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For instance members, declare the computed field keys with side effec…
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…ts as separate statements added before the class declaration.

PiperOrigin-RevId: 565794428
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@copybara-github
Closure Team authored and copybara-github committed Sep 15, 2023
1 parent 0e9335f commit ec5741d
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Showing 2 changed files with 72 additions and 56 deletions.
53 changes: 23 additions & 30 deletions src/com/google/javascript/jscomp/RewriteClassMembers.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.parsing.parser.FeatureSet;
import com.google.javascript.jscomp.parsing.parser.FeatureSet.Feature;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import java.util.ArrayDeque;
import java.util.Deque;
Expand Down Expand Up @@ -253,11 +254,10 @@ private void moveComputedFieldsWithSideEffectsInsideComputedFunction(
* becomes
*
* <pre>
* var $jscomp$computedfield$0;
* var $jscomp$computedfield$0 = bar('str');
* class Foo {
* [$jscomp$computedfield$0] = 4;
* }
* $jscomp$computedfield$0 = bar('str');
* </pre>
*/
private void extractExpressionFromCompField(
Expand All @@ -271,16 +271,12 @@ private void extractExpressionFromCompField(

Node compExpression = memberField.getFirstChild().detach();
Node compFieldVar =
astFactory.createSingleVarNameDeclaration(generateUniqueCompFieldVarName(t));
astFactory.createSingleVarNameDeclaration(
generateUniqueCompFieldVarName(t), compExpression);
Node compFieldName = compFieldVar.getFirstChild();
memberField.addChildToFront(compFieldName.cloneNode());
compFieldVar.insertBefore(record.insertionPointBeforeClass);
compFieldVar.srcrefTreeIfMissing(record.classNode);
Node exprResult =
astFactory.exprResult(astFactory.createAssign(compFieldName.cloneNode(), compExpression));
exprResult.insertAfter(record.insertionPointAfterClass);
record.insertionPointAfterClass = exprResult;
exprResult.srcrefTreeIfMissing(record.classNode);
}

/** Returns $jscomp$compfield$[FILE_ID]$[number] */
Expand All @@ -298,7 +294,7 @@ private void rewriteInstanceMembers(NodeTraversal t, ClassRecord record) {
ctorCreator.synthesizeClassConstructorIfMissing(t, record.classNode);
Node ctor = NodeUtil.getEs6ClassConstructorMemberFunctionDef(record.classNode);
Node ctorBlock = ctor.getFirstChild().getLastChild();
Node insertionPoint = findInitialInstanceInsertionPoint(ctorBlock);
Node insertionPoint = addTemporaryInsertionPoint(ctorBlock);

while (!instanceMembers.isEmpty()) {
Node instanceMember = instanceMembers.pop();
Expand All @@ -314,14 +310,14 @@ private void rewriteInstanceMembers(NodeTraversal t, ClassRecord record) {
instanceMember.isMemberFieldDef()
? convNonCompFieldToGetProp(thisNode, instanceMember.detach())
: convCompFieldToGetElem(thisNode, instanceMember.detach());
if (insertionPoint == ctorBlock) { // insert the field at the beginning of the block, no super
ctorBlock.addChildToFront(transpiledNode);
} else {
transpiledNode.insertAfter(insertionPoint);
}
t.reportCodeChange(); // we moved the field from the class body
t.reportCodeChange(ctorBlock); // to the constructor, so we need both

transpiledNode.insertBefore(insertionPoint);
}

insertionPoint.detach();

t.reportCodeChange(); // we moved the field from the class body
t.reportCodeChange(ctorBlock); // to the constructor, so we need both
}

/** Rewrites and moves all static blocks and fields */
Expand Down Expand Up @@ -399,25 +395,22 @@ private Node convCompFieldToGetElem(Node receiver, Node computedField) {
}

/**
* Finds the location in the constructor to put the transpiled instance fields
*
* <p>Returns the constructor body if there is no super() call so the field can be put at the
* beginning of the class
* Finds the location of super() call in the constructor and add a temporary empty node after the
* super() call. If there is no super() call, add a temporary empty node at the beginning of the
* constructor body.
*
* <p>Returns the super() call otherwise so the field can be put after the super() call
* <p>Returns the added temporary empty node
*/
private Node findInitialInstanceInsertionPoint(Node ctorBlock) {
if (NodeUtil.referencesSuper(ctorBlock)) {
// will use the fact that if there is super in the constructor, the first appearance of
// super
// must be the super call
private Node addTemporaryInsertionPoint(Node ctorBlock) {
Node tempNode = IR.empty();
for (Node stmt = ctorBlock.getFirstChild(); stmt != null; stmt = stmt.getNext()) {
if (NodeUtil.isExprCall(stmt) && stmt.getFirstFirstChild().isSuper()) {
return stmt;
tempNode.insertAfter(stmt);
return tempNode;
}
}
}
return ctorBlock; // in case the super loop doesn't work, insert at beginning of block
ctorBlock.addChildToFront(tempNode);
return tempNode;
}

