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Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically
embedded into Java applications to provide scripting to end users.
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.WeakHashMap;
/**
* This is an implementation of the ES6 WeakMap class. As per the spec, keys must be ordinary
* objects. Since there is no defined "equality" for objects, comparisions are done strictly by
* object equality. Both ES6 and the java.util.WeakHashMap class have the same basic structure --
* entries are removed automatically when the sole remaining reference to the key is a weak
* reference. Therefore, we can use WeakHashMap as the basis of this implementation and preserve the
* same semantics.
*/
public class NativeWeakMap extends IdScriptableObject {
private static final long serialVersionUID = 8670434366883930453L;
private static final Object MAP_TAG = "WeakMap";
private boolean instanceOfWeakMap = false;
private transient WeakHashMap map = new WeakHashMap<>();
private static final Object NULL_VALUE = new Object();
static void init(Scriptable scope, boolean sealed) {
NativeWeakMap m = new NativeWeakMap();
m.exportAsJSClass(MAX_PROTOTYPE_ID, scope, sealed);
}
@Override
public String getClassName() {
return "WeakMap";
}
@Override
public Object execIdCall(
IdFunctionObject f, Context cx, Scriptable scope, Scriptable thisObj, Object[] args) {
if (!f.hasTag(MAP_TAG)) {
return super.execIdCall(f, cx, scope, thisObj, args);
}
int id = f.methodId();
switch (id) {
case Id_constructor:
if (thisObj == null) {
NativeWeakMap nm = new NativeWeakMap();
nm.instanceOfWeakMap = true;
if (args.length > 0) {
NativeMap.loadFromIterable(cx, scope, nm, NativeMap.key(args));
}
return nm;
}
throw ScriptRuntime.typeErrorById("msg.no.new", "WeakMap");
case Id_delete:
return realThis(thisObj, f).js_delete(NativeMap.key(args));
case Id_get:
return realThis(thisObj, f).js_get(NativeMap.key(args));
case Id_has:
return realThis(thisObj, f).js_has(NativeMap.key(args));
case Id_set:
return realThis(thisObj, f)
.js_set(
NativeMap.key(args),
args.length > 1 ? args[1] : Undefined.instance);
}
throw new IllegalArgumentException(
"WeakMap.prototype has no method: " + f.getFunctionName());
}
private Object js_delete(Object key) {
if (!ScriptRuntime.isObject(key)) {
return Boolean.FALSE;
}
return Boolean.valueOf(map.remove(key) != null);
}
private Object js_get(Object key) {
if (!ScriptRuntime.isObject(key)) {
return Undefined.instance;
}
Object result = map.get(key);
if (result == null) {
return Undefined.instance;
} else if (result == NULL_VALUE) {
return null;
}
return result;
}
private Object js_has(Object key) {
if (!ScriptRuntime.isObject(key)) {
return Boolean.FALSE;
}
return Boolean.valueOf(map.containsKey(key));
}
private Object js_set(Object key, Object v) {
// As the spec says, only a true "Object" can be the key to a WeakMap.
// Use the default object equality here. ScriptableObject does not override
// equals or hashCode, which means that in effect we are only keying on object identity.
// This is all correct according to the ECMAscript spec.
if (!ScriptRuntime.isObject(key)) {
throw ScriptRuntime.typeErrorById("msg.arg.not.object", ScriptRuntime.typeof(key));
}
// Map.get() does not distinguish between "not found" and a null value. So,
// replace true null here with a marker so that we can re-convert in "get".
final Object value = (v == null ? NULL_VALUE : v);
map.put((Scriptable) key, value);
return this;
}
private static NativeWeakMap realThis(Scriptable thisObj, IdFunctionObject f) {
final NativeWeakMap nm = ensureType(thisObj, NativeWeakMap.class, f);
if (!nm.instanceOfWeakMap) {
// Check for "Map internal data tag"
throw ScriptRuntime.typeErrorById("msg.incompat.call", f.getFunctionName());
}
return nm;
}
@Override
protected void initPrototypeId(int id) {
if (id == SymbolId_toStringTag) {
initPrototypeValue(
SymbolId_toStringTag,
SymbolKey.TO_STRING_TAG,
getClassName(),
DONTENUM | READONLY);
return;
}
String s, fnName = null;
int arity;
switch (id) {
case Id_constructor:
arity = 0;
s = "constructor";
break;
case Id_delete:
arity = 1;
s = "delete";
break;
case Id_get:
arity = 1;
s = "get";
break;
case Id_has:
arity = 1;
s = "has";
break;
case Id_set:
arity = 2;
s = "set";
break;
default:
throw new IllegalArgumentException(String.valueOf(id));
}
initPrototypeMethod(MAP_TAG, id, s, fnName, arity);
}
@Override
protected int findPrototypeId(Symbol k) {
if (SymbolKey.TO_STRING_TAG.equals(k)) {
return SymbolId_toStringTag;
}
return 0;
}
@Override
protected int findPrototypeId(String s) {
int id;
switch (s) {
case "constructor":
id = Id_constructor;
break;
case "delete":
id = Id_delete;
break;
case "get":
id = Id_get;
break;
case "has":
id = Id_has;
break;
case "set":
id = Id_set;
break;
default:
id = 0;
break;
}
return id;
}
private static final int Id_constructor = 1,
Id_delete = 2,
Id_get = 3,
Id_has = 4,
Id_set = 5,
SymbolId_toStringTag = 6,
MAX_PROTOTYPE_ID = SymbolId_toStringTag;
private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
stream.defaultReadObject();
map = new WeakHashMap<>();
}
}
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