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