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Microbouji patch/8136 (#9073)
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* Fix optional chaining bug regarding spread in function calls

* Revamp optional-chain to be top down

Instead of going both upwards and downwards from the first real optional expression, we can just start from the top down.

* Add more tests
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@jridgewell
jridgewell committed Nov 24, 2018
1 parent 856edbf commit 844dd33
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Showing 4 changed files with 121 additions and 120 deletions.
221 changes: 101 additions & 120 deletions packages/babel-plugin-proposal-optional-chaining/src/index.js
View file
Expand Up @@ -7,136 +7,117 @@ export default declare((api, options) => {

const { loose = false } = options;

function optional(path, replacementPath) {
const { scope } = path;
const optionals = [];

let objectPath = path;
while (
objectPath.isOptionalMemberExpression() ||
objectPath.isOptionalCallExpression()
) {
const { node } = objectPath;
if (node.optional) {
optionals.push(node);
}

if (objectPath.isOptionalMemberExpression()) {
objectPath.node.type = "MemberExpression";
objectPath = objectPath.get("object");
} else {
objectPath.node.type = "CallExpression";
objectPath = objectPath.get("callee");
}
}

for (let i = optionals.length - 1; i >= 0; i--) {
const node = optionals[i];
node.optional = false;
return {
name: "proposal-optional-chaining",
inherits: syntaxOptionalChaining,

const isCall = t.isCallExpression(node);
const replaceKey = isCall ? "callee" : "object";
const chain = node[replaceKey];
visitor: {
"OptionalCallExpression|OptionalMemberExpression"(path) {
const { parentPath, scope } = path;
const optionals = [];

let optionalPath = path;
while (
optionalPath.isOptionalMemberExpression() ||
optionalPath.isOptionalCallExpression()
) {
const { node } = optionalPath;
if (node.optional) {
optionals.push(node);
}

let ref;
let check;
if (loose && isCall) {
// If we are using a loose transform (avoiding a Function#call) and we are at the call,
// we can avoid a needless memoize.
check = ref = chain;
} else {
ref = scope.maybeGenerateMemoised(chain);
if (ref) {
check = t.assignmentExpression(
"=",
t.cloneNode(ref),
// Here `chain` MUST NOT be cloned because it could be updated
// when generating the memoised context of a call espression
chain,
);
node[replaceKey] = ref;
} else {
check = ref = chain;
if (optionalPath.isOptionalMemberExpression()) {
optionalPath.node.type = "MemberExpression";
optionalPath = optionalPath.get("object");
} else if (optionalPath.isOptionalCallExpression()) {
optionalPath.node.type = "CallExpression";
optionalPath = optionalPath.get("callee");
}
}
}

// Ensure call expressions have the proper `this`
// `foo.bar()` has context `foo`.
if (isCall && t.isMemberExpression(chain)) {
if (loose) {
// To avoid a Function#call, we can instead re-grab the property from the context object.
// `a.?b.?()` translates roughly to `_a.b != null && _a.b()`
node.callee = chain;
} else {
// Otherwise, we need to memoize the context object, and change the call into a Function#call.
// `a.?b.?()` translates roughly to `(_b = _a.b) != null && _b.call(_a)`
const { object } = chain;
let context = scope.maybeGenerateMemoised(object);
if (context) {
chain.object = t.assignmentExpression("=", context, object);
let replacementPath = path;
if (parentPath.isUnaryExpression({ operator: "delete" })) {
replacementPath = parentPath;
}
for (let i = optionals.length - 1; i >= 0; i--) {
const node = optionals[i];

const isCall = t.isCallExpression(node);
const replaceKey = isCall ? "callee" : "object";
const chain = node[replaceKey];

let ref;
let check;
if (loose && isCall) {
// If we are using a loose transform (avoiding a Function#call) and we are at the call,
// we can avoid a needless memoize.
check = ref = chain;
} else {
context = object;
ref = scope.maybeGenerateMemoised(chain);
if (ref) {
check = t.assignmentExpression(
"=",
t.cloneNode(ref),
// Here `chain` MUST NOT be cloned because it could be updated
// when generating the memoised context of a call espression
chain,
);
node[replaceKey] = ref;
} else {
check = ref = chain;
}
}

