				e = portage.exception.PackageNotFound(
					("%s is not in a valid portage tree " + \
					"hierarchy or does not exist") % x)
				if not portage.isvalidatom(cp):
					raise e
				cat = portage.catsplit(cp)[0]
				mykey = cat + "/" + os.path.basename(ebuild_path[:-7])
				if not portage.isvalidatom("="+mykey):
					raise e
				ebuild_path = portdb.findname(mykey)
				if ebuild_path:
					if ebuild_path != os.path.join(os.path.realpath(tree_root),
						cp, os.path.basename(ebuild_path)):
						print(colorize("BAD", "\n*** You need to adjust PORTDIR or PORTDIR_OVERLAY to emerge this package.\n"))
						return 0, myfavorites
					if mykey not in portdb.xmatch(
						"match-visible", portage.cpv_getkey(mykey)):
						print(colorize("BAD", "\n*** You are emerging a masked package. It is MUCH better to use"))
						print(colorize("BAD", "*** /etc/portage/package.* to accomplish this. See portage(5) man"))
						print(colorize("BAD", "*** page for details."))
						countdown(int(self._frozen_config.settings["EMERGE_WARNING_DELAY"]),
							"Continuing...")
				else:
					raise portage.exception.PackageNotFound(
						"%s is not in a valid portage tree hierarchy or does not exist" % x)
				pkg = self._pkg(mykey, "ebuild", root_config,
					onlydeps=onlydeps)
				args.append(PackageArg(arg=x, package=pkg,
					root_config=root_config))
			elif x.startswith(os.path.sep):
				if not x.startswith(myroot):
					portage.writemsg(("\n\n!!! '%s' does not start with" + \
						" $ROOT.\n") % x, noiselevel=-1)
					return 0, []
				# Queue these up since it's most efficient to handle
				# multiple files in a single iter_owners() call.
				lookup_owners.append(x)
			else:
				if x in ("system", "world"):
					x = SETPREFIX + x
				if x.startswith(SETPREFIX):
					s = x[len(SETPREFIX):]
					if s not in sets:
						raise portage.exception.PackageSetNotFound(s)
					if s in self._dynamic_config._sets:
						continue
					# Recursively expand sets so that containment tests in
					# self._get_parent_sets() properly match atoms in nested
					# sets (like if world contains system).
					expanded_set = InternalPackageSet(
						initial_atoms=getSetAtoms(s))
					self._dynamic_config._sets[s] = expanded_set
					args.append(SetArg(arg=x, set=expanded_set,
						root_config=root_config))
					continue
				if not is_valid_package_atom(x):
					portage.writemsg("\n\n!!! '%s' is not a valid package atom.\n" % x,
						noiselevel=-1)
					portage.writemsg("!!! Please check ebuild(5) for full details.\n")
					portage.writemsg("!!! (Did you specify a version but forget to prefix with '='?)\n")
					return (0,[])
				# Don't expand categories or old-style virtuals here unless
				# necessary. Expansion of old-style virtuals here causes at
				# least the following problems:
				#   1) It's more difficult to determine which set(s) an atom
				#      came from, if any.
				#   2) It takes away freedom from the resolver to choose other
				#      possible expansions when necessary.
				if "/" in x:
					args.append(AtomArg(arg=x, atom=Atom(x),
						root_config=root_config))
					continue
				expanded_atoms = self._dep_expand(root_config, x)
				installed_cp_set = set()
				for atom in expanded_atoms:
					if vardb.cp_list(atom.cp):
						installed_cp_set.add(atom.cp)

				if len(installed_cp_set) > 1:
					non_virtual_cps = set()
					for atom_cp in installed_cp_set:
						if not atom_cp.startswith("virtual/"):
							non_virtual_cps.add(atom_cp)
					if len(non_virtual_cps) == 1:
						installed_cp_set = non_virtual_cps

				if len(expanded_atoms) > 1 and len(installed_cp_set) == 1:
					installed_cp = next(iter(installed_cp_set))
					for atom in expanded_atoms:
						if atom.cp == installed_cp:
							available = False
							for pkg in self._iter_match_pkgs_any(
								root_config, atom.without_use,
								onlydeps=onlydeps):
								if not pkg.installed:
									available = True
									break
							if available:
								expanded_atoms = [atom]
								break

				# If a non-virtual package and one or more virtual packages
				# are in expanded_atoms, use the non-virtual package.
				if len(expanded_atoms) > 1:
					number_of_virtuals = 0
					for expanded_atom in expanded_atoms:
						if expanded_atom.cp.startswith("virtual/"):
							number_of_virtuals += 1
						else:
							candidate = expanded_atom
					if len(expanded_atoms) - number_of_virtuals == 1:
						expanded_atoms = [ candidate ]

				if len(expanded_atoms) > 1:
					print()
					print()
					ambiguous_package_name(x, expanded_atoms, root_config,
						self._frozen_config.spinner, self._frozen_config.myopts)
					return False, myfavorites
				if expanded_atoms:
					atom = expanded_atoms[0]
				else:
					null_atom = Atom(insert_category_into_atom(x, "null"))
					cat, atom_pn = portage.catsplit(null_atom.cp)
					virts_p = root_config.settings.get_virts_p().get(atom_pn)
					if virts_p:
						# Allow the depgraph to choose which virtual.
						atom = Atom(null_atom.replace('null/', 'virtual/', 1))
					else:
						atom = null_atom

				args.append(AtomArg(arg=x, atom=atom,
					root_config=root_config))

		if lookup_owners:
			relative_paths = []
			search_for_multiple = False
			if len(lookup_owners) > 1:
				search_for_multiple = True

			for x in lookup_owners:
				if not search_for_multiple and os.path.isdir(x):
					search_for_multiple = True
				relative_paths.append(x[len(myroot)-1:])

			owners = set()
			for pkg, relative_path in \
				real_vardb._owners.iter_owners(relative_paths):
				owners.add(pkg.mycpv)
				if not search_for_multiple:
					break

			if not owners:
				portage.writemsg(("\n\n!!! '%s' is not claimed " + \
					"by any package.\n") % lookup_owners[0], noiselevel=-1)
				return 0, []

			for cpv in owners:
				slot = vardb.aux_get(cpv, ["SLOT"])[0]
				if not slot:
					# portage now masks packages with missing slot, but it's
					# possible that one was installed by an older version
					atom = Atom(portage.cpv_getkey(cpv))
				else:
					atom = Atom("%s:%s" % (portage.cpv_getkey(cpv), slot))
				args.append(AtomArg(arg=atom, atom=atom,
					root_config=root_config))

		if "--update" in self._frozen_config.myopts:
			# In some cases, the greedy slots behavior can pull in a slot that
			# the user would want to uninstall due to it being blocked by a
			# newer version in a different slot. Therefore, it's necessary to
			# detect and discard any that should be uninstalled. Each time
			# that arguments are updated, package selections are repeated in
			# order to ensure consistency with the current arguments:
			#
			#  1) Initialize args
			#  2) Select packages and generate initial greedy atoms
			#  3) Update args with greedy atoms
			#  4) Select packages and generate greedy atoms again, while
			#     accounting for any blockers between selected packages
			#  5) Update args with revised greedy atoms

			self._set_args(args)
			greedy_args = []
			for arg in args:
				greedy_args.append(arg)
				if not isinstance(arg, AtomArg):
					continue
				for atom in self._greedy_slots(arg.root_config, arg.atom):
					greedy_args.append(
						AtomArg(arg=arg.arg, atom=atom,
							root_config=arg.root_config))

			self._set_args(greedy_args)
			del greedy_args

			# Revise greedy atoms, accounting for any blockers
			# between selected packages.
			revised_greedy_args = []
			for arg in args:
				revised_greedy_args.append(arg)
				if not isinstance(arg, AtomArg):
					continue
				for atom in self._greedy_slots(arg.root_config, arg.atom,
					blocker_lookahead=True):
					revised_greedy_args.append(
						AtomArg(arg=arg.arg, atom=atom,
							root_config=arg.root_config))
			args = revised_greedy_args
			del revised_greedy_args

		self._set_args(args)

		myfavorites = set(myfavorites)
		for arg in args:
			if isinstance(arg, (AtomArg, PackageArg)):
				myfavorites.add(arg.atom)
			elif isinstance(arg, SetArg):
				myfavorites.add(arg.arg)
		myfavorites = list(myfavorites)

		if debug:
			portage.writemsg("\n", noiselevel=-1)
		# Order needs to be preserved since a feature of --nodeps
		# is to allow the user to force a specific merge order.
		self._dynamic_config._initial_arg_list = args[:]
	
		return self._resolve(myfavorites)
	
	def _resolve(self, myfavorites):
		"""Given self._dynamic_config._initial_arg_list, pull in the root nodes, 
		call self._creategraph to process theier deps and return 
		a favorite list."""
		debug = "--debug" in self._frozen_config.myopts
		onlydeps = "--onlydeps" in self._frozen_config.myopts
		myroot = self._frozen_config.target_root
		pkgsettings = self._frozen_config.pkgsettings[myroot]
		pprovideddict = pkgsettings.pprovideddict
		virtuals = pkgsettings.getvirtuals()
		for arg in self._dynamic_config._initial_arg_list:
			for atom in arg.set:
				self._spinner_update()
				dep = Dependency(atom=atom, onlydeps=onlydeps,
					root=myroot, parent=arg)
				try:
					pprovided = pprovideddict.get(atom.cp)
					if pprovided and portage.match_from_list(atom, pprovided):
						# A provided package has been specified on the command line.
						self._dynamic_config._pprovided_args.append((arg, atom))
						continue
					if isinstance(arg, PackageArg):
						if not self._add_pkg(arg.package, dep) or \
							not self._create_graph():
							if not self._dynamic_config._need_restart:
								sys.stderr.write(("\n\n!!! Problem " + \
									"resolving dependencies for %s\n") % \
									arg.arg)
							return 0, myfavorites
						continue
					if debug:
						portage.writemsg("      Arg: %s\n     Atom: %s\n" % \
							(arg, atom), noiselevel=-1)
					pkg, existing_node = self._select_package(
						myroot, atom, onlydeps=onlydeps)
					if not pkg:
						pprovided_match = False
						for virt_choice in virtuals.get(atom.cp, []):
							expanded_atom = portage.dep.Atom(
								atom.replace(atom.cp, virt_choice.cp, 1))
							pprovided = pprovideddict.get(expanded_atom.cp)
							if pprovided and \
								portage.match_from_list(expanded_atom, pprovided):
								# A provided package has been
								# specified on the command line.
								self._dynamic_config._pprovided_args.append((arg, atom))
								pprovided_match = True
								break
						if pprovided_match:
							continue

						if not (isinstance(arg, SetArg) and \
							arg.name in ("selected", "system", "world")):
							self._dynamic_config._unsatisfied_deps_for_display.append(
								((myroot, atom), {}))
							return 0, myfavorites
						self._dynamic_config._missing_args.append((arg, atom))
						continue
					if atom.cp != pkg.cp:
						# For old-style virtuals, we need to repeat the
						# package.provided check against the selected package.
						expanded_atom = atom.replace(atom.cp, pkg.cp)
						pprovided = pprovideddict.get(pkg.cp)
						if pprovided and \
							portage.match_from_list(expanded_atom, pprovided):
							# A provided package has been
							# specified on the command line.
							self._dynamic_config._pprovided_args.append((arg, atom))
							continue
					if pkg.installed and "selective" not in self._dynamic_config.myparams:
						self._dynamic_config._unsatisfied_deps_for_display.append(
							((myroot, atom), {}))
						# Previous behavior was to bail out in this case, but
						# since the dep is satisfied by the installed package,
						# it's more friendly to continue building the graph
						# and just show a warning message. Therefore, only bail
						# out here if the atom is not from either the system or
						# world set.
						if not (isinstance(arg, SetArg) and \
							arg.name in ("selected", "system", "world")):
							return 0, myfavorites

					# Add the selected package to the graph as soon as possible
					# so that later dep_check() calls can use it as feedback
					# for making more consistent atom selections.
					if not self._add_pkg(pkg, dep):
						if self._dynamic_config._need_restart:
							pass
						elif isinstance(arg, SetArg):
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s from %s\n") % \
								(atom, arg.arg))
						else:
							sys.stderr.write(("\n\n!!! Problem resolving " + \
								"dependencies for %s\n") % atom)
						return 0, myfavorites

				except portage.exception.MissingSignature as e:
					portage.writemsg("\n\n!!! A missing gpg signature is preventing portage from calculating the\n")
					portage.writemsg("!!! required dependencies. This is a security feature enabled by the admin\n")
					portage.writemsg("!!! to aid in the detection of malicious intent.\n\n")
					portage.writemsg("!!! THIS IS A POSSIBLE INDICATION OF TAMPERED FILES -- CHECK CAREFULLY.\n")
					portage.writemsg("!!! Affected file: %s\n" % (e), noiselevel=-1)
					return 0, myfavorites
				except portage.exception.InvalidSignature as e:
					portage.writemsg("\n\n!!! An invalid gpg signature is preventing portage from calculating the\n")
					portage.writemsg("!!! required dependencies. This is a security feature enabled by the admin\n")
					portage.writemsg("!!! to aid in the detection of malicious intent.\n\n")
					portage.writemsg("!!! THIS IS A POSSIBLE INDICATION OF TAMPERED FILES -- CHECK CAREFULLY.\n")
					portage.writemsg("!!! Affected file: %s\n" % (e), noiselevel=-1)
					return 0, myfavorites
				except SystemExit as e:
					raise # Needed else can't exit
				except Exception as e:
					print("\n\n!!! Problem in '%s' dependencies." % atom, file=sys.stderr)
					print("!!!", str(e), getattr(e, "__module__", None), file=sys.stderr)
					raise

		# Now that the root packages have been added to the graph,
		# process the dependencies.
		if not self._create_graph():
			return 0, myfavorites

		missing=0
		if "--usepkgonly" in self._frozen_config.myopts:
			for xs in self._dynamic_config.digraph.all_nodes():
				if not isinstance(xs, Package):
					continue
				if len(xs) >= 4 and xs[0] != "binary" and xs[3] == "merge":
					if missing == 0:
						print()
					missing += 1
					print("Missing binary for:",xs[2])

		try:
			self.altlist()
		except self._unknown_internal_error:
			return False, myfavorites

		if set(self._dynamic_config.digraph.nodes.keys()).intersection( \
			set(self._dynamic_config._needed_user_config_changes.keys())) or \
			set(self._dynamic_config.digraph.nodes.keys()).intersection( \
			set(self._dynamic_config._needed_use_config_changes.keys())) :
			#We failed if the user needs to change the configuration
			return False, myfavorites

		# We're true here unless we are missing binaries.
		return (not missing,myfavorites)

	def _set_args(self, args):
		"""
		Create the "args" package set from atoms and packages given as
		arguments. This method can be called multiple times if necessary.
		The package selection cache is automatically invalidated, since
		arguments influence package selections.
		"""
		args_set = self._dynamic_config._sets["args"]
		args_set.clear()
		for arg in args:
			if not isinstance(arg, (AtomArg, PackageArg)):
				continue
			atom = arg.atom
			if atom in args_set:
				continue
			args_set.add(atom)

		self._dynamic_config._set_atoms.clear()
		self._dynamic_config._set_atoms.update(chain(*self._dynamic_config._sets.values()))
		atom_arg_map = self._dynamic_config._atom_arg_map
		atom_arg_map.clear()
		for arg in args:
			for atom in arg.set:
				atom_key = (atom, arg.root_config.root)
				refs = atom_arg_map.get(atom_key)
				if refs is None:
					refs = []
					atom_arg_map[atom_key] = refs
					if arg not in refs:
						refs.append(arg)

