com.puppetlabs.geppetto.puppetdb.ui.treenode.TreeNode.java Source code

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Here is the source code for com.puppetlabs.geppetto.puppetdb.ui.treenode.TreeNode.java

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/**
 * Copyright (c) 2013 Puppet Labs, Inc. and other contributors, as listed below.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *   Puppet Labs
 */
package com.puppetlabs.geppetto.puppetdb.ui.treenode;

import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Image;

/**
 * Represents a node in a TreeViewer that uses {@link SWT#VIRTUAL} style,
 * a {@link TreeNodeContentProvider}, and a {@link TreeNodeLabelProvider}.
 * 
 * @param <P>
 *            The type of the parent node
 * @param <C>
 *            The type of the children nodes
 */
public abstract class TreeNode<P extends TreeNode<?, ?>, C extends TreeNode<?, ?>> {
    private final P parent;

    protected TreeNode(P parent) {
        this.parent = parent;
    }

    /**
     * Returns the children of this node
     * 
     * @return the children
     */
    protected abstract C[] getChildren();

    /**
     * Returns the text for the column at the given <code>colIdx</code>.
     * 
     * @param colIdx
     *            The index of the column.
     * @return The text for the column at <code>colIdx</code> or an empty string if not applicable
     */
    public String getColumnText(int colIdx) {
        return "";
    }

    /**
     * Returns the tooltip for the column at the given <code>colIdx</code>.
     * 
     * @param colIdx
     *            The index of the column.
     * @return The tooltip for the column at <code>colIdx</code> or <code>null</code> if not applicable
     */
    public String getColumnTooltip(int colIdx) {
        return null;
    }

    /**
     * @param colIdx
     *            The index of the column.
     * @return The image for the column at <code>colIdx</code> or <code>null</code> if not applicable
     */
    public Image getImage(int colIdx) {
        return null;
    }

    /**
     * Returns the parent node.
     * 
     * @return The parent node or <code>null</code> if this is the top node
     */
    public final P getParent() {
        return parent;
    }

    /**
     * Updates the child count for this node in the given <code>viewer</code> using the method {@link TreeViewer#setChildCount(Object, int)}
     * unless is equal to the <code>currentChildCount</code>.
     * 
     * @param viewer
     *            The viewer that will receive the call
     * @param currentChildCount
     *            The viewers current child count for this node
     */
    public void updateChildCount(TreeViewer viewer, int currentChildCount) {
        C[] children = getChildren();
        if (children.length != currentChildCount)
            viewer.setChildCount(this, children.length);
    }

    /**
     * <p>
     * Replaces the child at the given <code>index</code> in the <code>viewer</code> with the child that this instance has at the given
     * <code>index</code> using the method {@link TreeViewer#replace(Object, int, Object)} and also calls
     * {@link #updateChildCount(TreeViewer, int)} on that child.
     * </p>
     * 
     * @param viewer
     *            The viewer that will receive the call
     * @param index
     *            The index of the child node
     */
    public void updateElement(TreeViewer viewer, int index) {
        C[] children = getChildren();
        if (index < children.length) {
            C child = children[index];
            viewer.replace(this, index, child);
            child.updateHasChildren(viewer);
        }
    }

    /**
     * Updates the <code>viewer</code> with information if this node has children or not
     * 
     * @param viewer
     *            The viewer that will receive the call
     */
    public void updateHasChildren(TreeViewer viewer) {
        viewer.setChildCount(this, getChildren().length);
    }
}