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module.exports = grammar({
name: 'Calc',
rules: {
source_file: $ => $.expression,
expression: $ => choice(
$.term,
$.unary_expression,
$.binary_expression,
),
unary_expression: $ => prec.left(1, seq('-', $.term)),
binary_expression: $ => choice(
prec.left(2, seq($.expression, '+', $.expression)),
prec.left(2, seq($.expression, '-', $.expression)),
prec.left(3, seq($.expression, '*', $.expression)),
prec.left(3, seq($.expression, '/', $.expression)),
),
term: $ => choice(
$.identifier,
$.number,
seq('(', $.expression, ')'),
),
identifier: $ => /[a-z_]+/,
number: $ => /[0-9][0-9.]*/,
}
});
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