org.springframework.expression.spel.ast.Selection Maven / Gradle / Ivy

/*
 * Copyright 2002-2010 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.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.core.convert.TypeDescriptor;
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.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]
 *
 * 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
 * @since 3.0
 */
public class Selection extends SpelNodeImpl {

	public final static int ALL = 0; // ?[]
	public final static int FIRST = 1; // ^[]
	public final static int LAST = 2; // $[]

	private final int variant;
	private final boolean nullSafe;

	public Selection(boolean nullSafe, int variant,int pos,SpelNodeImpl expression) {
		super(pos,expression); 
		this.nullSafe = nullSafe;
		this.variant = variant;
	}

	@SuppressWarnings("unchecked")
	@Override
	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
		TypedValue op = state.getActiveContextObject();
		Object operand = op.getValue();
		
		SpelNodeImpl selectionCriteria = children[0];
		if (operand instanceof Map) {
			Map mapdata = (Map) operand;
			// TODO don't lose generic info for the new map
			Map result = new HashMap();
			Object lastKey = null;
			for (Map.Entry entry : mapdata.entrySet()) {
				try {
					TypedValue kvpair = new TypedValue(entry,TypeDescriptor.valueOf(Map.Entry.class));
					state.pushActiveContextObject(kvpair);
					Object o = selectionCriteria.getValueInternal(state).getValue();
					if (o instanceof Boolean) {
						if (((Boolean) o).booleanValue() == true) {
							if (variant == FIRST) {
								result.put(entry.getKey(),entry.getValue());
								return new TypedValue(result);
							}
							result.put(entry.getKey(),entry.getValue());
							lastKey = entry.getKey();
						}
					} else {
						throw new SpelEvaluationException(selectionCriteria.getStartPosition(),
								SpelMessage.RESULT_OF_SELECTION_CRITERIA_IS_NOT_BOOLEAN);// ,selectionCriteria.stringifyAST());
					}
				} finally {
					state.popActiveContextObject();
				}
			}
			if ((variant == FIRST || variant == LAST) && result.size() == 0) {
				return new TypedValue(null,TypeDescriptor.NULL);
			}
			if (variant == LAST) {
				Map resultMap = new HashMap();
				Object lastValue = result.get(lastKey);
				resultMap.put(lastKey,lastValue);
				return new TypedValue(resultMap,TypeDescriptor.valueOf(Map.class));
			}
			return new TypedValue(result,op.getTypeDescriptor());
		} else if ((operand instanceof Collection) || ObjectUtils.isArray(operand)) {
			List