58 lines
1.7 KiB
Python
58 lines
1.7 KiB
Python
u"""
|
|
Base classes for features that are backwards-incompatible.
|
|
|
|
Usage:
|
|
features = Features()
|
|
features.add(Feature("py3k_feature", "power< 'py3k' any* >", "2.7"))
|
|
PATTERN = features.PATTERN
|
|
"""
|
|
|
|
pattern_unformatted = u"%s=%s" # name=pattern, for dict lookups
|
|
message_unformatted = u"""
|
|
%s is only supported in Python %s and above."""
|
|
|
|
class Feature(object):
|
|
u"""
|
|
A feature has a name, a pattern, and a minimum version of Python 2.x
|
|
required to use the feature (or 3.x if there is no backwards-compatible
|
|
version of 2.x)
|
|
"""
|
|
def __init__(self, name, PATTERN, version):
|
|
self.name = name
|
|
self._pattern = PATTERN
|
|
self.version = version
|
|
|
|
def message_text(self):
|
|
u"""
|
|
Format the above text with the name and minimum version required.
|
|
"""
|
|
return message_unformatted % (self.name, self.version)
|
|
|
|
class Features(set):
|
|
u"""
|
|
A set of features that generates a pattern for the features it contains.
|
|
This set will act like a mapping in that we map names to patterns.
|
|
"""
|
|
mapping = {}
|
|
|
|
def update_mapping(self):
|
|
u"""
|
|
Called every time we care about the mapping of names to features.
|
|
"""
|
|
self.mapping = dict([(f.name, f) for f in iter(self)])
|
|
|
|
@property
|
|
def PATTERN(self):
|
|
u"""
|
|
Uses the mapping of names to features to return a PATTERN suitable
|
|
for using the lib2to3 patcomp.
|
|
"""
|
|
self.update_mapping()
|
|
return u" |\n".join([pattern_unformatted % (f.name, f._pattern) for f in iter(self)])
|
|
|
|
def __getitem__(self, key):
|
|
u"""
|
|
Implement a simple mapping to get patterns from names.
|
|
"""
|
|
return self.mapping[key]
|