74 lines
1.9 KiB
JavaScript
74 lines
1.9 KiB
JavaScript
var traverse = require("../../traverse");
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var Scope = require("../../traverse/scope");
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var util = require("../../util");
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var t = require("../../types");
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var _ = require("lodash");
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exports.Function = function (node, parent, file, scope) {
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if (!node.defaults || !node.defaults.length) return;
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t.ensureBlock(node);
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var ids = node.params.map(function (param) {
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return t.getIds(param);
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});
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var iife = false;
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for (var i in node.defaults) {
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var def = node.defaults[i];
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if (!def) continue;
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var param = node.params[i];
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// temporal dead zone check - here we prevent accessing of params that
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// are to the right - ie. uninitialized parameters
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_.each(ids.slice(i), function (ids) {
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var check = function (node, parent) {
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if (!t.isIdentifier(node) || !t.isReferenced(node, parent)) return;
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if (_.contains(ids, node.name)) {
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throw file.errorWithNode(node, "Temporal dead zone - accessing a variable before it's initialized");
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}
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if (scope.has(node.name)) {
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iife = true;
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}
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};
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check(def, node);
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traverse(def, check);
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});
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// we're accessing a variable that's already defined within this function
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var has = scope.get(param.name);
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if (has && !_.contains(node.params, has)) {
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iife = true;
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}
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}
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var body = [];
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for (var i in node.defaults) {
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var def = node.defaults[i];
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if (!def) continue;
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body.push(util.template("if-undefined-set-to", {
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VARIABLE: node.params[i],
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DEFAULT: def
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}, true));
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}
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if (iife) {
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var container = t.functionExpression(null, [], node.body, node.generator);
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container._aliasFunction = true;
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body.push(t.returnStatement(t.callExpression(container, [])));
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node.body = t.blockStatement(body);
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} else {
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node.body.body = body.concat(node.body.body);
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}
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node.defaults = [];
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};
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