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FEAT: Implement Symbol.hasInstance for Function.prototype
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Adds support for Function.prototype[Symbol.hasInstance].
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0xe authored Jan 15, 2025
1 parent 5ce34e3 commit 44f1c09
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Showing 6 changed files with 214 additions and 14 deletions.
41 changes: 39 additions & 2 deletions rhino/src/main/java/org/mozilla/javascript/BaseFunction.java
Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,7 @@ protected boolean hasDefaultParameters() {
/**
* Gets the value returned by calling the typeof operator on this object.
*
* @see org.mozilla.javascript.ScriptableObject#getTypeOf()
* @see ScriptableObject#getTypeOf()
* @return "function" or "undefined" if {@link #avoidObjectDetection()} returns <code>true
* </code>
*/
Expand Down Expand Up @@ -156,6 +156,8 @@ protected int findInstanceIdInfo(String s) {
@Override
protected String getInstanceIdName(int id) {
switch (id) {
case SymbolId_hasInstance:
return "SymbolId_hasInstance";
case Id_length:
return "length";
case Id_arity:
Expand Down Expand Up @@ -265,6 +267,17 @@ protected void fillConstructorProperties(IdFunctionObject ctor) {

@Override
protected void initPrototypeId(int id) {
if (id == SymbolId_hasInstance) {
initPrototypeMethod(
FUNCTION_TAG,
id,
SymbolKey.HAS_INSTANCE,
String.valueOf(SymbolKey.HAS_INSTANCE),
1,
CONST | DONTENUM);
return;
}

String s;
int arity;
switch (id) {
Expand Down Expand Up @@ -368,6 +381,23 @@ public Object execIdCall(
boundArgs = ScriptRuntime.emptyArgs;
}
return new BoundFunction(cx, scope, targetFunction, boundThis, boundArgs);

case SymbolId_hasInstance:
if (thisObj != null && args.length == 1 && args[0] instanceof Scriptable) {
Scriptable obj = (Scriptable) args[0];
Object protoProp = null;
if (thisObj instanceof BoundFunction)
protoProp =
((NativeFunction) ((BoundFunction) thisObj).getTargetFunction())
.getPrototypeProperty();
else protoProp = ScriptableObject.getProperty(thisObj, "prototype");
if (protoProp instanceof IdScriptableObject) {
return ScriptRuntime.jsDelegatesTo(obj, (Scriptable) protoProp);
}
throw ScriptRuntime.typeErrorById(
"msg.instanceof.bad.prototype", getFunctionName());
}
return false; // NOT_FOUND, null etc.
}
throw new IllegalArgumentException(String.valueOf(id));
}
Expand Down Expand Up @@ -632,6 +662,12 @@ private Object jsConstructor(Context cx, Scriptable scope, Object[] args) {
return cx.compileFunction(global, source, evaluator, reporter, sourceURI, 1, null);
}

@Override
protected int findPrototypeId(Symbol k) {
if (SymbolKey.HAS_INSTANCE.equals(k)) return SymbolId_hasInstance;
return 0;
}

@Override
protected int findPrototypeId(String s) {
int id;
Expand Down Expand Up @@ -675,7 +711,8 @@ public Scriptable getHomeObject() {
Id_apply = 4,
Id_call = 5,
Id_bind = 6,
MAX_PROTOTYPE_ID = Id_bind;
SymbolId_hasInstance = 7,
MAX_PROTOTYPE_ID = SymbolId_hasInstance;

private Object prototypeProperty;
private Object argumentsObj = NOT_FOUND;
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -201,7 +201,13 @@ final void delete(int id) {
Context cx = Context.getContext();
if (cx.isStrictMode()) {
int nameSlot = (id - 1) * SLOT_SPAN + NAME_SLOT;
String name = (String) valueArray[nameSlot];

String name = null;
if (valueArray[nameSlot] instanceof String)
name = (String) valueArray[nameSlot];
else if (valueArray[nameSlot] instanceof Symbol) {
name = valueArray[nameSlot].toString();
}
throw ScriptRuntime.typeErrorById(
"msg.delete.property.with.configurable.false", name);
}
Expand Down Expand Up @@ -764,6 +770,14 @@ public final IdFunctionObject initPrototypeMethod(
return function;
}

public final IdFunctionObject initPrototypeMethod(
Object tag, int id, Symbol key, String functionName, int arity, int attributes) {
Scriptable scope = ScriptableObject.getTopLevelScope(this);
IdFunctionObject function = newIdFunction(tag, id, functionName, arity, scope);
prototypeValues.initValue(id, key, function, attributes);
return function;
}

