com.jfinal.template.stat.ast.ForIteratorStatus Maven / Gradle / Ivy

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/**
 * Copyright (c) 2011-2019, James Zhan 詹波 ([email protected]).
 *
 * 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 com.jfinal.template.stat.ast;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import com.jfinal.template.TemplateException;
import com.jfinal.template.stat.Location;

/**
 * ForIteratorStatus
 * 封装 #for( id : expr) 迭代语句状态，便于模板中获取
 * 
 * 使用以下表达式可以模板中获取迭代状态：
 * for.size 被迭代集合元素数量，不支持 Iterator 与 Iterable
 * for.index 从 0 下始的下标
 * for.count 从 1 开始的计数器
 * for.first 是否第一个元素
 * for.last 是否最后一个元素
 * for.odd 是否第奇数个元素
 * for.even 是否第偶数个元素
 * for.outer 获取外层 for 对象，便于获取外层 for 循环状态
 *           例如: for.outer.index
 */
public class ForIteratorStatus {
	
	private Object outer;
	private int index;
	private int size;
	private Iterator iterator;
	private Location location;
	
	public ForIteratorStatus(Object outer, Object target, Location location) {
		this.outer = outer;
		this.index = 0;
		this.location = location;
		init(target);
	}
	
	@SuppressWarnings("unchecked")
	private void init(Object target) {
		if (target instanceof Collection) {
			size = ((Collection)target).size();
			iterator = ((Collection)target).iterator();
			return ;
		}
		if (target instanceof Map) {
			size = ((Map)target).size();
			iterator = new MapIterator(((Map)target).entrySet().iterator());
			return ;
		}
		if (target == null) {	// 必须放在 target.getClass() 之前，避免空指针异常
			size = 0;
			iterator = NullIterator.me;
			return ;
		}
		if (target.getClass().isArray()) {
			size = Array.getLength(target);
			iterator = new ArrayIterator(target, size);
			return ;
		}
		if (target instanceof Iterator) {
			size = -1;
			iterator = (Iterator)target;
			return ;
		}
		if (target instanceof Iterable) {
			size = -1;
			iterator = ((Iterable)target).iterator();
			return ;
		}
		if (target instanceof Enumeration) {
			ArrayList list = Collections.list((Enumeration)target);
			size = list.size();
			iterator = list.iterator();
			return ;
		}
		
		size = 1;
		iterator = new SingleObjectIterator(target);
	}
	
	Iterator getIterator() {
		return iterator;
	}
	
	void nextState() {
		index++;
	}
	
	public Object getOuter() {
		return outer;
	}
	
	public int getIndex() {
		return index;
	}
	
	public int getCount() {
		return index + 1;
	}
	
	public int getSize() {
		if (size >= 0) {
			return size;
		}
		throw new TemplateException("No such method getSize() of the iterator", location);
	}
	
	public boolean getFirst() {
		return index == 0;
	}
	
	public boolean getLast() {
		return !iterator.hasNext();
	}
	
	public boolean getOdd() {
		return index % 2 == 0;
	}
	
	public boolean getEven() {
		return index % 2 != 0;
	}
}

class MapIterator implements Iterator> {
	
	private Iterator> iterator;
	private ForEntry forEntry = new ForEntry();
	
	public MapIterator(Iterator> iterator) {
		this.iterator = iterator;
	}
	
	public boolean hasNext() {
		return iterator.hasNext();
	}
	
	public Entry next() {
		forEntry.init(iterator.next());
		return forEntry;
	}
	
	public void remove() {
		throw new UnsupportedOperationException();
	}
}

class ArrayIterator implements Iterator