001/* 002 * Copyright 2002-2019 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.util.Assert; 028import org.springframework.util.ObjectUtils; 029 030/** 031 * Represents a ternary expression, for example: "someCheck()?true:false". 032 * 033 * @author Andy Clement 034 * @author Juergen Hoeller 035 * @since 3.0 036 */ 037public class Ternary extends SpelNodeImpl { 038 039 public Ternary(int startPos, int endPos, SpelNodeImpl... args) { 040 super(startPos, endPos, args); 041 } 042 043 044 /** 045 * Evaluate the condition and if true evaluate the first alternative, otherwise 046 * evaluate the second alternative. 047 * @param state the expression state 048 * @throws EvaluationException if the condition does not evaluate correctly to 049 * a boolean or there is a problem executing the chosen alternative 050 */ 051 @Override 052 public TypedValue getValueInternal(ExpressionState state) throws EvaluationException { 053 Boolean value = this.children[0].getValue(state, Boolean.class); 054 if (value == null) { 055 throw new SpelEvaluationException(getChild(0).getStartPosition(), 056 SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean"); 057 } 058 TypedValue result = this.children[value ? 1 : 2].getValueInternal(state); 059 computeExitTypeDescriptor(); 060 return result; 061 } 062 063 @Override 064 public String toStringAST() { 065 return getChild(0).toStringAST() + " ? " + getChild(1).toStringAST() + " : " + getChild(2).toStringAST(); 066 } 067 068 private void computeExitTypeDescriptor() { 069 if (this.exitTypeDescriptor == null && this.children[1].exitTypeDescriptor != null && 070 this.children[2].exitTypeDescriptor != null) { 071 String leftDescriptor = this.children[1].exitTypeDescriptor; 072 String rightDescriptor = this.children[2].exitTypeDescriptor; 073 if (ObjectUtils.nullSafeEquals(leftDescriptor, rightDescriptor)) { 074 this.exitTypeDescriptor = leftDescriptor; 075 } 076 else { 077 // Use the easiest to compute common super type 078 this.exitTypeDescriptor = "Ljava/lang/Object"; 079 } 080 } 081 } 082 083 @Override 084 public boolean isCompilable() { 085 SpelNodeImpl condition = this.children[0]; 086 SpelNodeImpl left = this.children[1]; 087 SpelNodeImpl right = this.children[2]; 088 return (condition.isCompilable() && left.isCompilable() && right.isCompilable() && 089 CodeFlow.isBooleanCompatible(condition.exitTypeDescriptor) && 090 left.exitTypeDescriptor != null && right.exitTypeDescriptor != null); 091 } 092 093 @Override 094 public void generateCode(MethodVisitor mv, CodeFlow cf) { 095 // May reach here without it computed if all elements are literals 096 computeExitTypeDescriptor(); 097 cf.enterCompilationScope(); 098 this.children[0].generateCode(mv, cf); 099 String lastDesc = cf.lastDescriptor(); 100 Assert.state(lastDesc != null, "No last descriptor"); 101 if (!CodeFlow.isPrimitive(lastDesc)) { 102 CodeFlow.insertUnboxInsns(mv, 'Z', lastDesc); 103 } 104 cf.exitCompilationScope(); 105 Label elseTarget = new Label(); 106 Label endOfIf = new Label(); 107 mv.visitJumpInsn(IFEQ, elseTarget); 108 cf.enterCompilationScope(); 109 this.children[1].generateCode(mv, cf); 110 if (!CodeFlow.isPrimitive(this.exitTypeDescriptor)) { 111 lastDesc = cf.lastDescriptor(); 112 Assert.state(lastDesc != null, "No last descriptor"); 113 CodeFlow.insertBoxIfNecessary(mv, lastDesc.charAt(0)); 114 } 115 cf.exitCompilationScope(); 116 mv.visitJumpInsn(GOTO, endOfIf); 117 mv.visitLabel(elseTarget); 118 cf.enterCompilationScope(); 119 this.children[2].generateCode(mv, cf); 120 if (!CodeFlow.isPrimitive(this.exitTypeDescriptor)) { 121 lastDesc = cf.lastDescriptor(); 122 Assert.state(lastDesc != null, "No last descriptor"); 123 CodeFlow.insertBoxIfNecessary(mv, lastDesc.charAt(0)); 124 } 125 cf.exitCompilationScope(); 126 mv.visitLabel(endOfIf); 127 cf.pushDescriptor(this.exitTypeDescriptor); 128 } 129 130}