| # Copyright 2017 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """Regular expression helpers.""" |
| |
| import re |
| |
| |
| def _CreateIdentifierRegex(parts): |
| assert parts |
| if parts[0]: |
| # Allow word boundary or a _ prefix. |
| prefix_pattern = r'\b_?' |
| else: |
| # Allow word boundary, _, or a case transition. |
| prefix_pattern = r'(?:\b|(?<=_)|(?<=[a-z])(?=[A-Z]))' |
| parts = parts[1:] |
| assert parts |
| |
| if parts[-1]: |
| # Allow word boundary, trailing _, or single trailing digit. |
| suffix_pattern = r'\d?_?\b' |
| else: |
| # Allow word boundary, _, or a case transition. |
| suffix_pattern = r'(?:\b|(?=_|\d)|(?<=[a-z])(?=[A-Z]))' |
| parts = parts[:-1] |
| assert parts |
| |
| shouty_pattern = '_'.join(a.upper() for a in parts) |
| snake_pattern = '_'.join(a.lower() for a in parts) |
| camel_remainder = parts[0][1:] |
| for token in parts[1:]: |
| camel_remainder += token.title() |
| first_letter = parts[0][0] |
| prefixed_pattern = '[a-z]' + first_letter.upper() + camel_remainder |
| camel_pattern = '[%s%s]%s' % (first_letter.lower(), first_letter.upper(), |
| camel_remainder) |
| middle_patterns = '|'.join( |
| (shouty_pattern, snake_pattern, prefixed_pattern, camel_pattern)) |
| return r'(?:%s(?:%s)%s)' % (prefix_pattern, middle_patterns, suffix_pattern) |
| |
| |
| def ExpandRegexIdentifierPlaceholder(pattern): |
| """Expands {{identifier}} within a given regular expression. |
| |
| Returns |pattern|, with the addition that {{some_name}} is expanded to match: |
| SomeName, kSomeName, SOME_NAME, etc. |
| |
| To match part of a name, use {{_some_name_}}. This will additionally match: |
| kPrefixSomeNameSuffix, PREFIX_SOME_NAME_SUFFIX, etc. |
| |
| Note: SymbolGroup.Where* methods call this function already, so there is |
| generally no need to call it directly. |
| """ |
| return re.sub(r'\{\{(.*?)\}\}', |
| lambda m: _CreateIdentifierRegex(m.group(1).split('_')), |
| pattern) |