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Comment walker module

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Marijn Haverbeke 2012-11-06 11:10:58 +01:00
parent 043386067a
commit 3ba6913d30
1 changed files with 33 additions and 1 deletions
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34
util/walk.js
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@ -1,6 +1,23 @@
// AST walker module for Mozilla Parser API compatible trees
(function(exports) {
"use strict";
// A simple walk is one where you simply specify callbacks to be
// called on specific nodes. The last two arguments are optional. A
// simple use would be
//
// walk.simple(myTree, {
// Expression: function(node) { ... }
// });
//
// to do something with all expressions. All Parser API node types
// can be used to identify node types, as well as Expression,
// Statement, and ScopeBody, which denote categories of nodes.
//
// The base argument can be used to pass a custom (recursive)
// walker, and state can be used to give this walked an initial
// state.
exports.simple = function(node, visitors, base, state) {
if (!base) base = exports;
function c(node, st, override) {
@ -10,6 +27,12 @@
}
c(node, state);
};
// A recursive walk is one where your functions override the default
// walkers. They can modify and replace the state parameter that's
// threaded through the walk, and can opt how and whether to walk
// their child nodes (by calling their third argument on these
// nodes).
exports.recursive = function(node, state, funcs, base) {
var visitor = exports.make(funcs, base);
function c(node, st, override) {
@ -17,6 +40,9 @@
}
c(node, state);
};
// Used to create a custom walker. Will fill in all missing node
// type properties with the defaults.
exports.make = function(funcs, base) {
if (!base) base = exports;
var visitor = {};
@ -28,6 +54,8 @@
function skipThrough(node, st, c) { c(node, st); }
function ignore(node, st, c) {}
// Node walkers.
exports.Program = exports.BlockStatement = function(node, st, c) {
for (var i = 0; i < node.body.length; ++i)
c(node.body[i], st, "Statement");
@ -106,7 +134,9 @@
exports.Function = function(node, st, c) {
c(node.body, st, "ScopeBody");
};
exports.ScopeBody = skipThrough;
exports.ScopeBody = function(node, st, c) {
c(node, st, "Statement");
};
exports.Expression = skipThrough;
exports.ThisExpression = ignore;
@ -148,6 +178,8 @@
};
exports.Identifier = exports.Literal = ignore;
// A custom walker that keeps track of the scope chain and the
// variables defined in it.
function makeScope(prev) {
return {vars: Object.create(null), prev: prev};
}