/**
Expand Down Expand Up @@ -489,7 +482,7 @@ void enterField(Node field) {
if (field.isStaticMember()) {
staticMembers.push(field);
} else {
instanceMembers.push(field);
instanceMembers.offer(field);
}
}

Expand Down
75 changes: 49 additions & 26 deletions test/com/google/javascript/jscomp/RewriteClassMembersTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -283,17 +283,11 @@ public void testSuperInStaticField() {
"class Bar {",
" static a = { method1() {} };",
" static b = { method2() { super.method1(); } };",
"}",
"Object.setPrototypeOf = function(c, d) {}",
"Object.setPrototypeOf(Foo.b, Foo.a);",
"Foo.b.method2();"),
"}"),
lines(
"class Bar {}",
"Bar.a = { method1() {} };",
"Bar.b = { method2() { super.method1(); } };",
"Object.setPrototypeOf = function(c, d) {}",
"Object.setPrototypeOf(Foo.b, Foo.a);",
"Foo.b.method2();"));
"Bar.b = { method2() { super.method1(); } };"));
}

@Test
Expand All @@ -302,15 +296,17 @@ public void testComputedPropInNonStaticField() {
lines(
"/** @unrestricted */",
"class C {", //
" ['x'];",
" ['y'] = 3;",
" [x+=1];",
" [x+=2] = 3;",
"}"),
lines(
"class C {", //
"var $jscomp$compfield$m1146332801$0 = x += 1;",
"var $jscomp$compfield$m1146332801$1 = x += 2;",
"class C {",
" constructor() {",
" this['x'];",
" this['y'] = 3;",
" }",
" this[$jscomp$compfield$m1146332801$0];",
" this[$jscomp$compfield$m1146332801$1] = 3;",
" }",
"}"));

test(
Expand Down Expand Up @@ -492,14 +488,13 @@ public void testSideEffectsInComputedField() {
lines(
"function bar() {",
" this.x = 3;",
" var COMPFIELD$0;",
" var COMPFIELD$0 = this.x;",
" class Foo {",
" constructor() {",
" this.y;",
" this[COMPFIELD$0] = 2;",
" }",
" }",
" COMPFIELD$0 = this.x;",
"}")));

computedFieldTest(
Expand All @@ -522,13 +517,12 @@ public void testSideEffectsInComputedField() {
"}",
"class F extends E {",
" x() {",
" var COMPFIELD$0;",
" var COMPFIELD$0 = super.y();",
" const testcode$classdecl$var0 = class {",
" constructor() {",
" this[COMPFIELD$0] = 4;",
" }",
" };",
" COMPFIELD$0 = super.y();",
" return testcode$classdecl$var0;",
" }",
"}")));
Expand All @@ -546,15 +540,13 @@ public void testSideEffectsInComputedField() {
expected(
lines(
"function bar(num) {}",
"var COMPFIELD$0;",
"var COMPFIELD$1;",
"var COMPFIELD$0 = bar(1);",
"var COMPFIELD$1 = bar(2);",
"class Foo {",
" constructor() {",
" this[COMPFIELD$0] = 'a'",
" }",
"}",
"COMPFIELD$0 = bar(1);",
"COMPFIELD$1 = bar(2);",
"Foo.b = bar(3);",
"Foo[COMPFIELD$1] = bar(4);")));

Expand All @@ -569,9 +561,8 @@ public void testSideEffectsInComputedField() {
expected(
lines(
"let x = 'hello';",
"var COMPFIELD$0;",
"var COMPFIELD$0 = x;",
"class Foo {}",
"COMPFIELD$0 = x;",
"Foo.n = x = 5;",
"Foo[COMPFIELD$0] = 'world';")));

Expand Down Expand Up @@ -843,16 +834,20 @@ public void testStaticNoncomputed() {
public void testInstanceNoncomputedWithNonemptyConstructor() {
test(
lines(
"class C {", //
"class C extends Object {", //
" x = 1;",
" z = 3;",
" constructor() {",
" super();",
" this.y = 2;",
" }",
"}"),
lines(
"class C {", //
"class C extends Object{", //
" constructor() {",
" super();",
" this.x = 1",
" this.z = 3",
" this.y = 2;",
" }",
"}"));
Expand Down Expand Up @@ -962,6 +957,34 @@ public void testInstanceNoncomputedWithNonemptyConstructor() {
"}"));
}

@Test
public void testInstanceComputedWithNonemptyConstructorAndSuper() {

computedFieldTest(
srcs(
lines(
"class A { constructor() { alert(1); } }",
"/** @unrestricted */ class C extends A {", //
" ['x'] = 1;",
" constructor() {",
" super();",
" this['y'] = 2;",
" this['z'] = 3;",
" }",
"}")),
expected(
lines(
"class A { constructor() { alert(1); } }",
"class C extends A {", //
" constructor() {",
" super()",
" this['x'] = 1",
" this['y'] = 2;",
" this['z'] = 3;",
" }",
"}")));
}

@Test
public void testInstanceNoncomputedWithNonemptyConstructorAndSuper() {
test(
Expand Down

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