In find_unmapped_histograms.py, remove comments from histogram names

tools/metrics/histograms/find_unmapped_histograms.py

 # Copyright 2013 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.
 
 """Scans the Chromium source for histograms that are absent from histograms.xml.
 
 This is a heuristic scan, so a clean run of this script does not guarantee that
 all histograms in the Chromium source are properly mapped.  Notably, field
 trials are entirely ignored by this script.
 
 """
 
 import hashlib
 import logging
 import optparse
 import os
 import re
 import subprocess
 import sys
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
 import path_util
 
 import extract_histograms
 
 
+CPP_COMMENT = re.compile(r"""
+    \s*             # Optional whitespace
+    (?:             # Non-capturing group
+        //.*        # C++-style comment
+        \n          # Newline
+        |           # or
+        /\*         # Start C-style comment
+        (?:         # Non-capturing group
+            (?!\*/) # Negative lookahead for comment end
+            [\s\S]  # Any character including newline
+        )*          # Repeated zero or more times
+        \*/         # End C-style comment
+    )               # End group
+    \s*             # Optional whitespace
+    """, re.VERBOSE);
 ADJACENT_C_STRING_REGEX = re.compile(r"""
     ("      # Opening quotation mark
     [^"]*)  # Literal string contents
     "       # Closing quotation mark
     \s*     # Any number of spaces
     "       # Another opening quotation mark
     """, re.VERBOSE)
 CONSTANT_REGEX = re.compile(r"""
     (\w*::)*  # Optional namespace(s)
     k[A-Z]    # Match a constant identifier: 'k' followed by an uppercase letter
@@ skipping 35 matching lines @@
 
 class DirectoryNotFoundException(Exception):
   """Base class to distinguish locally defined exceptions from standard ones."""
   def __init__(self, msg):
     self.msg = msg
 
   def __str__(self):
     return self.msg
 
 
+def removeComments(string):
+  """Remove any comments from an expression, including leading and trailing
+  whitespace. This does not correctly ignore comments embedded in strings,
+  but that shouldn't matter for this script.
+
+  Args:
+    string: The string to remove comments from, e.g.
+    '  // My histogram\n   "My.Important.Counts" '
+
+  Returns:
+    The string with comments removed, e.g. '"My.Important.Counts" '
+  """
+  return CPP_COMMENT.sub('', string)
+
+
 def collapseAdjacentCStrings(string):
   """Collapses any adjacent C strings into a single string.
 
   Useful to re-combine strings that were split across multiple lines to satisfy
   the 80-col restriction.
 
   Args:
     string: The string to recombine, e.g. '"Foo"\n    "bar"'
 
   Returns:
@@ skipping 67 matching lines @@
 
   histograms = set()
   location_map = dict()
   for filename in filenames:
     contents = ''
     with open(filename, 'r') as f:
       contents = f.read()
 
     for match in HISTOGRAM_REGEX.finditer(contents):
       histogram = collapseAdjacentCStrings(match.group(1))
+      histogram = removeComments(histogram)
 
       # Must begin and end with a quotation mark.
       if not histogram or histogram[0] != '"' or histogram[-1] != '"':
         logNonLiteralHistogram(filename, histogram)
         continue
 
       # Must not include any quotation marks other than at the beginning or end.
       histogram_stripped = histogram.strip('"')
       if '"' in histogram_stripped:
         logNonLiteralHistogram(filename, histogram)
@@ skipping 96 matching lines @@
         logging.info('%s: %s - %s', location_map[histogram], histogram,
                      hashHistogramName(histogram))
       else:
         logging.info('  %s - %s', histogram, hashHistogramName(histogram))
   else:
     logging.info('Success!  No unmapped histograms found.')
 
 
 if __name__ == '__main__':
   main()