text: # Copyright (C) 2009 Google Inc. All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are
  # met:
  #
  #    * Redistributions of source code must retain the above copyright
  # notice, this list of conditions and the following disclaimer.
  #    * Redistributions in binary form must reproduce the above
  # copyright notice, this list of conditions and the following disclaimer
  # in the documentation and/or other materials provided with the
  # distribution.
  #    * Neither the name of Google Inc. nor the names of its
  # contributors may be used to endorse or promote products derived from
  # this software without specific prior written permission.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  """WebKit's Python module for interacting with patches."""
  
  import logging
  import re
  
  _log = logging.getLogger(__name__)
  
  
  # FIXME: This is broken. We should compile our regexps up-front
  # instead of using a custom cache.
  _regexp_compile_cache = {}
  
  
  # FIXME: This function should be removed.
  def match(pattern, string):
      """Matches the string with the pattern, caching the compiled regexp."""
      if not pattern in _regexp_compile_cache:
          _regexp_compile_cache[pattern] = re.compile(pattern)
      return _regexp_compile_cache[pattern].match(string)
  
  
  # FIXME: This belongs on DiffParser (e.g. as to_svn_diff()).
  def git_diff_to_svn_diff(line):
      """Converts a git formatted diff line to a svn formatted line.
  
      Args:
        line: A string representing a line of the diff.
      """
      # FIXME: This list should be a class member on DiffParser.
      # These regexp patterns should be compiled once instead of every time.
      conversion_patterns = (("^diff --git \w/(.+) \w/(?P<FilePath>.+)", lambda matched: "Index: " + matched.group('FilePath') + "\n"),
                             ("^new file.*", lambda matched: "\n"),
                             ("^index [0-9a-f]{7}\.\.[0-9a-f]{7} [0-9]{6}", lambda matched: "===================================================================\n"),
                             ("^--- \w/(?P<FilePath>.+)", lambda matched: "--- " + matched.group('FilePath') + "\n"),
                             ("^\+\+\+ \w/(?P<FilePath>.+)", lambda matched: "+++ " + matched.group('FilePath') + "\n"))
  
      for pattern, conversion in conversion_patterns:
          matched = match(pattern, line)
          if matched:
              return conversion(matched)
      return line
  
  
  # FIXME: This method belongs on DiffParser
  def get_diff_converter(first_diff_line):
      """Gets a converter function of diff lines.
  
      Args:
        first_diff_line: The first filename line of a diff file.
                         If this line is git formatted, we'll return a
                         converter from git to SVN.
      """
      if match(r"^diff --git \w/", first_diff_line):
          return git_diff_to_svn_diff
      return lambda input: input
  
  
  _INITIAL_STATE = 1
  _DECLARED_FILE_PATH = 2
  _PROCESSING_CHUNK = 3
  
  
  class DiffFile(object):
      """Contains the information for one file in a patch.
  
      The field "lines" is a list which contains tuples in this format:
         (deleted_line_number, new_line_number, line_string)
      If deleted_line_number is zero, it means this line is newly added.
      If new_line_number is zero, it means this line is deleted.
      """
      # FIXME: Tuples generally grow into classes.  We should consider
      # adding a DiffLine object.
  
      def added_or_modified_line_numbers(self):
          # This logic was moved from patchreader.py, but may not be
          # the right API for this object long-term.
          return [line[1] for line in self.lines if not line[0]]
  
      def __init__(self, filename):
          self.filename = filename
          self.lines = []
  
      def add_new_line(self, line_number, line):
          self.lines.append((0, line_number, line))
  
      def add_deleted_line(self, line_number, line):
          self.lines.append((line_number, 0, line))
  
      def add_unchanged_line(self, deleted_line_number, new_line_number, line):
          self.lines.append((deleted_line_number, new_line_number, line))
  
  
  # If this is going to be called DiffParser, it should be a re-useable parser.
  # Otherwise we should rename it to ParsedDiff or just Diff.
  class DiffParser(object):
      """A parser for a patch file.
  
      The field "files" is a dict whose key is the filename and value is
      a DiffFile object.
      """
  
      def __init__(self, diff_input):
          """Parses a diff.
  
          Args:
            diff_input: An iterable object.
          """
          self.files = self._parse_into_diff_files(diff_input)
  
      # FIXME: This function is way too long and needs to be broken up.
      def _parse_into_diff_files(self, diff_input):
          files = {}
          state = _INITIAL_STATE
          current_file = None
          old_diff_line = None
          new_diff_line = None
          for line in diff_input:
              line = line.rstrip("\n")
              if state == _INITIAL_STATE:
                  transform_line = get_diff_converter(line)
              line = transform_line(line)
  
              file_declaration = match(r"^Index: (?P<FilePath>.+)", line)
              if file_declaration:
                  filename = file_declaration.group('FilePath')
                  current_file = DiffFile(filename)
                  files[filename] = current_file
                  state = _DECLARED_FILE_PATH
                  continue
  
              lines_changed = match(r"^@@ -(?P<OldStartLine>\d+)(,\d+)? \+(?P<NewStartLine>\d+)(,\d+)? @@", line)
              if lines_changed:
                  if state != _DECLARED_FILE_PATH and state != _PROCESSING_CHUNK:
                      _log.error('Unexpected line change without file path '
                                 'declaration: %r' % line)
                  old_diff_line = int(lines_changed.group('OldStartLine'))
                  new_diff_line = int(lines_changed.group('NewStartLine'))
                  state = _PROCESSING_CHUNK
                  continue
  
              if state == _PROCESSING_CHUNK:
                  if line.startswith('+'):
                      current_file.add_new_line(new_diff_line, line[1:])
                      new_diff_line += 1
                  elif line.startswith('-'):
                      current_file.add_deleted_line(old_diff_line, line[1:])
                      old_diff_line += 1
                  elif line.startswith(' '):
                      current_file.add_unchanged_line(old_diff_line, new_diff_line, line[1:])
                      old_diff_line += 1
                      new_diff_line += 1
                  elif line == '\\ No newline at end of file':
                      # Nothing to do.  We may still have some added lines.
                      pass
                  else:
                      _log.error('Unexpected diff format when parsing a '
                                 'chunk: %r' % line)
          return files
  