| /* |
| * 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; |
| |
| /** |
| * Represents a JavaScript binary operation. |
| */ |
| public final class JsBinaryOperation extends JsExpression { |
| |
| private JsExpression arg1; |
| |
| private JsExpression arg2; |
| |
| private final JsBinaryOperator op; |
| |
| public JsBinaryOperation(SourceInfo sourceInfo, JsBinaryOperator op) { |
| this(sourceInfo, op, null, null); |
| } |
| |
| public JsBinaryOperation(SourceInfo sourceInfo, JsBinaryOperator op, |
| JsExpression arg1, JsExpression arg2) { |
| super(sourceInfo); |
| this.op = op; |
| this.arg1 = arg1; |
| this.arg2 = arg2; |
| } |
| |
| public JsExpression getArg1() { |
| return arg1; |
| } |
| |
| public JsExpression getArg2() { |
| return arg2; |
| } |
| |
| public JsBinaryOperator getOperator() { |
| return op; |
| } |
| |
| @Override |
| public boolean hasSideEffects() { |
| return op.isAssignment() || arg1.hasSideEffects() || arg2.hasSideEffects(); |
| } |
| |
| @Override |
| public boolean isDefinitelyNotNull() { |
| // Precarious coding, but none of these can have null results. |
| if (op.getPrecedence() > 5) { |
| return true; |
| } |
| if (op == JsBinaryOperator.OR) { |
| if (arg1 instanceof CanBooleanEval) { |
| if (((CanBooleanEval) arg1).isBooleanTrue()) { |
| assert arg1.isDefinitelyNotNull(); |
| return true; |
| } |
| } |
| } |
| // AND and OR can return nulls |
| if (op.isAssignment()) { |
| if (op == JsBinaryOperator.ASG) { |
| return arg2.isDefinitelyNotNull(); |
| } else { |
| // All other ASG's are math ops. |
| return true; |
| } |
| } |
| |
| if (op == JsBinaryOperator.COMMA) { |
| return arg2.isDefinitelyNotNull(); |
| } |
| |
| return false; |
| } |
| |
| @Override |
| public boolean isDefinitelyNull() { |
| if (op == JsBinaryOperator.AND) { |
| return arg1.isDefinitelyNull(); |
| } |
| return false; |
| } |
| |
| public void setArg1(JsExpression arg1) { |
| this.arg1 = arg1; |
| } |
| |
| public void setArg2(JsExpression arg2) { |
| this.arg2 = arg2; |
| } |
| |
| public void traverse(JsVisitor v, JsContext<JsExpression> ctx) { |
| if (v.visit(this, ctx)) { |
| if (op.isAssignment()) { |
| arg1 = v.acceptLvalue(arg1); |
| } else { |
| arg1 = v.accept(arg1); |
| } |
| arg2 = v.accept(arg2); |
| } |
| v.endVisit(this, ctx); |
| } |
| } |