Initial source commit to grit-i18n project.

grit/gather/tr_html.py

+#!/usr/bin/python2.4
+# Copyright (c) 2006-2008 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.
+
+'''A gatherer for the TotalRecall brand of HTML templates with replaceable
+portions.  We wanted to reuse extern.tclib.api.handlers.html.TCHTMLParser
+but this proved impossible due to the fact that the TotalRecall HTML templates
+are in general quite far from parseable HTML and the TCHTMLParser derives
+from HTMLParser.HTMLParser which requires relatively well-formed HTML.  Some
+examples of "HTML" from the TotalRecall HTML templates that wouldn't be
+parseable include things like:
+
+  <a [PARAMS]>blabla</a>  (not parseable because attributes are invalid)
+
+  <table><tr><td>[LOTSOFSTUFF]</tr></table> (not parseable because closing
+                                            </td> is in the HTML [LOTSOFSTUFF]
+                                            is replaced by)
+
+The other problem with using general parsers (such as TCHTMLParser) is that
+we want to make sure we output the TotalRecall template with as little changes
+as possible in terms of whitespace characters, layout etc.  With any parser
+that generates a parse tree, and generates output by dumping the parse tree,
+we would always have little inconsistencies which could cause bugs (the
+TotalRecall template stuff is quite brittle and can break if e.g. a tab
+character is replaced with spaces).
+
+The solution, which may be applicable to some other HTML-like template
+languages floating around Google, is to create a parser with a simple state
+machine that keeps track of what kind of tag it's inside, and whether it's in
+a translateable section or not.  Translateable sections are:
+
+a) text (including [BINGO] replaceables) inside of tags that
+   can contain translateable text (which is all tags except
+   for a few)
+
+b) text inside of an 'alt' attribute in an <image> element, or
+   the 'value' attribute of a <submit>, <button> or <text>
+   element.
+
+The parser does not build up a parse tree but rather a "skeleton" which
+is a list of nontranslateable strings intermingled with grit.clique.MessageClique
+objects.  This simplifies the parser considerably compared to a regular HTML
+parser.  To output a translated document, each item in the skeleton is
+printed out, with the relevant Translation from each MessageCliques being used
+for the requested language.
+
+This implementation borrows some code, constants and ideas from
+extern.tclib.api.handlers.html.TCHTMLParser.
+'''
+
+
+import re
+import types
+
+from grit import clique
+from grit import exception
+from grit import util
+from grit import tclib
+
+from grit.gather import interface
+
+
+# HTML tags which break (separate) chunks.
+_BLOCK_TAGS = ['script', 'p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'br',
+              'body', 'style', 'head', 'title', 'table', 'tr', 'td', 'th',
+              'ul', 'ol', 'dl', 'nl', 'li', 'div', 'object', 'center',
+              'html', 'link', 'form', 'select', 'textarea',
+              'button', 'option', 'map', 'area', 'blockquote', 'pre',
+              'meta', 'xmp', 'noscript', 'label', 'tbody', 'thead',
+              'script', 'style', 'pre', 'iframe', 'img', 'input', 'nowrap']
+
+# HTML tags which may appear within a chunk.
+_INLINE_TAGS = ['b', 'i', 'u', 'tt', 'code', 'font', 'a', 'span', 'small',
+               'key', 'nobr', 'url', 'em', 's', 'sup', 'strike',
+               'strong']
+
+# HTML tags within which linebreaks are significant.
+_PREFORMATTED_TAGS = ['textarea', 'xmp', 'pre']
+
+# An array mapping some of the inline HTML tags to more meaningful
+# names for those tags.  This will be used when generating placeholders
+# representing these tags.
+_HTML_PLACEHOLDER_NAMES = { 'a' : 'link', 'br' : 'break', 'b' : 'bold',
+  'i' : 'italic', 'li' : 'item', 'ol' : 'ordered_list', 'p' : 'paragraph',
+  'ul' : 'unordered_list', 'img' : 'image', 'em' : 'emphasis' }
+
+# We append each of these characters in sequence to distinguish between
+# different placeholders with basically the same name (e.g. BOLD1, BOLD2).
+# Keep in mind that a placeholder name must not be a substring of any other
+# placeholder name in the same message, so we can't simply count (BOLD_1
+# would be a substring of BOLD_10).
+_SUFFIXES = '123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+
+# Matches whitespace in an HTML document.  Also matches HTML comments, which are
+# treated as whitespace.
