524 lines
18 KiB
Text
524 lines
18 KiB
Text
# -*- test-case-name: twisted.words.test.test_xpath -*-
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# Copyright (c) Twisted Matrix Laboratories.
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# See LICENSE for details.
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# pylint: disable=W9401,W9402
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# DO NOT EDIT xpathparser.py!
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#
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# It is generated from xpathparser.g using Yapps. Make needed changes there.
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# This also means that the generated Python may not conform to Twisted's coding
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# standards, so it is wrapped in exec to prevent automated checkers from
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# complaining.
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# HOWTO Generate me:
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#
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# 1.) Grab a copy of yapps2:
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# https://github.com/smurfix/yapps
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#
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# Note: Do NOT use the package in debian/ubuntu as it has incompatible
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# modifications. The original at http://theory.stanford.edu/~amitp/yapps/
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# hasn't been touched since 2003 and has not been updated to work with
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# Python 3.
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#
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# 2.) Generate the grammar:
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#
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# yapps2 xpathparser.g xpathparser.py.proto
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#
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# 3.) Edit the output to depend on the embedded runtime, and remove extraneous
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# imports:
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#
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# sed -e '/^# Begin/,${/^[^ ].*mport/d}' -e 's/runtime\.//g' \
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# -e "s/^\(from __future\)/exec(r'''\n\1/" -e"\$a''')"
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# xpathparser.py.proto > xpathparser.py
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"""
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XPath Parser.
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Besides the parser code produced by Yapps, this module also defines the
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parse-time exception classes, a scanner class, a base class for parsers
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produced by Yapps, and a context class that keeps track of the parse stack.
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These have been copied from the Yapps runtime module.
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"""
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from __future__ import print_function
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import sys, re
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MIN_WINDOW=4096
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# File lookup window
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class SyntaxError(Exception):
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"""When we run into an unexpected token, this is the exception to use"""
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def __init__(self, pos=None, msg="Bad Token", context=None):
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Exception.__init__(self)
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self.pos = pos
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self.msg = msg
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self.context = context
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def __str__(self):
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if not self.pos: return 'SyntaxError'
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else: return 'SyntaxError@%s(%s)' % (repr(self.pos), self.msg)
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class NoMoreTokens(Exception):
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"""Another exception object, for when we run out of tokens"""
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pass
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class Token(object):
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"""Yapps token.
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This is a container for a scanned token.
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"""
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def __init__(self, type,value, pos=None):
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"""Initialize a token."""
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self.type = type
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self.value = value
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self.pos = pos
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def __repr__(self):
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output = '<%s: %s' % (self.type, repr(self.value))
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if self.pos:
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output += " @ "
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if self.pos[0]:
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output += "%s:" % self.pos[0]
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if self.pos[1]:
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output += "%d" % self.pos[1]
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if self.pos[2] is not None:
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output += ".%d" % self.pos[2]
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output += ">"
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return output
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in_name=0
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class Scanner(object):
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"""Yapps scanner.
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The Yapps scanner can work in context sensitive or context
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insensitive modes. The token(i) method is used to retrieve the
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i-th token. It takes a restrict set that limits the set of tokens
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it is allowed to return. In context sensitive mode, this restrict
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set guides the scanner. In context insensitive mode, there is no
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restriction (the set is always the full set of tokens).
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"""
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def __init__(self, patterns, ignore, input="",
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file=None,filename=None,stacked=False):
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"""Initialize the scanner.
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Parameters:
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patterns : [(terminal, uncompiled regex), ...] or None
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ignore : {terminal:None, ...}
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input : string
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If patterns is None, we assume that the subclass has
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defined self.patterns : [(terminal, compiled regex), ...].
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Note that the patterns parameter expects uncompiled regexes,
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whereas the self.patterns field expects compiled regexes.
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The 'ignore' value is either None or a callable, which is called
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with the scanner and the to-be-ignored match object; this can
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be used for include file or comment handling.
