com.google.gwt.dev.js.ast.JsNullLiteral Maven / Gradle / Ivy
/*
* Copyright 2008 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 com.google.gwt.dev.js.ast;
import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.jjs.SourceOrigin;
/**
* A JavaScript null literal.
*/
public final class JsNullLiteral extends JsValueLiteral {
public static final JsNullLiteral INSTANCE = new JsNullLiteral(SourceOrigin.UNKNOWN);
private JsNullLiteral(SourceInfo sourceInfo) {
super(sourceInfo);
}
@Override
public NodeKind getKind() {
return NodeKind.NULL;
}
@Override
public boolean isBooleanFalse() {
return true;
}
@Override
public boolean isBooleanTrue() {
return false;
}
@Override
public boolean isDefinitelyNull() {
return true;
}
@Override
public void traverse(JsVisitor v, JsContext ctx) {
v.visit(this, ctx);
v.endVisit(this, ctx);
}
/**
* Note, if this ever becomes not-a-singleton, we'll need to check the SourceInfo ==
* SourceOrigin.UNKNOWN.
*/
private Object readResolve() {
return INSTANCE;
}
}