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Greater spec compliance for class properties (#4544)

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* Desugar class properties to Object.defineProperty per spec
* Define uninitialized static class properties with value=undefined
* Make class-properties increased spec compliance opt-in (spec: true)
This commit is contained in:
Moti Zilberman
2016-11-15 23:35:51 +02:00
committed by Henry Zhu
parent cf3a38fb40
commit f8ddd80f96
39 changed files with 466 additions and 11 deletions
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39
packages/babel-plugin-transform-class-properties/src/index.js
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@@ -1,6 +1,6 @@
/* eslint max-len: 0 */
// todo: define instead of assign
import nameFunction from "babel-helper-function-name";
import template from "babel-template";
export default function ({ types: t }) {
let findBareSupers = {
@@ -20,11 +20,31 @@ export default function ({ types: t }) {
}
};
const buildObjectDefineProperty = template(`
Object.defineProperty(REF, KEY, {
// configurable is false by default
enumerable: true,
writable: true,
value: VALUE
});
`);
const buildClassPropertySpec = (ref, {key, value, computed}) => buildObjectDefineProperty({
REF: ref,
KEY: (t.isIdentifier(key) && !computed) ? t.stringLiteral(key.name) : key,
VALUE: value ? value : t.identifier("undefined")
});
const buildClassPropertyNonSpec = (ref, {key, value, computed}) => t.expressionStatement(
t.assignmentExpression("=", t.memberExpression(ref, key, computed || t.isLiteral(key)), value)
);
return {
inherits: require("babel-plugin-syntax-class-properties"),
visitor: {
Class(path) {
Class(path, state) {
const buildClassProperty = state.opts.spec ? buildClassPropertySpec : buildClassPropertyNonSpec;
let isDerived = !!path.node.superClass;
let constructor;
let props = [];
@@ -55,19 +75,18 @@ export default function ({ types: t }) {
for (let prop of props) {
let propNode = prop.node;
if (propNode.decorators && propNode.decorators.length > 0) continue;
if (!propNode.value) continue;
// In non-spec mode, all properties without values are ignored.
// In spec mode, *static* properties without values are still defined (see below).
if (!state.opts.spec && !propNode.value) continue;
let isStatic = propNode.static;
let isComputed = propNode.computed || t.isLiteral(prop.key);
if (isStatic) {
nodes.push(t.expressionStatement(
t.assignmentExpression("=", t.memberExpression(ref, propNode.key, isComputed), propNode.value)
));
nodes.push(buildClassProperty(ref, propNode));
} else {
instanceBody.push(t.expressionStatement(
t.assignmentExpression("=", t.memberExpression(t.thisExpression(), propNode.key, isComputed), propNode.value)
));
if (!propNode.value) continue; // Ignore instance property with no value in spec mode
instanceBody.push(buildClassProperty(t.thisExpression(), propNode));
}
}