688 lines
19 KiB
Python
688 lines
19 KiB
Python
#!/usr/bin/env python2
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import sys
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import re
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from sys import stderr
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from utils import choplist
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STRICT = 0
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## PS Exceptions
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##
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class PSException(Exception): pass
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class PSEOF(PSException): pass
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class PSSyntaxError(PSException): pass
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class PSTypeError(PSException): pass
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class PSValueError(PSException): pass
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## Basic PostScript Types
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##
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## PSObject
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##
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class PSObject(object):
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"""Base class for all PS or PDF-related data types."""
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pass
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## PSLiteral
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##
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class PSLiteral(PSObject):
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"""A class that represents a PostScript literal.
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Postscript literals are used as identifiers, such as
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variable names, property names and dictionary keys.
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Literals are case sensitive and denoted by a preceding
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slash sign (e.g. "/Name")
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Note: Do not create an instance of PSLiteral directly.
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Always use PSLiteralTable.intern().
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"""
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def __init__(self, name):
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self.name = name
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return
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def __repr__(self):
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return '/%s' % self.name
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## PSKeyword
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##
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class PSKeyword(PSObject):
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"""A class that represents a PostScript keyword.
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PostScript keywords are a dozen of predefined words.
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Commands and directives in PostScript are expressed by keywords.
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They are also used to denote the content boundaries.
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Note: Do not create an instance of PSKeyword directly.
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Always use PSKeywordTable.intern().
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"""
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def __init__(self, name):
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self.name = name
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return
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def __repr__(self):
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return self.name
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## PSSymbolTable
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##
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class PSSymbolTable(object):
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"""A utility class for storing PSLiteral/PSKeyword objects.
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Interned objects can be checked its identity with "is" operator.
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"""
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def __init__(self, klass):
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self.dict = {}
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self.klass = klass
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return
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def intern(self, name):
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if name in self.dict:
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lit = self.dict[name]
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else:
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lit = self.klass(name)
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self.dict[name] = lit
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return lit
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PSLiteralTable = PSSymbolTable(PSLiteral)
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PSKeywordTable = PSSymbolTable(PSKeyword)
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LIT = PSLiteralTable.intern
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KWD = PSKeywordTable.intern
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KEYWORD_PROC_BEGIN = KWD('{')
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KEYWORD_PROC_END = KWD('}')
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KEYWORD_ARRAY_BEGIN = KWD('[')
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KEYWORD_ARRAY_END = KWD(']')
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KEYWORD_DICT_BEGIN = KWD('<<')
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KEYWORD_DICT_END = KWD('>>')
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def literal_name(x):
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if not isinstance(x, PSLiteral):
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if STRICT:
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raise PSTypeError('Literal required: %r' % x)
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else:
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return str(x)
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return x.name
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def keyword_name(x):
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if not isinstance(x, PSKeyword):
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if STRICT:
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raise PSTypeError('Keyword required: %r' % x)
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else:
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return str(x)
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return x.name
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## PSBaseParser
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##
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EOL = re.compile(r'[\r\n]')
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SPC = re.compile(r'\s')
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NONSPC = re.compile(r'\S')
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HEX = re.compile(r'[0-9a-fA-F]')
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END_LITERAL = re.compile(r'[#/%\[\]()<>{}\s]')
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END_HEX_STRING = re.compile(r'[^\s0-9a-fA-F]')
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HEX_PAIR = re.compile(r'[0-9a-fA-F]{2}|.')
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END_NUMBER = re.compile(r'[^0-9]')
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END_KEYWORD = re.compile(r'[#/%\[\]()<>{}\s]')
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END_STRING = re.compile(r'[()\134]')
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OCT_STRING = re.compile(r'[0-7]')
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ESC_STRING = { 'b':8, 't':9, 'n':10, 'f':12, 'r':13, '(':40, ')':41, '\\':92 }
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class PSBaseParser(object):
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"""Most basic PostScript parser that performs only tokenization.
