1# Copyright 2014 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5
6def RegexCheck(re, line_number, line, regex, msg):
7  """Searches for |regex| in |line| to check for a particular style
8     violation, returning a message like the one below if the regex matches.
9     The |regex| must have exactly one capturing group so that the relevant
10     part of |line| can be highlighted. If more groups are needed, use
11     "(?:...)" to make a non-capturing group. Sample message:
12
13       line 6: Use var instead of const.
14           const foo = bar();
15           ^^^^^
16  """
17
18  def _highlight(match):
19    """Takes a start position and a length, and produces a row of '^'s to
20       highlight the corresponding part of a string.
21    """
22    return match.start(1) * ' ' + (match.end(1) - match.start(1)) * '^'
23
24  match = re.search(regex, line)
25  if match:
26    assert len(match.groups()) == 1
27    return '  line %d: %s\n%s\n%s' % (line_number, msg, line, _highlight(match))
28  return ''
29