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Java > Open Source Codes > com > google > gwt > dev > jjs > ast > JBinaryOperation


1 /*
2  * Copyright 2007 Google Inc.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5  * use this file except in compliance with the License. You may obtain a copy of
6  * the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13  * License for the specific language governing permissions and limitations under
14  * the License.
15  */
16 package com.google.gwt.dev.jjs.ast;
17
18 import com.google.gwt.dev.jjs.SourceInfo;
19
20 /**
21  * Binary operator expression.
22  */
23 public class JBinaryOperation extends JExpression implements HasSettableType {
24
25   private JExpression lhs;
26   private final JBinaryOperator op;
27   private JExpression rhs;
28   private JType type;
29
30   public JBinaryOperation(JProgram program, SourceInfo info, JType type,
31       JBinaryOperator op, JExpression lhs, JExpression rhs) {
32     super(program, info);
33     this.op = op;
34     this.type = type;
35     this.lhs = lhs;
36     this.rhs = rhs;
37   }
38
39   public JExpression getLhs() {
40     return lhs;
41   }
42
43   public JBinaryOperator getOp() {
44     return op;
45   }
46
47   public JExpression getRhs() {
48     return rhs;
49   }
50
51   public JType getType() {
52     if (op == JBinaryOperator.ASG) {
53       // Use rhs because (generality lhs >= generality rhs)
54 return getRhs().getType();
55     } else if (isAssignment()) {
56       // Use lhs because this is really a write-then-read
57 return getLhs().getType();
58     } else {
59       // Most binary operators never change type
60 return type;
61     }
62   }
63
64   public boolean hasSideEffects() {
65     return op.isAssignment() || getLhs().hasSideEffects()
66         || getRhs().hasSideEffects();
67   }
68
69   public boolean isAssignment() {
70     return op.isAssignment();
71   }
72
73   public void setType(JType newType) {
74     type = newType;
75   }
76
77   public void traverse(JVisitor visitor, Context ctx) {
78     if (visitor.visit(this, ctx)) {
79       lhs = visitor.accept(lhs);
80       rhs = visitor.accept(rhs);
81     }
82     visitor.endVisit(this, ctx);
83   }
84
85 }
86
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