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"""
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if not filename:
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global in_name
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filename="<f.%d>" % in_name
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in_name += 1
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self.input = input
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self.ignore = ignore
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self.file = file
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self.filename = filename
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self.pos = 0
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self.del_pos = 0 # skipped
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self.line = 1
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self.del_line = 0 # skipped
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self.col = 0
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self.tokens = []
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self.stack = None
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self.stacked = stacked
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self.last_read_token = None
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self.last_token = None
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self.last_types = None
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if patterns is not None:
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# Compile the regex strings into regex objects
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self.patterns = []
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for terminal, regex in patterns:
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self.patterns.append( (terminal, re.compile(regex)) )
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def stack_input(self, input="", file=None, filename=None):
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"""Temporarily parse from a second file."""
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# Already reading from somewhere else: Go on top of that, please.
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if self.stack:
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# autogenerate a recursion-level-identifying filename
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if not filename:
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filename = 1
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else:
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try:
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filename += 1
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except TypeError:
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pass
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# now pass off to the include file
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self.stack.stack_input(input,file,filename)
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else:
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try:
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filename += 0
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except TypeError:
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pass
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else:
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filename = "<str_%d>" % filename
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# self.stack = object.__new__(self.__class__)
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# Scanner.__init__(self.stack,self.patterns,self.ignore,input,file,filename, stacked=True)
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# Note that the pattern+ignore are added by the generated
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# scanner code
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self.stack = self.__class__(input,file,filename, stacked=True)
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def get_pos(self):
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"""Return a file/line/char tuple."""
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if self.stack: return self.stack.get_pos()
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return (self.filename, self.line+self.del_line, self.col)
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# def __repr__(self):
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# """Print the last few tokens that have been scanned in"""
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# output = ''
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# for t in self.tokens:
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# output += '%s\n' % (repr(t),)
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# return output
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def print_line_with_pointer(self, pos, length=0, out=sys.stderr):
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"""Print the line of 'text' that includes position 'p',
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along with a second line with a single caret (^) at position p"""
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file,line,p = pos
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if file != self.filename:
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if self.stack: return self.stack.print_line_with_pointer(pos,length=length,out=out)
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print >>out, "(%s: not in input buffer)" % file
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return
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text = self.input
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p += length-1 # starts at pos 1
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origline=line
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line -= self.del_line
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spos=0
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if line > 0:
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while 1:
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line = line - 1
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try:
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cr = text.index("\n",spos)
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except ValueError:
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if line:
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text = ""
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break
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if line == 0:
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text = text[spos:cr]
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break
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spos = cr+1
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else:
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print >>out, "(%s:%d not in input buffer)" % (file,origline)
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return
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# Now try printing part of the line
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text = text[max(p-80, 0):p+80]
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p = p - max(p-80, 0)
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# Strip to the left
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i = text[:p].rfind('\n')
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j = text[:p].rfind('\r')
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if i < 0 or (0 <= j < i): i = j
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if 0 <= i < p:
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p = p - i - 1
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text = text[i+1:]
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# Strip to the right
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i = text.find('\n', p)
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j = text.find('\r', p)
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if i < 0 or (0 <= j < i): i = j
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if i >= 0:
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text = text[:i]
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# Now shorten the text
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while len(text) > 70 and p > 60:
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# Cut off 10 chars
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text = "..." + text[10:]
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p = p - 7
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# Now print the string, along with an indicator
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print >>out, '> ',text
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print >>out, '> ',' '*p + '^'
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def grab_input(self):
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"""Get more input if possible."""
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if not self.file: return
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if len(self.input) - self.pos >= MIN_WINDOW: return
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data = self.file.read(MIN_WINDOW)
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if data is None or data == "":
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self.file = None
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# Drop bytes from the start, if necessary.
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if self.pos > 2*MIN_WINDOW:
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self.del_pos += MIN_WINDOW
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self.del_line += self.input[:MIN_WINDOW].count("\n")
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self.pos -= MIN_WINDOW
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self.input = self.input[MIN_WINDOW:] + data
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else:
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self.input = self.input + data
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def getchar(self):
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"""Return the next character."""
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self.grab_input()
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c = self.input[self.pos]
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self.pos += 1
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return c
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def token(self, restrict, context=None):
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"""Scan for another token."""
