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Fix folding array literals - bail on spread element #698

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Merged
boopathi merged 1 commit into from
Sep 25, 2017
Merged

Fix folding array literals - bail on spread element #698

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8 changes: 8 additions & 0 deletions packages/babel-plugin-minify-constant-folding/__tests__/constant-folding-test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -246,4 +246,12 @@ describe("constant-folding-plugin", () => {
}
`
);

thePlugin(
"should not fold array literals with spread element",
`
[...bar].reverse();
[...foo].join("a");
`
);
});
32 changes: 21 additions & 11 deletions packages/babel-plugin-minify-constant-folding/src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -20,18 +20,17 @@ function getName(member) {

function swap(path, member, handlers, ...args) {
const key = getName(member.node);
if (key === undefined) return;
let handler = handlers[key];
if (
typeof handler !== "function" ||
!Object.hasOwnProperty.call(handlers, key)
) {
if (typeof handlers[FALLBACK_HANDLER] === "function") {
handler = handlers[FALLBACK_HANDLER].bind(member.get("object"), key);
} else {
return false;
}
if (key === void 0) return false;

let handler;
if (hop(handlers, key) && typeof handlers[key] === "function") {
handler = handlers[key];
} else if (typeof handlers[FALLBACK_HANDLER] === "function") {
handler = handlers[FALLBACK_HANDLER].bind(member.get("object"), key);
} else {
return false;
}

const replacement = handler.apply(member.get("object"), args);
if (replacement) {
path.replaceWith(replacement);
Expand Down Expand Up @@ -172,6 +171,13 @@ module.exports = babel => {
if (t.isMemberExpression(member)) {
const helpers = replacements[member.node.object.type];
if (!helpers || !helpers.calls) return;
// find if the input can be constant folded
if (
typeof helpers.canReplace === "function" &&
!helpers.canReplace.call(member.get("object"))
) {
return;
}
swap(path, member, helpers.calls, ...node.arguments);
}
},
Expand All @@ -184,3 +190,7 @@ module.exports = babel => {
}
};
};

function hop(o, key) {
return Object.prototype.hasOwnProperty.call(o, key);
}
13 changes: 10 additions & 3 deletions packages/babel-plugin-minify-constant-folding/src/replacements.js
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Expand Up @@ -19,17 +19,24 @@ module.exports = ({ types: t }) => {
};
}

function hasSpread(node) {
return node.elements.some(el => t.isSpreadElement(el));
}

return {
ArrayExpression: {
canReplace() {
return !hasSpread(this.node);
},
members: {
length() {
if (this.node.elements.some(el => t.isSpreadElement(el))) {
if (hasSpread(this.node)) {
return;
}
return t.numericLiteral(this.node.elements.length);
},
[FALLBACK_HANDLER](i) {
if (this.node.elements.some(el => t.isSpreadElement(el))) {
if (hasSpread(this.node)) {
return;
}
if (typeof i === "number" || i.match(/^\d+$/)) {
Expand All @@ -51,7 +58,7 @@ module.exports = ({ types: t }) => {
return evaled.value;
})
.join(sep.value);
return bad ? undefined : t.stringLiteral(str);
return bad ? void 0 : t.stringLiteral(str);
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@j-f1 j-f1 Sep 25, 2017

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Why does this use void 0 instead of undefined?

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@boopathi boopathi Sep 25, 2017

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we use void 0 everywhere in the project. Just sticking to that.

},
push(...args) {
return t.numericLiteral(this.node.elements.length + args.length);
Expand Down