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pegjs/lib/compiler/passes/report-duplicate-rules.js

27 lines
553 B
JavaScript

"use strict";
var GrammarError = require("../../grammar-error"),
visitor = require("../visitor");
/* Checks that each rule is defined only once. */
function reportDuplicateRules(ast) {
var rules = {};
var check = visitor.build({
rule: function(node) {
if (rules.hasOwnProperty(node.name)) {
throw new GrammarError(
"Rule \"" + node.name + "\" is already defined.",
node.location
);
}
rules[node.name] = true;
}
});
check(ast);
}
module.exports = reportDuplicateRules;