		# Invalidate the package selection cache, since
		# arguments influence package selections.
		self._dynamic_config._highest_pkg_cache.clear()
		for trees in self._dynamic_config._filtered_trees.values():
			trees["porttree"].dbapi._clear_cache()

	def _greedy_slots(self, root_config, atom, blocker_lookahead=False):
		"""
		Return a list of slot atoms corresponding to installed slots that
		differ from the slot of the highest visible match. When
		blocker_lookahead is True, slot atoms that would trigger a blocker
		conflict are automatically discarded, potentially allowing automatic
		uninstallation of older slots when appropriate.
		"""
		highest_pkg, in_graph = self._select_package(root_config.root, atom)
		if highest_pkg is None:
			return []
		vardb = root_config.trees["vartree"].dbapi
		slots = set()
		for cpv in vardb.match(atom):
			# don't mix new virtuals with old virtuals
			if portage.cpv_getkey(cpv) == highest_pkg.cp:
				slots.add(vardb.aux_get(cpv, ["SLOT"])[0])

		slots.add(highest_pkg.metadata["SLOT"])
		if len(slots) == 1:
			return []
		greedy_pkgs = []
		slots.remove(highest_pkg.metadata["SLOT"])
		while slots:
			slot = slots.pop()
			slot_atom = portage.dep.Atom("%s:%s" % (highest_pkg.cp, slot))
			pkg, in_graph = self._select_package(root_config.root, slot_atom)
			if pkg is not None and \
				pkg.cp == highest_pkg.cp and pkg < highest_pkg:
				greedy_pkgs.append(pkg)
		if not greedy_pkgs:
			return []
		if not blocker_lookahead:
			return [pkg.slot_atom for pkg in greedy_pkgs]

		blockers = {}
		blocker_dep_keys = ["DEPEND", "PDEPEND", "RDEPEND"]
		for pkg in greedy_pkgs + [highest_pkg]:
			dep_str = " ".join(pkg.metadata[k] for k in blocker_dep_keys)
			try:
				selected_atoms = self._select_atoms(
					pkg.root, dep_str, self._pkg_use_enabled(pkg),
					parent=pkg, strict=True)
			except portage.exception.InvalidDependString:
				continue
			blocker_atoms = []
			for atoms in selected_atoms.values():
				blocker_atoms.extend(x for x in atoms if x.blocker)
			blockers[pkg] = InternalPackageSet(initial_atoms=blocker_atoms)

		if highest_pkg not in blockers:
			return []

		# filter packages with invalid deps
		greedy_pkgs = [pkg for pkg in greedy_pkgs if pkg in blockers]

		# filter packages that conflict with highest_pkg
		greedy_pkgs = [pkg for pkg in greedy_pkgs if not \
			(blockers[highest_pkg].findAtomForPackage(pkg) or \
			blockers[pkg].findAtomForPackage(highest_pkg))]

		if not greedy_pkgs:
			return []

		# If two packages conflict, discard the lower version.
		discard_pkgs = set()
		greedy_pkgs.sort(reverse=True)
		for i in range(len(greedy_pkgs) - 1):
			pkg1 = greedy_pkgs[i]
			if pkg1 in discard_pkgs:
				continue
			for j in range(i + 1, len(greedy_pkgs)):
				pkg2 = greedy_pkgs[j]
				if pkg2 in discard_pkgs:
					continue
				if blockers[pkg1].findAtomForPackage(pkg2) or \
					blockers[pkg2].findAtomForPackage(pkg1):
					# pkg1 > pkg2
					discard_pkgs.add(pkg2)

		return [pkg.slot_atom for pkg in greedy_pkgs \
			if pkg not in discard_pkgs]

	def _select_atoms_from_graph(self, *pargs, **kwargs):
		"""
		Prefer atoms matching packages that have already been
		added to the graph or those that are installed and have
		not been scheduled for replacement.
		"""
		kwargs["trees"] = self._dynamic_config._graph_trees
		return self._select_atoms_highest_available(*pargs, **kwargs)

	def _select_atoms_highest_available(self, root, depstring,
		myuse=None, parent=None, strict=True, trees=None, priority=None):
		"""This will raise InvalidDependString if necessary. If trees is
		None then self._dynamic_config._filtered_trees is used."""

		_autounmask_backup = self._dynamic_config._autounmask
		self._dynamic_config._autounmask = False
		pkgsettings = self._frozen_config.pkgsettings[root]
		if trees is None:
			trees = self._dynamic_config._filtered_trees
		atom_graph = digraph()
		if True:
			try:
				if parent is not None:
					trees[root]["parent"] = parent
					trees[root]["atom_graph"] = atom_graph
				if priority is not None:
					trees[root]["priority"] = priority
				if not strict:
					portage.dep._dep_check_strict = False
				mycheck = portage.dep_check(depstring, None,
					pkgsettings, myuse=myuse,
					myroot=root, trees=trees)
			finally:
				if parent is not None:
					trees[root].pop("parent")
					trees[root].pop("atom_graph")
				if priority is not None:
					trees[root].pop("priority")
				portage.dep._dep_check_strict = True
			if not mycheck[0]:
				raise portage.exception.InvalidDependString(mycheck[1])
		if parent is None:
			selected_atoms = mycheck[1]
		else:
			chosen_atoms = frozenset(mycheck[1])
			selected_atoms = {parent : []}
			for node in atom_graph:
				if isinstance(node, Atom):
					continue
				if node is parent:
					pkg = parent
				else:
					pkg, virt_atom = node
					if virt_atom not in chosen_atoms:
						continue
					if not portage.match_from_list(virt_atom, [pkg]):
						# Typically this means that the atom
						# specifies USE deps that are unsatisfied
						# by the selected package. The caller will
						# record this as an unsatisfied dependency
						# when necessary.
						continue

				selected_atoms[pkg] = [atom for atom in \
					atom_graph.child_nodes(node) if atom in chosen_atoms]

		self._dynamic_config._autounmask = _autounmask_backup
		return selected_atoms

	def _show_unsatisfied_dep(self, root, atom, myparent=None, arg=None,
		check_backtrack=False):
		"""
		When check_backtrack=True, no output is produced and
		the method either returns or raises _backtrack_mask if
		a matching package has been masked by backtracking.
		"""
		backtrack_mask = False
		atom_set = InternalPackageSet(initial_atoms=(atom,))
		xinfo = '"%s"' % atom.unevaluated_atom
		if arg:
			xinfo='"%s"' % arg
		# Discard null/ from failed cpv_expand category expansion.
		xinfo = xinfo.replace("null/", "")
		masked_packages = []
		missing_use = []
		masked_pkg_instances = set()
		missing_licenses = []
		have_eapi_mask = False
		pkgsettings = self._frozen_config.pkgsettings[root]
		implicit_iuse = pkgsettings._get_implicit_iuse()
		root_config = self._frozen_config.roots[root]
		portdb = self._frozen_config.roots[root].trees["porttree"].dbapi
		dbs = self._dynamic_config._filtered_trees[root]["dbs"]
		for db, pkg_type, built, installed, db_keys in dbs:
			if installed:
				continue
			match = db.match
			if hasattr(db, "xmatch"):
				cpv_list = db.xmatch("match-all", atom.without_use)
			else:
				cpv_list = db.match(atom.without_use)
			# descending order
			cpv_list.reverse()
			for cpv in cpv_list:
				metadata, mreasons  = get_mask_info(root_config, cpv,
					pkgsettings, db, pkg_type, built, installed, db_keys)
				if metadata is not None:
					pkg = self._pkg(cpv, pkg_type, root_config,
						installed=installed)
					# pkg.metadata contains calculated USE for ebuilds,
					# required later for getMissingLicenses.
					metadata = pkg.metadata
					if pkg.cp != atom.cp:
						# A cpv can be returned from dbapi.match() as an
						# old-style virtual match even in cases when the
						# package does not actually PROVIDE the virtual.
						# Filter out any such false matches here.
						if not atom_set.findAtomForPackage(pkg):
							continue
					if pkg in self._dynamic_config._runtime_pkg_mask:
						backtrack_reasons = \
							self._dynamic_config._runtime_pkg_mask[pkg]
						mreasons.append('backtracking: %s' % \
							', '.join(sorted(backtrack_reasons)))
						backtrack_mask = True
					if not mreasons and self._frozen_config.excluded_pkgs.findAtomForPackage(pkg):
						mreasons = ["exclude option"]
					if mreasons:
						masked_pkg_instances.add(pkg)
					if atom.unevaluated_atom.use:
						if not pkg.iuse.is_valid_flag(atom.unevaluated_atom.use.required) \
							or atom.violated_conditionals(self._pkg_use_enabled(pkg)).use:
							missing_use.append(pkg)
							if not mreasons:
								continue
					if pkg.built and not mreasons:
						mreasons = ["use flag configuration mismatch"]
				masked_packages.append(
					(root_config, pkgsettings, cpv, metadata, mreasons))

		if check_backtrack:
			if backtrack_mask:
				raise self._backtrack_mask()
			else:
				return

		missing_use_reasons = []
		missing_iuse_reasons = []
		for pkg in missing_use:
			use = self._pkg_use_enabled(pkg)
			missing_iuse = pkg.iuse.get_missing_iuse(atom.use.required)
			mreasons = []
			if missing_iuse:
				mreasons.append("Missing IUSE: %s" % " ".join(missing_iuse))
				missing_iuse_reasons.append((pkg, mreasons))
			else:
				need_enable = sorted(atom.use.enabled.difference(use))
				need_disable = sorted(atom.use.disabled.intersection(use))
				if need_enable or need_disable:
					changes = []
					changes.extend(colorize("red", "+" + x) \
						for x in need_enable)
					changes.extend(colorize("blue", "-" + x) \
						for x in need_disable)
					mreasons.append("Change USE: %s" % " ".join(changes))
					missing_use_reasons.append((pkg, mreasons))

			if not missing_iuse and myparent and atom.unevaluated_atom.use.conditional:
				# Lets see if the violated use deps are conditional.
				# If so, suggest to change them on the parent.
				mreasons = []
				violated_atom = atom.unevaluated_atom.violated_conditionals(self._pkg_use_enabled(pkg), myparent.use.enabled)
				if not (violated_atom.use.enabled or violated_atom.use.disabled):
					#all violated use deps are conditional
					changes = []
					conditional = violated_atom.use.conditional
					involved_flags = set()
					involved_flags.update(conditional.equal, conditional.not_equal, \
						conditional.enabled, conditional.disabled)
					for x in involved_flags:
						if x in myparent.use.enabled:
							changes.append(colorize("blue", "-" + x))
						else:
							changes.append(colorize("red", "+" + x))
					mreasons.append("Change USE: %s" % " ".join(changes))
					if (myparent, mreasons) not in missing_use_reasons:
						missing_use_reasons.append((myparent, mreasons))

		unmasked_use_reasons = [(pkg, mreasons) for (pkg, mreasons) \
			in missing_use_reasons if pkg not in masked_pkg_instances]

		unmasked_iuse_reasons = [(pkg, mreasons) for (pkg, mreasons) \
			in missing_iuse_reasons if pkg not in masked_pkg_instances]

		show_missing_use = False
		if unmasked_use_reasons:
			# Only show the latest version.
			show_missing_use = unmasked_use_reasons[:1]
			for pkg, mreasons in unmasked_use_reasons:
				if myparent and pkg == myparent:
					#This happens if a use change on the parent
					#leads to a satisfied conditional use dep.
					show_missing_use.append((pkg, mreasons))
					break
				
		elif unmasked_iuse_reasons:
			masked_with_iuse = False
			for pkg in masked_pkg_instances:
				if not pkg.iuse.get_missing_iuse(atom.use.required):
					# Package(s) with required IUSE are masked,
					# so display a normal masking message.
					masked_with_iuse = True
					break
			if not masked_with_iuse:
				show_missing_use = unmasked_iuse_reasons

		mask_docs = False

		if show_missing_use:
			print("\nemerge: there are no ebuilds built with USE flags to satisfy "+green(xinfo)+".")
			print("!!! One of the following packages is required to complete your request:")
			for pkg, mreasons in show_missing_use:
				print("- "+pkg.cpv+" ("+", ".join(mreasons)+")")

		elif masked_packages:
			print("\n!!! " + \
				colorize("BAD", "All ebuilds that could satisfy ") + \
				colorize("INFORM", xinfo) + \
				colorize("BAD", " have been masked."))
			print("!!! One of the following masked packages is required to complete your request:")
			have_eapi_mask = show_masked_packages(masked_packages)
			if have_eapi_mask:
				print()
				msg = ("The current version of portage supports " + \
					"EAPI '%s'. You must upgrade to a newer version" + \
					" of portage before EAPI masked packages can" + \
					" be installed.") % portage.const.EAPI
				for line in textwrap.wrap(msg, 75):
					print(line)
			print()
			mask_docs = True
		else:
			print("\nemerge: there are no ebuilds to satisfy "+green(xinfo)+".")

		# Show parent nodes and the argument that pulled them in.
		traversed_nodes = set()
		node = myparent
		msg = []
		while node is not None:
			traversed_nodes.add(node)
			msg.append('(dependency required by "%s" [%s])' % \
				(colorize('INFORM', str(node.cpv)), node.type_name))

			if node not in self._dynamic_config.digraph:
				# The parent is not in the graph due to backtracking.
				break

			# When traversing to parents, prefer arguments over packages
			# since arguments are root nodes. Never traverse the same
			# package twice, in order to prevent an infinite loop.
			selected_parent = None
			for parent in self._dynamic_config.digraph.parent_nodes(node):
				if isinstance(parent, DependencyArg):
					msg.append('(dependency required by "%s" [argument])' % \
						(colorize('INFORM', str(parent))))
					selected_parent = None
					break
				if parent not in traversed_nodes:
					selected_parent = parent
			node = selected_parent
		for line in msg:
			print(line)

		print()

		if mask_docs:
			show_mask_docs()
			print()

	def _iter_match_pkgs_any(self, root_config, atom, onlydeps=False):
		for db, pkg_type, built, installed, db_keys in \
			self._dynamic_config._filtered_trees[root_config.root]["dbs"]:
			for pkg in self._iter_match_pkgs(root_config,
				pkg_type, atom, onlydeps=onlydeps):
				yield pkg

	def _iter_match_pkgs(self, root_config, pkg_type, atom, onlydeps=False):
		"""
		Iterate over Package instances of pkg_type matching the given atom.
		This does not check visibility and it also does not match USE for
		unbuilt ebuilds since USE are lazily calculated after visibility
		checks (to avoid the expense when possible).
		"""

		db = root_config.trees[self.pkg_tree_map[pkg_type]].dbapi

		if hasattr(db, "xmatch"):
			cpv_list = db.xmatch("match-all", atom)
		else:
			cpv_list = db.match(atom)

		# USE=multislot can make an installed package appear as if
		# it doesn't satisfy a slot dependency. Rebuilding the ebuild
		# won't do any good as long as USE=multislot is enabled since
		# the newly built package still won't have the expected slot.
		# Therefore, assume that such SLOT dependencies are already
		# satisfied rather than forcing a rebuild.
		installed = pkg_type == 'installed'
		if installed and not cpv_list and atom.slot:
			for cpv in db.match(atom.cp):
				slot_available = False
				for other_db, other_type, other_built, \
					other_installed, other_keys in \
					self._dynamic_config._filtered_trees[root_config.root]["dbs"]:
					try:
						if atom.slot == \
							other_db.aux_get(cpv, ["SLOT"])[0]:
							slot_available = True
							break
					except KeyError:
						pass
				if not slot_available:
					continue
				inst_pkg = self._pkg(cpv, "installed",
					root_config, installed=installed)
				# Remove the slot from the atom and verify that
				# the package matches the resulting atom.
				atom_without_slot = portage.dep.remove_slot(atom)
				if atom.use:
					atom_without_slot += str(atom.use)
				atom_without_slot = portage.dep.Atom(atom_without_slot)
				if portage.match_from_list(
					atom_without_slot, [inst_pkg]):
					cpv_list = [inst_pkg.cpv]
				break

		if cpv_list:

