tools/metrics/histograms/pretty_print.py

#!/usr/bin/env python
# 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.

"""Pretty-prints the histograms.xml file, alphabetizing tags, wrapping text
at 80 chars, enforcing standard attribute ordering, and standardizing
indentation.

This is quite a bit more complicated than just calling tree.toprettyxml();
we need additional customization, like special attribute ordering in tags
and wrapping text nodes, so we implement our own full custom XML pretty-printer.
"""

from __future__ import with_statement

import logging
import os
import shutil
import sys

sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
import diff_util
import presubmit_util

import etree_util
import histograms_print_style

class Error(Exception):
  pass

UNIT_REWRITES = {
  'microsecond': 'microseconds',
  'us': 'microseconds',
  'millisecond': 'ms',
  'milliseconds': 'ms',
  'kb': 'KB',
  'kB': 'KB',
  'kilobytes': 'KB',
  'kbits/s': 'kbps',
  'mb': 'MB',
  'mB': 'MB',
  'megabytes': 'MB',
  'mbits/s': 'mbps',
  'percent': '%',
  'Percent': '%',
  'percentage': '%',
}

def canonicalizeUnits(tree):
  """Canonicalize the spelling of certain units in histograms."""
  if tree.tag == 'histogram':
    units = tree.get('units')
    if units and units in UNIT_REWRITES:
      tree.set('units', UNIT_REWRITES[units])

  for child in tree:
    canonicalizeUnits(child)

def fixObsoleteOrder(tree):
  """Put obsolete tags at the beginning of histogram tags."""
  obsoletes = []

  for child in tree:
    if child.tag == 'obsolete':
      obsoletes.append(child)
    else:
      fixObsoleteOrder(child)

  for obsolete in obsoletes:
    tree.remove(obsolete)

  # Only keep the first obsolete tag.
  if obsoletes:
    tree.insert(0, obsoletes[0])

def DropNodesByTagName(tree, tag):
  """Drop all nodes with named tag from the XML tree."""
  removes = []

  for child in tree:
    if child.tag == tag:
      removes.append(child)
    else:
      DropNodesByTagName(child, tag)

  for child in removes:
    tree.remove(child)

def PrettyPrintHistograms(raw_xml):
  """Pretty-print the given histograms XML.

  Args:
    raw_xml: The contents of the histograms XML file, as a string.

  Returns:
    The pretty-printed version.
  """
  top_level_content = etree_util.GetTopLevelContent(raw_xml)
  root = etree_util.ParseXMLString(raw_xml)
  return top_level_content + PrettyPrintHistogramsTree(root)

def PrettyPrintHistogramsTree(tree):
  """Pretty-print the given ElementTree element.

  Args:
    tree: The ElementTree element.

  Returns:
    The pretty-printed version as an XML string.
  """
  # Prevent accidentally adding enums to histograms.xml
  DropNodesByTagName(tree, 'enums')
  canonicalizeUnits(tree)
  fixObsoleteOrder(tree)
  return histograms_print_style.GetPrintStyle().PrettyPrintXml(tree)

def PrettyPrintEnums(raw_xml):
  """Pretty print the given enums XML."""

  root = etree_util.ParseXMLString(raw_xml)

  # Prevent accidentally adding histograms to enums.xml
  DropNodesByTagName(root, 'histograms')
  DropNodesByTagName(root, 'histogram_suffixes_list')

  top_level_content = etree_util.GetTopLevelContent(raw_xml)

  formatted_xml = (histograms_print_style.GetPrintStyle()
                  .PrettyPrintXml(root))
  return top_level_content + formatted_xml

def main():
  status1 = presubmit_util.DoPresubmit(sys.argv, 'enums.xml',
                                       'enums.before.pretty-print.xml',
                                       'pretty_print.py', PrettyPrintEnums)
  status2 = presubmit_util.DoPresubmit(sys.argv, 'histograms.xml',
                                        'histograms.before.pretty-print.xml',
                                        'pretty_print.py',
                                        PrettyPrintHistograms)
  sys.exit(status1 or status2)

if __name__ == '__main__':
  main()