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fix: use temp class fields to host decorator expr
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@JLHwung
JLHwung committed Mar 5, 2024
1 parent fff405f commit f4314e5
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Showing 2 changed files with 76 additions and 161 deletions.
185 changes: 24 additions & 161 deletions packages/babel-helper-create-class-features-plugin/src/decorators.ts
View file
@@ -1,8 +1,7 @@
import type { NodePath, Scope, Visitor } from "@babel/traverse";
import { types as t, template, traverse } from "@babel/core";
import { types as t, template } from "@babel/core";
import ReplaceSupers from "@babel/helper-replace-supers";
import splitExportDeclaration from "@babel/helper-split-export-declaration";
import environmentVisitor from "@babel/helper-environment-visitor";
import * as charCodes from "charcodes";
import type { PluginAPI, PluginObject, PluginPass } from "@babel/core";
import { skipTransparentExprWrappers } from "@babel/helper-skip-transparent-expression-wrappers";
Expand Down Expand Up @@ -836,58 +835,6 @@ function createPrivateBrandCheckClosure(brandName: t.PrivateName) {
);
}

/**
* create a super() delegate
* (...args) => super(...args)
*
*/
function createSuperCallDelegate() {
return t.arrowFunctionExpression(
[t.restElement(t.identifier("args"))],
t.callExpression(t.super(), [t.spreadElement(t.identifier("args"))]),
);
}

/**
* create a super[prop] delegate
* (prop) => Object.defineProperty({}, "_", {
* get: () => super[prop],
* set: (v) => super[prop] = v
* })
*
*/
function createSuperPropDelegate() {
const getDelegate = t.arrowFunctionExpression(
[],
t.memberExpression(t.super(), t.identifier("prop"), true),
);
const setDelegate = t.assignmentExpression(
"=",
t.memberExpression(t.super(), t.identifier("prop"), true),
t.identifier("v"),
);
return t.arrowFunctionExpression(
[t.identifier("prop")],
t.callExpression(
t.memberExpression(
t.identifier("Object"),
t.identifier("defineProperty"),
),
[
t.objectExpression([]),
t.stringLiteral("_"),
t.objectExpression([
t.objectProperty(t.identifier("get"), getDelegate),
t.objectProperty(
t.identifier("set"),
t.arrowFunctionExpression([t.identifier("v")], setDelegate),
),
]),
],
),
);
}

// Check if the expression does not reference function-specific
// context or the given identifier name.
// `true` means "maybe" and `false` means "no".
Expand Down Expand Up @@ -1728,9 +1675,12 @@ function transformClass(
}

originalClass.body.body.unshift(t.staticBlock([]));
const applyDecoratorWrapperPath = originalClassPath
.get("body")
.get("body")[0] as NodePath<t.StaticBlock>;
if (computedKeyAssignments.length > 0) {
// todo: the following branch will fail on 2023-05 version
if (version === "2023-11") {
if (process.env.BABEL_8_BREAKING || version === "2023-11") {
const elements = originalClassPath.get("body.body");
let lastPublicElement: NodePath<t.ClassProperty | t.ClassMethod>;
for (let i = elements.length - 1; i >= 0; i--) {
Expand All @@ -1753,119 +1703,32 @@ function transformClass(
);
computedKeyAssignments = [];
}
// when there is no public class elements, the decorator expressions
// assignment will be injected right before the `applyDecs` call.
}
}
const applyDecoratorWrapperPath = originalClassPath
.get("body")
.get("body")[0] as NodePath<t.StaticBlock>;

if (computedKeyAssignments.length > 0) {
// when there is no public class elements or decorators version is earlier than 2305,
// we inject a temporary computed field whose key will host the decorator expressions
// assignment.
originalClass.body.body.unshift(
t.classProperty(
t.sequenceExpression([...computedKeyAssignments, t.stringLiteral("_")]),
undefined,
undefined,
undefined,
/* computed */ true,
/* static */ true,
),
);
applyDecoratorWrapperPath.pushContainer(
"body",
t.expressionStatement(maybeSequenceExpression(computedKeyAssignments)),
);

const computedKeysPath = applyDecoratorWrapperPath.get("body")[0];