+_WHITESPACE = re.compile(r'(\s|&nbsp;|\\n|\\r|<!--\s*desc\s*=.*?-->)+',
+                         re.DOTALL)
+
+# Finds a non-whitespace character
+_NON_WHITESPACE = re.compile(r'\S')
+
+# Matches two or more &nbsp; in a row (a single &nbsp is not changed into
+# placeholders because different languages require different numbers of spaces
+# and placeholders must match exactly; more than one is probably a "special"
+# whitespace sequence and should be turned into a placeholder).
+_NBSP = re.compile(r'&nbsp;(&nbsp;)+')
+
+# Matches nontranslateable chunks of the document
+_NONTRANSLATEABLES = re.compile(r'''
+  <\s*script.+?<\s*/\s*script\s*>
+  |
+  <\s*style.+?<\s*/\s*style\s*>
+  |
+  <!--.+?-->
+  |
+  <\?IMPORT\s.+?>           # import tag
+  |
+  <\s*[a-zA-Z_]+:.+?>       # custom tag (open)
+  |
+  <\s*/\s*[a-zA-Z_]+:.+?>   # custom tag (close)
+  |
+  <!\s*[A-Z]+\s*([^>]+|"[^"]+"|'[^']+')*?>
+  ''', re.MULTILINE | re.DOTALL | re.VERBOSE | re.IGNORECASE)
+
+# Matches a tag and its attributes
+_ELEMENT = re.compile(r'''
+  # Optional closing /, element name
+  <\s*(?P<closing>/)?\s*(?P<element>[a-zA-Z0-9]+)\s*
+  # Attributes and/or replaceables inside the tag, if any
+  (?P<atts>(
+    \s*([a-zA-Z_][-:.a-zA-Z_0-9]*) # Attribute name
+    (\s*=\s*(\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~\'"@]*))?
+    |
+    \s*\[(\$?\~)?([A-Z0-9-_]+?)(\~\$?)?\]
+  )*)
+  \s*(?P<empty>/)?\s*> # Optional empty-tag closing /, and tag close
+  ''',
+  re.MULTILINE | re.DOTALL | re.VERBOSE)
+
+# Matches elements that may have translateable attributes.  The value of these
+# special attributes is given by group 'value1' or 'value2'.  Note that this
+# regexp demands that the attribute value be quoted; this is necessary because
+# the non-tree-building nature of the parser means we don't know when we're
+# writing out attributes, so we wouldn't know to escape spaces.
+_SPECIAL_ELEMENT = re.compile(r'''
+  <\s*(
+    input[^>]+?value\s*=\s*(\'(?P<value3>[^\']*)\'|"(?P<value4>[^"]*)")
+    [^>]+type\s*=\s*"?'?(button|reset|text|submit)'?"?
+    |
+    (
+      table[^>]+?title\s*=
+      |
+      img[^>]+?alt\s*=
+      |
+      input[^>]+?type\s*=\s*"?'?(button|reset|text|submit)'?"?[^>]+?value\s*=
+    )
+    \s*(\'(?P<value1>[^\']*)\'|"(?P<value2>[^"]*)")
+  )[^>]*?>
+  ''', re.MULTILINE | re.DOTALL | re.VERBOSE | re.IGNORECASE)
+
+# Matches stuff that is translateable if it occurs in the right context
+# (between tags).  This includes all characters and character entities.
+# Note that this also matches &nbsp; which needs to be handled as whitespace
+# before this regexp is applied.
+_CHARACTERS = re.compile(r'''
+  (
+    \w
+    |
+    [\!\@\#\$\%\^\*\(\)\-\=\_\+\[\]\{\}\\\|\;\:\'\"\,\.\/\?\`\~]
+    |
+    &(\#[0-9]+|\#x[0-9a-fA-F]+|[A-Za-z0-9]+);
+  )+
+  ''', re.MULTILINE | re.DOTALL | re.VERBOSE)
+
+# Matches Total Recall's "replaceable" tags, which are just any text
+# in capitals enclosed by delimiters like [] or [~~] or [$~~$] (e.g. [HELLO],
+# [~HELLO~] and [$~HELLO~$]).
+_REPLACEABLE = re.compile(r'\[(\$?\~)?(?P<name>[A-Z0-9-_]+?)(\~\$?)?\]',
+                          re.MULTILINE)
+
+
+# Matches the silly [!]-prefixed "header" that is used in some TotalRecall
+# templates.
