org.apache.wicket.markup.html.list.Loop.java Source code

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Here is the source code for org.apache.wicket.markup.html.list.Loop.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.markup.html.list;

import java.util.Iterator;

import org.apache.wicket.Component;
import org.apache.wicket.markup.repeater.AbstractRepeater;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.Model;
import org.apache.wicket.util.collections.ReadOnlyIterator;

/**
 * A very simple loop component whose model is an Integer defining the number of iterations the loop
 * should render. During rendering, Loop iterates from 0 to getIterations() - 1, creating a new
 * MarkupContainer for each iteration. The MarkupContainer is populated by the Loop subclass by
 * implementing the abstract method populate(LoopItem). The populate() method is called just before
 * the LoopItem container is rendered.
 * 
 * @author Juergen Donnerstag
 * @author Eelco Hillenius
 * @author Jonathan Locke
 */
public abstract class Loop extends AbstractRepeater {
    private static final long serialVersionUID = 1L;

    /**
     * Construct.
     * 
     * @param id
     *            See Component
     * @param iterations
     *            max index of the loop
     * @see org.apache.wicket.Component#Component(String, IModel)
     */
    public Loop(final String id, final int iterations) {
        super(id, new Model<Integer>(iterations));
    }

    /**
     * Construct.
     * 
     * @param id
     *            See Component
     * @param model
     *            Must contain a Integer model object
     * @see org.apache.wicket.Component#Component(String, IModel)
     */
    public Loop(final String id, final IModel<Integer> model) {
        super(id, model);
    }

    /**
     * @return The number of loop iterations
     */
    public final int getIterations() {
        return (Integer) getDefaultModelObject();
    }

    /**
     * @see org.apache.wicket.Component#onBeforeRender()
     */
    @Override
    protected final void onPopulate() {
        // Remove any previous loop contents
        removeAll();

        // Get number of iterations
        final int iterations = getIterations();
        if (iterations > 0) {
            // Create LoopItems for each iteration
            for (int iteration = 0; iteration < iterations; iteration++) {
                // Create item for loop iteration
                LoopItem item = newItem(iteration);

                // Add and populate item
                add(item);
                populateItem(item);
            }
        }
    }

    /**
     * Create a new LoopItem for loop at iteration.
     * 
     * @param iteration
     *            iteration in the loop
     * @return LoopItem
     */
    protected LoopItem newItem(int iteration) {
        return new LoopItem(iteration);
    }

    /**
     * @see org.apache.wicket.markup.repeater.AbstractRepeater#renderIterator()
     */
    @Override
    protected Iterator<Component> renderIterator() {
        final int iterations = size();

        return new ReadOnlyIterator<Component>() {
            private int index = 0;

            @Override
            public boolean hasNext() {
                return index < iterations;
            }

            @Override
            public Component next() {
                return get(Integer.toString(index++));
            }
        };
    }

    /**
     * Populates this loop item.
     * 
     * @param item
     *            The iteration of the loop
     */
    protected abstract void populateItem(LoopItem item);

    /**
     * @param child
     */
    @Override
    protected final void renderChild(Component child) {
        renderItem((LoopItem) child);
    }

    /**
     * Renders this loop iteration.
     * 
     * @param item
     *            The loop iteration
     */
    protected void renderItem(final LoopItem item) {
        item.render();
    }
}