public final void initPrototypeConstructor(IdFunctionObject f) {
int id = prototypeValues.constructorId;
if (id == 0) throw new IllegalStateException();
Expand Down
2 changes: 1 addition & 1 deletion rhino/src/main/java/org/mozilla/javascript/Node.java
Original file line number Diff line number Diff line change
Expand Up @@ -1181,7 +1181,7 @@ private void toString(Map<Node, Integer> printIds, StringBuilder sb) {
Object[] a = (Object[]) x.objectValue;
sb.append("[");
for (int i = 0; i < a.length; i++) {
sb.append(a[i].toString());
if (a[i] != null) sb.append(a[i].toString());
if (i + 1 < a.length) sb.append(", ");
}
sb.append("]");
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -864,6 +864,12 @@ public boolean hasInstance(Scriptable instance) {
// chasing. This will be overridden in NativeFunction and non-JS
// objects.

Context cx = Context.getCurrentContext();
Object hasInstance = ScriptRuntime.getObjectElem(this, SymbolKey.HAS_INSTANCE, cx);
if (hasInstance instanceof Callable) {
return ScriptRuntime.toBoolean(
((Callable) hasInstance).call(cx, getParentScope(), this, new Object[] {this}));
}
return ScriptRuntime.jsDelegatesTo(instance, this);
}

Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,152 @@
package org.mozilla.javascript;

import org.junit.Ignore;
import org.junit.Test;
import org.mozilla.javascript.tests.Utils;

public class FunctionPrototypeSymbolHasInstanceTest {
@Test
public void testSymbolHasInstanceIsPresent() {
String script =
""
+ "var f = {\n"
+ " [Symbol.hasInstance](value) { "
+ " }"
+ "};\n"
+ "var g = {};\n"
+ "`${f.hasOwnProperty(Symbol.hasInstance)}:${g.hasOwnProperty(Symbol.hasInstance)}`";
Utils.assertWithAllModes("true:false", script);
}

@Test
public void testSymbolHasInstanceCanBeCalledLikeAnotherMethod() {
String script =
""
+ "var f = {\n"
+ " [Symbol.hasInstance](value) { "
+ " return 42;"
+ " }"
+ "};\n"
+ "f[Symbol.hasInstance]() == 42";
Utils.assertWithAllModes(true, script);
}

// See: https://tc39.es/ecma262/#sec-function.prototype-%symbol.hasinstance%
@Test
public void testFunctionPrototypeSymbolHasInstanceHasAttributes() {
String script =
"var a = Object.getOwnPropertyDescriptor(Function.prototype, Symbol.hasInstance);\n"
+ "a.writable + ':' + a.configurable + ':' + a.enumerable";
Utils.assertWithAllModes("false:false:false", script);
}

// See: https://tc39.es/ecma262/#sec-function.prototype-%symbol.hasinstance%
@Test
public void testFunctionPrototypeSymbolHasInstanceHasAttributesStrictMode() {
String script =
"'use strict';\n"
+ "var t = typeof Function.prototype[Symbol.hasInstance];\n"
+ "var a = Object.getOwnPropertyDescriptor(Function.prototype, Symbol.hasInstance);\n"
+ "var typeErrorThrown = false;\n"
+ "try { \n"
+ " delete Function.prototype[Symbol.hasInstance] \n"
+ "} catch (e) { \n"
+ " typeErrorThrown = true \n"
+ "}\n"
+ "Object.prototype.hasOwnProperty.call(Function.prototype, Symbol.hasInstance) + ':' + typeErrorThrown + ':' + t + ':' + a.writable + ':' + a.configurable + ':' + a.enumerable; \n";
Utils.assertWithAllModes("true:true:function:false:false:false", script);
}

@Test
@Ignore("name-length-params-prototype-set-incorrectly")
public void testFunctionPrototypeSymbolHasInstanceHasProperties() {
String script =
"var a = Object.getOwnPropertyDescriptor(Function.prototype[Symbol.hasInstance], 'length');\n"
+ "a.value + ':' + a.writable + ':' + a.configurable + ':' + a.enumerable";

String script2 =
"var a = Object.getOwnPropertyDescriptor(Function.prototype[Symbol.hasInstance], 'name');\n"
+ "a.value + ':' + a.writable + ':' + a.configurable + ':' + a.enumerable";
Utils.assertWithAllModes("1:false:true:false", script);
Utils.assertWithAllModes("Symbol(Symbol.hasInstance):false:true:false", script2);
}

