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# Copyright 2014 Google Inc.
#
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Miscellaneous utilities."""
import re
class ReSearch(object):
"""A collection of static methods for regexing things."""
@staticmethod
def search_within_stream(input_stream, pattern, default=None):
"""Search for regular expression in a file-like object.
Opens a file for reading and searches line by line for a match to
the regex and returns the parenthesized group named return for the
first match. Does not search across newlines.
For example:
pattern = '^root(:[^:]*){4}:(?P<return>[^:]*)'
with open('/etc/passwd', 'r') as stream:
return search_within_file(stream, pattern)
should return root's home directory (/root on my system).
Args:
input_stream: file-like object to be read
pattern: (string) to be passed to re.compile
default: what to return if no match
Returns:
A string or whatever default is
"""
pattern_object = re.compile(pattern)
for line in input_stream:
match = pattern_object.search(line)
if match:
return match.group('return')
return default
@staticmethod
def search_within_string(input_string, pattern, default=None):
"""Search for regular expression in a string.
Args:
input_string: (string) to be searched
pattern: (string) to be passed to re.compile
default: what to return if no match
Returns:
A string or whatever default is
"""
match = re.search(pattern, input_string)
return match.group('return') if match else default
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