content: # This module contains abstractions for the input stream. You don't have to
  # looks further, there are no pretty code.
  #
  # We define two classes here.
  #
  #   Mark(source, line, column)
  # It's just a record and its only use is producing nice error messages.
  # Parser does not use it for any other purposes.
  #
  #   Reader(source, data)
  # Reader determines the encoding of `data` and converts it to unicode.
  # Reader provides the following methods and attributes:
  #   reader.peek(length=1) - return the next `length` characters
  #   reader.forward(length=1) - move the current position to `length` characters.
  #   reader.index - the number of the current character.
  #   reader.line, stream.column - the line and the column of the current character.
  
  __all__ = ['Reader', 'ReaderError']
  
  from error import YAMLError, Mark
  
  import codecs, re
  
  class ReaderError(YAMLError):
  
      def __init__(self, name, position, character, encoding, reason):
          self.name = name
          self.character = character
          self.position = position
          self.encoding = encoding
          self.reason = reason
  
      def __str__(self):
          if isinstance(self.character, str):
              return "'%s' codec can't decode byte #x%02x: %s\n"  \
                      "  in \"%s\", position %d"    \
                      % (self.encoding, ord(self.character), self.reason,
                              self.name, self.position)
          else:
              return "unacceptable character #x%04x: %s\n"    \
                      "  in \"%s\", position %d"    \
                      % (self.character, self.reason,
                              self.name, self.position)
  
  class Reader(object):
      # Reader:
      # - determines the data encoding and converts it to unicode,
      # - checks if characters are in allowed range,
      # - adds '\0' to the end.
  
      # Reader accepts
      #  - a `str` object,
      #  - a `unicode` object,
      #  - a file-like object with its `read` method returning `str`,
      #  - a file-like object with its `read` method returning `unicode`.
  
      # Yeah, it's ugly and slow.
  
      def __init__(self, stream):
          self.name = None
          self.stream = None
          self.stream_pointer = 0
          self.eof = True
          self.buffer = u''
          self.pointer = 0
          self.raw_buffer = None
          self.raw_decode = None
          self.encoding = None
          self.index = 0
          self.line = 0
          self.column = 0
          if isinstance(stream, unicode):
              self.name = "<unicode string>"
              self.check_printable(stream)
              self.buffer = stream+u'\0'
          elif isinstance(stream, str):
              self.name = "<string>"
              self.raw_buffer = stream
              self.determine_encoding()
          else:
              self.stream = stream
              self.name = getattr(stream, 'name', "<file>")
              self.eof = False
              self.raw_buffer = ''
              self.determine_encoding()
  
      def peek(self, index=0):
          try:
              return self.buffer[self.pointer+index]
          except IndexError:
              self.update(index+1)
              return self.buffer[self.pointer+index]
  
      def prefix(self, length=1):
          if self.pointer+length >= len(self.buffer):
              self.update(length)
          return self.buffer[self.pointer:self.pointer+length]
  
      def forward(self, length=1):
          if self.pointer+length+1 >= len(self.buffer):
              self.update(length+1)
          while length:
              ch = self.buffer[self.pointer]
              self.pointer += 1
              self.index += 1
              if ch in u'\n\x85\u2028\u2029'  \
                      or (ch == u'\r' and self.buffer[self.pointer] != u'\n'):
                  self.line += 1
                  self.column = 0
              elif ch != u'\uFEFF':
                  self.column += 1
              length -= 1
  
      def get_mark(self):
          if self.stream is None:
              return Mark(self.name, self.index, self.line, self.column,
                      self.buffer, self.pointer)
          else:
              return Mark(self.name, self.index, self.line, self.column,
                      None, None)
  
      def determine_encoding(self):
          while not self.eof and len(self.raw_buffer) < 2:
              self.update_raw()
          if not isinstance(self.raw_buffer, unicode):
              if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
                  self.raw_decode = codecs.utf_16_le_decode
                  self.encoding = 'utf-16-le'
              elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
                  self.raw_decode = codecs.utf_16_be_decode
                  self.encoding = 'utf-16-be'
              else:
                  self.raw_decode = codecs.utf_8_decode
                  self.encoding = 'utf-8'
          self.update(1)
  
      NON_PRINTABLE = re.compile(u'[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD]')
      def check_printable(self, data):
          match = self.NON_PRINTABLE.search(data)
          if match:
              character = match.group()
              position = self.index+(len(self.buffer)-self.pointer)+match.start()
              raise ReaderError(self.name, position, ord(character),
                      'unicode', "special characters are not allowed")
  
      def update(self, length):
          if self.raw_buffer is None:
              return
          self.buffer = self.buffer[self.pointer:]
          self.pointer = 0
          while len(self.buffer) < length:
              if not self.eof:
                  self.update_raw()
              if self.raw_decode is not None:
                  try:
                      data, converted = self.raw_decode(self.raw_buffer,
                              'strict', self.eof)
                  except UnicodeDecodeError, exc:
                      character = exc.object[exc.start]
                      if self.stream is not None:
                          position = self.stream_pointer-len(self.raw_buffer)+exc.start
                      else:
                          position = exc.start
                      raise ReaderError(self.name, position, character,
                              exc.encoding, exc.reason)
              else:
                  data = self.raw_buffer
                  converted = len(data)
              self.check_printable(data)
              self.buffer += data
              self.raw_buffer = self.raw_buffer[converted:]
              if self.eof:
                  self.buffer += u'\0'
                  self.raw_buffer = None
                  break
  
      def update_raw(self, size=1024):
          data = self.stream.read(size)
          if data:
              self.raw_buffer += data
              self.stream_pointer += len(data)
          else:
              self.eof = True
  
  #try:
  #    import psyco
  #    psyco.bind(Reader)
  #except ImportError:
  #    pass
  
  