/*
* 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;
/**
* An abstract base class for all JavaScript expressions.
*/
public abstract class JsExpression extends JsNode {
protected JsExpression(SourceInfo sourceInfo) {
super(sourceInfo);
}
/**
* Determines whether the expression can cause side effects.
*/
public abstract boolean hasSideEffects();
/**
* True if the target expression is definitely not null.
*/
public abstract boolean isDefinitelyNotNull();
/**
* True if the target expression is definitely null.
*/
public abstract boolean isDefinitelyNull();
/**
* Determines whether or not this expression is a leaf, such as a {@link JsNameRef},
* {@link JsBooleanLiteral}, and so on. Leaf expressions never need to be parenthesized.
*/
public boolean isLeaf() {
// Conservatively say that it isn't a leaf.
// Individual subclasses can speak for themselves if they are a leaf.
return false;
}
public JsExprStmt makeStmt() {
return new JsExprStmt(getSourceInfo(), this);
}
}