			# descending order
			cpv_list.reverse()
			for cpv in cpv_list:
				try:
					pkg = self._pkg(cpv, pkg_type, root_config,
						installed=installed, onlydeps=onlydeps)
				except portage.exception.PackageNotFound:
					pass
				else:
					if pkg.cp != atom.cp:
						# A cpv can be returned from dbapi.match() as an
						# old-style virtual match even in cases when the
						# package does not actually PROVIDE the virtual.
						# Filter out any such false matches here.
						if not InternalPackageSet(initial_atoms=(atom,)
							).findAtomForPackage(pkg):
							continue
					yield pkg

	def _select_pkg_highest_available(self, root, atom, onlydeps=False):
		cache_key = (root, atom, onlydeps)
		ret = self._dynamic_config._highest_pkg_cache.get(cache_key)
		if ret is not None:
			pkg, existing = ret
			if pkg and not existing:
				existing = self._dynamic_config._slot_pkg_map[root].get(pkg.slot_atom)
				if existing and existing == pkg:
					# Update the cache to reflect that the
					# package has been added to the graph.
					ret = pkg, pkg
					self._dynamic_config._highest_pkg_cache[cache_key] = ret
			return ret
		ret = self._select_pkg_highest_available_imp(root, atom, onlydeps=onlydeps)
		self._dynamic_config._highest_pkg_cache[cache_key] = ret
		pkg, existing = ret
		if pkg is not None:
			settings = pkg.root_config.settings
			if self._pkg_visibility_check(pkg) and not (pkg.installed and \
				settings._getMissingKeywords(pkg.cpv, pkg.metadata)):
				self._dynamic_config._visible_pkgs[pkg.root].cpv_inject(pkg)
		return ret

	def _want_installed_pkg(self, pkg):
		"""
		Given an installed package returned from select_pkg, return
		True if the user has not explicitly requested for this package
		to be replaced (typically via an atom on the command line).
		"""
		if "selective" not in self._dynamic_config.myparams and \
			pkg.root == self._frozen_config.target_root:
			try:
				next(self._iter_atoms_for_pkg(pkg))
			except StopIteration:
				pass
			except portage.exception.InvalidDependString:
				pass
			else:
				return False
		return True

	def _select_pkg_highest_available_imp(self, root, atom, onlydeps=False):
		pkg, existing = self._wrapped_select_pkg_highest_available_imp(root, atom, onlydeps=onlydeps)

		if self._dynamic_config._autounmask is True:
			if pkg is not None and \
				pkg.installed and \
				not self._want_installed_pkg(pkg):
				pkg = None

			for allow_missing_keywords in False, True:
				if pkg is not None:
					break

				pkg, existing = \
					self._wrapped_select_pkg_highest_available_imp(
						root, atom, onlydeps=onlydeps,
						allow_use_changes=True, allow_missing_keywords=allow_missing_keywords)

				if pkg is not None and not pkg.visible:
					self._dynamic_config._needed_user_config_changes.setdefault(pkg, set()).add("unstable keyword")
			
			if self._dynamic_config._need_restart:
				return None, None

		return pkg, existing

	def _pkg_visibility_check(self, pkg, allow_missing_keywords=False):
		pkgsettings = self._frozen_config.pkgsettings[pkg.root]
		root_config = self._frozen_config.roots[pkg.root]
		if pkg.visible:
			return True

		pending_keyword_change = self._dynamic_config._needed_user_config_changes.get(pkg)
		if pending_keyword_change is not None and \
			"unstable keyword" in pending_keyword_change:
			return True

		if not allow_missing_keywords:
			return False
		mreasons = _get_masking_status(pkg, pkgsettings, root_config)
		if len(mreasons) == 1 and \
			mreasons[0].hint == 'unstable keyword':
			return True
		else:
			return False

	def _pkg_use_enabled(self, pkg, target_use=None):
		"""
		If target_use is None, returns pkg.use.enabled + changes in _needed_use_config_changes.
		If target_use is given, the need changes are computed to make the package useable.
		Example: target_use = { "foo": True, "bar": False }
		The flags target_use must be in the pkg's IUSE.
		"""
		needed_use_config_change = self._dynamic_config._needed_use_config_changes.get(pkg)

		if target_use is None:
			if needed_use_config_change is None:
				return pkg.use.enabled
			else:
				return needed_use_config_change[0]

		if needed_use_config_change is not None:
			old_use = needed_use_config_change[0]
			new_use = set()
			old_changes = needed_use_config_change[1]
			new_changes = old_changes.copy()
		else:
			old_use = pkg.use.enabled
			new_use = set()
			old_changes = {}
			new_changes = {}

		for flag, state in target_use.items():
			if state:
				if flag not in old_use:
					if new_changes.get(flag) == False:
						return old_use
					new_changes[flag] = True
				new_use.add(flag)
			else:
				if flag in old_use:
					if new_changes.get(flag) == True:
						return old_use
					new_changes[flag] = False
		new_use.update(old_use.difference(target_use.keys()))

		def want_restart_for_use_change(pkg):
			if pkg not in self._dynamic_config.digraph.nodes:
				return False
			#TODO: We can be more clever here. No need to restart if 
			#	1) we don't have a parent that can't work with our 
			#		new use config
			#	and
			#	2) none of pkg's *DEPEND vars changed
			return True

		if new_changes != old_changes:
			self._dynamic_config._needed_use_config_changes[pkg] = (new_use, new_changes)
			if want_restart_for_use_change(pkg):
				self._dynamic_config._need_restart = True
		return new_use

	def _wrapped_select_pkg_highest_available_imp(self, root, atom, onlydeps=False, \
		allow_use_changes=False, allow_missing_keywords=False):
		root_config = self._frozen_config.roots[root]
		pkgsettings = self._frozen_config.pkgsettings[root]
		dbs = self._dynamic_config._filtered_trees[root]["dbs"]
		vardb = self._frozen_config.roots[root].trees["vartree"].dbapi
		portdb = self._frozen_config.roots[root].trees["porttree"].dbapi
		# List of acceptable packages, ordered by type preference.
		matched_packages = []
		highest_version = None
		if not isinstance(atom, portage.dep.Atom):
			atom = portage.dep.Atom(atom)
		atom_cp = atom.cp
		atom_set = InternalPackageSet(initial_atoms=(atom,))
		existing_node = None
		myeb = None
		rebuilt_binaries = 'rebuilt_binaries' in self._dynamic_config.myparams
		usepkgonly = "--usepkgonly" in self._frozen_config.myopts
		empty = "empty" in self._dynamic_config.myparams
		selective = "selective" in self._dynamic_config.myparams
		reinstall = False
		noreplace = "--noreplace" in self._frozen_config.myopts
		avoid_update = "--update" not in self._frozen_config.myopts
		dont_miss_updates = "--update" in self._frozen_config.myopts
		use_ebuild_visibility = self._frozen_config.myopts.get(
			'--use-ebuild-visibility', 'n') != 'n'
		# Behavior of the "selective" parameter depends on
		# whether or not a package matches an argument atom.
		# If an installed package provides an old-style
		# virtual that is no longer provided by an available
		# package, the installed package may match an argument
		# atom even though none of the available packages do.
		# Therefore, "selective" logic does not consider
		# whether or not an installed package matches an
		# argument atom. It only considers whether or not
		# available packages match argument atoms, which is
		# represented by the found_available_arg flag.
		found_available_arg = False
		packages_with_invalid_use_config = []
		for find_existing_node in True, False:
			if existing_node:
				break
			for db, pkg_type, built, installed, db_keys in dbs:
				if existing_node:
					break
				if installed and not find_existing_node:
					want_reinstall = reinstall or empty or \
						(found_available_arg and not selective)
					if want_reinstall and matched_packages:
						continue

				# Ignore USE deps for the initial match since we want to
				# ensure that updates aren't missed solely due to the user's
				# USE configuration.
				for pkg in self._iter_match_pkgs(root_config, pkg_type, atom.without_use, 
					onlydeps=onlydeps):
					if pkg in self._dynamic_config._runtime_pkg_mask:
						# The package has been masked by the backtracking logic
						continue

					if not pkg.installed and \
						self._frozen_config.excluded_pkgs.findAtomForPackage(pkg):
						continue

					if dont_miss_updates:
						# Check if a higher version was rejected due to user
						# USE configuration. The packages_with_invalid_use_config
						# list only contains unbuilt ebuilds since USE can't
						# be changed for built packages.
						higher_version_rejected = False
						for rejected in packages_with_invalid_use_config:
							if rejected.cp != pkg.cp:
								continue
							if rejected > pkg:
								higher_version_rejected = True
								break
						if higher_version_rejected:
							continue

					cpv = pkg.cpv
					# Make --noreplace take precedence over --newuse.
					if not pkg.installed and noreplace and \
						cpv in vardb.match(atom):
						# If the installed version is masked, it may
						# be necessary to look at lower versions,
						# in case there is a visible downgrade.
						continue
					reinstall_for_flags = None

					if not pkg.installed or \
						(matched_packages and not avoid_update):
						# Only enforce visibility on installed packages
						# if there is at least one other visible package
						# available. By filtering installed masked packages
						# here, packages that have been masked since they
						# were installed can be automatically downgraded
						# to an unmasked version.

						if not self._pkg_visibility_check(pkg, allow_missing_keywords=allow_missing_keywords):
							continue

						# Enable upgrade or downgrade to a version
						# with visible KEYWORDS when the installed
						# version is masked by KEYWORDS, but never
						# reinstall the same exact version only due
						# to a KEYWORDS mask. See bug #252167.
						if matched_packages:

							different_version = None
							for avail_pkg in matched_packages:
								if not portage.dep.cpvequal(
									pkg.cpv, avail_pkg.cpv):
									different_version = avail_pkg
									break
							if different_version is not None:
								# If the ebuild no longer exists or it's
								# keywords have been dropped, reject built
								# instances (installed or binary).
								# If --usepkgonly is enabled, assume that
								# the ebuild status should be ignored.
								if not use_ebuild_visibility and usepkgonly:
									if installed and \
										pkgsettings._getMissingKeywords(
										pkg.cpv, pkg.metadata):
										continue
								else:
									try:
										pkg_eb = self._pkg(
											pkg.cpv, "ebuild", root_config)
									except portage.exception.PackageNotFound:
										continue
									else:
										if not self._pkg_visibility_check(pkg_eb, \
											allow_missing_keywords=allow_missing_keywords):
											continue

					# Calculation of USE for unbuilt ebuilds is relatively
					# expensive, so it is only performed lazily, after the
					# above visibility checks are complete.

					myarg = None
					if root == self._frozen_config.target_root:
						try:
							myarg = next(self._iter_atoms_for_pkg(pkg))
						except StopIteration:
							pass
						except portage.exception.InvalidDependString:
							if not installed:
								# masked by corruption
								continue
					if not installed and myarg:
						found_available_arg = True

					if atom.use:
						missing_iuse = pkg.iuse.get_missing_iuse(atom.use.required)
						if missing_iuse:
							# Don't add this to packages_with_invalid_use_config
							# since IUSE cannot be adjusted by the user.
							continue

						if allow_use_changes:
							target_use = {}
							for flag in atom.use.enabled:
								target_use[flag] = True
							for flag in atom.use.disabled:
								target_use[flag] = False
							use = self._pkg_use_enabled(pkg, target_use)
						else:
							use = self._pkg_use_enabled(pkg)

						if atom.use.enabled.difference(use):
							if not pkg.built:
								packages_with_invalid_use_config.append(pkg)
							continue
						if atom.use.disabled.intersection(use):
							if not pkg.built:
								packages_with_invalid_use_config.append(pkg)
							continue

					if pkg.cp == atom_cp:
						if highest_version is None:
							highest_version = pkg
						elif pkg > highest_version:
							highest_version = pkg
					# At this point, we've found the highest visible
					# match from the current repo. Any lower versions
					# from this repo are ignored, so this so the loop
					# will always end with a break statement below
					# this point.
					if find_existing_node:
						e_pkg = self._dynamic_config._slot_pkg_map[root].get(pkg.slot_atom)
						if not e_pkg:
							break
						# Use PackageSet.findAtomForPackage()
						# for PROVIDE support.
						if atom_set.findAtomForPackage(e_pkg):
							if highest_version and \
								e_pkg.cp == atom_cp and \
								e_pkg < highest_version and \
								e_pkg.slot_atom != highest_version.slot_atom:
								# There is a higher version available in a
								# different slot, so this existing node is
								# irrelevant.
								pass
							else:
								matched_packages.append(e_pkg)
								existing_node = e_pkg
						break
					# Compare built package to current config and
					# reject the built package if necessary.
					if built and not installed and \
						("--newuse" in self._frozen_config.myopts or \
						"--reinstall" in self._frozen_config.myopts or \
						"--binpkg-respect-use" in self._frozen_config.myopts):
						iuses = pkg.iuse.all
						old_use = self._pkg_use_enabled(pkg)
						if myeb:
							pkgsettings.setcpv(myeb)
						else:
							pkgsettings.setcpv(pkg)
						now_use = pkgsettings["PORTAGE_USE"].split()
						forced_flags = set()
						forced_flags.update(pkgsettings.useforce)
						forced_flags.update(pkgsettings.usemask)
						cur_iuse = iuses
						if myeb and not usepkgonly:
							cur_iuse = myeb.iuse.all
						if self._reinstall_for_flags(forced_flags,
							old_use, iuses,
							now_use, cur_iuse):
							break
					# Compare current config to installed package
					# and do not reinstall if possible.
					if not installed and \
						("--newuse" in self._frozen_config.myopts or \
						"--reinstall" in self._frozen_config.myopts) and \
						cpv in vardb.match(atom):
						pkgsettings.setcpv(pkg)
						forced_flags = set()
						forced_flags.update(pkgsettings.useforce)
						forced_flags.update(pkgsettings.usemask)
						old_use = vardb.aux_get(cpv, ["USE"])[0].split()
						old_iuse = set(filter_iuse_defaults(
							vardb.aux_get(cpv, ["IUSE"])[0].split()))
						cur_use = self._pkg_use_enabled(pkg)
						cur_iuse = pkg.iuse.all
						reinstall_for_flags = \
							self._reinstall_for_flags(
							forced_flags, old_use, old_iuse,
							cur_use, cur_iuse)
						if reinstall_for_flags:
							reinstall = True
					if not built:
						myeb = pkg
					matched_packages.append(pkg)
					if reinstall_for_flags:
						self._dynamic_config._reinstall_nodes[pkg] = \
							reinstall_for_flags
					break

		if not matched_packages:
			return None, None

		if "--debug" in self._frozen_config.myopts:
			for pkg in matched_packages:
				portage.writemsg("%s %s\n" % \
					((pkg.type_name + ":").rjust(10), pkg.cpv), noiselevel=-1)

		# Filter out any old-style virtual matches if they are
		# mixed with new-style virtual matches.
		cp = atom.cp
		if len(matched_packages) > 1 and \
			"virtual" == portage.catsplit(cp)[0]:
			for pkg in matched_packages:
				if pkg.cp != cp:
					continue
				# Got a new-style virtual, so filter
				# out any old-style virtuals.
				matched_packages = [pkg for pkg in matched_packages \
					if pkg.cp == cp]
				break

		if existing_node is not None and \
			existing_node in matched_packages:
			return existing_node, existing_node

		if len(matched_packages) > 1:
			if rebuilt_binaries:
				inst_pkg = None
				built_pkg = None
				for pkg in matched_packages:
					if pkg.installed:
						inst_pkg = pkg
					elif pkg.built:
						built_pkg = pkg
				if built_pkg is not None and inst_pkg is not None:
					# Only reinstall if binary package BUILD_TIME is
					# non-empty, in order to avoid cases like to
					# bug #306659 where BUILD_TIME fields are missing
					# in local and/or remote Packages file.
					try:
						built_timestamp = int(built_pkg.metadata['BUILD_TIME'])
					except (KeyError, ValueError):
						built_timestamp = 0

					try:
						installed_timestamp = int(inst_pkg.metadata['BUILD_TIME'])
					except (KeyError, ValueError):
						installed_timestamp = 0

					if "--rebuilt-binaries-timestamp" in self._frozen_config.myopts:
						minimal_timestamp = self._frozen_config.myopts["--rebuilt-binaries-timestamp"]
						if built_timestamp and \
							built_timestamp > installed_timestamp and \
							built_timestamp >= minimal_timestamp:
							return built_pkg, existing_node
					else:
						#Don't care if the binary has an older BUILD_TIME than the installed
						#package. This is for closely tracking a binhost.
						#Use --rebuilt-binaries-timestamp 0 if you want only newer binaries
						#pulled in here.
						if built_timestamp and \
							built_timestamp != installed_timestamp:
							return built_pkg, existing_node

			if avoid_update:
				for pkg in matched_packages:
					if pkg.installed and self._pkg_visibility_check(pkg, \
						allow_missing_keywords=allow_missing_keywords):
						return pkg, existing_node

			bestmatch = portage.best(
				[pkg.cpv for pkg in matched_packages \
					if self._pkg_visibility_check(pkg, allow_missing_keywords=allow_missing_keywords)])
			if not bestmatch:
				# all are masked, so ignore visibility
				bestmatch = portage.best(
					[pkg.cpv for pkg in matched_packages])
			matched_packages = [pkg for pkg in matched_packages \
				if portage.dep.cpvequal(pkg.cpv, bestmatch)]

		# ordered by type preference ("ebuild" type is the last resort)
		return  matched_packages[-1], existing_node

	def _select_pkg_from_graph(self, root, atom, onlydeps=False):
		"""
		Select packages that have already been added to the graph or
		those that are installed and have not been scheduled for
		replacement.
		"""
		graph_db = self._dynamic_config._graph_trees[root]["porttree"].dbapi
		matches = graph_db.match_pkgs(atom)
		if not matches:
			return None, None
		pkg = matches[-1] # highest match
		in_graph = self._dynamic_config._slot_pkg_map[root].get(pkg.slot_atom)
		return pkg, in_graph

	def _complete_graph(self, required_sets=None):
		"""
		Add any deep dependencies of required sets (args, system, world) that
		have not been pulled into the graph yet. This ensures that the graph
		is consistent such that initially satisfied deep dependencies are not
		broken in the new graph. Initially unsatisfied dependencies are
		irrelevant since we only want to avoid breaking dependencies that are
		intially satisfied.

