001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.wicket.markup.html.list; 018 019import java.util.Iterator; 020 021import org.apache.wicket.Component; 022import org.apache.wicket.markup.repeater.AbstractRepeater; 023import org.apache.wicket.model.IModel; 024import org.apache.wicket.model.Model; 025import org.apache.wicket.util.collections.ReadOnlyIterator; 026 027/** 028 * A very simple loop component whose model is an Integer defining the number of iterations the loop 029 * should render. During rendering, Loop iterates from 0 to getIterations() - 1, creating a new 030 * MarkupContainer for each iteration. The MarkupContainer is populated by the Loop subclass by 031 * implementing the abstract method populate(LoopItem). The populate() method is called just before 032 * the LoopItem container is rendered. 033 * 034 * @author Juergen Donnerstag 035 * @author Eelco Hillenius 036 * @author Jonathan Locke 037 */ 038public abstract class Loop extends AbstractRepeater 039{ 040 private static final long serialVersionUID = 1L; 041 042 /** 043 * Construct. 044 * 045 * @param id 046 * See Component 047 * @param iterations 048 * max index of the loop 049 * @see org.apache.wicket.Component#Component(String, IModel) 050 */ 051 public Loop(final String id, final int iterations) 052 { 053 super(id, new Model<Integer>(iterations)); 054 } 055 056 /** 057 * Construct. 058 * 059 * @param id 060 * See Component 061 * @param model 062 * Must contain a Integer model object 063 * @see org.apache.wicket.Component#Component(String, IModel) 064 */ 065 public Loop(final String id, final IModel<Integer> model) 066 { 067 super(id, model); 068 } 069 070 /** 071 * @return The number of loop iterations 072 */ 073 public final int getIterations() 074 { 075 return (Integer)getDefaultModelObject(); 076 } 077 078 /** 079 * @see org.apache.wicket.Component#onBeforeRender() 080 */ 081 @Override 082 protected final void onPopulate() 083 { 084 // Remove any previous loop contents 085 removeAll(); 086 087 // Get number of iterations 088 final int iterations = getIterations(); 089 if (iterations > 0) 090 { 091 // Create LoopItems for each iteration 092 for (int iteration = 0; iteration < iterations; iteration++) 093 { 094 // Create item for loop iteration 095 LoopItem item = newItem(iteration); 096 097 // Add and populate item 098 add(item); 099 populateItem(item); 100 } 101 } 102 } 103 104 /** 105 * Create a new LoopItem for loop at iteration. 106 * 107 * @param iteration 108 * iteration in the loop 109 * @return LoopItem 110 */ 111 protected LoopItem newItem(int iteration) 112 { 113 return new LoopItem(iteration); 114 } 115 116 /** 117 * @see org.apache.wicket.markup.repeater.AbstractRepeater#renderIterator() 118 */ 119 @Override 120 protected Iterator<Component> renderIterator() 121 { 122 final int iterations = size(); 123 124 return new ReadOnlyIterator<Component>() 125 { 126 private int index = 0; 127 128 @Override 129 public boolean hasNext() 130 { 131 return index < iterations; 132 } 133 134 @Override 135 public Component next() 136 { 137 return get(Integer.toString(index++)); 138 } 139 }; 140 } 141 142 /** 143 * Populates this loop item. 144 * 145 * @param item 146 * The iteration of the loop 147 */ 148 protected abstract void populateItem(LoopItem item); 149 150 /** 151 * @param child 152 */ 153 @Override 154 protected final void renderChild(Component child) 155 { 156 renderItem((LoopItem)child); 157 } 158 159 /** 160 * Renders this loop iteration. 161 * 162 * @param item 163 * The loop iteration 164 */ 165 protected void renderItem(final LoopItem item) 166 { 167 item.render(); 168 } 169}