statesystem/org.eclipse.tracecompass.segmentstore.core/src/org/eclipse/tracecompass/segmentstore/core/segment/interfaces/SegmentTypeComparators.java

/*******************************************************************************
 * Copyright (c) 2016 École Polytechnique de Montréal
 *
 * All rights reserved. This program and the accompanying materials are
 * made available under the terms of the Eclipse Public License 2.0 which
 * accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *******************************************************************************/

package org.eclipse.tracecompass.segmentstore.core.segment.interfaces;

import java.util.Comparator;
import java.util.Objects;

import org.eclipse.jdt.annotation.Nullable;
import org.eclipse.tracecompass.segmentstore.core.ISegment;

/**
 * Segments comparators for specific segment interfaces
 *
 * @author Geneviève Bastien
 * @noimplement This interface only contains static definitions.
 * @since 2.0
 */
public interface SegmentTypeComparators {

    /**
     * Compare named segments. If segments that are not named are mixed with
     * named segments, their order will be undefined by they will be greater
     * than all the named ones.
     */
    Comparator<ISegment> NAMED_SEGMENT_COMPARATOR = (@Nullable ISegment o1, @Nullable ISegment o2) -> {
        if (o1 == null || o2 == null) {
            throw new IllegalArgumentException("One of the segment to compare is null, that should never happen"); //$NON-NLS-1$
        }
        String name1 = SegmentAspects.getName(o1);
        String name2 = SegmentAspects.getName(o2);
        if (Objects.equals(name1, name2)) {
            return 0;
        }
        // Segments that are not named are greater than named ones
        if (name2 == null) {
            return -1;
        }
        if (name1 == null) {
            return 1;
        }
        return name1.compareTo(name2);
    };
}