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pegjs/lib/compiler/passes/remove-proxy-rules.js

43 lines
946 B
JavaScript

"use strict";
var arrays = require("../../utils/arrays"),
visitor = require("../visitor");
/*
* Removes proxy rules -- that is, rules that only delegate to other rule.
*/
function removeProxyRules(ast, options) {
function isProxyRule(node) {
return node.type === "rule" && node.expression.type === "rule_ref";
}
function replaceRuleRefs(ast, from, to) {
var replace = visitor.build({
rule_ref: function(node) {
if (node.name === from) {
node.name = to;
}
}
});
replace(ast);
}
var indices = [];
arrays.each(ast.rules, function(rule, i) {
if (isProxyRule(rule)) {
replaceRuleRefs(ast, rule.name, rule.expression.name);
if (!arrays.contains(options.allowedStartRules, rule.name)) {
indices.push(i);
}
}
});
indices.reverse();
11 years ago
arrays.each(indices, function(i) { ast.rules.splice(i, 1); });
}
module.exports = removeProxyRules;