var utils = require("../../utils"); /* * Removes proxy rules -- that is, rules that only delegate to other rule. */ module.exports = function(ast, options) { function isProxyRule(node) { return node.type === "rule" && node.expression.type === "rule_ref"; } function replaceRuleRefs(ast, from, to) { function nop() {} function replaceInExpression(node, from, to) { replace(node.expression, from, to); } function replaceInSubnodes(propertyName) { return function(node, from, to) { utils.each(node[propertyName], function(subnode) { replace(subnode, from, to); }); }; } var replace = utils.buildNodeVisitor({ grammar: replaceInSubnodes("rules"), rule: replaceInExpression, named: replaceInExpression, choice: replaceInSubnodes("alternatives"), sequence: replaceInSubnodes("elements"), labeled: replaceInExpression, text: replaceInExpression, simple_and: replaceInExpression, simple_not: replaceInExpression, semantic_and: nop, semantic_not: nop, optional: replaceInExpression, zero_or_more: replaceInExpression, one_or_more: replaceInExpression, action: replaceInExpression, rule_ref: function(node, from, to) { if (node.name === from) { node.name = to; } }, literal: nop, "class": nop, any: nop }); replace(ast, from, to); } var indices = []; utils.each(ast.rules, function(rule, i) { if (isProxyRule(rule)) { replaceRuleRefs(ast, rule.name, rule.expression.name); if (!utils.contains(options.allowedStartRules, rule.name)) { indices.push(i); } } }); indices.reverse(); utils.each(indices, function(index) { ast.rules.splice(index, 1); }); };