<?php /* vim: set expandtab tabstop=4 shiftwidth=4 foldmethod=marker: */ // +-----------------------------------------------------------------------------+ // | Copyright (c) 2003 S�rgio Gon�alves 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: S�rgio 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 S�rgio Carvalho <sergio.carvalho@portugalmail.com> * @copyright (c) 2004 by S�rgio 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; } } ?>