1# Copyright 2013 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"""Updates ExtensionFunctions enum in histograms.xml file with values read from
6extension_function_histogram_value.h.
7
8If the file was pretty-printed, the updated version is pretty-printed too.
9"""
10
11import logging
12import re
13import sys
14
15from xml.dom import minidom
16
17from diffutil import PromptUserToAcceptDiff
18from pretty_print import PrettyPrintNode
19
20HISTOGRAMS_PATH = 'histograms.xml'
21ENUM_NAME = 'ExtensionFunctions'
22
23EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH = \
24  '../../../chrome/browser/extensions/extension_function_histogram_value.h'
25ENUM_START_MARKER = "^enum HistogramValue {"
26ENUM_END_MARKER = "^ENUM_BOUNDARY"
27
28
29class UserError(Exception):
30  def __init__(self, message):
31    Exception.__init__(self, message)
32
33  @property
34  def message(self):
35    return self.args[0]
36
37def ExtractRegexGroup(line, regex):
38    m = re.match(regex, line)
39    if m:
40      return m.group(1)
41    else:
42      return None
43
44
45def ReadHistogramValues(filename):
46  """Returns a list of pairs (label, value) corresponding to HistogramValue.
47
48  Reads the extension_functions_histogram_value.h file, locates the
49  HistogramValue enum definition and returns a pair for each entry.
50  """
51
52  # Read the file as a list of lines
53  with open(filename) as f:
54    content = f.readlines()
55
56  # Locate the enum definition and collect all entries in it
57  inside_enum = False # We haven't found the enum definition yet
58  result = []
59  for line in content:
60    line = line.strip()
61    if inside_enum:
62      # Exit condition: we reached last enum value
63      if re.match(ENUM_END_MARKER, line):
64        inside_enum = False
65      else:
66        # Inside enum: generate new xml entry
67        label = ExtractRegexGroup(line.strip(), "^([\w]+)")
68        if label:
69          result.append((label, enum_value))
70          enum_value += 1
71    else:
72      if re.match(ENUM_START_MARKER, line):
73        inside_enum = True
74        enum_value = 0 # Start at 'UNKNOWN'
75  return result
76
77
78def UpdateHistogramDefinitions(histogram_values, document):
79  """Sets the children of <enum name="ExtensionFunctions" ...> node in
80  |document| to values generated from policy ids contained in
81  |policy_templates|.
82
83  Args:
84    histogram_values: A list of pairs (label, value) defining each extension
85                      function
86    document: A minidom.Document object representing parsed histogram
87              definitions XML file.
88
89  """
90  # Find ExtensionFunctions enum.
91  for enum_node in document.getElementsByTagName('enum'):
92    if enum_node.attributes['name'].value == ENUM_NAME:
93        extension_functions_enum_node = enum_node
94        break
95  else:
96    raise UserError('No policy enum node found')
97
98  # Remove existing values.
99  while extension_functions_enum_node.hasChildNodes():
100    extension_functions_enum_node.removeChild(
101      extension_functions_enum_node.lastChild)
102
103  # Add a "Generated from (...)" comment
104  comment = ' Generated from {0} '.format(
105    EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
106  extension_functions_enum_node.appendChild(document.createComment(comment))
107
108  # Add values generated from policy templates.
109  for (label, value) in histogram_values:
110    node = document.createElement('int')
111    node.attributes['value'] = str(value)
112    node.attributes['label'] = label
113    extension_functions_enum_node.appendChild(node)
114
115def Log(message):
116  logging.info(message)
117
118def main():
119  if len(sys.argv) > 1:
120    print >>sys.stderr, 'No arguments expected!'
121    sys.stderr.write(__doc__)
122    sys.exit(1)
123
124  Log('Reading histogram enum definition from "%s".'
125      % (EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH))
126  histogram_values = ReadHistogramValues(
127    EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
128
129  Log('Reading existing histograms from "%s".' % (HISTOGRAMS_PATH))
130  with open(HISTOGRAMS_PATH, 'rb') as f:
131    histograms_doc = minidom.parse(f)
132    f.seek(0)
133    xml = f.read()
134
135  Log('Comparing histograms enum with new enum definition.')
136  UpdateHistogramDefinitions(histogram_values, histograms_doc)
137
138  Log('Writing out new histograms file.')
139  new_xml = PrettyPrintNode(histograms_doc)
140  if PromptUserToAcceptDiff(xml, new_xml, 'Is the updated version acceptable?'):
141    with open(HISTOGRAMS_PATH, 'wb') as f:
142      f.write(new_xml)
143
144  Log('Done.')
145
146
147if __name__ == '__main__':
148  main()
149