/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
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package org.springframework.expression.spel.ast;

import org.springframework.asm.Label;
import org.springframework.asm.MethodVisitor;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.support.BooleanTypedValue;

Represents a NOT operation.
Author:Andy Clement, Mark Fisher, Oliver Becker
Since:3.0
/** * Represents a NOT operation. * * @author Andy Clement * @author Mark Fisher * @author Oliver Becker * @since 3.0 */
public class OperatorNot extends SpelNodeImpl { // Not is a unary operator so does not extend BinaryOperator public OperatorNot(int pos, SpelNodeImpl operand) { super(pos, operand); this.exitTypeDescriptor = "Z"; } @Override public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException { try { Boolean value = this.children[0].getValue(state, Boolean.class); if (value == null) { throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean"); } return BooleanTypedValue.forValue(!value); } catch (SpelEvaluationException ex) { ex.setPosition(getChild(0).getStartPosition()); throw ex; } } @Override public String toStringAST() { return "!" + getChild(0).toStringAST(); } @Override public boolean isCompilable() { SpelNodeImpl child = this.children[0]; return (child.isCompilable() && CodeFlow.isBooleanCompatible(child.exitTypeDescriptor)); } @Override public void generateCode(MethodVisitor mv, CodeFlow cf) { this.children[0].generateCode(mv, cf); cf.unboxBooleanIfNecessary(mv); Label elseTarget = new Label(); Label endOfIf = new Label(); mv.visitJumpInsn(IFNE,elseTarget); mv.visitInsn(ICONST_1); // TRUE mv.visitJumpInsn(GOTO,endOfIf); mv.visitLabel(elseTarget); mv.visitInsn(ICONST_0); // FALSE mv.visitLabel(endOfIf); cf.pushDescriptor(this.exitTypeDescriptor); } }