001    // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
002    // for details. All rights reserved. Use of this source code is governed by a
003    // BSD-style license that can be found in the LICENSE file.
004    
005    package com.google.dart.compiler.backend.js.ast;
006    
007    public abstract class JsUnaryOperation extends JsExpressionImpl {
008    
009        private JsExpression arg;
010    
011        private final JsUnaryOperator op;
012    
013        public JsUnaryOperation(JsUnaryOperator op) {
014            this(op, null);
015        }
016    
017        public JsUnaryOperation(JsUnaryOperator op, JsExpression arg) {
018            super();
019            this.op = op;
020            this.arg = arg;
021        }
022    
023        public JsExpression getArg() {
024            return arg;
025        }
026    
027        public JsUnaryOperator getOperator() {
028            return op;
029        }
030    
031        public void setArg(JsExpression arg) {
032            this.arg = arg;
033        }
034    
035        @Override
036        public void acceptChildren(JsVisitor visitor) {
037            if (op.isModifying()) {
038                // The delete operator is practically like an assignment of undefined, so
039                // for practical purposes we're treating it as an lvalue.
040                visitor.acceptLvalue(arg);
041            }
042            else {
043                visitor.accept(arg);
044            }
045        }
046    
047        @Override
048        public void traverse(JsVisitorWithContext v, JsContext ctx) {
049            if (op.isModifying()) {
050          /*
051           * The delete operator is practically like an assignment of undefined, so for practical
052           * purposes we're treating it as an lvalue.
053           */
054                arg = v.acceptLvalue(arg);
055            } else {
056                arg = v.accept(arg);
057            }
058        }
059    }