"use strict"; var GrammarError = require("../../grammar-error"), objects = require("../../utils/objects"), visitor = require("../visitor"); /* Checks that each label is defined only once within each scope. */ function reportDuplicateLabels(ast) { function checkExpressionWithClonedEnv(node, env) { check(node.expression, objects.clone(env)); } var check = visitor.build({ rule: function(node) { check(node.expression, { }); }, choice: function(node, env) { node.alternatives.forEach(function(alternative) { check(alternative, objects.clone(env)); }); }, action: checkExpressionWithClonedEnv, labeled: function(node, env) { if (env.hasOwnProperty(node.label)) { throw new GrammarError( "Label \"" + node.label + "\" is already defined " + "at line " + env[node.label].start.line + ", " + "column " + env[node.label].start.column + ".", node.location ); } check(node.expression, env); env[node.label] = node.location; }, text: checkExpressionWithClonedEnv, simple_and: checkExpressionWithClonedEnv, simple_not: checkExpressionWithClonedEnv, optional: checkExpressionWithClonedEnv, zero_or_more: checkExpressionWithClonedEnv, one_or_more: checkExpressionWithClonedEnv, group: checkExpressionWithClonedEnv }); check(ast); } module.exports = reportDuplicateLabels;