com.google.gwt.emul.java.util.InternalJsStringMap Maven / Gradle / Ivy
/*
* Copyright 2014 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package java.util;
import static com.google.gwt.core.shared.impl.InternalPreconditions.checkElement;
import static com.google.gwt.core.shared.impl.InternalPreconditions.checkState;
import com.google.gwt.core.client.JavaScriptObject;
import java.util.Map.Entry;
/**
* A simple wrapper around JavaScriptObject to provide {@link java.util.Map}-like semantics where
* the key type is string.
*
* Implementation notes:
*
* String keys are mapped to their values via a JS associative map. String keys could collide with
* intrinsic properties (like watch, constructor). To avoid that; {@link InternalJsStringMap}) uses
* {@code Object.create(null)} so it doesn't inherit any properties. For legacy browsers where
* {@code Object.create} is not available, {@link InternalJsStringMapLegacy} prepends each key with
* a ':' while storing.
*/
class InternalJsStringMap {
/**
* String map implementation for browsers that doesn't support Object.create (IE8, FF3.6).
*/
static class InternalJsStringMapLegacy extends InternalJsStringMap {
@Override
native JavaScriptObject createMap() /*-{
return {};
}-*/;
@Override
public V get(String key) {
return super.get(normalize(key));
}
@Override
public V put(String key, V value) {
return super.put(normalize(key), value);
}
@Override
public V remove(String key) {
return super.remove(normalize(key));
}
private String normalize(String key) {
return ':' + key;
}
@Override
public native boolean containsValue(Object value) /*-{
var map = this.@InternalJsStringMap::backingMap;
for (var key in map) {
// only keys that start with a colon ':' count
if (key.charCodeAt(0) == 58) {
var entryValue = map[key];
if (this.@InternalJsStringMap::equalsBridge(*)(value, entryValue)) {
return true;
}
}
}
return false;
}-*/;
@Override
public native Iterator> entries() /*-{
var list = this.@InternalJsStringMapLegacy::newEntryList()();
for (var key in this.@InternalJsStringMap::backingMap) {
// only keys that start with a colon ':' count
if (key.charCodeAt(0) == 58) {
var entry = this.@InternalJsStringMap::newMapEntry(*)(key.substring(1));
list.@ArrayList::add(Ljava/lang/Object;)(entry);
}
}
return list.@ArrayList::iterator()();
}-*/;
/**
* Returns a custom ArrayList so that we could intercept removal to forward into our map.
*/
private ArrayList> newEntryList() {
return new ArrayList>() {
@Override
public Entry remove(int index) {
Entry removed = super.remove(index);
InternalJsStringMapLegacy.this.remove((String) removed.getKey());
return removed;
}
};
}
}
/**
* String map implementation for browsers that includes __proto__ while iterating keys (i.e.
* FireFox). See the Firefox bug: https://bugzilla.mozilla.org/show_bug.cgi?id=837630.
*/
static class InternalJsStringMapWithKeysWorkaround extends InternalJsStringMap {
private static final String PROTO = "__proto__";
@Override
public boolean containsValue(Object value) {
V protoValue = get(PROTO);
if (!isUndefined(protoValue) && equalsBridge(value, protoValue)) {
return true;
}
return super.containsValue(value);
}
@Override
protected String[] keys() {
String[] keys = super.keys();
if (contains(PROTO)) {
keys[keys.length] = PROTO; // safe in webmode
}
return keys;
}
}
private final JavaScriptObject backingMap = createMap();
AbstractHashMap host;
native JavaScriptObject createMap() /*-{
return Object.create(null);
}-*/;
public final boolean contains(String key) {
return !isUndefined(get(key));
}
public V get(String key) {
return at(key);
}
public V put(String key, V value) {
V oldValue = at(key);
if (isUndefined(oldValue)) {
host.elementAdded();
}
set(key, toNullIfUndefined(value));
return oldValue;
}
public V remove(String key) {
V value = at(key);
if (!isUndefined(value)) {
delete(key);
host.elementRemoved();
}
return value;
}
private native V at(String key) /*-{
return this.@InternalJsStringMap::backingMap[key];
}-*/;
private native void set(String key, V value) /*-{
this.@InternalJsStringMap::backingMap[key] = value;
}-*/;
private native void delete(String key) /*-{
delete this.@InternalJsStringMap::backingMap[key];
}-*/;
public native boolean containsValue(Object value) /*-{
var map = this.@InternalJsStringMap::backingMap;
for (var key in map) {
if (this.@InternalJsStringMap::equalsBridge(*)(value, map[key])) {
return true;
}
}
return false;
}-*/;
public Iterator> entries() {
final String[] keys = keys();
return new Iterator>() {
int i = 0, last = -1;
@Override
public boolean hasNext() {
return i < keys.length;
}
@Override
public Entry next() {
checkElement(hasNext());
return newMapEntry(keys[last = i++]);
}
@Override
public void remove() {
checkState(last != -1);
InternalJsStringMap.this.remove(keys[last]);
last = -1;
}
};
}
protected native String[] keys() /*-{
return Object.getOwnPropertyNames(this.@InternalJsStringMap::backingMap);
}-*/;
protected final Entry newMapEntry(final String key) {
return new AbstractMapEntry() {
@Override
public K getKey() {
return (K) key;
}
@Override
public V getValue() {
return get(key);
}
@Override
public V setValue(V object) {
return put(key, object);
}
};
}
/**
* Bridge method from JSNI that keeps us from having to make polymorphic calls
* in JSNI. By putting the polymorphism in Java code, the compiler can do a
* better job of optimizing in most cases.
*/
protected final boolean equalsBridge(Object value1, Object value2) {
return host.equals(value1, value2);
}
private static T toNullIfUndefined(T value) {
return isUndefined(value) ? null : value;
}
private static native boolean isUndefined(Object value) /*-{
return value === undefined;
}-*/;
}