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/**
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* '$RCSfile$'
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* Purpose: A Class that sorts two NodeRecords
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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* Authors: Matt Jones
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* Release: @release@
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*
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* '$Author: jones $'
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* '$Date: 2001-01-18 11:52:00 -0800 (Thu, 18 Jan 2001) $'
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* '$Revision: 669 $'
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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package edu.ucsb.nceas.metacat;
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import java.util.Comparator;
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/**
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* A utility class that sorts two node records.
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* <p>
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* The order of the records
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* determines how the XML document is printed from DocumentImpl.toXml(),
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* so it is important that the sort order specified here results in a depth
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* first traversal of the nodes in tree. Currently, the nodes are inserted
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* into the database in this depth-forst order, so the nodeid identifiers
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* are a good indicator of the proper sort order.
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* <p>
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* However, if we modify data loading semantics to allow document nodes to
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* be rearranged, or otherwise change the nodeindex value, this current
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* sort algorithm will fail to work.
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*/
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public class NodeComparator implements Comparator {
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static int LESS = -1;
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static int EQUALS = 0;
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static int GREATER = 1;
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/**
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* Constructor
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*/
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public NodeComparator() {
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}
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/**
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* compare two objects to determine proper sort order -- delegates to
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* the compare(NodeRecord, NodeRecord) method.
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*/
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public int compare(Object o1, Object o2) {
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return compare((NodeRecord)o1, (NodeRecord)o2);
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}
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/**
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* compare two NodeRecord objects to determine proper sort order. The
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* node records are equal if their nodeid fields are equal. One is
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* less than another if its parentnodeid is less, or if its parentnodeid
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* is equal and its nodeindex is less. One is greater than another if
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* its parentnodeid is greater, or if its parentnodeid is equal and
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* its nodeindex is greater.
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*/
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public int compare(NodeRecord o1, NodeRecord o2) {
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if (o1.nodeid == o2.nodeid) {
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return EQUALS;
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} else if (o1.nodeid < o2.nodeid) {
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return LESS;
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} else if (o1.nodeid > o2.nodeid) {
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return GREATER;
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/* // This is old code that used to sort the records into breadth-first
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// traversal order, based on the parentnodeid and the nodeindex.
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//
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if (o1.nodeid == o2.nodeid) {
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return EQUALS;
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} else if (o1.parentnodeid < o2.parentnodeid) {
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return LESS;
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} else if (o1.parentnodeid > o2.parentnodeid) {
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return GREATER;
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} else if (o1.parentnodeid == o2.parentnodeid) {
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if (o1.nodeindex < o2.nodeindex) {
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return LESS;
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} else if (o1.nodeindex > o2.nodeindex) {
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return GREATER;
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} else {
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// this should never happen because (parentnodeid,nodeindex) is unique
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return EQUALS;
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}
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*/
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} else {
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// this should never happen because parentnodeid is always <,>, or =
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return EQUALS;
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}
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}
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}
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