		Since this method can consume enough time to disturb users, it is
		currently only enabled by the --complete-graph option.

		@param required_sets: contains required sets (currently only used
			for depclean and prune removal operations)
		@type required_sets: dict
		"""
		if "--buildpkgonly" in self._frozen_config.myopts or \
			"recurse" not in self._dynamic_config.myparams:
			return 1

		if "complete" not in self._dynamic_config.myparams:
			# Skip this to avoid consuming enough time to disturb users.
			return 1

		self._load_vdb()

		# Put the depgraph into a mode that causes it to only
		# select packages that have already been added to the
		# graph or those that are installed and have not been
		# scheduled for replacement. Also, toggle the "deep"
		# parameter so that all dependencies are traversed and
		# accounted for.
		self._select_atoms = self._select_atoms_from_graph
		self._select_package = self._select_pkg_from_graph
		already_deep = self._dynamic_config.myparams.get("deep") is True
		if not already_deep:
			self._dynamic_config.myparams["deep"] = True

		for root in self._frozen_config.roots:
			if root != self._frozen_config.target_root and \
				"remove" in self._dynamic_config.myparams:
				# Only pull in deps for the relevant root.
				continue
			if required_sets is None or root not in required_sets:
				required_set_names = self._frozen_config._required_set_names.copy()
			else:
				required_set_names = set(required_sets[root])
			if root == self._frozen_config.target_root and \
				(already_deep or "empty" in self._dynamic_config.myparams):
				required_set_names.difference_update(self._dynamic_config._sets)
			if not required_set_names and \
				not self._dynamic_config._ignored_deps and \
				not self._dynamic_config._dep_stack:
				continue
			root_config = self._frozen_config.roots[root]
			setconfig = root_config.setconfig
			args = []
			# Reuse existing SetArg instances when available.
			for arg in self._dynamic_config.digraph.root_nodes():
				if not isinstance(arg, SetArg):
					continue
				if arg.root_config != root_config:
					continue
				if arg.name in required_set_names:
					args.append(arg)
					required_set_names.remove(arg.name)
			# Create new SetArg instances only when necessary.
			for s in required_set_names:
				if required_sets is None or root not in required_sets:
					expanded_set = InternalPackageSet(
						initial_atoms=setconfig.getSetAtoms(s))
				else:
					expanded_set = required_sets[root][s]
				atom = SETPREFIX + s
				args.append(SetArg(arg=atom, set=expanded_set,
					root_config=root_config))
				if root == self._frozen_config.target_root:
					self._dynamic_config._sets[s] = expanded_set
			vardb = root_config.trees["vartree"].dbapi
			for arg in args:
				for atom in arg.set:
					self._dynamic_config._dep_stack.append(
						Dependency(atom=atom, root=root, parent=arg))
			if self._dynamic_config._ignored_deps:
				self._dynamic_config._dep_stack.extend(self._dynamic_config._ignored_deps)
				self._dynamic_config._ignored_deps = []
			if not self._create_graph(allow_unsatisfied=True):
				return 0
			# Check the unsatisfied deps to see if any initially satisfied deps
			# will become unsatisfied due to an upgrade. Initially unsatisfied
			# deps are irrelevant since we only want to avoid breaking deps
			# that are initially satisfied.
			while self._dynamic_config._unsatisfied_deps:
				dep = self._dynamic_config._unsatisfied_deps.pop()
				matches = vardb.match_pkgs(dep.atom)
				if not matches:
					self._dynamic_config._initially_unsatisfied_deps.append(dep)
					continue
				# An scheduled installation broke a deep dependency.
				# Add the installed package to the graph so that it
				# will be appropriately reported as a slot collision
				# (possibly solvable via backtracking).
				pkg = matches[-1] # highest match
				if not self._add_pkg(pkg, dep):
					return 0
				if not self._create_graph(allow_unsatisfied=True):
					return 0
		return 1

	def _pkg(self, cpv, type_name, root_config, installed=False, 
		onlydeps=False):
		"""
		Get a package instance from the cache, or create a new
		one if necessary. Raises PackageNotFound from aux_get if it
		failures for some reason (package does not exist or is
		corrupt).
		"""
		operation = "merge"
		if installed or onlydeps:
			operation = "nomerge"
		pkg = self._frozen_config._pkg_cache.get(
			(type_name, root_config.root, cpv, operation))
		if pkg is None and onlydeps and not installed:
			# Maybe it already got pulled in as a "merge" node.
			pkg = self._dynamic_config.mydbapi[root_config.root].get(
				(type_name, root_config.root, cpv, 'merge'))

		if pkg is None:
			tree_type = self.pkg_tree_map[type_name]
			db = root_config.trees[tree_type].dbapi
			db_keys = list(self._frozen_config._trees_orig[root_config.root][
				tree_type].dbapi._aux_cache_keys)
			try:
				metadata = zip(db_keys, db.aux_get(cpv, db_keys))
			except KeyError:
				raise portage.exception.PackageNotFound(cpv)
			pkg = Package(built=(type_name != "ebuild"), cpv=cpv,
				installed=installed, metadata=metadata, onlydeps=onlydeps,
				root_config=root_config, type_name=type_name)
			self._frozen_config._pkg_cache[pkg] = pkg

			if not self._pkg_visibility_check(pkg) and \
				'LICENSE' in pkg.masks and len(pkg.masks) == 1:
				slot_key = (pkg.root, pkg.slot_atom)
				other_pkg = self._frozen_config._highest_license_masked.get(slot_key)
				if other_pkg is None or pkg > other_pkg:
					self._frozen_config._highest_license_masked[slot_key] = pkg

		return pkg

	def _validate_blockers(self):
		"""Remove any blockers from the digraph that do not match any of the
		packages within the graph.  If necessary, create hard deps to ensure
		correct merge order such that mutually blocking packages are never
		installed simultaneously."""

		if "--buildpkgonly" in self._frozen_config.myopts or \
			"--nodeps" in self._frozen_config.myopts:
			return True

		complete = "complete" in self._dynamic_config.myparams
		deep = "deep" in self._dynamic_config.myparams

		if True:
			# Pull in blockers from all installed packages that haven't already
			# been pulled into the depgraph.  This is not enabled by default
			# due to the performance penalty that is incurred by all the
			# additional dep_check calls that are required.

			# For installed packages, always ignore blockers from DEPEND since
			# only runtime dependencies should be relevant for packages that
			# are already built.
			dep_keys = ["RDEPEND", "PDEPEND"]
			for myroot in self._frozen_config.trees:
				vardb = self._frozen_config.trees[myroot]["vartree"].dbapi
				portdb = self._frozen_config.trees[myroot]["porttree"].dbapi
				pkgsettings = self._frozen_config.pkgsettings[myroot]
				root_config = self._frozen_config.roots[myroot]
				dbs = self._dynamic_config._filtered_trees[myroot]["dbs"]
				final_db = self._dynamic_config.mydbapi[myroot]

				blocker_cache = BlockerCache(myroot, vardb)
				stale_cache = set(blocker_cache)
				for pkg in vardb:
					cpv = pkg.cpv
					stale_cache.discard(cpv)
					pkg_in_graph = self._dynamic_config.digraph.contains(pkg)
					pkg_deps_added = \
						pkg in self._dynamic_config._traversed_pkg_deps

					# Check for masked installed packages. Only warn about
					# packages that are in the graph in order to avoid warning
					# about those that will be automatically uninstalled during
					# the merge process or by --depclean. Always warn about
					# packages masked by license, since the user likely wants
					# to adjust ACCEPT_LICENSE.
					if pkg in final_db:
						if not self._pkg_visibility_check(pkg) and \
							(pkg_in_graph or 'LICENSE' in pkg.masks):
							self._dynamic_config._masked_installed.add(pkg)
						else:
							self._check_masks(pkg)

					blocker_atoms = None
					blockers = None
					if pkg_deps_added:
						blockers = []
						try:
							blockers.extend(
								self._dynamic_config._blocker_parents.child_nodes(pkg))
						except KeyError:
							pass
						try:
							blockers.extend(
								self._dynamic_config._irrelevant_blockers.child_nodes(pkg))
						except KeyError:
							pass
						if blockers:
							# Select just the runtime blockers.
							blockers = [blocker for blocker in blockers \
								if blocker.priority.runtime or \
								blocker.priority.runtime_post]
					if blockers is not None:
						blockers = set(blocker.atom for blocker in blockers)

					# If this node has any blockers, create a "nomerge"
					# node for it so that they can be enforced.
					self._spinner_update()
					blocker_data = blocker_cache.get(cpv)
					if blocker_data is not None and \
						blocker_data.counter != long(pkg.metadata["COUNTER"]):
						blocker_data = None

					# If blocker data from the graph is available, use
					# it to validate the cache and update the cache if
					# it seems invalid.
					if blocker_data is not None and \
						blockers is not None:
						if not blockers.symmetric_difference(
							blocker_data.atoms):
							continue
						blocker_data = None

					if blocker_data is None and \
						blockers is not None:
						# Re-use the blockers from the graph.
						blocker_atoms = sorted(blockers)
						counter = long(pkg.metadata["COUNTER"])
						blocker_data = \
							blocker_cache.BlockerData(counter, blocker_atoms)
						blocker_cache[pkg.cpv] = blocker_data
						continue

					if blocker_data:
						blocker_atoms = [Atom(atom) for atom in blocker_data.atoms]
					else:
						# Use aux_get() to trigger FakeVartree global
						# updates on *DEPEND when appropriate.
						depstr = " ".join(vardb.aux_get(pkg.cpv, dep_keys))
						# It is crucial to pass in final_db here in order to
						# optimize dep_check calls by eliminating atoms via
						# dep_wordreduce and dep_eval calls.
						try:
							portage.dep._dep_check_strict = False
							try:
								success, atoms = portage.dep_check(depstr,
									final_db, pkgsettings, myuse=self._pkg_use_enabled(pkg),
									trees=self._dynamic_config._graph_trees, myroot=myroot)
							except Exception as e:
								if isinstance(e, SystemExit):
									raise
								# This is helpful, for example, if a ValueError
								# is thrown from cpv_expand due to multiple
								# matches (this can happen if an atom lacks a
								# category).
								show_invalid_depstring_notice(
									pkg, depstr, str(e))
								del e
								raise
						finally:
							portage.dep._dep_check_strict = True
						if not success:
							replacement_pkg = final_db.match_pkgs(pkg.slot_atom)
							if replacement_pkg and \
								replacement_pkg[0].operation == "merge":
								# This package is being replaced anyway, so
								# ignore invalid dependencies so as not to
								# annoy the user too much (otherwise they'd be
								# forced to manually unmerge it first).
								continue
							show_invalid_depstring_notice(pkg, depstr, atoms)
							return False
						blocker_atoms = [myatom for myatom in atoms \
							if myatom.blocker]
						blocker_atoms.sort()
						counter = long(pkg.metadata["COUNTER"])
						blocker_cache[cpv] = \
							blocker_cache.BlockerData(counter, blocker_atoms)
					if blocker_atoms:
						try:
							for atom in blocker_atoms:
								blocker = Blocker(atom=atom,
									eapi=pkg.metadata["EAPI"],
									priority=self._priority(runtime=True),
									root=myroot)
								self._dynamic_config._blocker_parents.add(blocker, pkg)
						except portage.exception.InvalidAtom as e:
							depstr = " ".join(vardb.aux_get(pkg.cpv, dep_keys))
							show_invalid_depstring_notice(
								pkg, depstr, "Invalid Atom: %s" % (e,))
							return False
				for cpv in stale_cache:
					del blocker_cache[cpv]
				blocker_cache.flush()
				del blocker_cache

		# Discard any "uninstall" tasks scheduled by previous calls
		# to this method, since those tasks may not make sense given
		# the current graph state.
		previous_uninstall_tasks = self._dynamic_config._blocker_uninstalls.leaf_nodes()
		if previous_uninstall_tasks:
			self._dynamic_config._blocker_uninstalls = digraph()
			self._dynamic_config.digraph.difference_update(previous_uninstall_tasks)

		for blocker in self._dynamic_config._blocker_parents.leaf_nodes():
			self._spinner_update()
			root_config = self._frozen_config.roots[blocker.root]
			virtuals = root_config.settings.getvirtuals()
			myroot = blocker.root
			initial_db = self._frozen_config.trees[myroot]["vartree"].dbapi
			final_db = self._dynamic_config.mydbapi[myroot]
			
			provider_virtual = False
			if blocker.cp in virtuals and \
				not self._have_new_virt(blocker.root, blocker.cp):
				provider_virtual = True

			# Use this to check PROVIDE for each matched package
			# when necessary.
			atom_set = InternalPackageSet(
				initial_atoms=[blocker.atom])

			if provider_virtual:
				atoms = []
				for provider_entry in virtuals[blocker.cp]:
					atoms.append(Atom(blocker.atom.replace(
						blocker.cp, provider_entry.cp, 1)))
			else:
				atoms = [blocker.atom]

			blocked_initial = set()
			for atom in atoms:
				for pkg in initial_db.match_pkgs(atom):
					if atom_set.findAtomForPackage(pkg):
						blocked_initial.add(pkg)

			blocked_final = set()
			for atom in atoms:
				for pkg in final_db.match_pkgs(atom):
					if atom_set.findAtomForPackage(pkg):
						blocked_final.add(pkg)

			if not blocked_initial and not blocked_final:
				parent_pkgs = self._dynamic_config._blocker_parents.parent_nodes(blocker)
				self._dynamic_config._blocker_parents.remove(blocker)
				# Discard any parents that don't have any more blockers.
				for pkg in parent_pkgs:
					self._dynamic_config._irrelevant_blockers.add(blocker, pkg)
					if not self._dynamic_config._blocker_parents.child_nodes(pkg):
						self._dynamic_config._blocker_parents.remove(pkg)
				continue
			for parent in self._dynamic_config._blocker_parents.parent_nodes(blocker):
				unresolved_blocks = False
				depends_on_order = set()
				for pkg in blocked_initial:
					if pkg.slot_atom == parent.slot_atom and \
						not blocker.atom.blocker.overlap.forbid:
						# New !!atom blockers do not allow temporary
						# simulaneous installation, so unlike !atom
						# blockers, !!atom blockers aren't ignored
						# when they match other packages occupying
						# the same slot.
						continue
					if parent.installed:
						# Two currently installed packages conflict with
						# eachother. Ignore this case since the damage
						# is already done and this would be likely to
						# confuse users if displayed like a normal blocker.
						continue

					self._dynamic_config._blocked_pkgs.add(pkg, blocker)

					if parent.operation == "merge":
						# Maybe the blocked package can be replaced or simply
						# unmerged to resolve this block.
						depends_on_order.add((pkg, parent))
						continue
					# None of the above blocker resolutions techniques apply,
					# so apparently this one is unresolvable.
					unresolved_blocks = True
				for pkg in blocked_final:
					if pkg.slot_atom == parent.slot_atom and \
						not blocker.atom.blocker.overlap.forbid:
						# New !!atom blockers do not allow temporary
						# simulaneous installation, so unlike !atom
						# blockers, !!atom blockers aren't ignored
						# when they match other packages occupying
						# the same slot.
						continue
					if parent.operation == "nomerge" and \
						pkg.operation == "nomerge":
						# This blocker will be handled the next time that a
						# merge of either package is triggered.
						continue

					self._dynamic_config._blocked_pkgs.add(pkg, blocker)

					# Maybe the blocking package can be
					# unmerged to resolve this block.
					if parent.operation == "merge" and pkg.installed:
						depends_on_order.add((pkg, parent))
						continue
					elif parent.operation == "nomerge":
						depends_on_order.add((parent, pkg))
						continue
					# None of the above blocker resolutions techniques apply,
					# so apparently this one is unresolvable.
					unresolved_blocks = True

