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pegjs/lib/compiler/passes/report-infinite-repetition.js

44 lines
1.1 KiB
JavaScript

"use strict";
const GrammarError = require( "../../grammar-error" );
const asts = require( "../asts" );
const visitor = require( "../visitor" );
// Reports expressions that don't consume any input inside |*| or |+| in the
// grammar, which prevents infinite loops in the generated parser.
function reportInfiniteRepetition( ast ) {
const check = visitor.build( {
zero_or_more( node ) {
if ( ! asts.alwaysConsumesOnSuccess( ast, node.expression ) ) {
throw new GrammarError(
"Possible infinite loop when parsing (repetition used with an expression that may not consume any input).",
node.location
);
}
},
one_or_more( node ) {
if ( ! asts.alwaysConsumesOnSuccess( ast, node.expression ) ) {
throw new GrammarError(
"Possible infinite loop when parsing (repetition used with an expression that may not consume any input).",
node.location
);
}
}
} );
check( ast );
}
module.exports = reportInfiniteRepetition;