| /* |
| * 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); |
| } |
| } |