node.arguments.unshift(t.cloneNode(context));
node.callee = t.memberExpression(node.callee, t.identifier("call"));
}
}

replacementPath.replaceWith(
t.conditionalExpression(
loose
? t.binaryExpression("==", t.cloneNode(check), t.nullLiteral())
: t.logicalExpression(
"||",
t.binaryExpression("===", t.cloneNode(check), t.nullLiteral()),
t.binaryExpression(
"===",
t.cloneNode(ref),
scope.buildUndefinedNode(),
),
),
scope.buildUndefinedNode(),
replacementPath.node,
),
);

replacementPath = replacementPath.get("alternate");
}
}

function findReplacementPath(path) {
return path.find(path => {
const { parentPath } = path;

if (path.key == "object" && parentPath.isOptionalMemberExpression()) {
return false;
}
if (path.key == "callee" && parentPath.isOptionalCallExpression()) {
return false;
}
if (
path.key == "argument" &&
parentPath.isUnaryExpression({ operator: "delete" })
) {
return false;
}

return true;
});
}
// Ensure call expressions have the proper `this`
// `foo.bar()` has context `foo`.
if (isCall && t.isMemberExpression(chain)) {
if (loose) {
// To avoid a Function#call, we can instead re-grab the property from the context object.
// `a.?b.?()` translates roughly to `_a.b != null && _a.b()`
node.callee = chain;
} else {
// Otherwise, we need to memoize the context object, and change the call into a Function#call.
// `a.?b.?()` translates roughly to `(_b = _a.b) != null && _b.call(_a)`
const { object } = chain;
let context = scope.maybeGenerateMemoised(object);
if (context) {
chain.object = t.assignmentExpression("=", context, object);
} else {
context = object;
}

node.arguments.unshift(t.cloneNode(context));
node.callee = t.memberExpression(
node.callee,
t.identifier("call"),
);
}
}

return {
name: "proposal-optional-chaining",
inherits: syntaxOptionalChaining,
replacementPath.replaceWith(
t.conditionalExpression(
loose
? t.binaryExpression("==", t.cloneNode(check), t.nullLiteral())
: t.logicalExpression(
"||",
t.binaryExpression(
"===",
t.cloneNode(check),
t.nullLiteral(),
),
t.binaryExpression(
"===",
t.cloneNode(ref),
scope.buildUndefinedNode(),
),
),
scope.buildUndefinedNode(),
replacementPath.node,
),
);

visitor: {
"OptionalCallExpression|OptionalMemberExpression"(path) {
if (!path.node.optional) {
return;
replacementPath = replacementPath.get("alternate");
}

optional(path, findReplacementPath(path));
},
},
};
Expand Down
7 changes: 7 additions & 0 deletions ...bel-plugin-proposal-optional-chaining/test/fixtures/general/function-call-spread/input.js
View file
@@ -0,0 +1,7 @@
a?.(...args);

a?.b(...args);

a?.b(...args).c;

a?.b(...args).c(...args);
7 changes: 7 additions & 0 deletions ...plugin-proposal-optional-chaining/test/fixtures/general/function-call-spread/options.json
View file
@@ -0,0 +1,7 @@
{
"plugins": [
"external-helpers",
"proposal-optional-chaining",
"transform-spread"
]
}
6 changes: 6 additions & 0 deletions ...el-plugin-proposal-optional-chaining/test/fixtures/general/function-call-spread/output.js
View file
@@ -0,0 +1,6 @@
var _a, _a2, _a3, _a4, _a4$b;

(_a = a) === null || _a === void 0 ? void 0 : _a.apply(void 0, babelHelpers.toConsumableArray(args));
(_a2 = a) === null || _a2 === void 0 ? void 0 : _a2.b.apply(_a2, babelHelpers.toConsumableArray(args));
(_a3 = a) === null || _a3 === void 0 ? void 0 : _a3.b.apply(_a3, babelHelpers.toConsumableArray(args)).c;
(_a4 = a) === null || _a4 === void 0 ? void 0 : (_a4$b = _a4.b.apply(_a4, babelHelpers.toConsumableArray(args))).c.apply(_a4$b, babelHelpers.toConsumableArray(args));

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