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 java.util.Collections; 020import java.util.LinkedHashMap; 021import java.util.Map; 022 023import org.springframework.expression.EvaluationException; 024import org.springframework.expression.TypedValue; 025import org.springframework.expression.spel.ExpressionState; 026import org.springframework.expression.spel.SpelNode; 027import org.springframework.lang.Nullable; 028import org.springframework.util.Assert; 029 030/** 031 * Represent a map in an expression, e.g. '{name:'foo',age:12}' 032 * 033 * @author Andy Clement 034 * @since 4.1 035 */ 036public class InlineMap extends SpelNodeImpl { 037 038 // If the map is purely literals, it is a constant value and can be computed and cached 039 @Nullable 040 private TypedValue constant; 041 042 043 public InlineMap(int startPos, int endPos, SpelNodeImpl... args) { 044 super(startPos, endPos, args); 045 checkIfConstant(); 046 } 047 048 049 /** 050 * If all the components of the map are constants, or lists/maps that themselves 051 * contain constants, then a constant list can be built to represent this node. 052 * This will speed up later getValue calls and reduce the amount of garbage created. 053 */ 054 private void checkIfConstant() { 055 boolean isConstant = true; 056 for (int c = 0, max = getChildCount(); c < max; c++) { 057 SpelNode child = getChild(c); 058 if (!(child instanceof Literal)) { 059 if (child instanceof InlineList) { 060 InlineList inlineList = (InlineList) child; 061 if (!inlineList.isConstant()) { 062 isConstant = false; 063 break; 064 } 065 } 066 else if (child instanceof InlineMap) { 067 InlineMap inlineMap = (InlineMap) child; 068 if (!inlineMap.isConstant()) { 069 isConstant = false; 070 break; 071 } 072 } 073 else if (!(c % 2 == 0 && child instanceof PropertyOrFieldReference)) { 074 isConstant = false; 075 break; 076 } 077 } 078 } 079 if (isConstant) { 080 Map<Object, Object> constantMap = new LinkedHashMap<>(); 081 int childCount = getChildCount(); 082 for (int c = 0; c < childCount; c++) { 083 SpelNode keyChild = getChild(c++); 084 SpelNode valueChild = getChild(c); 085 Object key = null; 086 Object value = null; 087 if (keyChild instanceof Literal) { 088 key = ((Literal) keyChild).getLiteralValue().getValue(); 089 } 090 else if (keyChild instanceof PropertyOrFieldReference) { 091 key = ((PropertyOrFieldReference) keyChild).getName(); 092 } 093 else { 094 return; 095 } 096 if (valueChild instanceof Literal) { 097 value = ((Literal) valueChild).getLiteralValue().getValue(); 098 } 099 else if (valueChild instanceof InlineList) { 100 value = ((InlineList) valueChild).getConstantValue(); 101 } 102 else if (valueChild instanceof InlineMap) { 103 value = ((InlineMap) valueChild).getConstantValue(); 104 } 105 constantMap.put(key, value); 106 } 107 this.constant = new TypedValue(Collections.unmodifiableMap(constantMap)); 108 } 109 } 110 111 @Override 112 public TypedValue getValueInternal(ExpressionState expressionState) throws EvaluationException { 113 if (this.constant != null) { 114 return this.constant; 115 } 116 else { 117 Map<Object, Object> returnValue = new LinkedHashMap<>(); 118 int childcount = getChildCount(); 119 for (int c = 0; c < childcount; c++) { 120 // TODO allow for key being PropertyOrFieldReference like Indexer on maps 121 SpelNode keyChild = getChild(c++); 122 Object key = null; 123 if (keyChild instanceof PropertyOrFieldReference) { 124 PropertyOrFieldReference reference = (PropertyOrFieldReference) keyChild; 125 key = reference.getName(); 126 } 127 else { 128 key = keyChild.getValue(expressionState); 129 } 130 Object value = getChild(c).getValue(expressionState); 131 returnValue.put(key, value); 132 } 133 return new TypedValue(returnValue); 134 } 135 } 136 137 @Override 138 public String toStringAST() { 139 StringBuilder sb = new StringBuilder("{"); 140 int count = getChildCount(); 141 for (int c = 0; c < count; c++) { 142 if (c > 0) { 143 sb.append(","); 144 } 145 sb.append(getChild(c++).toStringAST()); 146 sb.append(":"); 147 sb.append(getChild(c).toStringAST()); 148 } 149 sb.append("}"); 150 return sb.toString(); 151 } 152 153 /** 154 * Return whether this list is a constant value. 155 */ 156 public boolean isConstant() { 157 return this.constant != null; 158 } 159 160 @SuppressWarnings("unchecked") 161 @Nullable 162 public Map<Object, Object> getConstantValue() { 163 Assert.state(this.constant != null, "No constant"); 164 return (Map<Object, Object>) this.constant.getValue(); 165 } 166 167}