+_SILLY_HEADER = re.compile(r'\[!\]\ntitle\t(?P<title>[^\n]+?)\n.+?\n\n',
+                           re.MULTILINE | re.DOTALL)
+
+
+# Matches a comment that provides a description for the message it occurs in.
+_DESCRIPTION_COMMENT = re.compile(
+  r'<!--\s*desc\s*=\s*(?P<description>.+?)\s*-->', re.DOTALL)
+
+
+_DEBUG = 0
+def _DebugPrint(text):
+  if _DEBUG:
+    print text.encode('utf-8')
+
+
+class HtmlChunks(object):
+  '''A parser that knows how to break an HTML-like document into a list of
+  chunks, where each chunk is either translateable or non-translateable.
+  The chunks are unmodified sections of the original document, so concatenating
+  the text of all chunks would result in the original document.'''
+
+  def InTranslateable(self):
+    return self.last_translateable != -1
+
+  def Rest(self):
+    return self.text_[self.current:]
+
+  def StartTranslateable(self):
+    assert not self.InTranslateable()
+    if self.current != 0:
+      # Append a nontranslateable chunk
+      chunk_text = self.text_[self.chunk_start : self.last_nontranslateable + 1]
+      # Needed in the case where document starts with a translateable.
+      if len(chunk_text) > 0:
+        self.AddChunk(False, chunk_text)
+    self.chunk_start = self.last_nontranslateable + 1
+    self.last_translateable = self.current
+    self.last_nontranslateable = -1
+
+  def EndTranslateable(self):
+    assert self.InTranslateable()
+    # Append a translateable chunk
+    self.AddChunk(True,
+                  self.text_[self.chunk_start : self.last_translateable + 1])
+    self.chunk_start = self.last_translateable + 1
+    self.last_translateable = -1
+    self.last_nontranslateable = self.current
+
+  def AdvancePast(self, match):
+    self.current += match.end()
+
+  def AddChunk(self, translateable, text):
+    '''Adds a chunk to self, removing linebreaks and duplicate whitespace
+    if appropriate.
+    '''
+    if translateable and not self.last_element_ in _PREFORMATTED_TAGS:
+      text = text.replace('\n', ' ')
+      text = text.replace('\r', ' ')
+      text = text.replace('   ', ' ')
+      text = text.replace('  ', ' ')
+
+    m = _DESCRIPTION_COMMENT.search(text)
+    if m:
+      self.last_description = m.group('description')
+      # remove the description from the output text
+      text = _DESCRIPTION_COMMENT.sub('', text)
+
+    if translateable:
+      description = self.last_description
+      self.last_description = ''
+    else:
+      description = ''
+
+    if text != '':
+      self.chunks_.append((translateable, text, description))
+
+  def Parse(self, text):
+    '''Parses self.text_ into an intermediate format stored in self.chunks_
+    which is translateable and nontranslateable chunks.  Also returns
+    self.chunks_
+
+    Return:
+      [chunk1, chunk2, chunk3, ...]  (instances of class Chunk)
+    '''
+    #
+    # Chunker state
+    #
+
+    self.text_ = text
+
+    # A list of tuples (is_translateable, text) which represents the document
+    # after chunking.
+    self.chunks_ = []
+
+    # Start index of the last chunk, whether translateable or not
+    self.chunk_start = 0
+
+    # Index of the last for-sure translateable character if we are parsing
+    # a translateable chunk, -1 to indicate we are not in a translateable chunk.
+    # This is needed so that we don't include trailing whitespace in the
+    # translateable chunk (whitespace is neutral).
+    self.last_translateable = -1
+
+    # Index of the last for-sure nontranslateable character if we are parsing
+    # a nontranslateable chunk, -1 if we are not in a nontranslateable chunk.
+    # This is needed to make sure we can group e.g. "<b>Hello</b> there"
+    # together instead of just "Hello</b> there" which would be much worse
+    # for translation.
+    self.last_nontranslateable = -1
+
+    # Index of the character we're currently looking at.
+    self.current = 0
+
+    # The name of the last block element parsed.
+    self.last_element_ = ''
+
+    # The last explicit description we found.
+    self.last_description = ''
+
+    while self.current < len(self.text_):
+      _DebugPrint('REST: %s' % self.text_[self.current:self.current+60])
+
+      # First try to match whitespace
+      m = _WHITESPACE.match(self.Rest())
+      if m:
+        # Whitespace is neutral, it just advances 'current' and does not switch
+        # between translateable/nontranslateable.  If we are in a
+        # nontranslateable section that extends to the current point, we extend
+        # it to include the whitespace.  If we are in a translateable section,
+        # we do not extend it until we find
+        # more translateable parts, because we never want a translateable chunk
+        # to end with whitespace.
