SearchTreeNode.cc

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/*
 * SearchTreeNode.cc
 *
 * Smalltalk like class library for C++
 * Node of tree.
 *
 * Copyright (c) 2004 Milan Cermak, Petr Stepanek
 */
/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <stlib/searchTree/SearchTreeNode.h>

#include <stlib/Dictionary.h>
#include <stlib/SequenceableCollection.h>
#include <stlib/String.h>

#include <stlib/KeyNotFoundError.h>

using namespace Core;

SearchTreeNode::SearchTreeNode(void)
{
    branches = new Dictionary(2);
    _value = nil;
}

/* Class-accessing protocol */
String *SearchTreeNode::className(void) const
{
    return new String("SearchTreeNode");
}

SearchTreeNode *SearchTreeNode::createNewNode(void)
{
    return new SearchTreeNode;
}

/* Accessing protocol */
Object *SearchTreeNode::at(SequenceableCollection *key)
{
    return valueAt(key, 0, false);
}

Object *SearchTreeNode::at(SequenceableCollection *key, Object *ifAbsentValue)
{
    Object *obj;

    try {
        obj = at(key);
    }
    catch (KeyNotFoundError *ex) {
        obj = ifAbsentValue;
    }
    return obj;
}

void SearchTreeNode::put(SequenceableCollection *key, Object *value)
{
    putValueAt(key, value, 0);
}

Object *SearchTreeNode::atLongestPrefixOf(SequenceableCollection *key)
{
    return valueAt(key, 0, true);
}

/* Testing protocol */
bool SearchTreeNode::includesKey(SequenceableCollection *key)
{
    return at(key, nil) != nil;
}

/* Private protocol */
Object *SearchTreeNode::valueAt(SequenceableCollection *key,
                                int depth, bool prefix)
{
    if (key->size() > depth) {
        if (branches->isEmpty() && prefix)
            return _value;
        else {
            if (_value == nil || !prefix) {
                return privDeeperValueAt(key, depth, prefix);
            } else {
                /* I know the value. If there is no better answer, I got one. */
                try {
                    return privDeeperValueAt(key, depth, prefix);
                }
                catch (KeyNotFoundError *ex) {
                    return _value;
                }
            }
        }
    } else {
        if (_value == nil)
            (new KeyNotFoundError(__PRETTY_FUNCTION__, key))->raiseFrom(this);
        return _value;
    }
}

Object *SearchTreeNode::privDeeperValueAt(SequenceableCollection *key,
                                          int depth, bool prefix)
{
    SearchTreeNode *next;
    next = dynamic_cast<SearchTreeNode *>(branches->at(key->at(depth)));
    return next->valueAt(key, depth+1, prefix);
}

void SearchTreeNode::putValueAt(SequenceableCollection *key,
                                Object *value, int depth)
{
    if (key->size() > depth) {
        SearchTreeNode *next;
        if (branches->includesKey(key->at(depth)))
            next = dynamic_cast<SearchTreeNode *>(branches->at(key->at(depth)));
        else {
            next = createNewNode();
            branches->put(key->at(depth), next);
        }
        next->putValueAt(key, value, depth+1);
    } else {
        _value = value;
    }
}

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