/usr/share/pyshared/pdfrw/pdftokens.py is in python-pdfrw 0+svn136-3.
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# Copyright (C) 2006-2009 Patrick Maupin, Austin, Texas
# MIT license -- See LICENSE.txt for details
'''
A tokenizer for PDF streams.
In general, documentation used was "PDF reference",
sixth edition, for PDF version 1.7, dated November 2006.
'''
from __future__ import generators
try:
set
except NameError:
from sets import Set as set
import re
from pdfobjects import PdfString, PdfObject
class _PrimitiveTokens(object):
# Table 3.1, page 50 of reference, defines whitespace
whitespaceset = set('\x00\t\n\f\r ')
# Text on page 50 defines delimiter characters
delimiterset = set('()<>{}[]/%')
# Coalesce contiguous whitespace into a single token
whitespace_pattern = '[%s]+' % ''.join(whitespaceset)
# In addition to the delimiters, we also use '\', which
# is special in some contexts in PDF.
delimiter_pattern = '\\\\|\\' + '|\\'.join(delimiterset)
# Dictionary delimiters are '<<' and '>>'. Look for
# these before the single variety.
dictdelim_pattern = r'\<\<|\>\>'
pattern = '(%s|%s|%s)' % (whitespace_pattern,
dictdelim_pattern, delimiter_pattern)
re_func = re.compile(pattern).finditer
del whitespace_pattern, dictdelim_pattern
del delimiter_pattern, pattern
def __init__(self, fdata):
class MyIterator(object):
def next():
if not tokens:
startloc = self.startloc
for match in next_match[0]:
start = match.start()
end = match.end()
tappend(fdata[start:end])
if start > startloc:
tappend(fdata[startloc:start])
self.startloc = end
break
else:
s = fdata[startloc:]
self.startloc = len(fdata)
if s:
tappend(s)
if not tokens:
raise StopIteration
return tpop()
next = staticmethod(next)
self.fdata = fdata
self.tokens = tokens = []
self.iterator = iterator = MyIterator()
self.next = iterator.next
self.next_match = next_match = [None]
tappend = tokens.append
tpop = tokens.pop
def setstart(self, startloc):
self.startloc = startloc
self.next_match[0] = self.re_func(self.fdata, startloc)
def __iter__(self):
return self.iterator
def coalesce(self, result):
''' This function coalesces tokens together up until
the next delimiter or whitespace.
All of the coalesced tokens will either be non-matches,
or will be a matched backslash. We distinguish the
non-matches by the fact that next() will have left
a following match inside self.tokens for the actual match.
'''
tokens = self.tokens
whitespace = self.whitespaceset
# Optimized path for usual case -- regular data (not a name string),
# with no escape character, and followed by whitespace.
if tokens:
token = tokens.pop()
if token != '\\':
if token[0] not in whitespace:
tokens.append(token)
return
result.append(token)
# Non-optimized path. Either start of a name string received,
# or we just had one escape.
for token in self:
if tokens:
result.append(token)
token = tokens.pop()
if token != '\\':
if token[0] not in whitespace:
tokens.append(token)
return
result.append(token)
def floc(self):
return self.startloc - sum([len(x) for x in self.tokens])
class PdfTokens(object):
def __init__(self, fdata, startloc=0, strip_comments=True):
def comment(token):
tokens = [token]
for token in primitive:
tokens.append(token)
if token[0] in whitespaceset and ('\n' in token or '\r' in token):
break
return not strip_comments and ''.join(tokens)
def single(token):
return token
def regular_string(token):
def escaped():
escaped = False
i = -2
while tokens[i] == '\\':
escaped = not escaped
i -= 1
return escaped
tokens = [token]
nestlevel = 1
for token in primitive:
tokens.append(token)
if token in '()' and not escaped():
nestlevel += token == '(' or -1
if not nestlevel:
break
else:
assert 0, "Unexpected end of token stream"
return PdfString(''.join(tokens))
def hex_string(token):
tokens = [token]
for token in primitive:
tokens.append(token)
if token == '>':
break
while tokens[-2] == '>>':
tokens.append(tokens.pop(-2))
return PdfString(''.join(tokens))
def normal_data(token):
# Obscure optimization -- we can get here with
# whitespace or regular character data. If we get
# here with whitespace, then there won't be an additional
# token queued up in the primitive object, otherwise there
# will...
if primitive_tokens: #if token[0] not in whitespaceset:
tokens = [token]
primitive.coalesce(tokens)
return PdfObject(''.join(tokens))
def name_string(token):
tokens = [token]
primitive.coalesce(tokens)
token = ''.join(tokens)
if '#' in token:
substrs = token.split('#')
substrs.reverse()
tokens = [substrs.pop()]
while substrs:
s = substrs.pop()
tokens.append(chr(int(s[:2], 16)))
tokens.append(s[2:])
token = ''.join(tokens)
return PdfObject(token)
def broken(token):
assert 0, token
dispatch = {
'(': regular_string,
')': broken,
'<': hex_string,
'>': broken,
'[': single,
']': single,
'{': single,
'}': single,
'/': name_string,
'%' : comment,
'<<': single,
'>>': single,
}.get
class MyIterator(object):
def next():
while not tokens:
token = primitive_next()
token = dispatch(token, normal_data)(token)
if token:
return token
return tokens.pop()
next = staticmethod(next)
self.primitive = primitive = _PrimitiveTokens(fdata)
self.setstart = primitive.setstart
primitive.setstart(startloc)
self.fdata = fdata
self.strip_comments = strip_comments
self.tokens = tokens = []
self.iterator = iterator = MyIterator()
self.next = iterator.next
primitive_next = primitive.next
primitive_tokens = primitive.tokens
whitespaceset = _PrimitiveTokens.whitespaceset
def floc(self):
return self.primitive.floc() - sum([len(x) for x in self.tokens])
floc = property(floc)
def __iter__(self):
return self.iterator
def multiple(self, count):
next = self.next
return [next() for i in range(count)]
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