				# Make sure we don't unmerge any package that have been pulled
				# into the graph.
				if not unresolved_blocks and depends_on_order:
					for inst_pkg, inst_task in depends_on_order:
						if self._dynamic_config.digraph.contains(inst_pkg) and \
							self._dynamic_config.digraph.parent_nodes(inst_pkg):
							unresolved_blocks = True
							break

				if not unresolved_blocks and depends_on_order:
					for inst_pkg, inst_task in depends_on_order:
						uninst_task = Package(built=inst_pkg.built,
							cpv=inst_pkg.cpv, installed=inst_pkg.installed,
							metadata=inst_pkg.metadata,
							operation="uninstall",
							root_config=inst_pkg.root_config,
							type_name=inst_pkg.type_name)
						# Enforce correct merge order with a hard dep.
						self._dynamic_config.digraph.addnode(uninst_task, inst_task,
							priority=BlockerDepPriority.instance)
						# Count references to this blocker so that it can be
						# invalidated after nodes referencing it have been
						# merged.
						self._dynamic_config._blocker_uninstalls.addnode(uninst_task, blocker)
				if not unresolved_blocks and not depends_on_order:
					self._dynamic_config._irrelevant_blockers.add(blocker, parent)
					self._dynamic_config._blocker_parents.remove_edge(blocker, parent)
					if not self._dynamic_config._blocker_parents.parent_nodes(blocker):
						self._dynamic_config._blocker_parents.remove(blocker)
					if not self._dynamic_config._blocker_parents.child_nodes(parent):
						self._dynamic_config._blocker_parents.remove(parent)
				if unresolved_blocks:
					self._dynamic_config._unsolvable_blockers.add(blocker, parent)

		return True

	def _accept_blocker_conflicts(self):
		acceptable = False
		for x in ("--buildpkgonly", "--fetchonly",
			"--fetch-all-uri", "--nodeps"):
			if x in self._frozen_config.myopts:
				acceptable = True
				break
		return acceptable

	def _merge_order_bias(self, mygraph):
		"""
		For optimal leaf node selection, promote deep system runtime deps and
		order nodes from highest to lowest overall reference count.
		"""

		node_info = {}
		for node in mygraph.order:
			node_info[node] = len(mygraph.parent_nodes(node))
		deep_system_deps = _find_deep_system_runtime_deps(mygraph)

		def cmp_merge_preference(node1, node2):

			if node1.operation == 'uninstall':
				if node2.operation == 'uninstall':
					return 0
				return 1

			if node2.operation == 'uninstall':
				if node1.operation == 'uninstall':
					return 0
				return -1

			node1_sys = node1 in deep_system_deps
			node2_sys = node2 in deep_system_deps
			if node1_sys != node2_sys:
				if node1_sys:
					return -1
				return 1

			return node_info[node2] - node_info[node1]

		mygraph.order.sort(key=cmp_sort_key(cmp_merge_preference))

	def altlist(self, reversed=False):

		while self._dynamic_config._serialized_tasks_cache is None:
			self._resolve_conflicts()
			try:
				self._dynamic_config._serialized_tasks_cache, self._dynamic_config._scheduler_graph = \
					self._serialize_tasks()
			except self._serialize_tasks_retry:
				pass

		retlist = self._dynamic_config._serialized_tasks_cache[:]
		if reversed:
			retlist.reverse()
		return retlist

	def schedulerGraph(self):
		"""
		The scheduler graph is identical to the normal one except that
		uninstall edges are reversed in specific cases that require
		conflicting packages to be temporarily installed simultaneously.
		This is intended for use by the Scheduler in it's parallelization
		logic. It ensures that temporary simultaneous installation of
		conflicting packages is avoided when appropriate (especially for
		!!atom blockers), but allowed in specific cases that require it.

		Note that this method calls break_refs() which alters the state of
		internal Package instances such that this depgraph instance should
		not be used to perform any more calculations.
		"""
		if self._dynamic_config._scheduler_graph is None:
			self.altlist()
		self.break_refs(self._dynamic_config._scheduler_graph.order)

		# Break DepPriority.satisfied attributes which reference
		# installed Package instances.
		for parents, children, node in \
			self._dynamic_config._scheduler_graph.nodes.values():
			for priorities in chain(parents.values(), children.values()):
				for priority in priorities:
					if priority.satisfied:
						priority.satisfied = True

		return self._dynamic_config._scheduler_graph

	def break_refs(self, nodes):
		"""
		Take a mergelist like that returned from self.altlist() and
		break any references that lead back to the depgraph. This is
		useful if you want to hold references to packages without
		also holding the depgraph on the heap.
		"""
		for node in nodes:
			if hasattr(node, "root_config"):
				# The FakeVartree references the _package_cache which
				# references the depgraph. So that Package instances don't
				# hold the depgraph and FakeVartree on the heap, replace
				# the RootConfig that references the FakeVartree with the
				# original RootConfig instance which references the actual
				# vartree.
				node.root_config = \
					self._frozen_config._trees_orig[node.root_config.root]["root_config"]

	def _resolve_conflicts(self):
		if not self._complete_graph():
			raise self._unknown_internal_error()

		if not self._validate_blockers():
			raise self._unknown_internal_error()

		if self._dynamic_config._slot_collision_info:
			self._process_slot_conflicts()

	def _serialize_tasks(self):

		if "--debug" in self._frozen_config.myopts:
			writemsg("\ndigraph:\n\n", noiselevel=-1)
			self._dynamic_config.digraph.debug_print()
			writemsg("\n", noiselevel=-1)

		scheduler_graph = self._dynamic_config.digraph.copy()

		if '--nodeps' in self._frozen_config.myopts:
			# Preserve the package order given on the command line.
			return ([node for node in scheduler_graph \
				if isinstance(node, Package) \
				and node.operation == 'merge'], scheduler_graph)

		mygraph=self._dynamic_config.digraph.copy()
		# Prune "nomerge" root nodes if nothing depends on them, since
		# otherwise they slow down merge order calculation. Don't remove
		# non-root nodes since they help optimize merge order in some cases
		# such as revdep-rebuild.
		removed_nodes = set()
		while True:
			for node in mygraph.root_nodes():
				if not isinstance(node, Package) or \
					node.installed or node.onlydeps:
					removed_nodes.add(node)
			if removed_nodes:
				self._spinner_update()
				mygraph.difference_update(removed_nodes)
			if not removed_nodes:
				break
			removed_nodes.clear()
		self._merge_order_bias(mygraph)
		def cmp_circular_bias(n1, n2):
			"""
			RDEPEND is stronger than PDEPEND and this function
			measures such a strength bias within a circular
			dependency relationship.
			"""
			n1_n2_medium = n2 in mygraph.child_nodes(n1,
				ignore_priority=priority_range.ignore_medium_soft)
			n2_n1_medium = n1 in mygraph.child_nodes(n2,
				ignore_priority=priority_range.ignore_medium_soft)
			if n1_n2_medium == n2_n1_medium:
				return 0
			elif n1_n2_medium:
				return 1
			return -1
		myblocker_uninstalls = self._dynamic_config._blocker_uninstalls.copy()
		retlist=[]
		# Contains uninstall tasks that have been scheduled to
		# occur after overlapping blockers have been installed.
		scheduled_uninstalls = set()
		# Contains any Uninstall tasks that have been ignored
		# in order to avoid the circular deps code path. These
		# correspond to blocker conflicts that could not be
		# resolved.
		ignored_uninstall_tasks = set()
		have_uninstall_task = False
		complete = "complete" in self._dynamic_config.myparams
		asap_nodes = []

		def get_nodes(**kwargs):
			"""
			Returns leaf nodes excluding Uninstall instances
			since those should be executed as late as possible.
			"""
			return [node for node in mygraph.leaf_nodes(**kwargs) \
				if isinstance(node, Package) and \
					(node.operation != "uninstall" or \
					node in scheduled_uninstalls)]

		# sys-apps/portage needs special treatment if ROOT="/"
		running_root = self._frozen_config._running_root.root
		runtime_deps = InternalPackageSet(
			initial_atoms=[PORTAGE_PACKAGE_ATOM])
		running_portage = self._frozen_config.trees[running_root]["vartree"].dbapi.match_pkgs(
			PORTAGE_PACKAGE_ATOM)
		replacement_portage = self._dynamic_config.mydbapi[running_root].match_pkgs(
			PORTAGE_PACKAGE_ATOM)

		if running_portage:
			running_portage = running_portage[0]
		else:
			running_portage = None

		if replacement_portage:
			replacement_portage = replacement_portage[0]
		else:
			replacement_portage = None

		if replacement_portage == running_portage:
			replacement_portage = None

		if replacement_portage is not None and \
			(running_portage is None or \
			(running_portage.cpv != replacement_portage.cpv)):
			# update from running_portage to replacement_portage asap
			asap_nodes.append(replacement_portage)

		if running_portage is not None:
			try:
				portage_rdepend = self._select_atoms_highest_available(
					running_root, running_portage.metadata["RDEPEND"],
					myuse=running_portage.use.enabled,
					parent=running_portage, strict=False)
			except portage.exception.InvalidDependString as e:
				portage.writemsg("!!! Invalid RDEPEND in " + \
					"'%svar/db/pkg/%s/RDEPEND': %s\n" % \
					(running_root, running_portage.cpv, e), noiselevel=-1)
				del e
				portage_rdepend = {running_portage : []}
			for atoms in portage_rdepend.values():
				runtime_deps.update(atom for atom in atoms \
					if not atom.blocker)

		# Merge libc asap, in order to account for implicit
		# dependencies. See bug #303567.
		for root in (running_root,):
			libc_pkg = self._dynamic_config.mydbapi[root].match_pkgs(
				portage.const.LIBC_PACKAGE_ATOM)
			if libc_pkg:
				libc_pkg = libc_pkg[0]
				if libc_pkg.operation == 'merge':
					# Only add a dep when the version changes.
					if not libc_pkg.root_config.trees[
						'vartree'].dbapi.cpv_exists(libc_pkg.cpv):

						# If there's also an os-headers upgrade, we need to
						# pull that in first. See bug #328317.
						os_headers_pkg = self._dynamic_config.mydbapi[root].match_pkgs(
							portage.const.OS_HEADERS_PACKAGE_ATOM)
						if os_headers_pkg:
							os_headers_pkg = os_headers_pkg[0]
							if os_headers_pkg.operation == 'merge':
								# Only add a dep when the version changes.
								if not os_headers_pkg.root_config.trees[
									'vartree'].dbapi.cpv_exists(os_headers_pkg.cpv):
									asap_nodes.append(os_headers_pkg)

						asap_nodes.append(libc_pkg)

		def gather_deps(ignore_priority, mergeable_nodes,
			selected_nodes, node):
			"""
			Recursively gather a group of nodes that RDEPEND on
			eachother. This ensures that they are merged as a group
			and get their RDEPENDs satisfied as soon as possible.
			"""
			if node in selected_nodes:
				return True
			if node not in mergeable_nodes:
				return False
			if node == replacement_portage and \
				mygraph.child_nodes(node,
				ignore_priority=priority_range.ignore_medium_soft):
				# Make sure that portage always has all of it's
				# RDEPENDs installed first.
				return False
			selected_nodes.add(node)
			for child in mygraph.child_nodes(node,
				ignore_priority=ignore_priority):
				if not gather_deps(ignore_priority,
					mergeable_nodes, selected_nodes, child):
					return False
			return True

		def ignore_uninst_or_med(priority):
			if priority is BlockerDepPriority.instance:
				return True
			return priority_range.ignore_medium(priority)

		def ignore_uninst_or_med_soft(priority):
			if priority is BlockerDepPriority.instance:
				return True
			return priority_range.ignore_medium_soft(priority)

		tree_mode = "--tree" in self._frozen_config.myopts
		# Tracks whether or not the current iteration should prefer asap_nodes
		# if available.  This is set to False when the previous iteration
		# failed to select any nodes.  It is reset whenever nodes are
		# successfully selected.
		prefer_asap = True

		# Controls whether or not the current iteration should drop edges that
		# are "satisfied" by installed packages, in order to solve circular
		# dependencies. The deep runtime dependencies of installed packages are
		# not checked in this case (bug #199856), so it must be avoided
		# whenever possible.
		drop_satisfied = False

		# State of variables for successive iterations that loosen the
		# criteria for node selection.
		#
		# iteration   prefer_asap   drop_satisfied
		# 1           True          False
		# 2           False         False
		# 3           False         True
		#
		# If no nodes are selected on the last iteration, it is due to
		# unresolved blockers or circular dependencies.

		while not mygraph.empty():
			self._spinner_update()
			selected_nodes = None
			ignore_priority = None
			if drop_satisfied or (prefer_asap and asap_nodes):
				priority_range = DepPrioritySatisfiedRange
			else:
				priority_range = DepPriorityNormalRange
			if prefer_asap and asap_nodes:
				# ASAP nodes are merged before their soft deps. Go ahead and
				# select root nodes here if necessary, since it's typical for
				# the parent to have been removed from the graph already.
				asap_nodes = [node for node in asap_nodes \
					if mygraph.contains(node)]
				for node in asap_nodes:
					if not mygraph.child_nodes(node,
						ignore_priority=priority_range.ignore_soft):
						selected_nodes = [node]
						asap_nodes.remove(node)
						break
			if not selected_nodes and \
				not (prefer_asap and asap_nodes):
				for i in range(priority_range.NONE,
					priority_range.MEDIUM_SOFT + 1):
					ignore_priority = priority_range.ignore_priority[i]
					nodes = get_nodes(ignore_priority=ignore_priority)
					if nodes:
						# If there is a mixture of merges and uninstalls,
						# do the uninstalls first.
						if len(nodes) > 1:
							good_uninstalls = []
							for node in nodes:
								if node.operation == "uninstall":
									good_uninstalls.append(node)

							if good_uninstalls:
								nodes = good_uninstalls
							else:
								nodes = nodes

						if ignore_priority is None and not tree_mode:
							# Greedily pop all of these nodes since no
							# relationship has been ignored. This optimization
							# destroys --tree output, so it's disabled in tree
							# mode.
							selected_nodes = nodes
						else:
							# For optimal merge order:
							#  * Only pop one node.
							#  * Removing a root node (node without a parent)
							#    will not produce a leaf node, so avoid it.
							#  * It's normal for a selected uninstall to be a
							#    root node, so don't check them for parents.
							for node in nodes:
								if node.operation == "uninstall" or \
									mygraph.parent_nodes(node):
									selected_nodes = [node]
									break

						if selected_nodes:
							break

			if not selected_nodes:
				nodes = get_nodes(ignore_priority=priority_range.ignore_medium)
				if nodes:
					mergeable_nodes = set(nodes)
					if prefer_asap and asap_nodes:
						nodes = asap_nodes
					for i in range(priority_range.SOFT,
						priority_range.MEDIUM_SOFT + 1):
						ignore_priority = priority_range.ignore_priority[i]
						for node in nodes:
							if not mygraph.parent_nodes(node):
								continue
							selected_nodes = set()
							if gather_deps(ignore_priority,
								mergeable_nodes, selected_nodes, node):
								break
							else:
								selected_nodes = None
						if selected_nodes:
							break

					if prefer_asap and asap_nodes and not selected_nodes:
						# We failed to find any asap nodes to merge, so ignore
						# them for the next iteration.
						prefer_asap = False
						continue

			if selected_nodes and ignore_priority is not None:
				# Try to merge ignored medium_soft deps as soon as possible
				# if they're not satisfied by installed packages.
				for node in selected_nodes:
					children = set(mygraph.child_nodes(node))
					soft = children.difference(
						mygraph.child_nodes(node,
						ignore_priority=DepPrioritySatisfiedRange.ignore_soft))
					medium_soft = children.difference(
						mygraph.child_nodes(node,
							ignore_priority = \
							DepPrioritySatisfiedRange.ignore_medium_soft))
					medium_soft.difference_update(soft)
					for child in medium_soft:
						if child in selected_nodes:
							continue
						if child in asap_nodes:
							continue
						asap_nodes.append(child)

			if selected_nodes and len(selected_nodes) > 1:
				if not isinstance(selected_nodes, list):
					selected_nodes = list(selected_nodes)
				selected_nodes.sort(key=cmp_sort_key(cmp_circular_bias))

			if not selected_nodes and not myblocker_uninstalls.is_empty():
				# An Uninstall task needs to be executed in order to
				# avoid conflict if possible.

				if drop_satisfied:
					priority_range = DepPrioritySatisfiedRange
				else:
					priority_range = DepPriorityNormalRange

				mergeable_nodes = get_nodes(
					ignore_priority=ignore_uninst_or_med)

				min_parent_deps = None
				uninst_task = None

				# FIXME: This loop can be extremely slow when
				#        there of lots of blockers to solve
				#        (especially the gather_deps part).
				for task in myblocker_uninstalls.leaf_nodes():
					# Do some sanity checks so that system or world packages
					# don't get uninstalled inappropriately here (only really
					# necessary when --complete-graph has not been enabled).

