/*
* Copyright 2002-2016 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
* limitations under the License.
*/
package org.springframework.expression.spel.ast;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
/**
* Represents selection over a map or collection.
* For example: {1,2,3,4,5,6,7,8,9,10}.?{#isEven(#this) == 'y'} returns [2, 4, 6, 8, 10]
*
* <p>Basically a subset of the input data is returned based on the
* evaluation of the expression supplied as selection criteria.
*
* @author Andy Clement
* @author Mark Fisher
* @author Sam Brannen
* @author Juergen Hoeller
* @since 3.0
*/
public class Selection extends SpelNodeImpl {
public static final int ALL = 0; // ?[]
public static final int FIRST = 1; // ^[]
public static final int LAST = 2; // $[]
private final int variant;
private final boolean nullSafe;
public Selection(boolean nullSafe, int variant, int pos, SpelNodeImpl expression) {
super(pos, expression);
Assert.notNull(expression, "Expression must not be null");
this.nullSafe = nullSafe;
this.variant = variant;
}
@Override
public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
return getValueRef(state).getValue();
}
@Override
protected ValueRef getValueRef(ExpressionState state) throws EvaluationException {
TypedValue op = state.getActiveContextObject();
Object operand = op.getValue();
SpelNodeImpl selectionCriteria = this.children[0];
if (operand instanceof Map) {
Map<?, ?> mapdata = (Map<?, ?>) operand;
// TODO don't lose generic info for the new map
Map<Object, Object> result = new HashMap<>();
Object lastKey = null;
for (Map.Entry<?, ?> entry : mapdata.entrySet()) {
try {
TypedValue kvPair = new TypedValue(entry);
state.pushActiveContextObject(kvPair);
state.enterScope();
Object val = selectionCriteria.getValueInternal(state).getValue();
if (val instanceof Boolean) {
if ((Boolean) val) {
if (this.variant == FIRST) {
result.put(entry.getKey(), entry.getValue());
return new ValueRef.TypedValueHolderValueRef(new TypedValue(result), this);
}
result.put(entry.getKey(), entry.getValue());
lastKey = entry.getKey();
}
}
else {
throw new SpelEvaluationException(selectionCriteria.getStartPosition(),
SpelMessage.RESULT_OF_SELECTION_CRITERIA_IS_NOT_BOOLEAN);
}
}
finally {
state.popActiveContextObject();
state.exitScope();
}
}
if ((this.variant == FIRST || this.variant == LAST) && result.isEmpty()) {
return new ValueRef.TypedValueHolderValueRef(new TypedValue(null), this);
}
if (this.variant == LAST) {
Map<Object, Object> resultMap = new HashMap<>();
Object lastValue = result.get(lastKey);
resultMap.put(lastKey,lastValue);
return new ValueRef.TypedValueHolderValueRef(new TypedValue(resultMap),this);
}
return new ValueRef.TypedValueHolderValueRef(new TypedValue(result),this);
}
if (operand instanceof Iterable || ObjectUtils.isArray(operand)) {
Iterable<?> data = (operand instanceof Iterable ?
(Iterable<?>) operand : Arrays.asList(ObjectUtils.toObjectArray(operand)));
List<Object> result = new ArrayList<>();
int index = 0;
for (Object element : data) {
try {
state.pushActiveContextObject(new TypedValue(element));
state.enterScope("index", index);
Object val = selectionCriteria.getValueInternal(state).getValue();
if (val instanceof Boolean) {
if ((Boolean) val) {
if (this.variant == FIRST) {
return new ValueRef.TypedValueHolderValueRef(new TypedValue(element), this);
}
result.add(element);
}
}
else {
throw new SpelEvaluationException(selectionCriteria.getStartPosition(),
SpelMessage.RESULT_OF_SELECTION_CRITERIA_IS_NOT_BOOLEAN);
}
index++;
}
finally {
state.exitScope();
state.popActiveContextObject();
}
}
if ((this.variant == FIRST || this.variant == LAST) && result.isEmpty()) {
return ValueRef.NullValueRef.INSTANCE;
}
if (this.variant == LAST) {
return new ValueRef.TypedValueHolderValueRef(new TypedValue(result.get(result.size() - 1)), this);
}
if (operand instanceof Iterable) {
return new ValueRef.TypedValueHolderValueRef(new TypedValue(result), this);
}
Class<?> elementType = ClassUtils.resolvePrimitiveIfNecessary(
op.getTypeDescriptor().getElementTypeDescriptor().getType());
Object resultArray = Array.newInstance(elementType, result.size());
System.arraycopy(result.toArray(), 0, resultArray, 0, result.size());
return new ValueRef.TypedValueHolderValueRef(new TypedValue(resultArray), this);
}
if (operand == null) {
if (this.nullSafe) {
return ValueRef.NullValueRef.INSTANCE;
}
throw new SpelEvaluationException(getStartPosition(), SpelMessage.INVALID_TYPE_FOR_SELECTION, "null");
}
throw new SpelEvaluationException(getStartPosition(), SpelMessage.INVALID_TYPE_FOR_SELECTION,
operand.getClass().getName());
}
@Override
public String toStringAST() {
StringBuilder sb = new StringBuilder();
switch (this.variant) {
case ALL:
sb.append("?[");
break;
case FIRST:
sb.append("^[");
break;
case LAST:
sb.append("$[");
break;
}
return sb.append(getChild(0).toStringAST()).append("]").toString();
}
}