Transform private name bindings in destructuring assignments

Signed-off-by: Joseph Watts <[email protected]>

Author: Joseph Watts

src/compiler/transformers/esnext.ts

@@ -835,20 +835,105 @@ namespace ts {
             return visitEachChild(node, visitor, context);
         }
 
+        function wrapPrivateNameForDestructuringTarget(node: PrivateNamedPropertyAccessExpression) {
+            return createPropertyAccess(
+                createObjectLiteral([
+                    createSetAccessor(
+                        /*decorators*/ undefined,
+                        /*modifiers*/ undefined,
+                        "value",
+                        [createParameter(
+                            /*decorators*/ undefined,
+                            /*modifiers*/ undefined,
+                            /*dotDotDotToken*/ undefined, "x",
+                            /*questionToken*/ undefined,
+                            /*type*/ undefined,
+                            /*initializer*/ undefined
+                        )],
+                        createBlock(
+                            [createExpressionStatement(
+                                createAssignment(
+                                    visitNode(node, visitor),
+                                    createIdentifier("x")
+                                )
+                            )]
+                        )
+                    )
+                ]),
+                "value"
+            );
+        }
+
+        function transformDestructuringAssignmentTarget(node: ArrayLiteralExpression | ObjectLiteralExpression) {
+            const hasPrivateNames = isArrayLiteralExpression(node) ?
+                forEach(node.elements, isPrivateNamedPropertyAccessExpression) :
+                forEach(node.properties, property => isPropertyAssignment(property) && isPrivateNamedPropertyAccessExpression(property.initializer));
+            if (!hasPrivateNames) {
+                return node;
+            }
+            if (isArrayLiteralExpression(node)) {
+                // Transforms private names in destructuring assignment array bindings.
+                //
+                // Source:
+                // ([ this.#myProp ] = [ "hello" ]);
+                //
+                // Transformation:
+                // [ { set value(x) { this.#myProp = x; } }.value ] = [ "hello" ];
+                return updateArrayLiteral(
+                    node,
+                    node.elements.map(
+                        expr => isPrivateNamedPropertyAccessExpression(expr) ?
+                            wrapPrivateNameForDestructuringTarget(expr) :
+                            expr
+                    )
+                );
+            }
+            else {
+                // Transforms private names in destructuring assignment object bindings.
+                //
+                // Source:
+                // ({ stringProperty: this.#myProp } = { stringProperty: "hello" });
+                //
+                // Transformation:
+                // ({ stringProperty: { set value(x) { this.#myProp = x; } }.value }) = { stringProperty: "hello" };
+                return updateObjectLiteral(
+                    node,
+                    node.properties.map(
+                        prop => isPropertyAssignment(prop) && isPrivateNamedPropertyAccessExpression(prop.initializer) ?
+                            updatePropertyAssignment(
+                                prop,
+                                prop.name,
+                                wrapPrivateNameForDestructuringTarget(prop.initializer)
+                            ) :
+                            prop
+                    )
+                );
+            }
+        }
+
         /**
          * Visits a BinaryExpression that contains a destructuring assignment.
          *
          * @param node A BinaryExpression node.
          */
         function visitBinaryExpression(node: BinaryExpression, noDestructuringValue: boolean): Expression {
-            if (isDestructuringAssignment(node) && node.left.transformFlags & TransformFlags.ContainsObjectRestOrSpread) {
-                return flattenDestructuringAssignment(
-                    node,
-                    visitor,
-                    context,
-                    FlattenLevel.ObjectRest,
-                    !noDestructuringValue
-                );
+            if (isDestructuringAssignment(node)) {
+                const left = transformDestructuringAssignmentTarget(node.left);
+                if (left !== node.left || node.left.transformFlags & TransformFlags.ContainsObjectRestOrSpread) {
+                    return flattenDestructuringAssignment(
+                        left === node.left ? node : updateBinary(
+                            node,
+                            left,
+                            node.right,
+                            node.operatorToken.kind
+                        ) as DestructuringAssignment,
+                        visitor,
+                        context,
+                        node.left.transformFlags & TransformFlags.ContainsObjectRestOrSpread
+                            ? FlattenLevel.ObjectRest : FlattenLevel.All,
+                        !noDestructuringValue
+                    );
+                }
             }
             else if (node.operatorToken.kind === SyntaxKind.CommaToken) {
                 return updateBinary(

tests/baselines/reference/privateNameFieldDestructuredBinding.js

@@ -0,0 +1,37 @@
+//// [privateNameFieldDestructuredBinding.ts]
+class A {
+    #field = 1;
+    testObject() {
+        return { x: 10, y: 6 };
+    }
+    testArray() {
+        return [10, 11];
+    }
+    constructor() {
+        let y: number;
+        ({ x: this.#field, y } = this.testObject());
+        ([this.#field, y] = this.testArray());
+    }
+}
+
+
+//// [privateNameFieldDestructuredBinding.js]
+var _classPrivateFieldGet = function (receiver, privateMap) { if (!privateMap.has(receiver)) { throw new TypeError("attempted to get private field on non-instance"); } return privateMap.get(receiver); };
+var _field;
+var A = /** @class */ (function () {
+    function A() {
+        _field.set(this, 1);
+        var _a, _b;
+        var y;
+        (_a = this.testObject(), { set value(x) { _classPrivateFieldGet(this, _field) = x; } }.value = _a.x, y = _a.y);
+        (_b = this.testArray(), { set value(x) { _classPrivateFieldGet(this, _field) = x; } }.value = _b[0], y = _b[1]);
+    }
+    A.prototype.testObject = function () {
+        return { x: 10, y: 6 };
+    };
+    A.prototype.testArray = function () {
+        return [10, 11];
+    };
+    return A;
+}());
+_field = new WeakMap();