					if task in ignored_uninstall_tasks:
						continue

					if task in scheduled_uninstalls:
						# It's been scheduled but it hasn't
						# been executed yet due to dependence
						# on installation of blocking packages.
						continue

					root_config = self._frozen_config.roots[task.root]
					inst_pkg = self._pkg(task.cpv, "installed", root_config,
						installed=True)

					if self._dynamic_config.digraph.contains(inst_pkg):
						continue

					forbid_overlap = False
					heuristic_overlap = False
					for blocker in myblocker_uninstalls.parent_nodes(task):
						if blocker.eapi in ("0", "1"):
							heuristic_overlap = True
						elif blocker.atom.blocker.overlap.forbid:
							forbid_overlap = True
							break
					if forbid_overlap and running_root == task.root:
						continue

					if heuristic_overlap and running_root == task.root:
						# Never uninstall sys-apps/portage or it's essential
						# dependencies, except through replacement.
						try:
							runtime_dep_atoms = \
								list(runtime_deps.iterAtomsForPackage(task))
						except portage.exception.InvalidDependString as e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							continue

						# Don't uninstall a runtime dep if it appears
						# to be the only suitable one installed.
						skip = False
						vardb = root_config.trees["vartree"].dbapi
						for atom in runtime_dep_atoms:
							other_version = None
							for pkg in vardb.match_pkgs(atom):
								if pkg.cpv == task.cpv and \
									pkg.metadata["COUNTER"] == \
									task.metadata["COUNTER"]:
									continue
								other_version = pkg
								break
							if other_version is None:
								skip = True
								break
						if skip:
							continue

						# For packages in the system set, don't take
						# any chances. If the conflict can't be resolved
						# by a normal replacement operation then abort.
						skip = False
						try:
							for atom in root_config.sets[
								"system"].iterAtomsForPackage(task):
								skip = True
								break
						except portage.exception.InvalidDependString as e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							skip = True
						if skip:
							continue

					# Note that the world check isn't always
					# necessary since self._complete_graph() will
					# add all packages from the system and world sets to the
					# graph. This just allows unresolved conflicts to be
					# detected as early as possible, which makes it possible
					# to avoid calling self._complete_graph() when it is
					# unnecessary due to blockers triggering an abortion.
					if not complete:
						# For packages in the world set, go ahead an uninstall
						# when necessary, as long as the atom will be satisfied
						# in the final state.
						graph_db = self._dynamic_config.mydbapi[task.root]
						skip = False
						try:
							for atom in root_config.sets[
								"selected"].iterAtomsForPackage(task):
								satisfied = False
								for pkg in graph_db.match_pkgs(atom):
									if pkg == inst_pkg:
										continue
									satisfied = True
									break
								if not satisfied:
									skip = True
									self._dynamic_config._blocked_world_pkgs[inst_pkg] = atom
									break
						except portage.exception.InvalidDependString as e:
							portage.writemsg("!!! Invalid PROVIDE in " + \
								"'%svar/db/pkg/%s/PROVIDE': %s\n" % \
								(task.root, task.cpv, e), noiselevel=-1)
							del e
							skip = True
						if skip:
							continue

					# Check the deps of parent nodes to ensure that
					# the chosen task produces a leaf node. Maybe
					# this can be optimized some more to make the
					# best possible choice, but the current algorithm
					# is simple and should be near optimal for most
					# common cases.
					self._spinner_update()
					mergeable_parent = False
					parent_deps = set()
					for parent in mygraph.parent_nodes(task):
						parent_deps.update(mygraph.child_nodes(parent,
							ignore_priority=priority_range.ignore_medium_soft))
						if parent in mergeable_nodes and \
							gather_deps(ignore_uninst_or_med_soft,
							mergeable_nodes, set(), parent):
							mergeable_parent = True

					if not mergeable_parent:
						continue

					parent_deps.remove(task)
					if min_parent_deps is None or \
						len(parent_deps) < min_parent_deps:
						min_parent_deps = len(parent_deps)
						uninst_task = task

				if uninst_task is not None:
					# The uninstall is performed only after blocking
					# packages have been merged on top of it. File
					# collisions between blocking packages are detected
					# and removed from the list of files to be uninstalled.
					scheduled_uninstalls.add(uninst_task)
					parent_nodes = mygraph.parent_nodes(uninst_task)

					# Reverse the parent -> uninstall edges since we want
					# to do the uninstall after blocking packages have
					# been merged on top of it.
					mygraph.remove(uninst_task)
					for blocked_pkg in parent_nodes:
						mygraph.add(blocked_pkg, uninst_task,
							priority=BlockerDepPriority.instance)
						scheduler_graph.remove_edge(uninst_task, blocked_pkg)
						scheduler_graph.add(blocked_pkg, uninst_task,
							priority=BlockerDepPriority.instance)

					# Sometimes a merge node will render an uninstall
					# node unnecessary (due to occupying the same SLOT),
					# and we want to avoid executing a separate uninstall
					# task in that case.
					slot_node = self._dynamic_config.mydbapi[uninst_task.root
						].match_pkgs(uninst_task.slot_atom)
					if slot_node and \
						slot_node[0].operation == "merge":
						mygraph.add(slot_node[0], uninst_task,
							priority=BlockerDepPriority.instance)

					# Reset the state variables for leaf node selection and
					# continue trying to select leaf nodes.
					prefer_asap = True
					drop_satisfied = False
					continue

			if not selected_nodes:
				# Only select root nodes as a last resort. This case should
				# only trigger when the graph is nearly empty and the only
				# remaining nodes are isolated (no parents or children). Since
				# the nodes must be isolated, ignore_priority is not needed.
				selected_nodes = get_nodes()

			if not selected_nodes and not drop_satisfied:
				drop_satisfied = True
				continue

			if not selected_nodes and not myblocker_uninstalls.is_empty():
				# If possible, drop an uninstall task here in order to avoid
				# the circular deps code path. The corresponding blocker will
				# still be counted as an unresolved conflict.
				uninst_task = None
				for node in myblocker_uninstalls.leaf_nodes():
					try:
						mygraph.remove(node)
					except KeyError:
						pass
					else:
						uninst_task = node
						ignored_uninstall_tasks.add(node)
						break

				if uninst_task is not None:
					# Reset the state variables for leaf node selection and
					# continue trying to select leaf nodes.
					prefer_asap = True
					drop_satisfied = False
					continue

			if not selected_nodes:
				self._dynamic_config._circular_deps_for_display = mygraph
				raise self._unknown_internal_error()

			# At this point, we've succeeded in selecting one or more nodes, so
			# reset state variables for leaf node selection.
			prefer_asap = True
			drop_satisfied = False

			mygraph.difference_update(selected_nodes)

			for node in selected_nodes:
				if isinstance(node, Package) and \
					node.operation == "nomerge":
					continue

				# Handle interactions between blockers
				# and uninstallation tasks.
				solved_blockers = set()
				uninst_task = None
				if isinstance(node, Package) and \
					"uninstall" == node.operation:
					have_uninstall_task = True
					uninst_task = node
				else:
					vardb = self._frozen_config.trees[node.root]["vartree"].dbapi
					previous_cpv = vardb.match(node.slot_atom)
					if previous_cpv:
						# The package will be replaced by this one, so remove
						# the corresponding Uninstall task if necessary.
						previous_cpv = previous_cpv[0]
						uninst_task = \
							("installed", node.root, previous_cpv, "uninstall")
						try:
							mygraph.remove(uninst_task)
						except KeyError:
							pass

				if uninst_task is not None and \
					uninst_task not in ignored_uninstall_tasks and \
					myblocker_uninstalls.contains(uninst_task):
					blocker_nodes = myblocker_uninstalls.parent_nodes(uninst_task)
					myblocker_uninstalls.remove(uninst_task)
					# Discard any blockers that this Uninstall solves.
					for blocker in blocker_nodes:
						if not myblocker_uninstalls.child_nodes(blocker):
							myblocker_uninstalls.remove(blocker)
							if blocker not in \
								self._dynamic_config._unsolvable_blockers:
								solved_blockers.add(blocker)

				retlist.append(node)

				if (isinstance(node, Package) and \
					"uninstall" == node.operation) or \
					(uninst_task is not None and \
					uninst_task in scheduled_uninstalls):
					# Include satisfied blockers in the merge list
					# since the user might be interested and also
					# it serves as an indicator that blocking packages
					# will be temporarily installed simultaneously.
					for blocker in solved_blockers:
						retlist.append(blocker)

		unsolvable_blockers = set(self._dynamic_config._unsolvable_blockers.leaf_nodes())
		for node in myblocker_uninstalls.root_nodes():
			unsolvable_blockers.add(node)

		# If any Uninstall tasks need to be executed in order
		# to avoid a conflict, complete the graph with any
		# dependencies that may have been initially
		# neglected (to ensure that unsafe Uninstall tasks
		# are properly identified and blocked from execution).
		if have_uninstall_task and \
			not complete and \
			not unsolvable_blockers:
			self._dynamic_config.myparams["complete"] = True
			if '--debug' in self._frozen_config.myopts:
				msg = []
				msg.append("enabling 'complete' depgraph mode " + \
					"due to uninstall task(s):")
				msg.append("")
				for node in retlist:
					if isinstance(node, Package) and \
						node.operation == 'uninstall':
						msg.append("\t%s" % (node,))
				writemsg_level("\n%s\n" % \
					"".join("%s\n" % line for line in msg),
					level=logging.DEBUG, noiselevel=-1)
			raise self._serialize_tasks_retry("")

		# Set satisfied state on blockers, but not before the
		# above retry path, since we don't want to modify the
		# state in that case.
		for node in retlist:
			if isinstance(node, Blocker):
				node.satisfied = True

		for blocker in unsolvable_blockers:
			retlist.append(blocker)

		if unsolvable_blockers and \
			not self._accept_blocker_conflicts():
			self._dynamic_config._unsatisfied_blockers_for_display = unsolvable_blockers
			self._dynamic_config._serialized_tasks_cache = retlist[:]
			self._dynamic_config._scheduler_graph = scheduler_graph
			raise self._unknown_internal_error()

		if self._dynamic_config._slot_collision_info and \
			not self._accept_blocker_conflicts():
			self._dynamic_config._serialized_tasks_cache = retlist[:]
			self._dynamic_config._scheduler_graph = scheduler_graph
			raise self._unknown_internal_error()

		return retlist, scheduler_graph

	def _show_circular_deps(self, mygraph):
		# No leaf nodes are available, so we have a circular
		# dependency panic situation.  Reduce the noise level to a
		# minimum via repeated elimination of root nodes since they
		# have no parents and thus can not be part of a cycle.
		while True:
			root_nodes = mygraph.root_nodes(
				ignore_priority=DepPrioritySatisfiedRange.ignore_medium_soft)
			if not root_nodes:
				break
			mygraph.difference_update(root_nodes)
		# Display the USE flags that are enabled on nodes that are part
		# of dependency cycles in case that helps the user decide to
		# disable some of them.
		display_order = []
		tempgraph = mygraph.copy()
		while not tempgraph.empty():
			nodes = tempgraph.leaf_nodes()
			if not nodes:
				node = tempgraph.order[0]
			else:
				node = nodes[0]
			display_order.append(node)
			tempgraph.remove(node)
		display_order.reverse()
		self._frozen_config.myopts.pop("--quiet", None)
		self._frozen_config.myopts["--verbose"] = True
		self._frozen_config.myopts["--tree"] = True
		portage.writemsg("\n\n", noiselevel=-1)
		self.display(display_order)
		prefix = colorize("BAD", " * ")
		portage.writemsg("\n", noiselevel=-1)
		portage.writemsg(prefix + "Error: circular dependencies:\n",
			noiselevel=-1)
		portage.writemsg("\n", noiselevel=-1)
		mygraph.debug_print()
		portage.writemsg("\n", noiselevel=-1)
		portage.writemsg(prefix + "Note that circular dependencies " + \
			"can often be avoided by temporarily\n", noiselevel=-1)
		portage.writemsg(prefix + "disabling USE flags that trigger " + \
			"optional dependencies.\n", noiselevel=-1)

	def _show_merge_list(self):
		if self._dynamic_config._serialized_tasks_cache is not None and \
			not (self._dynamic_config._displayed_list and \
			(self._dynamic_config._displayed_list == self._dynamic_config._serialized_tasks_cache or \
			self._dynamic_config._displayed_list == \
				list(reversed(self._dynamic_config._serialized_tasks_cache)))):
			display_list = self._dynamic_config._serialized_tasks_cache[:]
			if "--tree" in self._frozen_config.myopts:
				display_list.reverse()
			self.display(display_list)

	def _show_unsatisfied_blockers(self, blockers):
		self._show_merge_list()
		msg = "Error: The above package list contains " + \
			"packages which cannot be installed " + \
			"at the same time on the same system."
		prefix = colorize("BAD", " * ")
		portage.writemsg("\n", noiselevel=-1)
		for line in textwrap.wrap(msg, 70):
			portage.writemsg(prefix + line + "\n", noiselevel=-1)

		# Display the conflicting packages along with the packages
		# that pulled them in. This is helpful for troubleshooting
		# cases in which blockers don't solve automatically and
		# the reasons are not apparent from the normal merge list
		# display.

		conflict_pkgs = {}
		for blocker in blockers:
			for pkg in chain(self._dynamic_config._blocked_pkgs.child_nodes(blocker), \
				self._dynamic_config._blocker_parents.parent_nodes(blocker)):
				parent_atoms = self._dynamic_config._parent_atoms.get(pkg)
				if not parent_atoms:
					atom = self._dynamic_config._blocked_world_pkgs.get(pkg)
					if atom is not None:
						parent_atoms = set([("@selected", atom)])
				if parent_atoms:
					conflict_pkgs[pkg] = parent_atoms

		if conflict_pkgs:
			# Reduce noise by pruning packages that are only
			# pulled in by other conflict packages.
			pruned_pkgs = set()
			for pkg, parent_atoms in conflict_pkgs.items():
				relevant_parent = False
				for parent, atom in parent_atoms:
					if parent not in conflict_pkgs:
						relevant_parent = True
						break
				if not relevant_parent:
					pruned_pkgs.add(pkg)
			for pkg in pruned_pkgs:
				del conflict_pkgs[pkg]

		if conflict_pkgs:
			msg = []
			msg.append("\n")
			indent = "  "
			# Max number of parents shown, to avoid flooding the display.
			max_parents = 3
			for pkg, parent_atoms in conflict_pkgs.items():

				pruned_list = set()

				# Prefer packages that are not directly involved in a conflict.
				for parent_atom in parent_atoms:
					if len(pruned_list) >= max_parents:
						break
					parent, atom = parent_atom
					if parent not in conflict_pkgs:
						pruned_list.add(parent_atom)

				for parent_atom in parent_atoms:
					if len(pruned_list) >= max_parents:
						break
					pruned_list.add(parent_atom)

				omitted_parents = len(parent_atoms) - len(pruned_list)
				msg.append(indent + "%s pulled in by\n" % pkg)

				for parent_atom in pruned_list:
					parent, atom = parent_atom
					msg.append(2*indent)
					if isinstance(parent,
						(PackageArg, AtomArg)):
						# For PackageArg and AtomArg types, it's
						# redundant to display the atom attribute.
						msg.append(str(parent))
					else:
						# Display the specific atom from SetArg or
						# Package types.
						msg.append("%s required by %s" % (atom, parent))
					msg.append("\n")

				if omitted_parents:
					msg.append(2*indent)
					msg.append("(and %d more)\n" % omitted_parents)

				msg.append("\n")

			sys.stderr.write("".join(msg))
			sys.stderr.flush()

		if "--quiet" not in self._frozen_config.myopts:
			show_blocker_docs_link()

	def display(self, mylist, favorites=[], verbosity=None):

