491106c347
A semantic predicate can prevent the parser to actually enter infinite recursion or loop. This is undetectable at compile-time.
30 lines
822 B
JavaScript
30 lines
822 B
JavaScript
"use strict";
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var GrammarError = require("../../grammar-error"),
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asts = require("../asts"),
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visitor = require("../visitor");
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/*
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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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*/
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function reportInfiniteLoops(ast) {
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var check = visitor.build({
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zero_or_more: function(node) {
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if (!asts.alwaysConsumesOnSuccess(ast, node.expression)) {
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throw new GrammarError("Possible infinite loop detected.", node.location);
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}
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},
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one_or_more: function(node) {
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if (!asts.alwaysConsumesOnSuccess(ast, node.expression)) {
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throw new GrammarError("Possible infinite loop detected.", node.location);
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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 = reportInfiniteLoops;
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