tests/baselines/reference/privateNameFieldDestructuredBinding.symbols

@@ -0,0 +1,42 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameFieldDestructuredBinding.ts ===
+class A {
+>A : Symbol(A, Decl(privateNameFieldDestructuredBinding.ts, 0, 0))
+
+    #field = 1;
+>#field : Symbol(A.#field, Decl(privateNameFieldDestructuredBinding.ts, 0, 9))
+
+    testObject() {
+>testObject : Symbol(A.testObject, Decl(privateNameFieldDestructuredBinding.ts, 1, 15))
+
+        return { x: 10, y: 6 };
+>x : Symbol(x, Decl(privateNameFieldDestructuredBinding.ts, 3, 16))
+>y : Symbol(y, Decl(privateNameFieldDestructuredBinding.ts, 3, 23))
+    }
+    testArray() {
+>testArray : Symbol(A.testArray, Decl(privateNameFieldDestructuredBinding.ts, 4, 5))
+
+        return [10, 11];
+    }
+    constructor() {
+        let y: number;
+>y : Symbol(y, Decl(privateNameFieldDestructuredBinding.ts, 9, 11))
+
+        ({ x: this.#field, y } = this.testObject());
+>x : Symbol(x, Decl(privateNameFieldDestructuredBinding.ts, 10, 10))
+>this.#field : Symbol(A.#field, Decl(privateNameFieldDestructuredBinding.ts, 0, 9))
+>this : Symbol(A, Decl(privateNameFieldDestructuredBinding.ts, 0, 0))
+>y : Symbol(y, Decl(privateNameFieldDestructuredBinding.ts, 10, 26))
+>this.testObject : Symbol(A.testObject, Decl(privateNameFieldDestructuredBinding.ts, 1, 15))
+>this : Symbol(A, Decl(privateNameFieldDestructuredBinding.ts, 0, 0))
+>testObject : Symbol(A.testObject, Decl(privateNameFieldDestructuredBinding.ts, 1, 15))
+
+        ([this.#field, y] = this.testArray());
+>this.#field : Symbol(A.#field, Decl(privateNameFieldDestructuredBinding.ts, 0, 9))
+>this : Symbol(A, Decl(privateNameFieldDestructuredBinding.ts, 0, 0))
+>y : Symbol(y, Decl(privateNameFieldDestructuredBinding.ts, 9, 11))
+>this.testArray : Symbol(A.testArray, Decl(privateNameFieldDestructuredBinding.ts, 4, 5))
+>this : Symbol(A, Decl(privateNameFieldDestructuredBinding.ts, 0, 0))
+>testArray : Symbol(A.testArray, Decl(privateNameFieldDestructuredBinding.ts, 4, 5))
+    }
+}
+

tests/baselines/reference/privateNameFieldDestructuredBinding.types

@@ -0,0 +1,57 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameFieldDestructuredBinding.ts ===
+class A {
+>A : A
+
+    #field = 1;
+>#field : number
+>1 : 1
+
+    testObject() {
+>testObject : () => { x: number; y: number; }
+
+        return { x: 10, y: 6 };
+>{ x: 10, y: 6 } : { x: number; y: number; }
+>x : number
+>10 : 10
+>y : number
+>6 : 6
+    }
+    testArray() {
+>testArray : () => number[]
+
+        return [10, 11];
+>[10, 11] : number[]
+>10 : 10
+>11 : 11
+    }
+    constructor() {
+        let y: number;
+>y : number
+
+        ({ x: this.#field, y } = this.testObject());
+>({ x: this.#field, y } = this.testObject()) : { x: number; y: number; }
+>{ x: this.#field, y } = this.testObject() : { x: number; y: number; }
+>{ x: this.#field, y } : { x: number; y: number; }
+>x : number
+>this.#field : number
+>this : this
+>y : number
+>this.testObject() : { x: number; y: number; }
+>this.testObject : () => { x: number; y: number; }
+>this : this
+>testObject : () => { x: number; y: number; }
+
+        ([this.#field, y] = this.testArray());
+>([this.#field, y] = this.testArray()) : number[]
+>[this.#field, y] = this.testArray() : number[]
+>[this.#field, y] : [number, number]
+>this.#field : number
+>this : this
+>y : number
+>this.testArray() : number[]
+>this.testArray : () => number[]
+>this : this
+>testArray : () => number[]
+    }
+}
+

tests/cases/conformance/classes/members/privateNames/privateNameFieldDestructuredBinding.ts

@@ -0,0 +1,14 @@
+class A {
+    #field = 1;
+    testObject() {
+        return { x: 10, y: 6 };
+    }
+    testArray() {
+        return [10, 11];
+    }
+    constructor() {
+        let y: number;
+        ({ x: this.#field, y } = this.testObject());
+        ([this.#field, y] = this.testArray());
+    }
+}