tmf/org.eclipse.tracecompass.tmf.ui/src/org/eclipse/tracecompass/tmf/ui/viewers/table/ViewerCompoundComparator.java

   1 /*******************************************************************************
   2  * Copyright (c) 2015 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   Matthew Khouzam - Initial API and implementation
  11  *******************************************************************************/
  12
  13 package org.eclipse.tracecompass.tmf.ui.viewers.table;
  14
  15 import java.util.Comparator;
  16
  17 import org.eclipse.jface.viewers.Viewer;
  18 import org.eclipse.jface.viewers.ViewerComparator;
  19 import org.eclipse.tracecompass.common.core.NonNullUtils;
  20
  21 /**
  22  * ViewerCompoundComparator that can be used to make compound comparisons (1st
  23  * key 2nd key etc...)
  24  *
  25  * @since 2.0
  26  *
  27  */
  28 public class ViewerCompoundComparator extends ViewerComparator {
  29
  30     /**
  31      * String comparator, compares two objects by their toString values, if an
  32      * object is null, it is assigned to an empty string
  33      */
  34     public static final ViewerCompoundComparator STRING_COMPARATOR = new ViewerCompoundComparator(new Comparator<Object>() {
  35         @Override
  36         public int compare(Object e1, Object e2) {
  37             String left = NonNullUtils.nullToEmptyString(e1);
  38             String right = NonNullUtils.nullToEmptyString(e2);
  39             return left.compareTo(right);
  40         }
  41     });
  42
  43     private ViewerCompoundComparator fNext;
  44
  45     /**
  46      * Create a viewer compound comparator
  47      *
  48      * @param comparator
  49      *            selected comparator
  50      */
  51     public ViewerCompoundComparator(Comparator<? extends Object> comparator) {
  52         super(comparator);
  53     }
  54
  55     /**
  56      * Sets the next comparator
  57      *
  58      * @param next
  59      *            the next comparator
  60      */
  61     public void setNext(ViewerCompoundComparator next) {
  62         fNext = next;
  63     }
  64
  65     /**
  66      * Get the next comparator
  67      *
  68      * @return the next comparator
  69      */
  70     public ViewerCompoundComparator getNext() {
  71         return fNext;
  72     }
  73
  74     private int getNextCompare(Viewer viewer, Object e1, Object e2) {
  75         return (fNext != null) ? fNext.compare(viewer, e1, e2) : 0;
  76     }
  77
  78     @Override
  79     public Comparator<Object> getComparator() {
  80         return super.getComparator();
  81     }
  82
  83     @Override
  84     public int compare(Viewer viewer, Object e1, Object e2) {
  85         int retVal = getComparator().compare(e1, e2);
  86         return (retVal != 0) ? retVal : getNextCompare(viewer, e1, e2);
  87     }
  88 }