		# This is used to prevent display_problems() from
		# redundantly displaying this exact same merge list
		# again via _show_merge_list().
		self._dynamic_config._displayed_list = mylist

		if verbosity is None:
			verbosity = ("--quiet" in self._frozen_config.myopts and 1 or \
				"--verbose" in self._frozen_config.myopts and 3 or 2)
		favorites_set = InternalPackageSet(favorites)
		oneshot = "--oneshot" in self._frozen_config.myopts or \
			"--onlydeps" in self._frozen_config.myopts
		columns = "--columns" in self._frozen_config.myopts
		tree_display = "--tree" in self._frozen_config.myopts
		changelogs=[]
		p=[]
		blockers = []

		counters = PackageCounters()

		if verbosity == 1 and "--verbose" not in self._frozen_config.myopts:
			def create_use_string(*args):
				return ""
		else:
			def create_use_string(name, cur_iuse, iuse_forced, cur_use,
				old_iuse, old_use,
				is_new, reinst_flags,
				all_flags=(verbosity == 3 or "--quiet" in self._frozen_config.myopts),
				alphabetical=("--alphabetical" in self._frozen_config.myopts)):
				enabled = []
				if alphabetical:
					disabled = enabled
					removed = enabled
				else:
					disabled = []
					removed = []
				cur_iuse = set(cur_iuse)
				enabled_flags = cur_iuse.intersection(cur_use)
				removed_iuse = set(old_iuse).difference(cur_iuse)
				any_iuse = cur_iuse.union(old_iuse)
				any_iuse = list(any_iuse)
				any_iuse.sort()
				for flag in any_iuse:
					flag_str = None
					isEnabled = False
					reinst_flag = reinst_flags and flag in reinst_flags
					if flag in enabled_flags:
						isEnabled = True
						if is_new or flag in old_use and \
							(all_flags or reinst_flag):
							flag_str = red(flag)
						elif flag not in old_iuse:
							flag_str = yellow(flag) + "%*"
						elif flag not in old_use:
							flag_str = green(flag) + "*"
					elif flag in removed_iuse:
						if all_flags or reinst_flag:
							flag_str = yellow("-" + flag) + "%"
							if flag in old_use:
								flag_str += "*"
							flag_str = "(" + flag_str + ")"
							removed.append(flag_str)
						continue
					else:
						if is_new or flag in old_iuse and \
							flag not in old_use and \
							(all_flags or reinst_flag):
							flag_str = blue("-" + flag)
						elif flag not in old_iuse:
							flag_str = yellow("-" + flag)
							if flag not in iuse_forced:
								flag_str += "%"
						elif flag in old_use:
							flag_str = green("-" + flag) + "*"
					if flag_str:
						if flag in iuse_forced:
							flag_str = "(" + flag_str + ")"
						if isEnabled:
							enabled.append(flag_str)
						else:
							disabled.append(flag_str)

				if alphabetical:
					ret = " ".join(enabled)
				else:
					ret = " ".join(enabled + disabled + removed)
				if ret:
					ret = '%s="%s" ' % (name, ret)
				return ret

		repo_display = RepoDisplay(self._frozen_config.roots)
		unsatisfied_blockers = []
		ordered_nodes = []
		for x in mylist:
			if isinstance(x, Blocker):
				counters.blocks += 1
				if x.satisfied:
					ordered_nodes.append(x)
					counters.blocks_satisfied += 1
				else:
					unsatisfied_blockers.append(x)
			else:
				ordered_nodes.append(x)

		if tree_display:
			display_list = self._tree_display(ordered_nodes)
		else:
			display_list = [(x, 0, True) for x in ordered_nodes]

		mylist = display_list
		for x in unsatisfied_blockers:
			mylist.append((x, 0, True))

		# files to fetch list - avoids counting a same file twice
		# in size display (verbose mode)
		myfetchlist=[]

		# Use this set to detect when all the "repoadd" strings are "[0]"
		# and disable the entire repo display in this case.
		repoadd_set = set()

		for mylist_index in range(len(mylist)):
			x, depth, ordered = mylist[mylist_index]
			pkg_type = x[0]
			myroot = x[1]
			pkg_key = x[2]
			portdb = self._frozen_config.trees[myroot]["porttree"].dbapi
			bindb  = self._frozen_config.trees[myroot]["bintree"].dbapi
			vardb = self._frozen_config.trees[myroot]["vartree"].dbapi
			vartree = self._frozen_config.trees[myroot]["vartree"]
			pkgsettings = self._frozen_config.pkgsettings[myroot]

			fetch=" "
			indent = " " * depth

			if isinstance(x, Blocker):
				if x.satisfied:
					blocker_style = "PKG_BLOCKER_SATISFIED"
					addl = "%s  %s  " % (colorize(blocker_style, "b"), fetch)
				else:
					blocker_style = "PKG_BLOCKER"
					addl = "%s  %s  " % (colorize(blocker_style, "B"), fetch)
				resolved = dep_expand(
					str(x.atom).lstrip("!"), mydb=vardb, settings=pkgsettings)
				if "--columns" in self._frozen_config.myopts and "--quiet" in self._frozen_config.myopts:
					addl += " " + colorize(blocker_style, str(resolved))
				else:
					addl = "[%s %s] %s%s" % \
						(colorize(blocker_style, "blocks"),
						addl, indent, colorize(blocker_style, str(resolved)))
				block_parents = self._dynamic_config._blocker_parents.parent_nodes(x)
				block_parents = set([pnode[2] for pnode in block_parents])
				block_parents = ", ".join(block_parents)
				if resolved!=x[2]:
					addl += colorize(blocker_style,
						" (\"%s\" is blocking %s)") % \
						(str(x.atom).lstrip("!"), block_parents)
				else:
					addl += colorize(blocker_style,
						" (is blocking %s)") % block_parents
				if isinstance(x, Blocker) and x.satisfied:
					if columns:
						continue
					p.append(addl)
				else:
					blockers.append(addl)
			else:
				pkg_status = x[3]
				pkg_merge = ordered and pkg_status == "merge"
				if not pkg_merge and pkg_status == "merge":
					pkg_status = "nomerge"
				built = pkg_type != "ebuild"
				installed = pkg_type == "installed"
				pkg = x
				metadata = pkg.metadata
				ebuild_path = None
				repo_name = metadata["repository"]
				if pkg.type_name == "ebuild":
					ebuild_path = portdb.findname(pkg.cpv)
					if ebuild_path is None:
						raise AssertionError(
							"ebuild not found for '%s'" % pkg.cpv)
					repo_path_real = os.path.dirname(os.path.dirname(
						os.path.dirname(ebuild_path)))
				else:
					repo_path_real = portdb.getRepositoryPath(repo_name)
				pkg_use = list(self._pkg_use_enabled(pkg))
				if not pkg.built and pkg.operation == 'merge' and \
					'fetch' in pkg.metadata.restrict:
					fetch = red("F")
					if ordered:
						counters.restrict_fetch += 1
					if portdb.fetch_check(pkg_key, pkg_use):
						fetch = green("f")
						if ordered:
							counters.restrict_fetch_satisfied += 1

				#we need to use "--emptrytree" testing here rather than "empty" param testing because "empty"
				#param is used for -u, where you still *do* want to see when something is being upgraded.
				myoldbest = []
				myinslotlist = None
				installed_versions = vardb.match(portage.cpv_getkey(pkg_key))
				if vardb.cpv_exists(pkg_key):
					addl="  "+yellow("R")+fetch+"  "
					if ordered:
						if pkg_merge:
							counters.reinst += 1
							if pkg_type == "binary":
								counters.binary += 1
						elif pkg_status == "uninstall":
							counters.uninst += 1
				# filter out old-style virtual matches
				elif installed_versions and \
					portage.cpv_getkey(installed_versions[0]) == \
					portage.cpv_getkey(pkg_key):
					myinslotlist = vardb.match(pkg.slot_atom)
					# If this is the first install of a new-style virtual, we
					# need to filter out old-style virtual matches.
					if myinslotlist and \
						portage.cpv_getkey(myinslotlist[0]) != \
						portage.cpv_getkey(pkg_key):
						myinslotlist = None
					if myinslotlist:
						myoldbest = myinslotlist[:]
						addl = "   " + fetch
						if not portage.dep.cpvequal(pkg_key,
							portage.best([pkg_key] + myoldbest)):
							# Downgrade in slot
							addl += turquoise("U")+blue("D")
							if ordered:
								counters.downgrades += 1
								if pkg_type == "binary":
									counters.binary += 1
						else:
							# Update in slot
							addl += turquoise("U") + " "
							if ordered:
								counters.upgrades += 1
								if pkg_type == "binary":
									counters.binary += 1
					else:
						# New slot, mark it new.
						addl = " " + green("NS") + fetch + "  "
						myoldbest = vardb.match(portage.cpv_getkey(pkg_key))
						if ordered:
							counters.newslot += 1
							if pkg_type == "binary":
								counters.binary += 1

					if "--changelog" in self._frozen_config.myopts:
						inst_matches = vardb.match(pkg.slot_atom)
						if inst_matches:
							ebuild_path_cl = ebuild_path
							if ebuild_path_cl is None:
								# binary package
								ebuild_path_cl = portdb.findname(pkg.cpv)

							if ebuild_path_cl is not None:
								changelogs.extend(calc_changelog(
									ebuild_path_cl, inst_matches[0], pkg.cpv))
				else:
					addl = " " + green("N") + " " + fetch + "  "
					if ordered:
						counters.new += 1
						if pkg_type == "binary":
							counters.binary += 1

				verboseadd = ""
				repoadd = None

				if True:
					# USE flag display
					forced_flags = set()
					pkgsettings.setcpv(pkg) # for package.use.{mask,force}
					forced_flags.update(pkgsettings.useforce)
					forced_flags.update(pkgsettings.usemask)

					cur_use = [flag for flag in self._pkg_use_enabled(pkg) \
						if flag in pkg.iuse.all]
					cur_iuse = sorted(pkg.iuse.all)

					if myoldbest and myinslotlist:
						previous_cpv = myoldbest[0]
					else:
						previous_cpv = pkg.cpv
					if vardb.cpv_exists(previous_cpv):
						old_iuse, old_use = vardb.aux_get(
								previous_cpv, ["IUSE", "USE"])
						old_iuse = list(set(
							filter_iuse_defaults(old_iuse.split())))
						old_iuse.sort()
						old_use = old_use.split()
						is_new = False
					else:
						old_iuse = []
						old_use = []
						is_new = True

					old_use = [flag for flag in old_use if flag in old_iuse]

					use_expand = pkgsettings["USE_EXPAND"].lower().split()
					use_expand.sort()
					use_expand.reverse()
					use_expand_hidden = \
						pkgsettings["USE_EXPAND_HIDDEN"].lower().split()

					def map_to_use_expand(myvals, forcedFlags=False,
						removeHidden=True):
						ret = {}
						forced = {}
						for exp in use_expand:
							ret[exp] = []
							forced[exp] = set()
							for val in myvals[:]:
								if val.startswith(exp.lower()+"_"):
									if val in forced_flags:
										forced[exp].add(val[len(exp)+1:])
									ret[exp].append(val[len(exp)+1:])
									myvals.remove(val)
						ret["USE"] = myvals
						forced["USE"] = [val for val in myvals \
							if val in forced_flags]
						if removeHidden:
							for exp in use_expand_hidden:
								ret.pop(exp, None)
						if forcedFlags:
							return ret, forced
						return ret

					# Prevent USE_EXPAND_HIDDEN flags from being hidden if they
					# are the only thing that triggered reinstallation.
					reinst_flags_map = {}
					reinstall_for_flags = self._dynamic_config._reinstall_nodes.get(pkg)
					reinst_expand_map = None
					if reinstall_for_flags:
						reinst_flags_map = map_to_use_expand(
							list(reinstall_for_flags), removeHidden=False)
						for k in list(reinst_flags_map):
							if not reinst_flags_map[k]:
								del reinst_flags_map[k]
						if not reinst_flags_map.get("USE"):
							reinst_expand_map = reinst_flags_map.copy()
							reinst_expand_map.pop("USE", None)
					if reinst_expand_map and \
						not set(reinst_expand_map).difference(
						use_expand_hidden):
						use_expand_hidden = \
							set(use_expand_hidden).difference(
							reinst_expand_map)

					cur_iuse_map, iuse_forced = \
						map_to_use_expand(cur_iuse, forcedFlags=True)
					cur_use_map = map_to_use_expand(cur_use)
					old_iuse_map = map_to_use_expand(old_iuse)
					old_use_map = map_to_use_expand(old_use)

					use_expand.sort()
					use_expand.insert(0, "USE")
					
					for key in use_expand:
						if key in use_expand_hidden:
							continue
						verboseadd += create_use_string(key.upper(),
							cur_iuse_map[key], iuse_forced[key],
							cur_use_map[key], old_iuse_map[key],
							old_use_map[key], is_new,
							reinst_flags_map.get(key))

				if verbosity == 3:
					# size verbose
					mysize=0
					if pkg_type == "ebuild" and pkg_merge:
						try:
							myfilesdict = portdb.getfetchsizes(pkg_key,
								useflags=pkg_use, debug=self._frozen_config.edebug)
						except portage.exception.InvalidDependString as e:
							src_uri = portdb.aux_get(pkg_key, ["SRC_URI"])[0]
							show_invalid_depstring_notice(x, src_uri, str(e))
							del e
							return 1
						if myfilesdict is None:
							myfilesdict="[empty/missing/bad digest]"
						else:
							for myfetchfile in myfilesdict:
								if myfetchfile not in myfetchlist:
									mysize+=myfilesdict[myfetchfile]
									myfetchlist.append(myfetchfile)
							if ordered:
								counters.totalsize += mysize
						verboseadd += format_size(mysize)

					# overlay verbose
					# assign index for a previous version in the same slot
					has_previous = False
					repo_name_prev = None
					slot_matches = vardb.match(pkg.slot_atom)
					if slot_matches:
						has_previous = True
						repo_name_prev = vardb.aux_get(slot_matches[0],
							["repository"])[0]

					# now use the data to generate output
					if pkg.installed or not has_previous:
						repoadd = repo_display.repoStr(repo_path_real)
					else:
						repo_path_prev = None
						if repo_name_prev:
							repo_path_prev = portdb.getRepositoryPath(
								repo_name_prev)
						if repo_path_prev == repo_path_real:
							repoadd = repo_display.repoStr(repo_path_real)
						else:
							repoadd = "%s=>%s" % (
								repo_display.repoStr(repo_path_prev),
								repo_display.repoStr(repo_path_real))
					if repoadd:
						repoadd_set.add(repoadd)

				xs = [portage.cpv_getkey(pkg_key)] + \
					list(portage.catpkgsplit(pkg_key)[2:])
				if xs[2] == "r0":
					xs[2] = ""
				else:
					xs[2] = "-" + xs[2]

				mywidth = 130
				if "COLUMNWIDTH" in self._frozen_config.settings:
					try:
						mywidth = int(self._frozen_config.settings["COLUMNWIDTH"])
					except ValueError as e:
						portage.writemsg("!!! %s\n" % str(e), noiselevel=-1)
						portage.writemsg(
							"!!! Unable to parse COLUMNWIDTH='%s'\n" % \
							self._frozen_config.settings["COLUMNWIDTH"], noiselevel=-1)
						del e
				oldlp = mywidth - 30
				newlp = oldlp - 30

