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<?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> |
// +-----------------------------------------------------------------------------+
//
/**
* The Graph.php file contains the definition of the Structures_Graph class
*
* @package Structures_Graph
*/
/* dependencies {{{ */
require_once 'PEAR.php';
require_once 'Structures/Graph/Node.php';
/* }}} */
define('STRUCTURES_GRAPH_ERROR_GENERIC', 100);
/* class Structures_Graph {{{ */
/**
* The Structures_Graph class represents a graph data structure.
*
* A Graph is a data structure composed by a set of nodes, connected by arcs.
* Graphs may either be directed or undirected. In a directed graph, arcs are
* directional, and can be traveled only one way. In an undirected graph, arcs
* are bidirectional, and can be traveled both ways.
*
* @author Sérgio Carvalho <sergio.carvalho@portugalmail.com>
* @copyright (c) 2004 by Sérgio Carvalho
* @package Structures_Graph
*/
/* }}} */
class Structures_Graph
{
/**
* List of node objects in this graph
* @access private
*/
var $_nodes = array();
/**
* If the graph is directed or not
* @access private
*/
var $_directed = false;
/**
* Constructor
*
* @param boolean $directed Set to true if the graph is directed.
* Set to false if it is not directed.
*/
public function __construct($directed = true)
{
$this->_directed = $directed;
}
/**
* Old constructor (PHP4-style; kept for BC with extending classes)
*
* @param boolean $directed Set to true if the graph is directed.
* Set to false if it is not directed.
*
* @return void
*/
public function Structures_Graph($directed = true)
{
$this->__construct($directed);
}
/**
* Return true if a graph is directed
*
* @return boolean true if the graph is directed
*/
public function isDirected()
{
return (boolean) $this->_directed;
}
/**
* Add a Node to the Graph
*
* @param Structures_Graph_Node $newNode The node to be added.
*
* @return void
*/
public function addNode(&$newNode)
{
// We only add nodes
if (!is_a($newNode, 'Structures_Graph_Node')) {
return Pear::raiseError(
'Structures_Graph::addNode received an object that is not'
. ' a Structures_Graph_Node',
STRUCTURES_GRAPH_ERROR_GENERIC
);
}
//Graphs are node *sets*, so duplicates are forbidden.
// We allow nodes that are exactly equal, but disallow equal references.
foreach ($this->_nodes as $key => $node) {
/*
ZE1 equality operators choke on the recursive cycle introduced
by the _graph field in the Node object.
So, we'll check references the hard way
(change $this->_nodes[$key] and check if the change reflects in
$node)
*/
$savedData = $this->_nodes[$key];
$referenceIsEqualFlag = false;
$this->_nodes[$key] = true;
if ($node === true) {
$this->_nodes[$key] = false;
if ($node === false) {
$referenceIsEqualFlag = true;
}
}
$this->_nodes[$key] = $savedData;
if ($referenceIsEqualFlag) {
return Pear::raiseError(
'Structures_Graph::addNode received an object that is'
. ' a duplicate for this dataset',
STRUCTURES_GRAPH_ERROR_GENERIC
);
}
}
$this->_nodes[] =& $newNode;
$newNode->setGraph($this);
}
/**
* Remove a Node from the Graph
*
* @param Structures_Graph_Node $node The node to be removed from the graph
*
* @return void
* @todo This is unimplemented
*/
public function removeNode(&$node)
{
}
/**
* Return the node set, in no particular order.
* For ordered node sets, use a Graph Manipulator insted.
*
* @return array The set of nodes in this graph
* @see Structures_Graph_Manipulator_TopologicalSorter
*/
public function &getNodes()
{
return $this->_nodes;
}
}
?>
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