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"""
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BUFSIZ = 4096
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debug = 0
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def __init__(self, fp):
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self.fp = fp
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self.seek(0)
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return
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def __repr__(self):
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return '<%s: %r, bufpos=%d>' % (self.__class__.__name__, self.fp, self.bufpos)
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def flush(self):
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return
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def close(self):
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self.flush()
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return
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def tell(self):
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return self.bufpos+self.charpos
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def poll(self, pos=None, n=80):
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pos0 = self.fp.tell()
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if not pos:
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pos = self.bufpos+self.charpos
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self.fp.seek(pos)
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print >>stderr, 'poll(%d): %r' % (pos, self.fp.read(n))
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self.fp.seek(pos0)
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return
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def seek(self, pos):
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"""Seeks the parser to the given position.
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"""
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if 2 <= self.debug:
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print >>stderr, 'seek: %r' % pos
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self.fp.seek(pos)
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# reset the status for nextline()
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self.bufpos = pos
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self.buf = ''
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self.charpos = 0
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# reset the status for nexttoken()
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self._parse1 = self._parse_main
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self._curtoken = ''
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self._curtokenpos = 0
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self._tokens = []
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return
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def fillbuf(self):
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if self.charpos < len(self.buf): return
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# fetch next chunk.
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self.bufpos = self.fp.tell()
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self.buf = self.fp.read(self.BUFSIZ)
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if not self.buf:
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raise PSEOF('Unexpected EOF')
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self.charpos = 0
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return
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def nextline(self):
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"""Fetches a next line that ends either with \\r or \\n.
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"""
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linebuf = ''
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linepos = self.bufpos + self.charpos
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eol = False
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while 1:
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self.fillbuf()
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if eol:
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c = self.buf[self.charpos]
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# handle '\r\n'
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if c == '\n':
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linebuf += c
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self.charpos += 1
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break
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m = EOL.search(self.buf, self.charpos)
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if m:
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linebuf += self.buf[self.charpos:m.end(0)]
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self.charpos = m.end(0)
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if linebuf[-1] == '\r':
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eol = True
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else:
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break
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else:
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linebuf += self.buf[self.charpos:]
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self.charpos = len(self.buf)
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if 2 <= self.debug:
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print >>stderr, 'nextline: %r' % ((linepos, linebuf),)
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return (linepos, linebuf)
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def revreadlines(self):
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"""Fetches a next line backword.
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This is used to locate the trailers at the end of a file.
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"""
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self.fp.seek(0, 2)
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pos = self.fp.tell()
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buf = ''
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while 0 < pos:
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prevpos = pos
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pos = max(0, pos-self.BUFSIZ)
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self.fp.seek(pos)
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s = self.fp.read(prevpos-pos)
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if not s: break
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while 1:
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n = max(s.rfind('\r'), s.rfind('\n'))
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if n == -1:
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buf = s + buf
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break
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yield s[n:]+buf
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s = s[:n]
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buf = ''
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return
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def _parse_main(self, s, i):
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m = NONSPC.search(s, i)
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if not m:
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return len(s)
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j = m.start(0)
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c = s[j]
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self._curtokenpos = self.bufpos+j
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if c == '%':
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self._curtoken = '%'
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self._parse1 = self._parse_comment
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return j+1
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elif c == '/':
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self._curtoken = ''
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self._parse1 = self._parse_literal
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return j+1
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elif c in '-+' or c.isdigit():
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self._curtoken = c
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self._parse1 = self._parse_number
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return j+1
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elif c == '.':
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self._curtoken = c
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self._parse1 = self._parse_float
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return j+1
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elif c.isalpha():
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self._curtoken = c
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self._parse1 = self._parse_keyword
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return j+1
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elif c == '(':
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self._curtoken = ''
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self.paren = 1
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self._parse1 = self._parse_string
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return j+1
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elif c == '<':
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self._curtoken = ''
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self._parse1 = self._parse_wopen
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return j+1
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elif c == '>':
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self._curtoken = ''
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self._parse1 = self._parse_wclose
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return j+1
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else:
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self._add_token(KWD(c))
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return j+1
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def _add_token(self, obj):
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self._tokens.append((self._curtokenpos, obj))
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return
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def _parse_comment(self, s, i):
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m = EOL.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return (self._parse_comment, len(s))
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j = m.start(0)
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self._curtoken += s[i:j]
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self._parse1 = self._parse_main
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# We ignore comments.
