| /* |
| * 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; |
| |
| /** |
| * A JavaScript prefix operation. |
| */ |
| public final class JsPrefixOperation extends JsUnaryOperation implements |
| CanBooleanEval { |
| |
| public JsPrefixOperation(SourceInfo sourceInfo, JsUnaryOperator op) { |
| this(sourceInfo, op, null); |
| } |
| |
| public JsPrefixOperation(SourceInfo sourceInfo, JsUnaryOperator op, |
| JsExpression arg) { |
| super(sourceInfo, op, arg); |
| } |
| |
| public boolean isBooleanFalse() { |
| if (getOperator() == JsUnaryOperator.VOID) { |
| return true; |
| } |
| if (getOperator() == JsUnaryOperator.NOT |
| && getArg() instanceof CanBooleanEval) { |
| CanBooleanEval eval = (CanBooleanEval) getArg(); |
| return eval.isBooleanTrue(); |
| } |
| return false; |
| } |
| |
| public boolean isBooleanTrue() { |
| if (getOperator() == JsUnaryOperator.NOT |
| && getArg() instanceof CanBooleanEval) { |
| CanBooleanEval eval = (CanBooleanEval) getArg(); |
| return eval.isBooleanFalse(); |
| } |
| if (getOperator() == JsUnaryOperator.TYPEOF) { |
| return true; |
| } |
| return false; |
| } |
| |
| @Override |
| public boolean isDefinitelyNotNull() { |
| if (getOperator() == JsUnaryOperator.TYPEOF) { |
| return true; |
| } |
| return getOperator() != JsUnaryOperator.VOID; |
| } |
| |
| @Override |
| public boolean isDefinitelyNull() { |
| return getOperator() == JsUnaryOperator.VOID; |
| } |
| |
| @Override |
| public void traverse(JsVisitor v, JsContext ctx) { |
| if (v.visit(this, ctx)) { |
| super.traverse(v, ctx); |
| } |
| v.endVisit(this, ctx); |
| } |
| } |