				# Convert myoldbest from a list to a string.
				if not myoldbest:
					myoldbest = ""
				else:
					for pos, key in enumerate(myoldbest):
						key = portage.catpkgsplit(key)[2] + \
							"-" + portage.catpkgsplit(key)[3]
						if key[-3:] == "-r0":
							key = key[:-3]
						myoldbest[pos] = key
					myoldbest = blue("["+", ".join(myoldbest)+"]")

				pkg_cp = xs[0]
				root_config = self._frozen_config.roots[myroot]
				system_set = root_config.sets["system"]
				world_set  = root_config.sets["selected"]

				pkg_system = False
				pkg_world = False
				try:
					pkg_system = system_set.findAtomForPackage(pkg)
					pkg_world  = world_set.findAtomForPackage(pkg)
					if not (oneshot or pkg_world) and \
						myroot == self._frozen_config.target_root and \
						favorites_set.findAtomForPackage(pkg):
						# Maybe it will be added to world now.
						if create_world_atom(pkg, favorites_set, root_config):
							pkg_world = True
				except portage.exception.InvalidDependString:
					# This is reported elsewhere if relevant.
					pass

				def pkgprint(pkg_str):
					if pkg_merge:
						if built:
							if pkg_system:
								return colorize("PKG_BINARY_MERGE_SYSTEM", pkg_str)
							elif pkg_world:
								return colorize("PKG_BINARY_MERGE_WORLD", pkg_str)
							else:
								return colorize("PKG_BINARY_MERGE", pkg_str)
						else:
							if pkg_system:
								return colorize("PKG_MERGE_SYSTEM", pkg_str)
							elif pkg_world:
								return colorize("PKG_MERGE_WORLD", pkg_str)
							else:
								return colorize("PKG_MERGE", pkg_str)
					elif pkg_status == "uninstall":
						return colorize("PKG_UNINSTALL", pkg_str)
					else:
						if pkg_system:
							return colorize("PKG_NOMERGE_SYSTEM", pkg_str)
						elif pkg_world:
							return colorize("PKG_NOMERGE_WORLD", pkg_str)
						else:
							return colorize("PKG_NOMERGE", pkg_str)

				if 'interactive' in pkg.metadata.properties and \
					pkg.operation == 'merge':
					addl = colorize("WARN", "I") + addl[1:]
					if ordered:
						counters.interactive += 1

				if x[1]!="/":
					if myoldbest:
						myoldbest +=" "
					if "--columns" in self._frozen_config.myopts:
						if "--quiet" in self._frozen_config.myopts:
							myprint=addl+" "+indent+pkgprint(pkg_cp)
							myprint=myprint+darkblue(" "+xs[1]+xs[2])+" "
							myprint=myprint+myoldbest
							myprint=myprint+darkgreen("to "+x[1])
							verboseadd = None
						else:
							if not pkg_merge:
								myprint = "[%s] %s%s" % \
									(pkgprint(pkg_status.ljust(13)),
									indent, pkgprint(pkg.cp))
							else:
								myprint = "[%s %s] %s%s" % \
									(pkgprint(pkg.type_name), addl,
									indent, pkgprint(pkg.cp))
							if (newlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(newlp-nc_len(myprint)))
							myprint=myprint+"["+darkblue(xs[1]+xs[2])+"] "
							if (oldlp-nc_len(myprint)) > 0:
								myprint=myprint+" "*(oldlp-nc_len(myprint))
							myprint=myprint+myoldbest
							myprint += darkgreen("to " + pkg.root)
					else:
						if not pkg_merge:
							myprint = "[%s] " % pkgprint(pkg_status.ljust(13))
						else:
							myprint = "[%s %s] " % (pkgprint(pkg_type), addl)
						myprint += indent + pkgprint(pkg_key) + " " + \
							myoldbest + darkgreen("to " + myroot)
				else:
					if "--columns" in self._frozen_config.myopts:
						if "--quiet" in self._frozen_config.myopts:
							myprint=addl+" "+indent+pkgprint(pkg_cp)
							myprint=myprint+" "+green(xs[1]+xs[2])+" "
							myprint=myprint+myoldbest
							verboseadd = None
						else:
							if not pkg_merge:
								myprint = "[%s] %s%s" % \
									(pkgprint(pkg_status.ljust(13)),
									indent, pkgprint(pkg.cp))
							else:
								myprint = "[%s %s] %s%s" % \
									(pkgprint(pkg.type_name), addl,
									indent, pkgprint(pkg.cp))
							if (newlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(newlp-nc_len(myprint)))
							myprint=myprint+green(" ["+xs[1]+xs[2]+"] ")
							if (oldlp-nc_len(myprint)) > 0:
								myprint=myprint+(" "*(oldlp-nc_len(myprint)))
							myprint += myoldbest
					else:
						if not pkg_merge:
							myprint = "[%s] %s%s %s" % \
								(pkgprint(pkg_status.ljust(13)),
								indent, pkgprint(pkg.cpv),
								myoldbest)
						else:
							myprint = "[%s %s] %s%s %s" % \
								(pkgprint(pkg_type), addl, indent,
								pkgprint(pkg.cpv), myoldbest)

				if columns and pkg.operation == "uninstall":
					continue
				p.append((myprint, verboseadd, repoadd))

				if "--tree" not in self._frozen_config.myopts and \
					"--quiet" not in self._frozen_config.myopts and \
					not self._frozen_config._opts_no_restart.intersection(self._frozen_config.myopts) and \
					pkg.root == self._frozen_config._running_root.root and \
					portage.match_from_list(
					portage.const.PORTAGE_PACKAGE_ATOM, [pkg]) and \
					not vardb.cpv_exists(pkg.cpv) and \
					"--quiet" not in self._frozen_config.myopts:
						if mylist_index < len(mylist) - 1:
							p.append(colorize("WARN", "*** Portage will stop merging at this point and reload itself,"))
							p.append(colorize("WARN", "    then resume the merge."))

		show_repos = repoadd_set and repoadd_set != set(["0"])

		for x in p:
			if isinstance(x, basestring):
				writemsg_stdout("%s\n" % (x,), noiselevel=-1)
				continue

			myprint, verboseadd, repoadd = x

			if verboseadd:
				myprint += " " + verboseadd

			if show_repos and repoadd:
				myprint += " " + teal("[%s]" % repoadd)

			writemsg_stdout("%s\n" % (myprint,), noiselevel=-1)

		for x in blockers:
			writemsg_stdout("%s\n" % (x,), noiselevel=-1)

		if verbosity == 3:
			writemsg_stdout('\n%s\n' % (counters,), noiselevel=-1)
			if show_repos:
				# In python-2.x, str() can trigger a UnicodeEncodeError here,
				# so call __str__() directly.
				writemsg_stdout(repo_display.__str__(), noiselevel=-1)

		if "--changelog" in self._frozen_config.myopts:
			writemsg_stdout('\n', noiselevel=-1)
			for revision,text in changelogs:
				writemsg_stdout(bold('*'+revision) + '\n' + text,
					noiselevel=-1)

		return os.EX_OK

	def _tree_display(self, mylist):

		# If there are any Uninstall instances, add the
		# corresponding blockers to the digraph.
		mygraph = self._dynamic_config.digraph.copy()

		executed_uninstalls = set(node for node in mylist \
			if isinstance(node, Package) and node.operation == "unmerge")

		for uninstall in self._dynamic_config._blocker_uninstalls.leaf_nodes():
			uninstall_parents = \
				self._dynamic_config._blocker_uninstalls.parent_nodes(uninstall)
			if not uninstall_parents:
				continue

			# Remove the corresponding "nomerge" node and substitute
			# the Uninstall node.
			inst_pkg = self._pkg(uninstall.cpv, "installed",
				uninstall.root_config, installed=True)

			try:
				mygraph.remove(inst_pkg)
			except KeyError:
				pass

			try:
				inst_pkg_blockers = self._dynamic_config._blocker_parents.child_nodes(inst_pkg)
			except KeyError:
				inst_pkg_blockers = []

			# Break the Package -> Uninstall edges.
			mygraph.remove(uninstall)

			# Resolution of a package's blockers
			# depend on it's own uninstallation.
			for blocker in inst_pkg_blockers:
				mygraph.add(uninstall, blocker)

			# Expand Package -> Uninstall edges into
			# Package -> Blocker -> Uninstall edges.
			for blocker in uninstall_parents:
				mygraph.add(uninstall, blocker)
				for parent in self._dynamic_config._blocker_parents.parent_nodes(blocker):
					if parent != inst_pkg:
						mygraph.add(blocker, parent)

			# If the uninstall task did not need to be executed because
			# of an upgrade, display Blocker -> Upgrade edges since the
			# corresponding Blocker -> Uninstall edges will not be shown.
			upgrade_node = \
				self._dynamic_config._slot_pkg_map[uninstall.root].get(uninstall.slot_atom)
			if upgrade_node is not None and \
				uninstall not in executed_uninstalls:
				for blocker in uninstall_parents:
					mygraph.add(upgrade_node, blocker)

		if "--unordered-display" in self._frozen_config.myopts:
			display_list = self._unordered_tree_display(mygraph, mylist)
		else:
			display_list = self._ordered_tree_display(mygraph, mylist)

		self._prune_tree_display(display_list)

		return display_list

	def _unordered_tree_display(self, mygraph, mylist):
		display_list = []
		seen_nodes = set()

		def print_node(node, depth):

			if node in seen_nodes:
				pass
			else:
				seen_nodes.add(node)

				if isinstance(node, (Blocker, Package)):
					display_list.append((node, depth, True))
				else:
					depth = -1

				for child_node in mygraph.child_nodes(node):
					print_node(child_node, depth + 1)

		for root_node in mygraph.root_nodes():
			print_node(root_node, 0)

		return display_list

	def _ordered_tree_display(self, mygraph, mylist):
		depth = 0
		shown_edges = set()
		tree_nodes = []
		display_list = []

		for x in mylist:
			depth = len(tree_nodes)
			while depth and x not in \
				mygraph.child_nodes(tree_nodes[depth-1]):
					depth -= 1
			if depth:
				tree_nodes = tree_nodes[:depth]
				tree_nodes.append(x)
				display_list.append((x, depth, True))
				shown_edges.add((x, tree_nodes[depth-1]))
			else:
				traversed_nodes = set() # prevent endless circles
				traversed_nodes.add(x)
				def add_parents(current_node, ordered):
					parent_nodes = None
					# Do not traverse to parents if this node is an
					# an argument or a direct member of a set that has
					# been specified as an argument (system or world).
					if current_node not in self._dynamic_config._set_nodes:
						parent_nodes = mygraph.parent_nodes(current_node)
					if parent_nodes:
						child_nodes = set(mygraph.child_nodes(current_node))
						selected_parent = None
						# First, try to avoid a direct cycle.
						for node in parent_nodes:
							if not isinstance(node, (Blocker, Package)):
								continue
							if node not in traversed_nodes and \
								node not in child_nodes:
								edge = (current_node, node)
								if edge in shown_edges:
									continue
								selected_parent = node
								break
						if not selected_parent:
							# A direct cycle is unavoidable.
							for node in parent_nodes:
								if not isinstance(node, (Blocker, Package)):
									continue
								if node not in traversed_nodes:
									edge = (current_node, node)
									if edge in shown_edges:
										continue
									selected_parent = node
									break
						if selected_parent:
							shown_edges.add((current_node, selected_parent))
							traversed_nodes.add(selected_parent)
							add_parents(selected_parent, False)
					display_list.append((current_node,
						len(tree_nodes), ordered))
					tree_nodes.append(current_node)
				tree_nodes = []
				add_parents(x, True)

		return display_list

	def _prune_tree_display(self, display_list):
		last_merge_depth = 0
		for i in range(len(display_list) - 1, -1, -1):
			node, depth, ordered = display_list[i]
			if not ordered and depth == 0 and i > 0 \
				and node == display_list[i-1][0] and \
				display_list[i-1][1] == 0:
				# An ordered node got a consecutive duplicate
				# when the tree was being filled in.
				del display_list[i]
				continue
			if ordered and isinstance(node, Package) \
				and node.operation in ('merge', 'uninstall'):
				last_merge_depth = depth
				continue
			if depth >= last_merge_depth or \
				i < len(display_list) - 1 and \
				depth >= display_list[i+1][1]:
					del display_list[i]

	def display_problems(self):
		"""
		Display problems with the dependency graph such as slot collisions.
		This is called internally by display() to show the problems _after_
		the merge list where it is most likely to be seen, but if display()
		is not going to be called then this method should be called explicitly
		to ensure that the user is notified of problems with the graph.

		All output goes to stderr, except for unsatisfied dependencies which
		go to stdout for parsing by programs such as autounmask.
		"""

		# Note that show_masked_packages() sends it's output to
		# stdout, and some programs such as autounmask parse the
		# output in cases when emerge bails out. However, when
		# show_masked_packages() is called for installed packages
		# here, the message is a warning that is more appropriate
		# to send to stderr, so temporarily redirect stdout to
		# stderr. TODO: Fix output code so there's a cleaner way
		# to redirect everything to stderr.
		sys.stdout.flush()
		sys.stderr.flush()
		stdout = sys.stdout
		try:
			sys.stdout = sys.stderr
			self._display_problems()
		finally:
			sys.stdout = stdout
			sys.stdout.flush()
			sys.stderr.flush()

		# This goes to stdout for parsing by programs like autounmask.
		for pargs, kwargs in self._dynamic_config._unsatisfied_deps_for_display:
			self._show_unsatisfied_dep(*pargs, **kwargs)

	def _display_problems(self):
		if self._dynamic_config._circular_deps_for_display is not None:
			self._show_circular_deps(
				self._dynamic_config._circular_deps_for_display)

		# The user is only notified of a slot conflict if
		# there are no unresolvable blocker conflicts.
		if self._dynamic_config._unsatisfied_blockers_for_display is not None:
			self._show_unsatisfied_blockers(
				self._dynamic_config._unsatisfied_blockers_for_display)
		elif self._dynamic_config._slot_collision_info:
			self._show_slot_collision_notice()
		else:
			self._show_missed_update()

		def get_dep_chain(pkg):
			traversed_nodes = set()
			msg = "#"
			node = pkg
			first = True
			while node is not None:
				traversed_nodes.add(node)
				if node is not pkg:
					if first:
						first = False
					else:
						msg += ", "
					msg += 'required by =%s' % node.cpv
	
				if node not in self._dynamic_config.digraph:
					# The parent is not in the graph due to backtracking.
					break
	
				# When traversing to parents, prefer arguments over packages
				# since arguments are root nodes. Never traverse the same
				# package twice, in order to prevent an infinite loop.
				selected_parent = None
				for parent in self._dynamic_config.digraph.parent_nodes(node):
					if isinstance(parent, DependencyArg):
						if first:
							first = False
						else:
							msg += ", "
						msg += 'required by %s (argument)' % str(parent)
						selected_parent = None
						break
					if parent not in traversed_nodes:
						selected_parent = parent
				node = selected_parent
			msg += "\n"
			return msg

		unstable_keyword_msg = []
		for pkg, changes in self._dynamic_config._needed_user_config_changes.items():
			self._show_merge_list()
			if pkg in self._dynamic_config.digraph.nodes.keys():
				for change in changes:
					if change == "unstable keyword":
						pkgsettings = self._frozen_config.pkgsettings[pkg.root]
						unstable_keyword_msg.append(get_dep_chain(pkg))
						unstable_keyword_msg.append("=%s ~%s\n" % (pkg.cpv, pkgsettings["ACCEPT_KEYWORDS"]))
					else:
						raise NotImplementedError()

		use_changes_msg = []
		for pkg, needed_use_config_change in self._dynamic_config._needed_use_config_changes.items():
			self._show_merge_list()
			if pkg in self._dynamic_config.digraph.nodes.keys():
				changes = needed_use_config_change[1]
				adjustments = []
				for flag, state in changes.items():
					if state:
						adjustments.append(flag)
					else:
						adjustments.append("-" + flag)
				use_changes_msg.append("=%s %s\n" % (pkg.cpv, " ".join(adjustments)))

		if unstable_keyword_msg:
			writemsg_stdout("\nThe following " + colorize("BAD", "keyword changes") + \
				" are necessary to proceed:\n", noiselevel=-1)
			writemsg_stdout("".join(unstable_keyword_msg), noiselevel=-1)

		if use_changes_msg:
			writemsg_stdout("\nThe following " + colorize("BAD", "USE changes") + \
				" are necessary to proceed:\n", noiselevel=-1)
			writemsg_stdout("".join(use_changes_msg), noiselevel=-1)

		# TODO: Add generic support for "set problem" handlers so that
		# the below warnings aren't special cases for world only.

		if self._dynamic_config._missing_args:
			world_problems = False
			if "world" in self._dynamic_config._sets:
				# Filter out indirect members of world (from nested sets)
				# since only direct members of world are desired here.
				world_set = self._frozen_config.roots[self._frozen_config.target_root].sets["selected"]
				for arg, atom in self._dynamic_config._missing_args:
					if arg.name in ("selected", "world") and atom in world_set:
						world_problems = True
						break

			if world_problems:
				sys.stderr.write("\n!!! Problems have been " + \
					"detected with your world file\n")
				sys.stderr.write("!!! Please run " + \
					green("emaint --check world")+"\n\n")

		if self._dynamic_config._missing_args:
			sys.stderr.write("\n" + colorize("BAD", "!!!") + \
				" Ebuilds for the following packages are either all\n")
			sys.stderr.write(colorize("BAD", "!!!") + \
				" masked or don't exist:\n")
			sys.stderr.write(" ".join(str(atom) for arg, atom in \
				self._dynamic_config._missing_args) + "\n")

		if self._dynamic_config._pprovided_args:
			arg_refs = {}
			for arg, atom in self._dynamic_config._pprovided_args:
				if isinstance(arg, SetArg):
					parent = arg.name
					arg_atom = (atom, atom)
				else:
					parent = "args"
					arg_atom = (arg.arg, atom)
				refs = arg_refs.setdefault(arg_atom, [])
				if parent not in refs:
					refs.append(parent)
			msg = []
			msg.append(bad("\nWARNING: "))
			if len(self._dynamic_config._pprovided_args) > 1:
				msg.append("Requested packages will not be " + \
					"merged because they are listed in\n")
			else:
				msg.append("A requested package will not be " + \
					"merged because it is listed in\n")
			msg.append<