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#self._tokens.append(self._curtoken)
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return j
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def _parse_literal(self, s, i):
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m = END_LITERAL.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return len(s)
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j = m.start(0)
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self._curtoken += s[i:j]
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c = s[j]
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if c == '#':
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self.hex = ''
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self._parse1 = self._parse_literal_hex
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return j+1
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self._add_token(LIT(self._curtoken))
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self._parse1 = self._parse_main
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return j
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def _parse_literal_hex(self, s, i):
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c = s[i]
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if HEX.match(c) and len(self.hex) < 2:
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self.hex += c
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return i+1
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if self.hex:
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self._curtoken += chr(int(self.hex, 16))
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self._parse1 = self._parse_literal
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return i
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def _parse_number(self, s, i):
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m = END_NUMBER.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return len(s)
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j = m.start(0)
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self._curtoken += s[i:j]
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c = s[j]
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if c == '.':
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self._curtoken += c
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self._parse1 = self._parse_float
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return j+1
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try:
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self._add_token(int(self._curtoken))
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except ValueError:
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pass
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self._parse1 = self._parse_main
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return j
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def _parse_float(self, s, i):
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m = END_NUMBER.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return len(s)
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j = m.start(0)
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self._curtoken += s[i:j]
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try:
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self._add_token(float(self._curtoken))
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except ValueError:
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pass
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self._parse1 = self._parse_main
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return j
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def _parse_keyword(self, s, i):
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m = END_KEYWORD.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return len(s)
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j = m.start(0)
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self._curtoken += s[i:j]
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if self._curtoken == 'true':
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token = True
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elif self._curtoken == 'false':
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token = False
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else:
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token = KWD(self._curtoken)
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self._add_token(token)
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self._parse1 = self._parse_main
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return j
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def _parse_string(self, s, i):
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m = END_STRING.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return len(s)
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j = m.start(0)
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self._curtoken += s[i:j]
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c = s[j]
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if c == '\\':
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self.oct = ''
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self._parse1 = self._parse_string_1
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return j+1
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if c == '(':
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self.paren += 1
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self._curtoken += c
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return j+1
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if c == ')':
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self.paren -= 1
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if self.paren: # WTF, they said balanced parens need no special treatment.
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self._curtoken += c
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return j+1
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self._add_token(self._curtoken)
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self._parse1 = self._parse_main
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return j+1
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def _parse_string_1(self, s, i):
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c = s[i]
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if OCT_STRING.match(c) and len(self.oct) < 3:
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self.oct += c
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return i+1
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if self.oct:
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self._curtoken += chr(int(self.oct, 8))
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self._parse1 = self._parse_string
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return i
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if c in ESC_STRING:
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self._curtoken += chr(ESC_STRING[c])
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self._parse1 = self._parse_string
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return i+1
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def _parse_wopen(self, s, i):
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c = s[i]
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if c == '<':
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self._add_token(KEYWORD_DICT_BEGIN)
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self._parse1 = self._parse_main
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i += 1
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else:
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self._parse1 = self._parse_hexstring
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return i
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def _parse_wclose(self, s, i):
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c = s[i]
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if c == '>':
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self._add_token(KEYWORD_DICT_END)
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i += 1
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self._parse1 = self._parse_main
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return i
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def _parse_hexstring(self, s, i):
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m = END_HEX_STRING.search(s, i)
