This project contains my experimental project with extendable syntax grammar.
Core of project is syntax grammar (gvm.language.Grammar).
General elements of it's:
gvm.language.TokenID- token identifier, e.g. terminal symbolgvm.language.ParseletID- parselet identifier, e.g. non-terminal symbol
Grammar also contains patterns for tokenize from source text to
syntax tokens (gvm.language.SyntaxToken).
This version is used explicit definition of grammar (e.g. parselet definition is imperative)
from gvm.language.combinators import make_sequence
from gvm.language.grammar import Grammar, ParseletKind
grammar = Grammar()
grammar.add_pattern(grammar.add_token('Whitespace'), r'\s+')
grammar.add_pattern(grammar.add_token('Name'), r'[a-zA-Z_][a-zA-Z0-9]*')
number_id = grammar.add_pattern(grammar.add_token('Number'), r'[0-9]+')
expr_id = grammar.add_parselet('expr', kind=ParseletKind.Pratt)
grammar.add_trivia(grammar.tokens['Whitespace'])
implicit = grammar.add_implicit
# expr := Number
grammar.add_parser(expr_id, number_id)
# expr := expr '+' expr
grammar.add_parser(expr_id, make_sequence(expr_id, implicit('+'), expr_id), priority=100)
# expr := expr '-' expr
grammar.add_parser(expr_id, make_sequence(expr_id, implicit('-'), expr_id), priority=100)
# expr := expr '*' expr
grammar.add_parser(expr_id, make_sequence(expr_id, implicit('*'), expr_id), priority=200)
# expr := expr '/' expr
grammar.add_parser(expr_id, make_sequence(expr_id, implicit('/'), expr_id), priority=200)
# expr := '-' expr
grammar.add_parser(expr_id, make_sequence(implicit('-'), expr_id))
# expr := '-' expr
grammar.add_parser(expr_id, make_sequence(implicit('+'), expr_id))
# expr := '(' expr ')'
grammar.add_parser(expr_id, make_sequence(implicit('('), expr_id, implicit(')')))This project is published by MIT license. For full test of license view LICENSE.md
This project is used Python 3.7 as minimum version.
Also install attrs and pytest (for tests)
Run pytest
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