eu.celar.ui.comparators.TableColumnComparator.java Source code

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Here is the source code for eu.celar.ui.comparators.TableColumnComparator.java

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/*****************************************************************************
 * Copyright (c) 2007-2008 g-Eclipse Consortium 
 * 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
 *
 * Initial development of the original code was made for the
 * g-Eclipse project founded by European Union
 * project number: FP6-IST-034327  http://www.geclipse.eu/
 *
 * Contributors:
 *    Ariel Garcia - initial API and implementation
 *****************************************************************************/

package eu.celar.ui.comparators;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.jface.viewers.IBaseLabelProvider;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerComparator;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;

/**
 * This comparator is used to sort the table entries according to the selected
 * sorting column, with a second ordering column as fallback if entries compare
 * equal.
 */
public class TableColumnComparator extends ViewerComparator {

    private TableViewer tableViewer;
    private Table table;
    private ITableLabelProvider labelProvider;
    private TableColumn defaultSortColumn;

    /**
     * Construct a <code>ViewerComparator</code> to use for a <code>TableViewer</code>,
     * with the given column as fallback sorting column. Remark that each TableViewer
     * needs a new instance of this TableColumnComparator.
     * 
     * @param defaultSortColumn The sorting column used as fallback if elements compare equal.
     */
    public TableColumnComparator(final TableColumn defaultSortColumn) {
        this.defaultSortColumn = defaultSortColumn;
    }

    @Override
    public int category(final Object element) {
        int type = 0;
        IResource res = null;

        /*
         * Analyze the element to be sorted to determine if it is a folder, file,
         * project, etc.
         */
        if (element instanceof IAdaptable) {
            IAdaptable adaptable = (IAdaptable) element;
            res = (IResource) adaptable.getAdapter(IResource.class);
        }
        if (res != null) {
            /*
             * The IResource types FILE, FOLDER, PROJECT, ROOT have non-zero values...
             * and FILEs should come last in the (ascending) sorting, thus the '-' 
             */
            type = -res.getType();
        }

        // We return 0 if the element is not a IResource
        return type;
    }

    @Override
    public int compare(final Viewer viewer, final Object element1, final Object element2) {

        /*
         * The object's fields are set only once, at the first method call. The LabelProvider
         * can change after the Viewer is set up, so we cannot do this in the constructor.
         */
        if (this.labelProvider == null) {
            initialize(viewer);
        }

        int cat1 = category(element1);
        int cat2 = category(element2);

        int result = cat1 - cat2;

        // Elements of different type (file, folder,...) are not mixed in the sorting
        if (result == 0) {
            int col;
            // Sort the table by the first column if there is no sorting defined
            if (this.table.getSortColumn() == null) {
                col = 0;
            } else {
                col = this.table.indexOf(this.table.getSortColumn());
            }

            int order = (this.table.getSortDirection() == SWT.DOWN) ? SWT.DOWN : SWT.UP;

            String value1 = this.labelProvider.getColumnText(element1, col);
            String value2 = this.labelProvider.getColumnText(element2, col);

            result = (order == SWT.UP) ? value1.compareToIgnoreCase(value2) : value2.compareToIgnoreCase(value1);
        }

        // If the elements compare equal, sort by ascending value of the preselected column
        if (result == 0) {
            int sCol = this.table.indexOf(this.defaultSortColumn);
            String value1 = this.labelProvider.getColumnText(element1, sCol);
            String value2 = this.labelProvider.getColumnText(element2, sCol);
            result = value1.compareToIgnoreCase(value2);
        }

        return result;
    }

    /**
     * Initialize the private fields according to the viewer.
     * 
     * @param viewer The viewer whose elements are to be sorted
     */
    private void initialize(final Viewer viewer) {

        // This comparator is only for tables
        assert viewer instanceof TableViewer;

        this.tableViewer = (TableViewer) viewer;
        this.table = this.tableViewer.getTable();

        IBaseLabelProvider lProvider = this.tableViewer.getLabelProvider();
        if (lProvider instanceof ITableLabelProvider) {
            this.labelProvider = (ITableLabelProvider) lProvider;
        }
    }

}