org.eclipse.tm4e.languageconfiguration.internal.widgets.ColumnViewerComparator.java Source code

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Here is the source code for org.eclipse.tm4e.languageconfiguration.internal.widgets.ColumnViewerComparator.java

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/**
 *  Copyright (c) 2015-2017 Angelo ZERR.
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 *  Contributors:
 *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
 */
package org.eclipse.tm4e.languageconfiguration.internal.widgets;

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;

/**
 * Viewer compoarator which sort a given column.
 *
 */
public class ColumnViewerComparator extends ViewerComparator {

    private int fSortColumn;

    private int fSortOrder; // 1 = asc, -1 = desc

    public ColumnViewerComparator() {
        fSortColumn = 0;
        fSortOrder = 1;
    }

    /**
     * Returns the {@linkplain SWT} style constant for the sort direction.
     *
     * @return {@link SWT#DOWN} for asc sorting, {@link SWT#UP} otherwise
     */
    public int getDirection() {
        return fSortOrder == 1 ? SWT.DOWN : SWT.UP;
    }

    /**
     * Sets the sort column. If the newly set sort column equals the previous set
     * sort column, the sort direction changes.
     *
     * @param column New sort column
     */
    public void setColumn(int column) {
        if (column == fSortColumn) {
            fSortOrder *= -1;
        } else {
            fSortColumn = column;
            fSortOrder = 1;
        }
    }

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

        if (viewer instanceof TableViewer) {
            IBaseLabelProvider baseLabel = ((TableViewer) viewer).getLabelProvider();

            String left = ((ITableLabelProvider) baseLabel).getColumnText(e1, fSortColumn);
            String right = ((ITableLabelProvider) baseLabel).getColumnText(e2, fSortColumn);
            int sortResult = getComparator().compare(left != null ? left : "", right != null ? right : ""); //$NON-NLS-1$ //$NON-NLS-2$
            return sortResult * fSortOrder;
        }

        return super.compare(viewer, e1, e2);
    }

}