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      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 """Updates MappedEditingCommands enum in histograms.xml file with values read
      6  from EditorCommand.cpp.
      7 
      8 If the file was pretty-printed, the updated version is pretty-printed too.
      9 """
     10 
     11 import logging
     12 import os
     13 import re
     14 import sys
     15 
     16 from xml.dom import minidom
     17 
     18 from diffutil import PromptUserToAcceptDiff
     19 import print_style
     20 
     21 # Import the metrics/common module.
     22 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
     23 from diff_util import PromptUserToAcceptDiff
     24 
     25 HISTOGRAMS_PATH = 'histograms.xml'
     26 ENUM_NAME = 'MappedEditingCommands'
     27 
     28 EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH = \
     29   '../../../third_party/WebKit/Source/core/editing/EditorCommand.cpp'
     30 ENUM_START_MARKER = "^    static const CommandEntry commands\[\] = {"
     31 ENUM_END_MARKER = "^    };"
     32 
     33 
     34 class UserError(Exception):
     35   def __init__(self, message):
     36     Exception.__init__(self, message)
     37 
     38   @property
     39   def message(self):
     40     return self.args[0]
     41 
     42 
     43 def ReadHistogramValues(filename):
     44   """Returns a list of pairs (label, value) corresponding to HistogramValue.
     45 
     46   Reads the EditorCommand.cpp file, locates the
     47   HistogramValue enum definition and returns a pair for each entry.
     48   """
     49 
     50   # Read the file as a list of lines
     51   with open(filename) as f:
     52     content = f.readlines()
     53 
     54   # Locate the enum definition and collect all entries in it
     55   inside_enum = False # We haven't found the enum definition yet
     56   result = []
     57   for line in content:
     58     if inside_enum:
     59       # Exit condition: we reached last enum value
     60       if re.match(ENUM_END_MARKER, line):
     61         inside_enum = False
     62       else:
     63           # Inside enum: generate new xml entry
     64         m = re.match("^{ \"([\w]+)\", \{([\w]+)", line.strip())
     65         if m:
     66           result.append((m.group(1), int(m.group(2))))
     67     else:
     68       if re.match(ENUM_START_MARKER, line):
     69         inside_enum = True
     70         enum_value = 0 # Start at 'UNKNOWN'
     71   return sorted(result, key=lambda pair: pair[1])
     72 
     73 
     74 def UpdateHistogramDefinitions(histogram_values, document):
     75   """Sets the children of <enum name="ExtensionFunctions" ...> node in
     76   |document| to values generated from policy ids contained in
     77   |policy_templates|.
     78 
     79   Args:
     80     histogram_values: A list of pairs (label, value) defining each extension
     81                       function
     82     document: A minidom.Document object representing parsed histogram
     83               definitions XML file.
     84 
     85   """
     86   # Find ExtensionFunctions enum.
     87   for enum_node in document.getElementsByTagName('enum'):
     88     if enum_node.attributes['name'].value == ENUM_NAME:
     89         extension_functions_enum_node = enum_node
     90         break
     91   else:
     92     raise UserError('No policy enum node found')
     93 
     94   # Remove existing values.
     95   while extension_functions_enum_node.hasChildNodes():
     96     extension_functions_enum_node.removeChild(
     97       extension_functions_enum_node.lastChild)
     98 
     99   # Add a "Generated from (...)" comment
    100   comment = ' Generated from {0} '.format(
    101     EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
    102   extension_functions_enum_node.appendChild(document.createComment(comment))
    103 
    104   # Add values generated from policy templates.
    105   for (label, value) in histogram_values:
    106     node = document.createElement('int')
    107     node.attributes['value'] = str(value)
    108     node.attributes['label'] = label
    109     extension_functions_enum_node.appendChild(node)
    110 
    111 def Log(message):
    112   logging.info(message)
    113 
    114 def main():
    115   if len(sys.argv) > 1:
    116     print >>sys.stderr, 'No arguments expected!'
    117     sys.stderr.write(__doc__)
    118     sys.exit(1)
    119 
    120   Log('Reading histogram enum definition from "%s".'
    121       % (EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH))
    122   histogram_values = ReadHistogramValues(
    123     EXTENSION_FUNCTIONS_HISTOGRAM_VALUE_PATH)
    124 
    125   Log('Reading existing histograms from "%s".' % (HISTOGRAMS_PATH))
    126   with open(HISTOGRAMS_PATH, 'rb') as f:
    127     histograms_doc = minidom.parse(f)
    128     f.seek(0)
    129     xml = f.read()
    130 
    131   Log('Comparing histograms enum with new enum definition.')
    132   UpdateHistogramDefinitions(histogram_values, histograms_doc)
    133 
    134   Log('Writing out new histograms file.')
    135   new_xml = print_style.GetPrintStyle().PrettyPrintNode(histograms_doc)
    136   if PromptUserToAcceptDiff(xml, new_xml, 'Is the updated version acceptable?'):
    137     with open(HISTOGRAMS_PATH, 'wb') as f:
    138       f.write(new_xml)
    139 
    140   Log('Done.')
    141 
    142 
    143 if __name__ == '__main__':
    144   main()
    145