text: 
  import logging
  from io import BytesIO
  from .psparser import PSStackParser
  from .psparser import PSSyntaxError
  from .psparser import PSEOF
  from .psparser import KWD
  from . import settings
  from .pdftypes import PDFException
  from .pdftypes import PDFStream
  from .pdftypes import PDFObjRef
  from .pdftypes import int_value
  from .pdftypes import dict_value
  
  log = logging.getLogger(__name__)
  
  
  ##  Exceptions
  ##
  class PDFSyntaxError(PDFException):
      pass
  
  
  ##  PDFParser
  ##
  class PDFParser(PSStackParser):
  
      """
      PDFParser fetch PDF objects from a file stream.
      It can handle indirect references by referring to
      a PDF document set by set_document method.
      It also reads XRefs at the end of every PDF file.
  
      Typical usage:
        parser = PDFParser(fp)
        parser.read_xref()
        parser.read_xref(fallback=True) # optional
        parser.set_document(doc)
        parser.seek(offset)
        parser.nextobject()
  
      """
  
      def __init__(self, fp):
          PSStackParser.__init__(self, fp)
          self.doc = None
          self.fallback = False
          return
  
      def set_document(self, doc):
          """Associates the parser with a PDFDocument object."""
          self.doc = doc
          return
  
      KEYWORD_R = KWD(b'R')
      KEYWORD_NULL = KWD(b'null')
      KEYWORD_ENDOBJ = KWD(b'endobj')
      KEYWORD_STREAM = KWD(b'stream')
      KEYWORD_XREF = KWD(b'xref')
      KEYWORD_STARTXREF = KWD(b'startxref')
  
      def do_keyword(self, pos, token):
          """Handles PDF-related keywords."""
  
          if token in (self.KEYWORD_XREF, self.KEYWORD_STARTXREF):
              self.add_results(*self.pop(1))
  
          elif token is self.KEYWORD_ENDOBJ:
              self.add_results(*self.pop(4))
  
          elif token is self.KEYWORD_NULL:
              # null object
              self.push((pos, None))
  
          elif token is self.KEYWORD_R:
              # reference to indirect object
              try:
                  ((_, objid), (_, genno)) = self.pop(2)
                  (objid, genno) = (int(objid), int(genno))
                  obj = PDFObjRef(self.doc, objid, genno)
                  self.push((pos, obj))
              except PSSyntaxError:
                  pass
  
          elif token is self.KEYWORD_STREAM:
              # stream object
              ((_, dic),) = self.pop(1)
              dic = dict_value(dic)
              objlen = 0
              if not self.fallback:
                  try:
                      objlen = int_value(dic['Length'])
                  except KeyError:
                      if settings.STRICT:
                          raise PDFSyntaxError('/Length is undefined: %r' % dic)
              self.seek(pos)
              try:
                  (_, line) = self.nextline()  # 'stream'
              except PSEOF:
                  if settings.STRICT:
                      raise PDFSyntaxError('Unexpected EOF')
                  return
              pos += len(line)
              self.fp.seek(pos)
              data = bytearray(self.fp.read(objlen))
              self.seek(pos + objlen)
              while True:
                  try:
                      (linepos, line) = self.nextline()
                  except PSEOF:
                      if settings.STRICT:
                          raise PDFSyntaxError('Unexpected EOF')
                      break
                  if b'endstream' in line:
                      i = line.index(b'endstream')
                      objlen += i
                      if self.fallback:
                          data += line[:i]
                      break
                  objlen += len(line)
                  if self.fallback:
                      data += line
              data = bytes(data)
              self.seek(pos + objlen)
              # XXX limit objlen not to exceed object boundary
              log.debug(
                  'Stream: pos=%d, objlen=%d, dic=%r, data=%r...',
                  pos,
                  objlen,
                  dic,
                  data[:10],
              )
              obj = PDFStream(dic, data, self.doc.decipher)
              self.push((pos, obj))
  
          else:
              # others
              self.push((pos, token))
  
          return
  
  
  ##  PDFStreamParser
  ##
  class PDFStreamParser(PDFParser):
  
      """
      PDFStreamParser is used to parse PDF content streams
      that is contained in each page and has instructions
      for rendering the page. A reference to a PDF document is
      needed because a PDF content stream can also have
      indirect references to other objects in the same document.
      """
  
      def __init__(self, data):
          PDFParser.__init__(self, BytesIO(data))
          return
  
      def flush(self):
          self.add_results(*self.popall())
          return
  
      KEYWORD_OBJ = KWD(b'obj')
  
      def do_keyword(self, pos, token):
          if token is self.KEYWORD_R:
              # reference to indirect object
              try:
                  ((_, objid), (_, genno)) = self.pop(2)
                  (objid, genno) = (int(objid), int(genno))
                  obj = PDFObjRef(self.doc, objid, genno)
                  self.push((pos, obj))
              except PSSyntaxError:
                  pass
              return
          elif token in (self.KEYWORD_OBJ, self.KEYWORD_ENDOBJ):
              if settings.STRICT:
                  # See PDF Spec 3.4.6: Only the object values are stored in the
                  # stream; the obj and endobj keywords are not used.
                  raise PDFSyntaxError('Keyword endobj found in stream')
              return
          # others
          self.push((pos, token))
          return
  