cc.xuloo.rcputils.tables.sort.SortColumnComparator.java Source code

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Here is the source code for cc.xuloo.rcputils.tables.sort.SortColumnComparator.java

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/*******************************************************************************
 * Copyright (c) 2008 Ralf Ebert
 * 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:
 * Ralf Ebert - initial API and implementation
 *******************************************************************************/
package cc.xuloo.rcputils.tables.sort;

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;

import cc.xuloo.rcputils.properties.IValue;
import cc.xuloo.rcputils.tables.TableViewerBuilder;

/**
 * ColumnComparator is a ViewerComparator that uses table.getSortColumn() as
 * column to compare values. The column is queries for an IValue by the
 * column.getData(SORT_BY) and used this value to sort values. It also pays
 * attention to table.getSortDirection(), if it's DESC (SWT.DOWN), the values
 * are exchanged.
 * 
 * Internal implementation class for {@link TableViewerBuilder}.
 * 
 * @author Ralf Ebert <info@ralfebert.de>
 */
public final class SortColumnComparator extends ViewerComparator {

    public static final String SORT_BY = SortColumnComparator.class.getName() + ".sortBy";

    @SuppressWarnings("unchecked")
    @Override
    public int compare(Viewer viewer, Object e1, Object e2) {

        Table table = (Table) viewer.getControl();

        // exchange values for descending sort direction
        if (table.getSortDirection() == SWT.DOWN) {
            Object tmp = e1;
            e1 = e2;
            e2 = tmp;
        }

        // resolve SORT_BY data value
        TableColumn column = table.getSortColumn();
        if (column == null)
            return super.compare(viewer, e1, e2);

        IValue sortBy = (IValue) column.getData(SORT_BY);

        if (sortBy == null)
            return super.compare(viewer, e1, e2);

        // compare using the SORT_BY value
        Object v1 = sortBy.getValue(e1);
        Object v2 = sortBy.getValue(e2);
        if (v1 instanceof Comparable && v2 instanceof Comparable) {
            return ((Comparable) v1).compareTo(v2);
        }

        // fallback on default ViewerComparator behaviour
        return super.compare(viewer, e1, e2);

    }
}