@Test
public void testFunctionPrototypeSymbolHasInstance() {
String script =
"(Function.prototype[Symbol.hasInstance] instanceof Function) + ':' + "
+ "Function.prototype[Symbol.hasInstance].call(Function, Object)\n";
Utils.assertWithAllModes("true:true", script);
}

@Test
public void testFunctionPrototypeSymbolHasInstanceOnObjectReturnsTrue() {
String script =
"var f = function() {};\n"
+ "var o = new f();\n"
+ "var o2 = Object.create(o);\n"
+ "(f[Symbol.hasInstance](o)) + ':' + "
+ "(f[Symbol.hasInstance](o2));\n";
Utils.assertWithAllModes("true:true", script);
}

@Test
public void testFunctionPrototypeSymbolHasInstanceOnBoundTargetReturnsTrue() {
String script =
"var BC = function() {};\n"
+ "var bc = new BC();\n"
+ "var bound = BC.bind();\n"
+ "bound[Symbol.hasInstance](bc);\n";
Utils.assertWithAllModes(true, script);
}

@Test
public void testFunctionInstanceNullVoidEtc() {
String script =
"var f = function() {};\n"
+ "var x;\n"
+ "a = (undefined instanceof f) + ':' +\n"
+ "(x instanceof f) + ':' +\n"
+ "(null instanceof f) + ':' +\n"
+ "(void 0 instanceof f)\n"
+ "a";
Utils.assertWithAllModes("false:false:false:false", script);
}

@Test
public void testFunctionPrototypeSymbolHasInstanceReturnsFalseOnUndefinedOrProtoypeNotFound() {
String script =
"Function.prototype[Symbol.hasInstance].call() + ':' +"
+ "Function.prototype[Symbol.hasInstance].call({});";
Utils.assertWithAllModes("false:false", script);
}

@Test
public void testSymbolHasInstanceIsInvokedInInstanceOf() {
String script =
""
+ "var globalSet = 0;"
+ "var f = {\n"
+ " [Symbol.hasInstance](value) { "
+ " globalSet = 1;"
+ " return true;"
+ " }"
+ "}\n"
+ "var g = {}\n"
+ "Object.setPrototypeOf(g, f);\n"
+ "g instanceof f;"
+ "globalSet == 1";
Utils.assertWithAllModes(true, script);
}

@Test
public void testThrowTypeErrorOnNonObjectIncludingSymbol() {
String script =
""
+ "var f = function() {}; \n"
+ "f.prototype = Symbol(); \n"
+ "f[Symbol.hasInstance]({})";
Utils.assertEcmaErrorES6(
"TypeError: 'prototype' property of is not an object. (test#3)", script);
}
}
11 changes: 1 addition & 10 deletions tests/testsrc/test262.properties
Original file line number Diff line number Diff line change
Expand Up @@ -660,7 +660,7 @@ built-ins/Error 5/41 (12.2%)

~built-ins/FinalizationRegistry

built-ins/Function 184/508 (36.22%)
built-ins/Function 175/508 (34.45%)
internals/Call 2/2 (100.0%)
internals/Construct 6/6 (100.0%)
length/S15.3.5.1_A1_T3.js strict
Expand Down Expand Up @@ -719,16 +719,7 @@ built-ins/Function 184/508 (36.22%)
prototype/call/S15.3.4.4_A6_T2.js compiled
prototype/call/S15.3.4.4_A6_T5.js compiled
prototype/call/S15.3.4.4_A6_T7.js compiled
prototype/Symbol.hasInstance/length.js
prototype/Symbol.hasInstance/name.js
prototype/Symbol.hasInstance/prop-desc.js
prototype/Symbol.hasInstance/this-val-bound-target.js
prototype/Symbol.hasInstance/this-val-not-callable.js
prototype/Symbol.hasInstance/this-val-poisoned-prototype.js
prototype/Symbol.hasInstance/value-get-prototype-of-err.js
prototype/Symbol.hasInstance/value-negative.js
prototype/Symbol.hasInstance/value-non-obj.js
prototype/Symbol.hasInstance/value-positive.js
prototype/toString/async-arrow-function.js {unsupported: [async-functions]}
prototype/toString/async-function-declaration.js {unsupported: [async-functions]}
prototype/toString/async-function-expression.js {unsupported: [async-functions]}
Expand Down

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