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"""
Package source manager is responsible for selecting the correct source
for a requested package, by a provided string.
Package sources can provide several handlers with different priorities.
A handler is a String -> Result function, which tries to parse the passed
value and return Ok(value).
The package would be handled by the handler with the lowest priority, which
was added the first.
Example:
@dispatcher.source
class BgoSource():
@dispatcher.handler(priority=5)
def parse_int(uri):
if uri.is_decimal():
return Result.Ok(int(uri))
elif uri[0] == '#' and uri[1:].is_decimal():
return Result.Ok(int(uri[1:]))
return Result.Err('NaN')
@dispatcher.handler(priority=1)
def parse_url(uri):
if uri.startswith('http://bugs.gentoo.org/'):
...
"""
#TODO: efficient sorted insertion
#import bisect
import inspect
class PackageDispatcher():
def __init__(self):
self.handlers = []
def source(self, cls):
for m, obj in inspect.getmembers(cls):
if isinstance(obj, self.handler._handler):
self.register_package_handler(cls, obj.handler, obj.priority)
return cls
class handler():
class _handler():
def __init__(self, handler):
self.handler = handler
def __call__(self, *args):
return self.handler(*args)
def __init__(self, priority=1000, *args, **kwargs):
self.priority = priority
def __call__(self, func, *args, **kwargs):
x = self._handler(func)
x.priority = self.priority
return x
def register_package_handler(self, source, handler, priority):
i = 0
for i in range(len(self.handlers)):
if self.handlers[0] > priority:
break
self.handlers.insert(i, (priority, source, handler))
def get_package_source(self, uri):
for priority, source, handler in self.handlers:
if handler(uri).is_ok():
return source
return None
|
GitWeb