+        if (not self.InTranslateable() and
+            self.last_nontranslateable == self.current - 1):
+          self.last_nontranslateable = self.current + m.end() - 1
+        self.AdvancePast(m)
+        continue
+
+      # Then we try to match nontranslateables
+      m = _NONTRANSLATEABLES.match(self.Rest())
+      if m:
+        if self.InTranslateable():
+          self.EndTranslateable()
+        self.last_nontranslateable = self.current + m.end() - 1
+        self.AdvancePast(m)
+        continue
+
+      # Now match all other HTML element tags (opening, closing, or empty, we
+      # don't care).
+      m = _ELEMENT.match(self.Rest())
+      if m:
+        element_name = m.group('element').lower()
+        if element_name in _BLOCK_TAGS:
+          self.last_element_ = element_name
+          if self.InTranslateable():
+            self.EndTranslateable()
+
+          # Check for "special" elements, i.e. ones that have a translateable
+          # attribute, and handle them correctly.  Note that all of the
+          # "special" elements are block tags, so no need to check for this
+          # if the tag is not a block tag.
+          sm = _SPECIAL_ELEMENT.match(self.Rest())
+          if sm:
+            # Get the appropriate group name
+            for group in sm.groupdict().keys():
+              if sm.groupdict()[group]:
+                break
+
+            # First make a nontranslateable chunk up to and including the
+            # quote before the translateable attribute value
+            self.AddChunk(False, self.text_[
+              self.chunk_start : self.current + sm.start(group)])
+            # Then a translateable for the translateable bit
+            self.AddChunk(True, self.Rest()[sm.start(group) : sm.end(group)])
+            # Finally correct the data invariant for the parser
+            self.chunk_start = self.current + sm.end(group)
+
+          self.last_nontranslateable = self.current + m.end() - 1
+        elif self.InTranslateable():
+          # We're in a translateable and the tag is an inline tag, so we
+          # need to include it in the translateable.
+          self.last_translateable = self.current + m.end() - 1
+        self.AdvancePast(m)
+        continue
+
+      # Anything else we find must be translateable, so we advance one character
+      # at a time until one of the above matches.
+      if not self.InTranslateable():
+        self.StartTranslateable()
+      else:
+        self.last_translateable = self.current
+      self.current += 1
+
+    # Close the final chunk
+    if self.InTranslateable():
+      self.AddChunk(True, self.text_[self.chunk_start : ])
+    else:
+      self.AddChunk(False, self.text_[self.chunk_start : ])
+
+    return self.chunks_
+
+
+def HtmlToMessage(html, include_block_tags=False, description=''):
+  '''Takes a bit of HTML, which must contain only "inline" HTML elements,
+  and changes it into a tclib.Message.  This involves escaping any entities and
+  replacing any HTML code with placeholders.
+
+  If include_block_tags is true, no error will be given if block tags (e.g.
+  <p> or <br>) are included in the HTML.
+
+  Args:
+    html: 'Hello <b>[USERNAME]</b>, how&nbsp;<i>are</i> you?'
+    include_block_tags: False
+
+  Return:
+    tclib.Message('Hello START_BOLD1USERNAMEEND_BOLD, '
+                  'howNBSPSTART_ITALICareEND_ITALIC you?',
+                  [ Placeholder('START_BOLD', '<b>', ''),
+                    Placeholder('USERNAME', '[USERNAME]', ''),
+                    Placeholder('END_BOLD', '</b>', ''),
+                    Placeholder('START_ITALIC', '<i>', ''),
+                    Placeholder('END_ITALIC', '</i>', ''), ])
+  '''
+  # Approach is:
+  # - first placeholderize, finding <elements>, [REPLACEABLES] and &nbsp;
+  # - then escape all character entities in text in-between placeholders
+
+  parts = []  # List of strings (for text chunks) and tuples (ID, original)
+              # for placeholders
+
+  count_names = {}  # Map of base names to number of times used
+  end_names = {}  # Map of base names to stack of end tags (for correct nesting)
+
+  def MakeNameClosure(base, type = ''):
+    '''Returns a closure that can be called once all names have been allocated
+    to return the final name of the placeholder.  This allows us to minimally
+    number placeholders for non-overlap.
