70 lines
2.8 KiB
Python
70 lines
2.8 KiB
Python
# -*- coding: utf-8 -*-
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#######################################################################
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# Name: cleanpeg.py
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# Purpose: This module is a variation of the original peg.py.
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# The syntax is slightly changed to be more readable and familiar to
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# python users. It is based on the Yash's suggestion - issue 11
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# Author: Igor R. Dejanovic <igor DOT dejanovic AT gmail DOT com>
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# Copyright: (c) 2014-2017 Igor R. Dejanovic <igor DOT dejanovic AT gmail DOT com>
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# License: MIT License
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#######################################################################
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from __future__ import print_function, unicode_literals
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from arpeggio import Optional, ZeroOrMore, Not, OneOrMore, EOF, ParserPython, \
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visit_parse_tree
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from arpeggio import RegExMatch as _
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from .peg import PEGVisitor
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from .peg import ParserPEG as ParserPEGOrig
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__all__ = ['ParserPEG']
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# Lexical invariants
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ASSIGNMENT = "="
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ORDERED_CHOICE = "/"
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ZERO_OR_MORE = "*"
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ONE_OR_MORE = "+"
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OPTIONAL = "?"
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UNORDERED_GROUP = "#"
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AND = "&"
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NOT = "!"
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OPEN = "("
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CLOSE = ")"
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# PEG syntax rules
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def peggrammar(): return OneOrMore(rule), EOF
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def rule(): return rule_name, ASSIGNMENT, ordered_choice
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def ordered_choice(): return sequence, ZeroOrMore(ORDERED_CHOICE, sequence)
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def sequence(): return OneOrMore(prefix)
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def prefix(): return Optional([AND, NOT]), sufix
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def sufix(): return expression, Optional([OPTIONAL,
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ZERO_OR_MORE,
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ONE_OR_MORE,
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UNORDERED_GROUP])
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def expression(): return [regex, rule_crossref,
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(OPEN, ordered_choice, CLOSE),
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str_match], Not(ASSIGNMENT)
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# PEG Lexical rules
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def regex(): return [("r'", _(r'''[^'\\]*(?:\\.[^'\\]*)*'''), "'"),
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('r"', _(r'''[^"\\]*(?:\\.[^"\\]*)*'''), '"')]
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def rule_name(): return _(r"[a-zA-Z_]([a-zA-Z_]|[0-9])*")
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def rule_crossref(): return rule_name
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def str_match(): return _(r'''(?s)('[^'\\]*(?:\\.[^'\\]*)*')|'''
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r'''("[^"\\]*(?:\\.[^"\\]*)*")''')
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def comment(): return "//", _(".*\n")
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class ParserPEG(ParserPEGOrig):
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def _from_peg(self, language_def):
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parser = ParserPython(peggrammar, comment, reduce_tree=False,
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debug=self.debug)
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parser.root_rule_name = self.root_rule_name
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parse_tree = parser.parse(language_def)
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return visit_parse_tree(parse_tree, PEGVisitor(self.root_rule_name,
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self.comment_rule_name,
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self.ignore_case,
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debug=self.debug))
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