// Capture lexical this, super() and other function contexts, replace their usage
// in computed key assignments
let outerThis: t.Identifier,
outerSuperCall: t.Identifier,
outerSuperProp: t.Identifier,
outerArguments: t.Identifier,
outerNewTarget: t.Identifier;
const computedKeysPathVisitor: Visitor = {
ThisExpression(path) {
outerThis ??= scopeParent.generateDeclaredUidIdentifier("outerThis");
path.replaceWith(t.cloneNode(outerThis));
},
CallExpression(path) {
const calleePath = path.get("callee");
if (calleePath.isSuper()) {
outerSuperCall ??=
scopeParent.generateDeclaredUidIdentifier("outerSuper");
calleePath.replaceWith(t.cloneNode(outerSuperCall));
}
},
MemberExpression(path) {
const objectPath = path.get("object");
if (objectPath.isSuper()) {
outerSuperProp ??=
scopeParent.generateDeclaredUidIdentifier("outerSuperProp");
path.replaceWith(
t.memberExpression(
t.callExpression(t.cloneNode(outerSuperProp), [
path.node.computed
? (path.node.property as t.Expression)
: t.stringLiteral((path.node.property as t.Identifier).name),
]),
t.identifier("_"),
),
);
}
},
Identifier(path) {
if (path.node.name === "arguments") {
outerArguments ??=
scopeParent.generateDeclaredUidIdentifier("outerArguments");
path.replaceWith(t.cloneNode(outerArguments));
}
},
MetaProperty(path) {
const object = path.node.meta;
if (object.name === "new") {
outerNewTarget ??=
scopeParent.generateDeclaredUidIdentifier("outerNewTarget");
path.replaceWith(t.cloneNode(outerNewTarget));
}
},
};
computedKeysPath.traverse(
traverse.visitors.merge([computedKeysPathVisitor, environmentVisitor]),
);
if (outerThis) {
classAssignments.push(
t.assignmentExpression("=", t.cloneNode(outerThis), t.thisExpression()),
);
}
if (outerSuperCall) {
classAssignments.push(
t.assignmentExpression(
"=",
t.cloneNode(outerSuperCall),
createSuperCallDelegate(),
),
);
}
if (outerSuperProp) {
classAssignments.push(
t.assignmentExpression(
"=",
t.cloneNode(outerSuperProp),
createSuperPropDelegate(),
),
);
}
if (outerArguments) {
classAssignments.push(
t.assignmentExpression(
"=",
t.cloneNode(outerArguments),
t.identifier("arguments"),
),
);
}
if (outerNewTarget) {
classAssignments.push(
t.assignmentExpression(
"=",
t.cloneNode(outerNewTarget),
t.metaProperty(t.identifier("new"), t.identifier("target")),
t.expressionStatement(
t.unaryExpression(
"delete",
t.memberExpression(t.thisExpression(), t.identifier("_")),
),
);
}
),
);
}

applyDecoratorWrapperPath.pushContainer(
Expand Down
52 changes: 52 additions & 0 deletions ...l-plugin-proposal-decorators/test/fixtures/2023-11-misc/class-underscore-property/exec.js
View file
@@ -0,0 +1,52 @@
function noopFactory() { return function noop() {} }

{
class B {
@noopFactory()
static _ = "B";
}

class C extends B {
@noopFactory() #p;
}

expect(C._).toBe("B");
}

{
class B {
@noopFactory()
static _ = "B";
}

@noopFactory()
class C extends B {
@noopFactory() #p;
}

expect(C._).toBe("B");
}

{
class C {
@noopFactory() #p;
}

expect(Reflect.ownKeys(C)).not.toContain("_");
}

{
@noopFactory()
class C {}

expect(Reflect.ownKeys(C)).not.toContain("_");
}

{
@noopFactory()
class C {
@noopFactory() #p;
}

expect(Reflect.ownKeys(C)).not.toContain("_");
}

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