Clean up and simplify preference selection logic for bug #171840. (trunk r6268:6269)

svn path=/main/branches/2.1.2/; revision=6270

1 files changed, 26 insertions, 47 deletions

diff --git a/pym/portage.py b/pym/portage.py
index 5b2ef1a6..bfe9060d 100644
--- a/pym/portage.py
+++ b/pym/portage.py
@@ -4162,65 +4162,44 @@ def dep_zapdeps(unreduced, reduced, myroot, use_binaries=0, trees=None):
 		else:
 			atoms = [dep]
 
+		if not vardb:
+			# called by repoman
+			other.append((atoms, None, False))
+			continue
+
 		all_available = True
+		versions = {}
 		for atom in atoms:
-			if not mydbapi.match(atom):
+			avail_pkg = best(mydbapi.match(atom))
+			if not avail_pkg and use_binaries:
 				# With --usepkgonly, count installed packages as "available".
 				# Note that --usepkgonly currently has no package.mask support.
 				# See bug #149816.
-				if use_binaries and vardb and vardb.match(atom):
-					continue
+				avail_pkg = best(vardb.match(atom))
+			if not avail_pkg:
 				all_available = False
 				break
-
-		if not vardb:
-			# called by repoman
-			preferred.append((atoms, None, all_available))
-			continue
-
-		""" The package names rather than the exact atoms are used for an
-		initial rough match against installed packages.  More specific
-		preference selection is handled later via slot and version comparison."""
-		all_installed = True
-		for atom in set([dep_getkey(atom) for atom in atoms]):
-			# New-style virtuals have zero cost to install.
-			if not vardb.match(atom) and not atom.startswith("virtual/"):
-				all_installed = False
-				break
-
-		# Check if the set of atoms will result in a downgrade of
-		# an installed package. If they will then don't prefer them
-		# over other atoms.
-		has_downgrade = False
-		versions = {}
-		if all_installed or all_available:
-			for atom in atoms:
-				mykey = dep_getkey(atom)
-				avail_pkg = best(mydbapi.match(atom))
-				if not avail_pkg:
-					continue
-				avail_slot = "%s:%s" % (mykey,
-					mydbapi.aux_get(avail_pkg, ["SLOT"])[0])
-				versions[avail_slot] = avail_pkg
-				inst_pkg = vardb.match(avail_slot)
-				if not inst_pkg:
-					continue
-				# emerge guarantees 1 package per slot here (highest counter)
-				inst_pkg = inst_pkg[0]
-				if avail_pkg != inst_pkg and \
-					avail_pkg != best([avail_pkg, inst_pkg]):
-					has_downgrade = True
-					break
+			avail_slot = "%s:%s" % (dep_getkey(atom),
+				mydbapi.aux_get(avail_pkg, ["SLOT"])[0])
+			versions[avail_slot] = avail_pkg
 
 		this_choice = (atoms, versions, all_available)
-		if not has_downgrade:
+		if all_available:
+			# The "all installed" criterion is not version or slot specific.
+			# If any version of a package is installed then we assume that it
+			# is preferred over other possible packages choices.
+			all_installed = True
+			for atom in set([dep_getkey(atom) for atom in atoms]):
+				# New-style virtuals have zero cost to install.
+				if not vardb.match(atom) and not atom.startswith("virtual/"):
+					all_installed = False
+					break
 			if all_installed:
 				preferred.append(this_choice)
-				continue
-			elif all_available:
+			else:
 				possible_upgrades.append(this_choice)
-				continue
-		other.append(this_choice)
+		else:
+			other.append(this_choice)
 
 	# Compare the "all_installed" choices against the "all_available" choices
 	# for possible missed upgrades.  The main purpose of this code is to find