tools/metrics/histograms/pretty_print.py

   1 #!/usr/bin/env python
   2 # Copyright 2013 The Chromium Authors. All rights reserved.
   3 # Use of this source code is governed by a BSD-style license that can be
   4 # found in the LICENSE file.
   5
   6 """Pretty-prints the histograms.xml file, alphabetizing tags, wrapping text
   7 at 80 chars, enforcing standard attribute ordering, and standardizing
   8 indentation.
   9
  10 This is quite a bit more complicated than just calling tree.toprettyxml();
  11 we need additional customization, like special attribute ordering in tags
  12 and wrapping text nodes, so we implement our own full custom XML pretty-printer.
  13 """
  14
  15 from __future__ import with_statement
  16
  17 import logging
  18 import os
  19 import shutil
  20 import sys
  21 import xml.dom.minidom
  22
  23 import print_style
  24
  25 sys.path.insert(1, os.path.join(sys.path[0], '..', '..', 'python'))
  26 from google import path_utils
  27
  28 # Import the metrics/common module.
  29 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
  30 import diff_util
  31
  32 # Tags whose children we want to alphabetize. The key is the parent tag name,
  33 # and the value is a pair of the tag name of the children we want to sort,
  34 # and a key function that maps each child node to the desired sort key.
  35 ALPHABETIZATION_RULES = {
  36   'histograms': ('histogram', lambda n: n.attributes['name'].value.lower()),
  37   'enums': ('enum', lambda n: n.attributes['name'].value.lower()),
  38   'enum': ('int', lambda n: int(n.attributes['value'].value)),
  39   'histogram_suffixes_list': (
  40       'histogram_suffixes', lambda n: n.attributes['name'].value.lower()),
  41   'histogram_suffixes': ('affected-histogram',
  42                          lambda n: n.attributes['name'].value.lower()),
  43   # TODO(yiyaoliu): Remove fieldtrial related pieces when it is not used.
  44   'fieldtrials': ('fieldtrial', lambda n: n.attributes['name'].value.lower()),
  45   'fieldtrial': ('affected-histogram',
  46                  lambda n: n.attributes['name'].value.lower()),
  47 }
  48
  49
  50 class Error(Exception):
  51   pass
  52
  53
  54 def unsafeAppendChild(parent, child):
  55   """Append child to parent's list of children, ignoring the possibility that it
  56   is already in another node's childNodes list.  Requires that the previous
  57   parent of child is discarded (to avoid non-tree DOM graphs).
  58   This can provide a significant speedup as O(n^2) operations are removed (in
  59   particular, each child insertion avoids the need to traverse the old parent's
  60   entire list of children)."""
  61   child.parentNode = None
  62   parent.appendChild(child)
  63   child.parentNode = parent
  64
  65
  66 def TransformByAlphabetizing(node):
  67   """Transform the given XML by alphabetizing specific node types according to
  68   the rules in ALPHABETIZATION_RULES.
  69
  70   Args:
  71     node: The minidom node to transform.
  72
  73   Returns:
  74     The minidom node, with children appropriately alphabetized. Note that the
  75     transformation is done in-place, i.e. the original minidom tree is modified
  76     directly.
  77   """
  78   if node.nodeType != xml.dom.minidom.Node.ELEMENT_NODE:
  79     for c in node.childNodes: TransformByAlphabetizing(c)
  80     return node
  81
  82   # Element node with a tag name that we alphabetize the children of?
  83   if node.tagName in ALPHABETIZATION_RULES:
  84     # Put subnodes in a list of node,key pairs to allow for custom sorting.
  85     subtag, key_function = ALPHABETIZATION_RULES[node.tagName]
  86     subnodes = []
  87     last_key = -1
  88     for c in node.childNodes:
  89       if (c.nodeType == xml.dom.minidom.Node.ELEMENT_NODE and
  90           c.tagName == subtag):
  91         last_key = key_function(c)
  92       # Subnodes that we don't want to rearrange use the last node's key,
  93       # so they stay in the same relative position.
  94       subnodes.append( (c, last_key) )
  95
  96     # Sort the subnode list.
  97     subnodes.sort(key=lambda pair: pair[1])
  98
  99     # Re-add the subnodes, transforming each recursively.
 100     while node.firstChild:
 101       node.removeChild(node.firstChild)
 102     for (c, _) in subnodes:
 103       unsafeAppendChild(node, TransformByAlphabetizing(c))
 104     return node
 105
 106   # Recursively handle other element nodes and other node types.
 107   for c in node.childNodes: TransformByAlphabetizing(c)
 108   return node
 109
 110
 111 def PrettyPrint(raw_xml):
 112   """Pretty-print the given XML.
 113
 114   Args:
 115     raw_xml: The contents of the histograms XML file, as a string.
 116
 117   Returns:
 118     The pretty-printed version.
 119   """
 120   tree = xml.dom.minidom.parseString(raw_xml)
 121   tree = TransformByAlphabetizing(tree)
 122   return print_style.GetPrintStyle().PrettyPrintNode(tree)
 123
 124
 125 def main():
 126   logging.basicConfig(level=logging.INFO)
 127
 128   presubmit = ('--presubmit' in sys.argv)
 129
 130   histograms_filename = 'histograms.xml'
 131   histograms_backup_filename = 'histograms.before.pretty-print.xml'
 132
 133   # If there is a histograms.xml in the current working directory, use that.
 134   # Otherwise, use the one residing in the same directory as this script.
 135   histograms_dir = os.getcwd()
 136   if not os.path.isfile(os.path.join(histograms_dir, histograms_filename)):
 137     histograms_dir = path_utils.ScriptDir()
 138
 139   histograms_pathname = os.path.join(histograms_dir, histograms_filename)
 140   histograms_backup_pathname = os.path.join(histograms_dir,
 141                                             histograms_backup_filename)
 142
 143   logging.info('Loading %s...' % os.path.relpath(histograms_pathname))
 144   with open(histograms_pathname, 'rb') as f:
 145     xml = f.read()
 146
 147   # Check there are no CR ('\r') characters in the file.
 148   if '\r' in xml:
 149     logging.info('DOS-style line endings (CR characters) detected - these are '
 150                  'not allowed. Please run dos2unix %s' % histograms_filename)
 151     sys.exit(1)
 152
 153   logging.info('Pretty-printing...')
 154   try:
 155     pretty = PrettyPrint(xml)
 156   except Error:
 157     logging.error('Aborting parsing due to fatal errors.')
 158     sys.exit(1)
 159
 160   if xml == pretty:
 161     logging.info('%s is correctly pretty-printed.' % histograms_filename)
 162     sys.exit(0)
 163   if presubmit:
 164     logging.info('%s is not formatted correctly; run pretty_print.py to fix.' %
 165                  histograms_filename)
 166     sys.exit(1)
 167   if not diff_util.PromptUserToAcceptDiff(
 168       xml, pretty,
 169       'Is the prettified version acceptable?'):
 170     logging.error('Aborting')
 171     return
 172
 173   logging.info('Creating backup file %s' % histograms_backup_filename)
 174   shutil.move(histograms_pathname, histograms_backup_pathname)
 175
 176   logging.info('Writing new %s file' % histograms_filename)
 177   with open(histograms_pathname, 'wb') as f:
 178     f.write(pretty)
 179
 180
 181 if __name__ == '__main__':
 182   main()