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while 1:
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if self.stack:
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try:
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return self.stack.token(restrict, context)
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except StopIteration:
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self.stack = None
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# Keep looking for a token, ignoring any in self.ignore
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self.grab_input()
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# special handling for end-of-file
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if self.stacked and self.pos==len(self.input):
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raise StopIteration
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# Search the patterns for the longest match, with earlier
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# tokens in the list having preference
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best_match = -1
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best_pat = '(error)'
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best_m = None
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for p, regexp in self.patterns:
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# First check to see if we're ignoring this token
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if restrict and p not in restrict and p not in self.ignore:
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continue
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m = regexp.match(self.input, self.pos)
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if m and m.end()-m.start() > best_match:
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# We got a match that's better than the previous one
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best_pat = p
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best_match = m.end()-m.start()
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best_m = m
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# If we didn't find anything, raise an error
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if best_pat == '(error)' and best_match < 0:
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msg = 'Bad Token'
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if restrict:
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msg = 'Trying to find one of '+', '.join(restrict)
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raise SyntaxError(self.get_pos(), msg, context=context)
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ignore = best_pat in self.ignore
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value = self.input[self.pos:self.pos+best_match]
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if not ignore:
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tok=Token(type=best_pat, value=value, pos=self.get_pos())
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self.pos += best_match
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npos = value.rfind("\n")
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if npos > -1:
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self.col = best_match-npos
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self.line += value.count("\n")
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else:
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self.col += best_match
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# If we found something that isn't to be ignored, return it
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if not ignore:
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if len(self.tokens) >= 10:
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del self.tokens[0]
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self.tokens.append(tok)
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self.last_read_token = tok
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# print repr(tok)
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return tok
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else:
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ignore = self.ignore[best_pat]
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if ignore:
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ignore(self, best_m)
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def peek(self, *types, **kw):
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"""Returns the token type for lookahead; if there are any args
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then the list of args is the set of token types to allow"""
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context = kw.get("context",None)
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if self.last_token is None:
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self.last_types = types
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self.last_token = self.token(types,context)
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elif self.last_types:
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for t in types:
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if t not in self.last_types:
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raise NotImplementedError("Unimplemented: restriction set changed")
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return self.last_token.type
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def scan(self, type, **kw):
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"""Returns the matched text, and moves to the next token"""
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context = kw.get("context",None)
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if self.last_token is None:
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tok = self.token([type],context)
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else:
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if self.last_types and type not in self.last_types:
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raise NotImplementedError("Unimplemented: restriction set changed")
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tok = self.last_token
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self.last_token = None
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if tok.type != type:
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if not self.last_types: self.last_types=[]
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raise SyntaxError(tok.pos, 'Trying to find '+type+': '+ ', '.join(self.last_types)+", got "+tok.type, context=context)
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return tok.value
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class Parser(object):
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"""Base class for Yapps-generated parsers.
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"""
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def __init__(self, scanner):
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self._scanner = scanner
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def _stack(self, input="",file=None,filename=None):
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"""Temporarily read from someplace else"""
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self._scanner.stack_input(input,file,filename)
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self._tok = None
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def _peek(self, *types, **kw):
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"""Returns the token type for lookahead; if there are any args
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then the list of args is the set of token types to allow"""
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return self._scanner.peek(*types, **kw)
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def _scan(self, type, **kw):
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"""Returns the matched text, and moves to the next token"""
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return self._scanner.scan(type, **kw)
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class Context(object):
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"""Class to represent the parser's call stack.
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Every rule creates a Context that links to its parent rule. The
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contexts can be used for debugging.
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"""
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def __init__(self, parent, scanner, rule, args=()):
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"""Create a new context.
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Args:
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parent: Context object or None
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scanner: Scanner object
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rule: string (name of the rule)
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args: tuple listing parameters to the rule
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"""
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self.parent = parent
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self.scanner = scanner
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self.rule = rule
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self.args = args
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while scanner.stack: scanner = scanner.stack
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self.token = scanner.last_read_token
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def __str__(self):
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output = ''
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if self.parent: output = str(self.parent) + ' > '
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output += self.rule
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return output
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def print_error(err, scanner, max_ctx=None):
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"""Print error messages, the parser stack, and the input text -- for human-readable error messages."""
