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

28 lines
765 B
JavaScript

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 reportInfiniteLoops(ast) {
var check = visitor.build({
zero_or_more: function(node) {
if (asts.matchesEmpty(ast, node.expression)) {
throw new GrammarError("Infinite loop detected.", node.location);
}
},
one_or_more: function(node) {
if (asts.matchesEmpty(ast, node.expression)) {
throw new GrammarError("Infinite loop detected.", node.location);
}
}
});
check(ast);
}
module.exports = reportInfiniteLoops;