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Optimize and remove state from typeof-symbol transform (#5955)

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Also fixes a bug with returning a Symbol from a Class constructor
(because the transform wasn’t run on helpers before).
This commit is contained in:
Justin Ridgewell
2017-07-17 10:51:36 -04:00
committed by Henry Zhu
parent 9d612e717e
commit 797fb3c2e4
8 changed files with 53 additions and 28 deletions
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2
packages/babel-helpers/src/helpers.js
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@@ -362,7 +362,7 @@ helpers.get = template(`
helpers.inherits = template(`
(function (subClass, superClass) {
if (typeof superClass !== "function" && superClass !== null) {
throw new TypeError("Super expression must either be null or a function, not " + typeof superClass);
throw new TypeError("Super expression must either be null or a function");
}
subClass.prototype = Object.create(superClass && superClass.prototype, {
constructor: {

2
packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/options.json vendored
View File

@@ -1,3 +1,3 @@
{
"plugins": ["transform-es2015-classes", "transform-es2015-block-scoping"]
"plugins": ["transform-es2015-classes", "transform-es2015-block-scoping", "transform-es2015-typeof-symbol"]
}

9
packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/return-symbol.js vendored Normal file
View File

@@ -0,0 +1,9 @@
class Foo {
constructor() {
return Symbol();
}
}
const f = new Foo;
assert.ok(f instanceof Foo);
assert.ok(typeof f === "object");

6
packages/babel-plugin-transform-es2015-classes/test/fixtures/regression/T7537/expected.js vendored
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@@ -1,8 +1,10 @@
"use strict";
function _possibleConstructorReturn(self, call) { if (call && (typeof call === "object" || typeof call === "function")) { return call; } if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }
var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };
function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
function _possibleConstructorReturn(self, call) { if (call && (_typeof(call) === "object" || typeof call === "function")) { return call; } if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }
function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function"); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

46
packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
View File

@@ -1,6 +1,4 @@
export default function({ types: t }) {
const IGNORE = Symbol();
return {
visitor: {
Scope({ scope }) {
@@ -13,8 +11,7 @@ export default function({ types: t }) {
UnaryExpression(path) {
const { node, parent } = path;
if (node[IGNORE]) return;
if (path.find(path => path.node && !!path.node._generated)) return;
if (node.operator !== "typeof") return;
if (
path.parentPath.isBinaryExpression() &&
@@ -32,24 +29,29 @@ export default function({ types: t }) {
}
}
if (node.operator === "typeof") {
const call = t.callExpression(this.addHelper("typeof"), [
node.argument,
]);
if (path.get("argument").isIdentifier()) {
const undefLiteral = t.stringLiteral("undefined");
const unary = t.unaryExpression("typeof", node.argument);
unary[IGNORE] = true;
path.replaceWith(
t.conditionalExpression(
t.binaryExpression("===", unary, undefLiteral),
undefLiteral,
call,
),
);
} else {
path.replaceWith(call);
}
const helper = this.addHelper("typeof");
const isUnderHelper = path.findParent(path => {
return path.isVariableDeclarator() && path.node.id === helper;
});
if (isUnderHelper) {
return;
}
const call = t.callExpression(helper, [node.argument]);
const arg = path.get("argument");
if (arg.isIdentifier() && !path.scope.hasBinding(arg.node.name)) {
const undefLiteral = t.stringLiteral("undefined");
const unary = t.unaryExpression("typeof", node.argument);
path.replaceWith(
t.conditionalExpression(
t.binaryExpression("===", unary, undefLiteral),
undefLiteral,
call,
),
);
} else {
path.replaceWith(call);
}
},
},

4
packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/actual.js vendored
View File

@@ -3,3 +3,7 @@ assert.ok(typeof s === "symbol");
assert.equal(typeof s, "symbol");
assert.equal(typeof typeof s.foo, "symbol");
typeof s === "string";
assert.isNotOk(typeof o === "symbol");
assert.notEqual(typeof o, "symbol");
assert.notEqual(typeof typeof o.foo, "symbol");
typeof o === "string";

4
packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/exec.js vendored
View File

@@ -2,3 +2,7 @@ var s = Symbol("s");
assert.equal(typeof s, "symbol");
assert.ok(typeof s === "symbol");
assert.ok(typeof Symbol.prototype === 'object', "`typeof Symbol.prototype` should be 'object'");
assert.isNotOk(typeof o === "symbol");
assert.notEqual(typeof o, "symbol");
assert.notEqual(typeof typeof o, "symbol");
typeof o === "string";

8
packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/expected.js vendored
View File

@@ -1,5 +1,9 @@
var s = Symbol("s");
assert.ok((typeof s === "undefined" ? "undefined" : babelHelpers.typeof(s)) === "symbol");
assert.equal(typeof s === "undefined" ? "undefined" : babelHelpers.typeof(s), "symbol");
assert.ok(babelHelpers.typeof(s) === "symbol");
assert.equal(babelHelpers.typeof(s), "symbol");
assert.equal(babelHelpers.typeof(babelHelpers.typeof(s.foo)), "symbol");
typeof s === "string";
assert.isNotOk((typeof o === "undefined" ? "undefined" : babelHelpers.typeof(o)) === "symbol");
assert.notEqual(typeof o === "undefined" ? "undefined" : babelHelpers.typeof(o), "symbol");
assert.notEqual(babelHelpers.typeof(babelHelpers.typeof(o.foo)), "symbol");
typeof o === "string";