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if not m:
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self._curtoken += s[i:]
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return len(s)
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j = m.start(0)
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self._curtoken += s[i:j]
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token = HEX_PAIR.sub(lambda m: chr(int(m.group(0), 16)),
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SPC.sub('', self._curtoken))
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self._add_token(token)
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self._parse1 = self._parse_main
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return j
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def nexttoken(self):
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while not self._tokens:
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self.fillbuf()
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self.charpos = self._parse1(self.buf, self.charpos)
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token = self._tokens.pop(0)
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if 2 <= self.debug:
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print >>stderr, 'nexttoken: %r' % (token,)
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return token
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## PSStackParser
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##
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class PSStackParser(PSBaseParser):
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def __init__(self, fp):
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PSBaseParser.__init__(self, fp)
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self.reset()
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return
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def reset(self):
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self.context = []
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self.curtype = None
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self.curstack = []
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self.results = []
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return
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def seek(self, pos):
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PSBaseParser.seek(self, pos)
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self.reset()
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return
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def push(self, *objs):
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self.curstack.extend(objs)
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return
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def pop(self, n):
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objs = self.curstack[-n:]
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self.curstack[-n:] = []
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return objs
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def popall(self):
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objs = self.curstack
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self.curstack = []
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return objs
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def add_results(self, *objs):
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if 2 <= self.debug:
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print >>stderr, 'add_results: %r' % (objs,)
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self.results.extend(objs)
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return
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def start_type(self, pos, type):
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self.context.append((pos, self.curtype, self.curstack))
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(self.curtype, self.curstack) = (type, [])
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if 2 <= self.debug:
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print >>stderr, 'start_type: pos=%r, type=%r' % (pos, type)
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return
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def end_type(self, type):
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if self.curtype != type:
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raise PSTypeError('Type mismatch: %r != %r' % (self.curtype, type))
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objs = [ obj for (_,obj) in self.curstack ]
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(pos, self.curtype, self.curstack) = self.context.pop()
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if 2 <= self.debug:
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print >>stderr, 'end_type: pos=%r, type=%r, objs=%r' % (pos, type, objs)
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return (pos, objs)
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def do_keyword(self, pos, token):
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return
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def nextobject(self):
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"""Yields a list of objects.
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Returns keywords, literals, strings, numbers, arrays and dictionaries.
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Arrays and dictionaries are represented as Python lists and dictionaries.
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"""
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while not self.results:
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(pos, token) = self.nexttoken()
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#print (pos,token), (self.curtype, self.curstack)
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if (isinstance(token, int) or
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isinstance(token, float) or
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isinstance(token, bool) or
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isinstance(token, str) or
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isinstance(token, PSLiteral)):
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# normal token
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self.push((pos, token))
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elif token == KEYWORD_ARRAY_BEGIN:
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# begin array
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self.start_type(pos, 'a')
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elif token == KEYWORD_ARRAY_END:
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# end array
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try:
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self.push(self.end_type('a'))
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except PSTypeError:
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if STRICT: raise
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elif token == KEYWORD_DICT_BEGIN:
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# begin dictionary
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|
self.start_type(pos, 'd')
|
|
elif token == KEYWORD_DICT_END:
|
|
# end dictionary
|
|
try:
|
|
(pos, objs) = self.end_type('d')
|
|
if len(objs) % 2 != 0:
|
|
raise PSSyntaxError('Invalid dictionary construct: %r' % objs)
|
|
# construct a Python dictionary.
|
|
d = dict( (literal_name(k), v) for (k,v) in choplist(2, objs) if v is not None )
|
|
self.push((pos, d))
|
|
except PSTypeError:
|
|
if STRICT: raise
|
|
elif token == KEYWORD_PROC_BEGIN:
|
|
# begin proc
|
|
self.start_type(pos, 'p')
|
|
elif token == KEYWORD_PROC_END:
|
|
# end proc
|
|
try:
|
|
self.push(self.end_type('p'))
|
|
except PSTypeError:
|
|
if STRICT: raise
|
|
else:
|
|
if 2 <= self.debug:
|
|
print >>stderr, 'do_keyword: pos=%r, token=%r, stack=%r' % \
|
|
(pos, token, self.curstack)
|
|
self.do_keyword(pos, token)
|
|
if self.context:
|
|
continue
|
|
else:
|
|
self.flush()
|
|
obj = self.results.pop(0)
|
|
if 2 <= self.debug:
|
|
print >>stderr, 'nextobject: %r' % (obj,)
|
|
return obj
|
|
|
|
|
|
## Simplistic Test cases
|
|
##
|
|
import unittest
|
|
class TestPSBaseParser(unittest.TestCase):
|
|
|
|
TESTDATA = r'''%!PS
|
|
begin end
|
|
" @ #
|
|
/a/BCD /Some_Name /foo#5f#xbaa
|
|
0 +1 -2 .5 1.234
|
|
(abc) () (abc ( def ) ghi)
|
|
(def\040\0\0404ghi) (bach\\slask) (foo\nbaa)
|
|
(this % is not a comment.)
