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/*
 * Copyright (C) 2004, 2005 Joe Walnes.
 * Copyright (C) 2006, 2007, 2010, 2011, 2013, 2016, 2018 XStream Committers.
 * All rights reserved.
 *
 * The software in this package is published under the terms of the BSD
 * style license a copy of which has been included with this distribution in
 * the LICENSE.txt file.
 * 
 * Created on 08. May 2004 by Joe Walnes
 */
package com.feilong.lib.xstream.converters.collections;

import java.lang.reflect.Field;
import java.util.Comparator;
import java.util.SortedMap;
import java.util.TreeMap;

import com.feilong.lib.xstream.converters.MarshallingContext;
import com.feilong.lib.xstream.converters.UnmarshallingContext;
import com.feilong.lib.xstream.converters.reflection.ObjectAccessException;
import com.feilong.lib.xstream.core.JVM;
import com.feilong.lib.xstream.core.util.Fields;
import com.feilong.lib.xstream.core.util.HierarchicalStreams;
import com.feilong.lib.xstream.core.util.PresortedMap;
import com.feilong.lib.xstream.io.HierarchicalStreamReader;
import com.feilong.lib.xstream.io.HierarchicalStreamWriter;
import com.feilong.lib.xstream.mapper.Mapper;

/**
 * Converts a java.util.TreeMap to XML, and serializes
 * the associated java.util.Comparator. The converter
 * assumes that the entries in the XML are already sorted
 * according the comparator.
 *
 * @author Joe Walnes
 * @author Jörg Schaible
 */
public class TreeMapConverter extends MapConverter{

    private static final class NullComparator extends Mapper.Null implements Comparator{

        @Override
        public int compare(Object o1,Object o2){
            Comparable c1 = (Comparable) o1;
            Comparable c2 = (Comparable) o2;
            return c1.compareTo(o2);
        }
    }

    private final static Comparator NULL_MARKER     = new NullComparator();

    private final static Field      comparatorField = Fields.locate(TreeMap.class, Comparator.class, false);

    public TreeMapConverter(Mapper mapper){
        super(mapper, TreeMap.class);
    }

    @Override
    public void marshal(Object source,HierarchicalStreamWriter writer,MarshallingContext context){
        SortedMap sortedMap = (SortedMap) source;
        marshalComparator(sortedMap.comparator(), writer, context);
        super.marshal(source, writer, context);
    }

    protected void marshalComparator(Comparator comparator,HierarchicalStreamWriter writer,MarshallingContext context){
        if (comparator != null){
            writer.startNode("comparator");
            writer.addAttribute(mapper().aliasForSystemAttribute("class"), mapper().serializedClass(comparator.getClass()));
            context.convertAnother(comparator);
            writer.endNode();
        }
    }

    @Override
    public Object unmarshal(HierarchicalStreamReader reader,UnmarshallingContext context){
        TreeMap result = comparatorField != null ? new TreeMap() : null;
        final Comparator comparator = unmarshalComparator(reader, context, result);
        if (result == null){
            result = comparator == null || comparator == NULL_MARKER ? new TreeMap() : new TreeMap(comparator);
        }
        populateTreeMap(reader, context, result, comparator);
        return result;
    }

    protected Comparator unmarshalComparator(HierarchicalStreamReader reader,UnmarshallingContext context,TreeMap result){
        final Comparator comparator;
        if (reader.hasMoreChildren()){
            reader.moveDown();
            if (reader.getNodeName().equals("comparator")){
                Class comparatorClass = HierarchicalStreams.readClassType(reader, mapper());
                comparator = (Comparator) context.convertAnother(result, comparatorClass);
            }else if (reader.getNodeName().equals("no-comparator")){ // pre 1.4 format
                comparator = null;
            }else{
                // we are already within the first entry
                return NULL_MARKER;
            }
            reader.moveUp();
        }else{
            comparator = null;
        }
        return comparator;
    }

    protected void populateTreeMap(HierarchicalStreamReader reader,UnmarshallingContext context,TreeMap result,Comparator comparator){
        boolean inFirstElement = comparator == NULL_MARKER;
        if (inFirstElement){
            comparator = null;
        }
        SortedMap sortedMap = new PresortedMap(comparator != null && JVM.hasOptimizedTreeMapPutAll() ? comparator : null);
        if (inFirstElement){
            // we are already within the first entry
            putCurrentEntryIntoMap(reader, context, result, sortedMap);
            reader.moveUp();
        }
        populateMap(reader, context, result, sortedMap);
        try{
            if (JVM.hasOptimizedTreeMapPutAll()){
                if (comparator != null && comparatorField != null){
                    comparatorField.set(result, comparator);
                }
                result.putAll(sortedMap); // internal optimization will not call comparator
            }else if (comparatorField != null){
                comparatorField.set(result, sortedMap.comparator());
                result.putAll(sortedMap); // "sort" by index
                comparatorField.set(result, comparator);
            }else{
                result.putAll(sortedMap); // will use comparator for already sorted map
            }
        }catch (final IllegalAccessException e){
            throw new ObjectAccessException("Cannot set comparator of TreeMap", e);
        }
    }
}