139 lines
3 KiB
Python
139 lines
3 KiB
Python
from enum import auto, IntEnum
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from re import compile, Pattern
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from typing import Collection, Mapping, Sequence, Tuple
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class Tok(IntEnum):
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"""
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All possible tokens used in the grammar
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"""
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Newline = auto()
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Whitespace = auto()
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PredicateSection = auto()
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VariablesSection = auto()
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ConstantsSection = auto()
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FunctionsSection = auto()
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ClausesSection = auto()
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Negate = auto()
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OpenP = auto()
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CloseP = auto()
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Comma = auto()
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Identifier = auto()
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Eof = auto()
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def __repr__(self):
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return self._name_
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LEX_TABLE: Collection[Tuple[Pattern[str], Tok]] = [
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(compile(r"\n"), Tok.Newline),
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(compile(r"[ \t]+"), Tok.Whitespace),
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(compile("Predicates:"), Tok.PredicateSection),
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(compile("Variables:"), Tok.VariablesSection),
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(compile("Constants:"), Tok.ConstantsSection),
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(compile("Functions:"), Tok.FunctionsSection),
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(compile("Clauses:"), Tok.ClausesSection),
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(compile("!"), Tok.Negate),
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(compile(r"\("), Tok.OpenP),
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(compile(r"\)"), Tok.CloseP),
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(compile(","), Tok.Comma),
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(compile(r"\w+"), Tok.Identifier),
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]
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"""
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A mapping of regexs to the tokens the identify
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Tokens earlier on in the list should be regarded as higher priority, even if a match lower
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on the list also matches. All unicode strings should be matched by at least one token.
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"""
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class Variable(IntEnum):
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Start = auto()
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Idents = auto()
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Clauses = auto()
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Clauses_ = auto()
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Clause = auto()
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Clause_ = auto()
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Term = auto()
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Func = auto()
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CSTerms = auto()
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def __repr__(self) -> str:
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return f'<{self._name_}>'
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GRAMMAR: Sequence[Tuple[Variable, Sequence[Variable | Tok]]] = [
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(Variable.Start,
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[ Tok.PredicateSection, Variable.Idents, Tok.Newline
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, Tok.VariablesSection, Variable.Idents, Tok.Newline
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, Tok.ConstantsSection, Variable.Idents, Tok.Newline
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, Tok.FunctionsSection, Variable.Idents, Tok.Newline
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, Tok.ClausesSection, Variable.Clauses, Tok.Eof ] ),
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(Variable.Idents,
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[ Tok.Identifier, Variable.Idents ]),
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(Variable.Idents,
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[ ]),
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(Variable.Clauses,
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[ Tok.Newline, Variable.Clauses_ ]),
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(Variable.Clauses,
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[ ]),
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(Variable.Clauses_,
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[ Variable.Clause, Variable.Clauses ]),
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(Variable.Clauses_,
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[ ]),
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(Variable.Clause,
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[ Variable.Term, Variable.Clause_ ]),
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(Variable.Clause_,
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[ Variable.Clause ]),
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(Variable.Clause_,
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[ ]),
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(Variable.Term,
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[ Tok.Negate, Variable.Term ]),
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(Variable.Term,
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[ Tok.Identifier, Variable.Func ]),
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(Variable.Func,
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[ Tok.OpenP, Variable.CSTerms, Tok.CloseP ]),
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(Variable.Func,
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[ ]),
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(Variable.CSTerms,
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[ Tok.Comma, Variable.Term, Variable.CSTerms ]),
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(Variable.CSTerms,
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[ ]),
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]
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"""
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Implements the following grammar:
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Start := PredicateSection <Idents> Newline
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VariablesSection <Idents> Newline
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ConstantsSection <Idents> Newline
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FunctionsSection <Idents> Newline
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ClausesSection <Clauses> Eof
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Idents := Identifier <Idents>
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:= ε
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Clauses := Newline <Clauses'>
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:= ε
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Clauses' := <Clause> <Clauses>
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:= ε
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Clause := <Term> <Clause'>
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Clause' := <Clause>
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:= ε
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Term := Negate <Term>
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:= Identifier <Func?>
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Func? := OpenP <Term> <CSTerms> CloseP
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:= ε
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CSTerms := Comma <Term> <CSTerms>
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:= ε
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""" |