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

36 lines
1.0 KiB
JavaScript

"use strict";
var GrammarError = require("../../grammar-error"),
asts = require("../asts"),
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) {
var check = visitor.build({
zero_or_more: function(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: function(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;