Histograms.xml python script housekeeping

tools/metrics/histograms/update_histogram_enum.py

 # Copyright 2014 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.
 
 """Updates enums in histograms.xml file with values read from provided C++ enum.
 
 If the file was pretty-printed, the updated version is pretty-printed too.
 """
 
 import logging
 import os
 import print_style
 import re
 import sys
 
 from xml.dom import minidom
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
 from diff_util import PromptUserToAcceptDiff
 
+import histograms_path
+
 class UserError(Exception):
   def __init__(self, message):
     Exception.__init__(self, message)
 
   @property
   def message(self):
     return self.args[0]
 
 
 def Log(message):
   logging.info(message)
 
 
 def ReadHistogramValues(filename, start_marker, end_marker):
-  """Reads in values from |filename|, returning a dictionary mapping value to
-  label corresponding to the enum framed by |start_marker| and |end_marker|.
+  """Returns a dictionary of enum values, read from a C++ file.
+
+  Args:
+      filename: The unix-style path (relative to src/) of the file to open.
+      start_marker: A regex that signifies the start of the enum values.
+      end_marker: A regex that signifies the end of the enum values.
   """
   # Read the file as a list of lines
-  with open(filename) as f:
+  with open(histograms_path.GetInputFile(filename)) as f:
     content = f.readlines()
 
   START_REGEX = re.compile(start_marker)
   ITEM_REGEX = re.compile(r'^(\w+)')
   ITEM_REGEX_WITH_INIT = re.compile(r'(\w+)\s*=\s*(\d+)')
   END_REGEX = re.compile(end_marker)
 
   # Locate the enum definition and collect all entries in it
   inside_enum = False # We haven't found the enum definition yet
   result = {}
@@ skipping 86 matching lines @@
     enum_node.appendChild(new_item_nodes[value])
 
 
 def UpdateHistogramFromDict(histogram_enum_name, source_enum_values,
                             source_enum_path):
   """Updates |histogram_enum_name| enum in histograms.xml file with values
   from the {value: 'key'} dictionary |source_enum_values|. A comment is added
   to histograms.xml citing that the values in |histogram_enum_name| were
   sourced from |source_enum_path|.
   """
-  # TODO(ahernandez.miralles): The line below is present in nearly every
-  # file in this directory; factor out into a central location
-  HISTOGRAMS_PATH = 'histograms.xml'
+
+  HISTOGRAMS_PATH = histograms_path.GetHistogramsFile()
 
   Log('Reading existing histograms from "{0}".'.format(HISTOGRAMS_PATH))
   with open(HISTOGRAMS_PATH, 'rb') as f:
     histograms_doc = minidom.parse(f)
     f.seek(0)
     xml = f.read()
 
   Log('Comparing histograms enum with new enum definition.')
   UpdateHistogramDefinitions(histogram_enum_name, source_enum_values,
                              source_enum_path, histograms_doc)
 
   Log('Writing out new histograms file.')
   new_xml = print_style.GetPrintStyle().PrettyPrintNode(histograms_doc)
   if not PromptUserToAcceptDiff(
       xml, new_xml, 'Is the updated version acceptable?'):
     Log('Cancelled.')
     return
 
   with open(HISTOGRAMS_PATH, 'wb') as f:
     f.write(new_xml)
 
   Log('Done.')
 
 
 def UpdateHistogramEnum(histogram_enum_name, source_enum_path,
                         start_marker, end_marker):
-  """Updates |histogram_enum_name| enum in histograms.xml file with values
-  read from |source_enum_path|, where |start_marker| and |end_marker| indicate
-  the beginning and end of the source enum definition, respectively.
+  """Reads a C++ enum from a .h file and updates histograms.xml to match.
+
+  Args:
+      histogram_enum_name: The name of the XML <enum> attribute to update.
+      source_enum_path: A unix-style path, relative to src/, giving
+          the C++ header file from which to read the enum.
+      start_marker: A regular expression that matches the start of the C++ enum.
+      end_marker: A regular expression that matches the end of the C++ enum.
   """
 
   Log('Reading histogram enum definition from "{0}".'.format(source_enum_path))
   source_enum_values = ReadHistogramValues(source_enum_path, start_marker,
                                            end_marker)
 
   UpdateHistogramFromDict(histogram_enum_name, source_enum_values,
       source_enum_path)