+
+    Also ensures that END_XXX_Y placeholders have the same Y as the
+    corresponding BEGIN_XXX_Y placeholder when we have nested tags of the same
+    type.
+
+    Args:
+      base: 'phname'
+      type: '' | 'begin' | 'end'
+
+    Return:
+      Closure()
+    '''
+    name = base
+    if type != '':
+      name = ('%s_%s' % (type, base)).upper()
+
+    if name in count_names.keys():
+      count_names[name] += 1
+    else:
+      count_names[name] = 1
+
+    def MakeFinalName(name_ = name, index = count_names[name] - 1):
+      if (type.lower() == 'end' and
+          base in end_names.keys() and len(end_names[base])):
+        return end_names[base].pop(-1)  # For correct nesting
+      if count_names[name_] != 1:
+        name_ = '%s_%s' % (name_, _SUFFIXES[index])
+        # We need to use a stack to ensure that the end-tag suffixes match
+        # the begin-tag suffixes.  Only needed when more than one tag of the
+        # same type.
+        if type == 'begin':
+          end_name = ('END_%s_%s' % (base, _SUFFIXES[index])).upper()
+          if base in end_names.keys():
+            end_names[base].append(end_name)
+          else:
+            end_names[base] = [end_name]
+
+      return name_
+
+    return MakeFinalName
+
+  current = 0
+
+  while current < len(html):
+    m = _NBSP.match(html[current:])
+    if m:
+      parts.append((MakeNameClosure('SPACE'), m.group()))
+      current += m.end()
+      continue
+
+    m = _REPLACEABLE.match(html[current:])
+    if m:
+      # Replaceables allow - but placeholders don't, so replace - with _
+      ph_name = MakeNameClosure('X_%s_X' % m.group('name').replace('-', '_'))
+      parts.append((ph_name, m.group()))
+      current += m.end()
+      continue
+
+    m = _SPECIAL_ELEMENT.match(html[current:])
+    if m:
+      if not include_block_tags:
+        raise exception.BlockTagInTranslateableChunk(html)
+      element_name = 'block'  # for simplification
+      # Get the appropriate group name
+      for group in m.groupdict().keys():
+        if m.groupdict()[group]:
+          break
+      parts.append((MakeNameClosure(element_name, 'begin'),
+                    html[current : current + m.start(group)]))
+      parts.append(m.group(group))
+      parts.append((MakeNameClosure(element_name, 'end'),
+                    html[current + m.end(group) : current + m.end()]))
+      current += m.end()
+      continue
+
+    m = _ELEMENT.match(html[current:])
+    if m:
+      element_name = m.group('element').lower()
+      if not include_block_tags and not element_name in _INLINE_TAGS:
+        raise exception.BlockTagInTranslateableChunk(html[current:])
+      if element_name in _HTML_PLACEHOLDER_NAMES:  # use meaningful names
+        element_name = _HTML_PLACEHOLDER_NAMES[element_name]
+
+      # Make a name for the placeholder
+      type = ''
+      if not m.group('empty'):
+        if m.group('closing'):
+          type = 'end'
+        else:
+          type = 'begin'
+      parts.append((MakeNameClosure(element_name, type), m.group()))
+      current += m.end()
+      continue
+
+    if len(parts) and isinstance(parts[-1], types.StringTypes):
+      parts[-1] += html[current]
+    else:
+      parts.append(html[current])
+    current += 1
+
+  msg_text = ''
+  placeholders = []
+  for part in parts:
+    if isinstance(part, types.TupleType):
+      final_name = part[0]()
+      original = part[1]
+      msg_text += final_name
+      placeholders.append(tclib.Placeholder(final_name, original, '(HTML code)'))
+    else:
+      msg_text += part
+
+  msg = tclib.Message(text=msg_text, placeholders=placeholders,
+                      description=description)
+  content = msg.GetContent()
+  for ix in range(len(content)):
+    if isinstance(content[ix], types.StringTypes):
+      content[ix] = util.UnescapeHtml(content[ix], replace_nbsp=False)
+
+  return msg
+
+
+class TrHtml(interface.GathererBase):
+  '''Represents a document or message in the template format used by
+  Total Recall for HTML documents.'''
+
+  def __init__(self, text):
+    '''Creates a new object that represents 'text'.
