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