631 lines
17 KiB
Python
631 lines
17 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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import re
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import logging
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import six # Python 2+3 compatibility
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from . import settings
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from .utils import choplist
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log = logging.getLogger(__name__)
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## PS Exceptions
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##
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class PSException(Exception):
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pass
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class PSEOF(PSException):
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pass
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class PSSyntaxError(PSException):
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pass
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class PSTypeError(PSException):
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pass
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class PSValueError(PSException):
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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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def __repr__(self):
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name=self.name
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return '/%r' % 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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name=self.name
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return '/%r' % 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(b'{')
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KEYWORD_PROC_END = KWD(b'}')
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KEYWORD_ARRAY_BEGIN = KWD(b'[')
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KEYWORD_ARRAY_END = KWD(b']')
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KEYWORD_DICT_BEGIN = KWD(b'<<')
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KEYWORD_DICT_END = KWD(b'>>')
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def literal_name(x):
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if not isinstance(x, PSLiteral):
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if settings.STRICT:
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raise PSTypeError('Literal required: %r' % (x,))
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else:
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name=x
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else:
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name=x.name
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if six.PY3:
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try:
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name = str(name,'utf-8')
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except:
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pass
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return name
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def keyword_name(x):
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if not isinstance(x, PSKeyword):
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if settings.STRICT:
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raise PSTypeError('Keyword required: %r' % x)
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else:
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name=x
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else:
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name=x.name
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if six.PY3:
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name = str(name,'utf-8','ignore')
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return name
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## PSBaseParser
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##
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EOL = re.compile(br'[\r\n]')
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SPC = re.compile(br'\s')
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NONSPC = re.compile(br'\S')
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HEX = re.compile(br'[0-9a-fA-F]')
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END_LITERAL = re.compile(br'[#/%\[\]()<>{}\s]')
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END_HEX_STRING = re.compile(br'[^\s0-9a-fA-F]')
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HEX_PAIR = re.compile(br'[0-9a-fA-F]{2}|.')
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END_NUMBER = re.compile(br'[^0-9]')
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END_KEYWORD = re.compile(br'[#/%\[\]()<>{}\s]')
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END_STRING = re.compile(br'[()\134]')
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OCT_STRING = re.compile(br'[0-7]')
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ESC_STRING = {b'b': 8, b't': 9, b'n': 10, b'f': 12, b'r': 13, b'(': 40, b')': 41, b'\\': 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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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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log.info('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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log.debug('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 = b''
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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 = b''
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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):
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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 = b''
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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:self.charpos+1]
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# handle b'\r\n'
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if c == b'\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:] == b'\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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log.debug('nextline: %r, %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 = b''
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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:
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break
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while 1:
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n = max(s.rfind(b'\r'), s.rfind(b'\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 = b''
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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:j+1]
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self._curtokenpos = self.bufpos+j
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if c == b'%':
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self._curtoken = b'%'
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self._parse1 = self._parse_comment
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return j+1
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elif c == b'/':
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self._curtoken = b''
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self._parse1 = self._parse_literal
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return j+1
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elif c in b'-+' 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 == b'.':
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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 == b'(':
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self._curtoken = b''
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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 == b'<':
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self._curtoken = b''
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self._parse1 = self._parse_wopen
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return j+1
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elif c == b'>':
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self._curtoken = b''
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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 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:j+1]
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if c == b'#':
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self.hex = b''
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self._parse1 = self._parse_literal_hex
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return j+1
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try:
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self._curtoken=str(self._curtoken,'utf-8')
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except:
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pass
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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:i+1]
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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 += six.int2byte(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:j+1]
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if c == b'.':
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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 == b'true':
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token = True
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elif self._curtoken == b'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:j+1]
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if c == b'\\':
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self.oct = b''
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self._parse1 = self._parse_string_1
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return j+1
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if c == b'(':
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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 == b')':
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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:i+1]
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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 += six.int2byte(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 += six.int2byte(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:i+1]
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if c == b'<':
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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:i+1]
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if c == b'>':
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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: six.int2byte(int(m.group(0), 16)),SPC.sub(b'', 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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log.debug('nexttoken: %r', token)
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return token
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|
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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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|
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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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try:
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log.debug('add_results: %r', objs)
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except:
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log.debug('add_results: (unprintable object)')
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self.results.extend(objs)
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return
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|
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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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log.debug('start_type: pos=%r, type=%r', pos, type)
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return
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|
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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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log.debug('end_type: pos=%r, type=%r, objs=%r', pos, type, objs)
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return (pos, objs)
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|
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def do_keyword(self, pos, token):
|
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return
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|
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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, (six.integer_types, float, bool, six.string_types, six.binary_type, 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 settings.STRICT:
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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')
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elif token == KEYWORD_DICT_END:
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# end dictionary
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try:
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(pos, objs) = self.end_type('d')
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if len(objs) % 2 != 0:
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raise PSSyntaxError('Invalid dictionary construct: %r' % objs)
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# construct a Python dictionary.
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d = dict((literal_name(k), v) for (k, v) in choplist(2, objs) if v is not None)
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self.push((pos, d))
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except PSTypeError:
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if settings.STRICT:
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raise
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elif token == KEYWORD_PROC_BEGIN:
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# begin proc
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self.start_type(pos, 'p')
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elif token == KEYWORD_PROC_END:
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# end proc
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try:
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self.push(self.end_type('p'))
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except PSTypeError:
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if settings.STRICT:
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raise
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elif isinstance(token,PSKeyword):
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log.debug('do_keyword: pos=%r, token=%r, stack=%r', pos, token, self.curstack)
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self.do_keyword(pos, token)
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else:
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log.error('unknown token: pos=%r, token=%r, stack=%r', pos, token, self.curstack)
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self.do_keyword(pos, token)
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raise
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if self.context:
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continue
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else:
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self.flush()
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obj = self.results.pop(0)
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try:
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log.debug('nextobject: %r', obj)
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except:
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log.debug('nextobject: (unprintable object)')
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return obj
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