|
|
(foo
|
|
baa)
|
|
(foo\
|
|
baa)
|
|
<> <20> < 40 4020 >
|
|
<abcd00
|
|
12345>
|
|
func/a/b{(c)do*}def
|
|
[ 1 (z) ! ]
|
|
<< /foo (bar) >>
|
|
'''
|
|
|
|
TOKENS = [
|
|
(5, KWD('begin')), (11, KWD('end')), (16, KWD('"')), (19, KWD('@')),
|
|
(21, KWD('#')), (23, LIT('a')), (25, LIT('BCD')), (30, LIT('Some_Name')),
|
|
(41, LIT('foo_xbaa')), (54, 0), (56, 1), (59, -2), (62, 0.5),
|
|
(65, 1.234), (71, 'abc'), (77, ''), (80, 'abc ( def ) ghi'),
|
|
(98, 'def \x00 4ghi'), (118, 'bach\\slask'), (132, 'foo\nbaa'),
|
|
(143, 'this % is not a comment.'), (170, 'foo\nbaa'), (180, 'foobaa'),
|
|
(191, ''), (194, ' '), (199, '@@ '), (211, '\xab\xcd\x00\x124\x05'),
|
|
(226, KWD('func')), (230, LIT('a')), (232, LIT('b')),
|
|
(234, KWD('{')), (235, 'c'), (238, KWD('do*')), (241, KWD('}')),
|
|
(242, KWD('def')), (246, KWD('[')), (248, 1), (250, 'z'), (254, KWD('!')),
|
|
(256, KWD(']')), (258, KWD('<<')), (261, LIT('foo')), (266, 'bar'),
|
|
(272, KWD('>>'))
|
|
]
|
|
|
|
OBJS = [
|
|
(23, LIT('a')), (25, LIT('BCD')), (30, LIT('Some_Name')),
|
|
(41, LIT('foo_xbaa')), (54, 0), (56, 1), (59, -2), (62, 0.5),
|
|
(65, 1.234), (71, 'abc'), (77, ''), (80, 'abc ( def ) ghi'),
|
|
(98, 'def \x00 4ghi'), (118, 'bach\\slask'), (132, 'foo\nbaa'),
|
|
(143, 'this % is not a comment.'), (170, 'foo\nbaa'), (180, 'foobaa'),
|
|
(191, ''), (194, ' '), (199, '@@ '), (211, '\xab\xcd\x00\x124\x05'),
|
|
(230, LIT('a')), (232, LIT('b')), (234, ['c']), (246, [1, 'z']),
|
|
(258, {'foo': 'bar'}),
|
|
]
|
|
|
|
def get_tokens(self, s):
|
|
import StringIO
|
|
class MyParser(PSBaseParser):
|
|
def flush(self):
|
|
self.add_results(*self.popall())
|
|
parser = MyParser(StringIO.StringIO(s))
|
|
r = []
|
|
try:
|
|
while 1:
|
|
r.append(parser.nexttoken())
|
|
except PSEOF:
|
|
pass
|
|
return r
|
|
|
|
def get_objects(self, s):
|
|
import StringIO
|
|
class MyParser(PSStackParser):
|
|
def flush(self):
|
|
self.add_results(*self.popall())
|
|
parser = MyParser(StringIO.StringIO(s))
|
|
r = []
|
|
try:
|
|
while 1:
|
|
r.append(parser.nextobject())
|
|
except PSEOF:
|
|
pass
|
|
return r
|
|
|
|
def test_1(self):
|
|
tokens = self.get_tokens(self.TESTDATA)
|
|
print tokens
|
|
self.assertEqual(tokens, self.TOKENS)
|
|
return
|
|
|
|
def test_2(self):
|
|
objs = self.get_objects(self.TESTDATA)
|
|
print objs
|
|
self.assertEqual(objs, self.OBJS)
|
|
return
|
|
|
|
if __name__ == '__main__': unittest.main()
|