001/*
002 * Copyright 2002-2017 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.TypedValue;
023import org.springframework.expression.spel.CodeFlow;
024import org.springframework.expression.spel.ExpressionState;
025import org.springframework.expression.spel.SpelEvaluationException;
026import org.springframework.expression.spel.SpelMessage;
027import org.springframework.expression.spel.support.BooleanTypedValue;
028
029/**
030 * Represents the boolean AND operation.
031 *
032 * @author Andy Clement
033 * @author Mark Fisher
034 * @author Oliver Becker
035 * @since 3.0
036 */
037public class OpAnd extends Operator {
038
039        public OpAnd(int pos, SpelNodeImpl... operands) {
040                super("and", pos, operands);
041                this.exitTypeDescriptor = "Z";
042        }
043
044
045        @Override
046        public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
047                if (!getBooleanValue(state, getLeftOperand())) {
048                        // no need to evaluate right operand
049                        return BooleanTypedValue.FALSE;
050                }
051                return BooleanTypedValue.forValue(getBooleanValue(state, getRightOperand()));
052        }
053
054        private boolean getBooleanValue(ExpressionState state, SpelNodeImpl operand) {
055                try {
056                        Boolean value = operand.getValue(state, Boolean.class);
057                        assertValueNotNull(value);
058                        return value;
059                }
060                catch (SpelEvaluationException ex) {
061                        ex.setPosition(operand.getStartPosition());
062                        throw ex;
063                }
064        }
065
066        private void assertValueNotNull(Boolean value) {
067                if (value == null) {
068                        throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
069                }
070        }
071
072        @Override
073        public boolean isCompilable() {
074                SpelNodeImpl left = getLeftOperand();
075                SpelNodeImpl right = getRightOperand();
076                return (left.isCompilable() && right.isCompilable() &&
077                                CodeFlow.isBooleanCompatible(left.exitTypeDescriptor) &&
078                                CodeFlow.isBooleanCompatible(right.exitTypeDescriptor));
079        }
080        
081        @Override
082        public void generateCode(MethodVisitor mv, CodeFlow cf) {
083                // Pseudo: if (!leftOperandValue) { result=false; } else { result=rightOperandValue; }
084                Label elseTarget = new Label();
085                Label endOfIf = new Label();
086                cf.enterCompilationScope();
087                getLeftOperand().generateCode(mv, cf);
088                cf.unboxBooleanIfNecessary(mv);
089                cf.exitCompilationScope();
090                mv.visitJumpInsn(IFNE, elseTarget);
091                mv.visitLdcInsn(0); // FALSE
092                mv.visitJumpInsn(GOTO,endOfIf);
093                mv.visitLabel(elseTarget);
094                cf.enterCompilationScope();
095                getRightOperand().generateCode(mv, cf);
096                cf.unboxBooleanIfNecessary(mv);
097                cf.exitCompilationScope();
098                mv.visitLabel(endOfIf);
099                cf.pushDescriptor(this.exitTypeDescriptor);
100        }
101
102}