001/*
002 * Copyright 2002-2014 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.expression.spel.ast;
018
019import org.springframework.asm.Label;
020import org.springframework.asm.MethodVisitor;
021import org.springframework.expression.EvaluationException;
022import org.springframework.expression.spel.CodeFlow;
023import org.springframework.expression.spel.ExpressionState;
024import org.springframework.expression.spel.SpelEvaluationException;
025import org.springframework.expression.spel.SpelMessage;
026import org.springframework.expression.spel.support.BooleanTypedValue;
027
028/**
029 * Represents a NOT operation.
030 *
031 * @author Andy Clement
032 * @author Mark Fisher
033 * @author Oliver Becker
034 * @since 3.0
035 */
036public class OperatorNot extends SpelNodeImpl {  // Not is a unary operator so does not extend BinaryOperator
037
038        public OperatorNot(int pos, SpelNodeImpl operand) {
039                super(pos, operand);
040                this.exitTypeDescriptor = "Z";
041        }
042
043
044        @Override
045        public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
046                try {
047                        Boolean value = this.children[0].getValue(state, Boolean.class);
048                        if (value == null) {
049                                throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
050                        }
051                        return BooleanTypedValue.forValue(!value);
052                }
053                catch (SpelEvaluationException ex) {
054                        ex.setPosition(getChild(0).getStartPosition());
055                        throw ex;
056                }
057        }
058
059        @Override
060        public String toStringAST() {
061                return "!" + getChild(0).toStringAST();
062        }
063        
064        @Override
065        public boolean isCompilable() {
066                SpelNodeImpl child = this.children[0];
067                return (child.isCompilable() && CodeFlow.isBooleanCompatible(child.exitTypeDescriptor));
068        }
069        
070        @Override
071        public void generateCode(MethodVisitor mv, CodeFlow cf) {
072                this.children[0].generateCode(mv, cf);
073                cf.unboxBooleanIfNecessary(mv);
074                Label elseTarget = new Label();
075                Label endOfIf = new Label();
076                mv.visitJumpInsn(IFNE,elseTarget);              
077                mv.visitInsn(ICONST_1); // TRUE
078                mv.visitJumpInsn(GOTO,endOfIf);
079                mv.visitLabel(elseTarget);
080                mv.visitInsn(ICONST_0); // FALSE
081                mv.visitLabel(endOfIf);
082                cf.pushDescriptor(this.exitTypeDescriptor);
083        }
084
085}