42 lines
876 B
JavaScript
42 lines
876 B
JavaScript
"use strict";
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let visitor = require("../visitor");
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/*
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* Removes proxy rules -- that is, rules that only delegate to other rule.
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*/
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function removeProxyRules(ast, options) {
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function isProxyRule(node) {
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return node.type === "rule" && node.expression.type === "rule_ref";
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}
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function replaceRuleRefs(ast, from, to) {
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let replace = visitor.build({
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rule_ref: function(node) {
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if (node.name === from) {
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node.name = to;
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}
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}
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});
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replace(ast);
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}
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let indices = [];
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ast.rules.forEach((rule, i) => {
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if (isProxyRule(rule)) {
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replaceRuleRefs(ast, rule.name, rule.expression.name);
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if (options.allowedStartRules.indexOf(rule.name) === -1) {
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indices.push(i);
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}
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}
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});
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indices.reverse();
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indices.forEach(i => { ast.rules.splice(i, 1); });
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}
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module.exports = removeProxyRules;
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