cerxes/babel
3
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Avoid duplicating impure expressions in object rest destructuring (#5151)

Browse Source 
* avoid duplicating impure initializers in object rest destructuring

* reuse existing VariableDeclarations in object rest destructuring, to fix two issues:

1. inserting an additional VariableDeclaration after the current one may change order of operations, which is unsafe if a future VariableDeclarator refers to a destructured variable.

2. The entire VariableDeclaration is removed when all properties are rest properties, indiscriminately removing other variables
This commit is contained in:
Erik Desjardins
2017-01-18 21:32:44 -05:00
committed by Henry Zhu
parent 3871236723
commit bca170ad79
11 changed files with 124 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
packages/babel-plugin-transform-object-rest-spread/src/index.js
View File

@@ -78,11 +78,31 @@ export default function ({ types: t }) {
// const { a, ...b } = c;
VariableDeclarator(path, file) {
if (!path.get("id").isObjectPattern()) { return; }
const kind = path.parentPath.node.kind;
const nodes = [];
path.traverse({
let insertionPath = path;
path.get("id").traverse({
RestProperty(path) {
if (
// skip single-property case, e.g.
// const { ...x } = foo();
// since the RHS will not be duplicated
this.originalPath.node.id.properties.length > 1 &&
!t.isIdentifier(this.originalPath.node.init)
) {
// const { a, ...b } = foo();
// to avoid calling foo() twice, as a first step convert it to:
// const _foo = foo(),
// { a, ...b } = _foo;
const initRef = path.scope.generateUidIdentifierBasedOnNode(this.originalPath.node.init, "ref");
// insert _foo = foo()
this.originalPath.insertBefore(t.variableDeclarator(initRef, this.originalPath.node.init));
// replace foo() with _foo
this.originalPath.replaceWith(t.variableDeclarator(this.originalPath.node.id, initRef));
return;
}
let ref = this.originalPath.node.init;
path.findParent((path) => {
@@ -99,29 +119,24 @@ export default function ({ types: t }) {
ref
);
nodes.push(
insertionPath.insertAfter(
t.variableDeclarator(
argument,
callExpression
)
);
insertionPath = insertionPath.getSibling(insertionPath.key + 1);
if (path.parentPath.node.properties.length === 0) {
path.findParent(
(path) => path.isObjectProperty() || path.isVariableDeclaration()
(path) => path.isObjectProperty() || path.isVariableDeclarator()
).remove();
}
}
}, {
originalPath: path
});
if (nodes.length > 0) {
path.parentPath.getSibling(path.parentPath.key + 1)
.insertBefore(
t.variableDeclaration(kind, nodes)
);
}
},
// taken from transform-es2015-destructuring/src/index.js#visitor
// export var { a, ...b } = c;