Node.php

Go to the documentation of this file.

<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 foldmethod=marker: */
// +-----------------------------------------------------------------------------+
// | Copyright (c) 2003 Sérgio Gonçalves Carvalho                                |
// +-----------------------------------------------------------------------------+
// | This file is part of Structures_Graph.                                      |
// |                                                                             |
// | Structures_Graph 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.                                         |
// |                                                                             |
// | Structures_Graph 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 Structures_Graph; if not, write to the Free Software             |
// | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA                    |
// | 02111-1307 USA                                                              |
// +-----------------------------------------------------------------------------+
// | Author: Sérgio Carvalho <sergio.carvalho@portugalmail.com>                  |
// +-----------------------------------------------------------------------------+
//
 
/* dependencies {{{ */
require_once 'PEAR.php';
require_once 'Structures/Graph.php';
/* }}} */
 
/* class Structures_Graph_Node {{{ */
/* }}} */
class Structures_Graph_Node {
    /* fields {{{ */
    var $_data = null;
    var $_metadata = array();
    var $_arcs = array();
    var $_graph = null;
    /* }}} */
 
    /* Constructor {{{ */
    function __construct() {
    }
    /* }}} */
 
    /* getGraph {{{ */
    function &getGraph() {
        return $this->_graph;
    }
    /* }}} */
 
    /* setGraph {{{ */
    function setGraph(&$graph) {
        $this->_graph =& $graph;
    }
    /* }}} */
 
    /* getData {{{ */
    function &getData() {
        return $this->_data;
    }
    /* }}} */
 
    /* setData {{{ */
    function setData(&$data) {
        $this->_data =& $data;
    }
    /* }}} */
 
    /* metadataKeyExists {{{ */
    function metadataKeyExists($key) {
        return array_key_exists($key, $this->_metadata);
    }
    /* }}} */
 
    /* getMetadata {{{ */
    function &getMetadata($key, $nullIfNonexistent = false) {
        if (array_key_exists($key, $this->_metadata)) {
            return $this->_metadata[$key];
        } else {
            if ($nullIfNonexistent) {
                $a = null;
                return $a;
            } else {
                $a = Pear::raiseError('Structures_Graph_Node::getMetadata: Requested key does not exist', STRUCTURES_GRAPH_ERROR_GENERIC);
                return $a;
            }
        }
    }
    /* }}} */
 
    /* unsetMetadata {{{ */
    function unsetMetadata($key) {
        if (array_key_exists($key, $this->_metadata)) unset($this->_metadata[$key]);
    }
    /* }}} */
 
    /* setMetadata {{{ */
    function setMetadata($key, &$data) {
        $this->_metadata[$key] =& $data;
    }
    /* }}} */
 
    /* _connectTo {{{ */
    function _connectTo(&$destinationNode) {
        $this->_arcs[] =& $destinationNode;
    }
    /* }}} */
 
    /* connectTo {{{ */
    function connectTo(&$destinationNode) {
        // We only connect to nodes
        if (!is_a($destinationNode, 'Structures_Graph_Node')) return Pear::raiseError('Structures_Graph_Node::connectTo received an object that is not a Structures_Graph_Node', STRUCTURES_GRAPH_ERROR_GENERIC);
        // Nodes must already be in graphs to be connected
        if ($this->_graph == null) return Pear::raiseError('Structures_Graph_Node::connectTo Tried to connect a node that is not in a graph', STRUCTURES_GRAPH_ERROR_GENERIC);
        if ($destinationNode->getGraph() == null) return Pear::raiseError('Structures_Graph_Node::connectTo Tried to connect to a node that is not in a graph', STRUCTURES_GRAPH_ERROR_GENERIC);
        // Connect here
        $this->_connectTo($destinationNode);
        // If graph is undirected, connect back
        if (!$this->_graph->isDirected()) {
            $destinationNode->_connectTo($this);
        }
    }
    /* }}} */
 
    /* getNeighbours {{{ */
    function getNeighbours() {
        return $this->_arcs;
    }
    /* }}} */
 
    /* connectsTo {{{ */
    function connectsTo(&$target) {
        if (version_compare(PHP_VERSION, '5.0.0') >= 0) {
            return in_array($target, $this->getNeighbours(), true);
        }
 
        $copy = $target;
        $arcKeys = array_keys($this->_arcs);
        foreach($arcKeys as $key) {
            /* ZE1 chokes on this expression:
                if ($target === $arc) return true;
              so, we'll use more convoluted stuff
            */
            $arc =& $this->_arcs[$key];
            $target = true;
            if ($arc === true) {
                $target = false;
                if ($arc === false) {
                    $target = $copy;
                    return true;
                }
            }
        }
        $target = $copy;
        return false;
    }
    /* }}} */
 
    /* inDegree {{{ */
    function inDegree() {
        if ($this->_graph == null) return 0;
        if (!$this->_graph->isDirected()) return $this->outDegree();
        $result = 0;
        $graphNodes =& $this->_graph->getNodes();
        foreach (array_keys($graphNodes) as $key) {
            if ($graphNodes[$key]->connectsTo($this)) $result++;
        }
        return $result;
        
    }
    /* }}} */
 
    /* outDegree {{{ */
    function outDegree() {
        if ($this->_graph == null) return 0;
        return sizeof($this->_arcs);
    }
    /* }}} */
}
?>