org.eclipse.wb.swt.TableViewerColumnSorter.java Source code

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Here is the source code for org.eclipse.wb.swt.TableViewerColumnSorter.java

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/*******************************************************************************
 * Copyright (c) 2011 Google, Inc.
 * 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:
 *    Google, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.wb.swt;

import java.lang.reflect.Method;

import org.eclipse.jface.viewers.EditingSupport;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.TableViewerColumn;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerColumn;
import org.eclipse.jface.viewers.ViewerComparator;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.widgets.Table;

/**
 * Helper for sorting {@link TableViewer} by one of its {@link TableViewerColumn}s.
 * <p>
 * Originally from http://wiki.eclipse.org/index.php/JFaceSnippets, Snippet040TableViewerSorting.
 * 
 * @author Tom Schindl <tom.schindl@bestsolution.at>
 * @author Konstantin Scheglov <Konstantin.Scheglov@gmail.com>
 */
public class TableViewerColumnSorter extends ViewerComparator {
    public static final int ASC = 1;
    public static final int NONE = 0;
    public static final int DESC = -1;
    ////////////////////////////////////////////////////////////////////////////
    //
    // Instance fields
    //
    ////////////////////////////////////////////////////////////////////////////
    private final TableViewerColumn m_column;
    private final TableViewer m_viewer;
    private final Table m_table;
    private int m_direction = NONE;

    ////////////////////////////////////////////////////////////////////////////
    //
    // Constructor
    //
    ////////////////////////////////////////////////////////////////////////////
    public TableViewerColumnSorter(TableViewerColumn column) {
        m_column = column;
        m_viewer = (TableViewer) column.getViewer();
        m_table = m_viewer.getTable();
        m_column.getColumn().addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                if (m_viewer.getComparator() != null) {
                    if (m_viewer.getComparator() == TableViewerColumnSorter.this) {
                        if (m_direction == ASC) {
                            setSorter(DESC);
                        } else if (m_direction == DESC) {
                            setSorter(NONE);
                        }
                    } else {
                        setSorter(ASC);
                    }
                } else {
                    setSorter(ASC);
                }
            }
        });
    }

    ////////////////////////////////////////////////////////////////////////////
    //
    // Utils
    //
    ////////////////////////////////////////////////////////////////////////////
    public void setSorter(int direction) {
        if (direction == NONE) {
            m_table.setSortColumn(null);
            m_table.setSortDirection(SWT.NONE);
            m_viewer.setComparator(null);
        } else {
            m_table.setSortColumn(m_column.getColumn());
            m_direction = direction;
            if (m_direction == ASC) {
                m_table.setSortDirection(SWT.DOWN);
            } else {
                m_table.setSortDirection(SWT.UP);
            }
            if (m_viewer.getComparator() == this) {
                m_viewer.refresh();
            } else {
                m_viewer.setComparator(this);
            }
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    //
    // ViewerComparator
    //
    ////////////////////////////////////////////////////////////////////////////
    public int compare(Viewer viewer, Object e1, Object e2) {
        return m_direction * doCompare(viewer, e1, e2);
    }

    /**
     * Compares to elements of viewer. By default tries to compare values extracted from these elements using
     * {@link #getValue(Object)}, because usually you want to compare value of some attribute.
     */
    @SuppressWarnings("unchecked")
    protected int doCompare(Viewer viewer, Object e1, Object e2) {
        Object o1 = getValue(e1);
        Object o2 = getValue(e2);
        if (o1 instanceof Comparable && o2 instanceof Comparable) {
            return ((Comparable) o1).compareTo(o2);
        }
        return 0;
    }

    /**
     * 
     * @return the value to compare in {@link #doCompare(Viewer, Object, Object)}. Be default tries to get it
     *         from {@link EditingSupport}. May return <code>null</code>.
     */
    protected Object getValue(Object o) {
        try {
            EditingSupport editingSupport;
            {
                Method getEditingMethod = ViewerColumn.class.getDeclaredMethod("getEditingSupport", new Class[] {});
                getEditingMethod.setAccessible(true);
                editingSupport = (EditingSupport) getEditingMethod.invoke(m_column, new Object[] {});
            }
            if (editingSupport != null) {
                Method getValueMethod = EditingSupport.class.getDeclaredMethod("getValue",
                        new Class[] { Object.class });
                getValueMethod.setAccessible(true);
                return getValueMethod.invoke(editingSupport, new Object[] { o });
            }
        } catch (Throwable e) {
        }
        return null;
    }
}