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Library providing immutable/persistent collection classes for Java. While collections are immutable they provide methods for adding and removing values by creating new modified copies of themselves. Each copy shares almost all of its structure with other copies to minimize memory consumption.
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// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2014, Burton Computer Corporation
// All rights reserved.
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package org.javimmutable.collections.listmap;

import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Insertable;
import org.javimmutable.collections.JImmutableList;
import org.javimmutable.collections.JImmutableListMap;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.common.IteratorAdaptor;
import org.javimmutable.collections.list.JImmutableArrayList;

import java.util.Iterator;

public abstract class AbstractJImmutableListMap
        implements JImmutableListMap
{
    private final JImmutableMap> contents;

    protected AbstractJImmutableListMap(JImmutableMap> contents)
    {
        this.contents = contents;
    }

    @Override
    public JImmutableList getList(K key)
    {
        if (key == null) {
            throw new NullPointerException();
        }
        Holder> current = contents.find(key);
        return current.isFilled() ? current.getValue() : emptyList();
    }

    @Override
    public JImmutableListMap assign(K key,
                                          JImmutableList value)
    {
        if (key == null || value == null) {
            throw new NullPointerException();
        }
        return create(contents.assign(key, copyList(value)));
    }

    @Override
    public JImmutableListMap insert(K key,
                                          V value)
    {
        return create(contents.assign(key, insertInList(getList(key), value)));
    }

    @Override
    public JImmutableListMap delete(K key)
    {
        return create(contents.delete(key));
    }

    @Override
    public int size()
    {
        return contents.size();
    }

    @Override
    public boolean isEmpty()
    {
        return contents.size() == 0;
    }

    @Override
    public Cursor keysCursor()
    {
        return contents.keysCursor();
    }

    @Override
    public Cursor valuesCursor(K key)
    {
        return getList(key).cursor();
    }

    @Override
    public Cursor>> cursor()
    {
        return contents.cursor();
    }

    @Override
    public Insertable> insert(JImmutableMap.Entry e)
    {
        return insert(e.getKey(), e.getValue());
    }

    @Override
    public Iterator>> iterator()
    {
        return IteratorAdaptor.of(cursor());
    }

    @Override
    public JImmutableList get(K key)
    {
        return contents.get(key);
    }

    @Override
    public JImmutableList getValueOr(K key,
                                        JImmutableList defaultValue)
    {
        return contents.getValueOr(key, defaultValue);
    }

    @Override
    public Holder> find(K key)
    {
        return contents.find(key);
    }

    @Override
    public JImmutableListMap deleteAll()
    {
        return create(contents.deleteAll());
    }

    /**
     * Implemented by derived classes to create a new instance of the appropriate class.
     *
     * @param map
     * @return
     */
    protected abstract JImmutableListMap create(JImmutableMap> map);

    /**
     * Overridable by derived classes to create a compatible copy of the specified list.
     * Default implementation simply returns the original.
     *
     * @return
     */
    protected JImmutableList copyList(JImmutableList original)
    {
        return original;
    }

    /**
     * Overridable by derived classes to create a new empty list
     *
     * @return
     */
    protected JImmutableList emptyList()
    {
        return JImmutableArrayList.of();
    }

    /**
     * Overridable by derived classes to insert a value into a list in some way.
     * Default implementation appends to end of the list.
     *
     * @return
     */
    protected JImmutableList insertInList(JImmutableList list,
                                             V value)
    {
        return list.insertLast(value);
    }
}