# encoding: utf-8
"""
This module provides the base definition for patterns.
"""
import re
from .compat import unicode
class Pattern(object):
"""
The :class:`Pattern` class is the abstract definition of a pattern.
"""
# Make the class dict-less.
__slots__ = ('include',)
def __init__(self, include):
"""
Initializes the :class:`Pattern` instance.
*include* (:class:`bool` or :data:`None`) is whether the matched
files should be included (:data:`True`), excluded (:data:`False`),
or is a null-operation (:data:`None`).
"""
self.include = include
"""
*include* (:class:`bool` or :data:`None`) is whether the matched
files should be included (:data:`True`), excluded (:data:`False`),
or is a null-operation (:data:`None`).
"""
def match(self, files):
"""
Matches this pattern against the specified files.
*files* (:class:`~collections.abc.Iterable` of :class:`str`) contains
each file relative to the root directory (e.g., ``"relative/path/to/file"``).
Returns an :class:`~collections.abc.Iterable` yielding each matched
file path (:class:`str`).
"""
raise NotImplementedError("{0}.{1} must override match().".format(self.__class__.__module__, self.__class__.__name__))
class RegexPattern(Pattern):
"""
The :class:`RegexPattern` class is an implementation of a pattern
using regular expressions.
"""
# Make the class dict-less.
__slots__ = ('regex',)
def __init__(self, pattern, include=None):
"""
Initializes the :class:`RegexPattern` instance.
*pattern* (:class:`unicode`, :class:`bytes`, :class:`re.RegexObject`,
or :data:`None`) is the pattern to compile into a regular
expression.
*include* (:class:`bool` or :data:`None`) must be :data:`None`
unless *pattern* is a precompiled regular expression (:class:`re.RegexObject`)
in which case it is whether matched files should be included
(:data:`True`), excluded (:data:`False`), or is a null operation
(:data:`None`).
.. NOTE:: Subclasses do not need to support the *include*
parameter.
"""
self.regex = None
"""
*regex* (:class:`re.RegexObject`) is the regular expression for the
pattern.
"""
if isinstance(pattern, (unicode, bytes)):
assert include is None, "include:{0!r} must be null when pattern:{1!r} is a string.".format(include, pattern)
regex, include = self.pattern_to_regex(pattern)
# NOTE: Make sure to allow a null regular expression to be
# returned for a null-operation.
if include is not None:
regex = re.compile(regex)
elif pattern is not None and hasattr(pattern, 'match'):
# Assume pattern is a precompiled regular expression.
# - NOTE: Used specified *include*.
regex = pattern
elif pattern is None:
# NOTE: Make sure to allow a null pattern to be passed for a
# null-operation.
assert include is None, "include:{0!r} must be null when pattern:{1!r} is null.".format(include, pattern)
else:
raise TypeError("pattern:{0!r} is not a string, RegexObject, or None.".format(pattern))
super(RegexPattern, self).__init__(include)
self.regex = regex
def __eq__(self, other):
"""
Tests the equality of this regex pattern with *other* (:class:`RegexPattern`)
by comparing their :attr:`~Pattern.include` and :attr:`~RegexPattern.regex`
attributes.
"""
if isinstance(other, RegexPattern):
return self.include == other.include and self.regex == other.regex
else:
return NotImplemented
def match(self, files):
"""
Matches this pattern against the specified files.
*files* (:class:`~collections.abc.Iterable` of :class:`str`)
contains each file relative to the root directory (e.g., "relative/path/to/file").
Returns an :class:`~collections.abc.Iterable` yielding each matched
file path (:class:`str`).
"""
if self.include is not None:
for path in files:
if self.regex.match(path) is not None:
yield path
@classmethod
def pattern_to_regex(cls, pattern):
"""
Convert the pattern into an uncompiled regular expression.
*pattern* (:class:`str`) is the pattern to convert into a regular
expression.
Returns the uncompiled regular expression (:class:`str` or :data:`None`),
and whether matched files should be included (:data:`True`),
excluded (:data:`False`), or is a null-operation (:data:`None`).
.. NOTE:: The default implementation simply returns *pattern* and
:data:`True`.
"""
return pattern, True
