104 lines
2.5 KiB
JavaScript
104 lines
2.5 KiB
JavaScript
"use strict";
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var traverse = require("../../../traverse");
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var util = require("../../../util");
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var t = require("../../../types");
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function checkTDZ(node, parent, scope, context, state) {
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if (!t.isReferencedIdentifier(node, parent)) return;
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if (state.ids.indexOf(node.name) >= 0) {
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throw state.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, true)) {
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state.iife = true;
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}
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}
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var checkTDZVisitor = {
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enter: checkTDZ
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};
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exports.Function = function (node, parent, scope, context, file) {
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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 def;
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var state = {
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file: file,
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iife: false
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};
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for (var i = 0; i < node.defaults.length; i++) {
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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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var rightIds = ids.slice(i);
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for (var i2 = 0; i2 < rightIds.length; i2++) {
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state.ids = rightIds[i2];
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checkTDZ(def, node, scope, context, state);
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if (!t.isPattern(param)) {
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traverse(def, checkTDZVisitor, scope, state);
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}
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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, true);
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if (has && node.params.indexOf(has) < 0) {
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state.iife = true;
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}
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}
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var body = [];
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var argsIdentifier = t.identifier("arguments");
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argsIdentifier._ignoreAliasFunctions = true;
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var lastNonDefaultParam = 0;
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for (i = 0; i < node.defaults.length; i++) {
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def = node.defaults[i];
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if (!def) {
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lastNonDefaultParam = +i + 1;
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continue;
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}
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var defNode = util.template("default-parameter", {
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VARIABLE_NAME: node.params[i],
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DEFAULT_VALUE: def,
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ARGUMENT_KEY: t.literal(+i),
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ARGUMENTS: argsIdentifier
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}, true);
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defNode._blockHoist = node.defaults.length - i;
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body.push(defNode);
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}
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// we need to cut off all trailing default parameters
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node.params = node.params.slice(0, lastNonDefaultParam);
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if (state.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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