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# NOTE: this function assumes 80 columns :-(
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# Figure out the line number
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pos = err.pos
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if not pos:
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pos = scanner.get_pos()
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file_name, line_number, column_number = pos
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print('%s:%d:%d: %s' % (file_name, line_number, column_number, err.msg), file=sys.stderr)
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scanner.print_line_with_pointer(pos)
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context = err.context
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token = None
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while context:
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print('while parsing %s%s:' % (context.rule, tuple(context.args)), file=sys.stderr)
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if context.token:
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token = context.token
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if token:
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scanner.print_line_with_pointer(token.pos, length=len(token.value))
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context = context.parent
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if max_ctx:
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max_ctx = max_ctx-1
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if not max_ctx:
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break
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def wrap_error_reporter(parser, rule, *args,**kw):
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try:
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return getattr(parser, rule)(*args,**kw)
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except SyntaxError as e:
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print_error(e, parser._scanner)
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except NoMoreTokens:
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print('Could not complete parsing; stopped around here:', file=sys.stderr)
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print(parser._scanner, file=sys.stderr)
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from twisted.words.xish.xpath import AttribValue, BooleanValue, CompareValue
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from twisted.words.xish.xpath import Function, IndexValue, LiteralValue
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from twisted.words.xish.xpath import _AnyLocation, _Location
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%%
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parser XPathParser:
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ignore: "\\s+"
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token INDEX: "[0-9]+"
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token WILDCARD: "\*"
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token IDENTIFIER: "[a-zA-Z][a-zA-Z0-9_\-]*"
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token ATTRIBUTE: "\@[a-zA-Z][a-zA-Z0-9_\-]*"
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token FUNCNAME: "[a-zA-Z][a-zA-Z0-9_]*"
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token CMP_EQ: "\="
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token CMP_NE: "\!\="
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token STR_DQ: '"([^"]|(\\"))*?"'
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token STR_SQ: "'([^']|(\\'))*?'"
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token OP_AND: "and"
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token OP_OR: "or"
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token END: "$"
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rule XPATH: PATH {{ result = PATH; current = result }}
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( PATH {{ current.childLocation = PATH; current = current.childLocation }} ) * END
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{{ return result }}
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rule PATH: ("/" {{ result = _Location() }} | "//" {{ result = _AnyLocation() }} )
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( IDENTIFIER {{ result.elementName = IDENTIFIER }} | WILDCARD {{ result.elementName = None }} )
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( "\[" PREDICATE {{ result.predicates.append(PREDICATE) }} "\]")*
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{{ return result }}
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rule PREDICATE: EXPR {{ return EXPR }} |
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INDEX {{ return IndexValue(INDEX) }}
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rule EXPR: FACTOR {{ e = FACTOR }}
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( BOOLOP FACTOR {{ e = BooleanValue(e, BOOLOP, FACTOR) }} )*
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{{ return e }}
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rule BOOLOP: ( OP_AND {{ return OP_AND }} | OP_OR {{ return OP_OR }} )
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rule FACTOR: TERM {{ return TERM }}
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| "\(" EXPR "\)" {{ return EXPR }}
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rule TERM: VALUE {{ t = VALUE }}
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[ CMP VALUE {{ t = CompareValue(t, CMP, VALUE) }} ]
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{{ return t }}
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rule VALUE: "@" IDENTIFIER {{ return AttribValue(IDENTIFIER) }} |
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FUNCNAME {{ f = Function(FUNCNAME); args = [] }}
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"\(" [ VALUE {{ args.append(VALUE) }}
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(
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"," VALUE {{ args.append(VALUE) }}
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)*
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] "\)" {{ f.setParams(*args); return f }} |
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STR {{ return LiteralValue(STR[1:len(STR)-1]) }}
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rule CMP: (CMP_EQ {{ return CMP_EQ }} | CMP_NE {{ return CMP_NE }})
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rule STR: (STR_DQ {{ return STR_DQ }} | STR_SQ {{ return STR_SQ }})
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