+    Args:
+      text: '<html>...</html>'
+    '''
+    super(type(self), self).__init__()
+
+    self.text_ = text
+    self.have_parsed_ = False
+    self.skeleton_ = []  # list of strings and MessageClique objects
+
+  def GetText(self):
+    '''Returns the original text of the HTML document'''
+    return self.text_
+
+  def GetCliques(self):
+    '''Returns the message cliques for each translateable message in the
+    document.'''
+    return filter(lambda x: isinstance(x, clique.MessageClique), self.skeleton_)
+
+  def Translate(self, lang, pseudo_if_not_available=True,
+                skeleton_gatherer=None, fallback_to_english=False):
+    '''Returns this document with translateable messages filled with
+    the translation for language 'lang'.
+
+    Args:
+      lang: 'en'
+      pseudo_if_not_available: True
+
+    Return:
+      'ID_THIS_SECTION TYPE\n...BEGIN\n  "Translated message"\n......\nEND
+
+    Raises:
+      grit.exception.NotReady() if used before Parse() has been successfully
+      called.
+      grit.exception.NoSuchTranslation() if 'pseudo_if_not_available' is false
+      and there is no translation for the requested language.
+    '''
+    if len(self.skeleton_) == 0:
+      raise exception.NotReady()
+
+    # TODO(joi) Implement support for skeleton gatherers here.
+
+    out = []
+    for item in self.skeleton_:
+      if isinstance(item, types.StringTypes):
+        out.append(item)
+      else:
+        msg = item.MessageForLanguage(lang,
+                                      pseudo_if_not_available,
+                                      fallback_to_english)
+        for content in msg.GetContent():
+          if isinstance(content, tclib.Placeholder):
+            out.append(content.GetOriginal())
+          else:
+            # We escape " characters to increase the chance that attributes
+            # will be properly escaped.
+            out.append(util.EscapeHtml(content, True))
+
+    return ''.join(out)
+
+
+  # Parsing is done in two phases:  First, we break the document into
+  # translateable and nontranslateable chunks.  Second, we run through each
+  # translateable chunk and insert placeholders for any HTML elements, unescape
+  # escaped characters, etc.
+  def Parse(self):
+    if self.have_parsed_:
+      return
+    self.have_parsed_ = True
+
+    text = self.text_
+
+    # First handle the silly little [!]-prefixed header because it's not
+    # handled by our HTML parsers.
+    m = _SILLY_HEADER.match(text)
+    if m:
+      self.skeleton_.append(text[:m.start('title')])
+      self.skeleton_.append(self.uberclique.MakeClique(
+        tclib.Message(text=text[m.start('title'):m.end('title')])))
+      self.skeleton_.append(text[m.end('title') : m.end()])
+      text = text[m.end():]
+
+    chunks = HtmlChunks().Parse(text)
+
+    for chunk in chunks:
+      if chunk[0]:  # Chunk is translateable
+        self.skeleton_.append(self.uberclique.MakeClique(
+          HtmlToMessage(chunk[1], description=chunk[2])))
+      else:
+        self.skeleton_.append(chunk[1])
+
+    # Go through the skeleton and change any messages that consist solely of
+    # placeholders and whitespace into nontranslateable strings.
+    for ix in range(len(self.skeleton_)):
+      got_text = False
+      if isinstance(self.skeleton_[ix], clique.MessageClique):
+        msg = self.skeleton_[ix].GetMessage()
+        for item in msg.GetContent():
+          if (isinstance(item, types.StringTypes) and _NON_WHITESPACE.search(item)
+              and item != '&nbsp;'):
+            got_text = True
+            break
+        if not got_text:
+          self.skeleton_[ix] = msg.GetRealContent()
+
+
+  # Static method
+  def FromFile(html, extkey=None, encoding = 'utf-8'):
+    '''Creates a TrHtml object from the contents of 'html' which are decoded
+    using 'encoding'.  Returns a new TrHtml object, upon which Parse() has not
+    been called.
+
+    Args:
+      html: file('') | 'filename.html'
+      extkey: ignored
+      encoding: 'utf-8' (note that encoding is ignored if 'html' is not a file
+                         name but instead an open file or file-like object)
+
+    Return:
+      TrHtml(text_of_file)
+    '''
+    if isinstance(html, types.StringTypes):
+      html = util.WrapInputStream(file(html, 'r'), encoding)
+    doc = html.read()
+
+    # Ignore the BOM character if the document starts with one.
+    if len(doc) and doc[0] == u'\ufeff':
+      doc = doc[1:]
+
+    return TrHtml(doc)
+  FromFile = staticmethod(FromFile)
+