155 lines
5.6 KiB
PHP
155 lines
5.6 KiB
PHP
<?php
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/* vim: set expandtab tabstop=4 shiftwidth=4 foldmethod=marker: */
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// +-----------------------------------------------------------------------------+
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// | Copyright (c) 2003 Sérgio Gonçalves Carvalho |
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// +-----------------------------------------------------------------------------+
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// | This file is part of Structures_Graph. |
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// | |
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// | Structures_Graph is free software; you can redistribute it and/or modify |
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// | it under the terms of the GNU Lesser General Public License as published by |
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// | the Free Software Foundation; either version 2.1 of the License, or |
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// | (at your option) any later version. |
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// | |
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// | Structures_Graph is distributed in the hope that it will be useful, |
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// | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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// | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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// | GNU Lesser General Public License for more details. |
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// | |
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// | You should have received a copy of the GNU Lesser General Public License |
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// | along with Structures_Graph; if not, write to the Free Software |
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// | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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// | 02111-1307 USA |
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// +-----------------------------------------------------------------------------+
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// | Author: Sérgio Carvalho <sergio.carvalho@portugalmail.com> |
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// +-----------------------------------------------------------------------------+
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//
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/**
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* The Graph.php file contains the definition of the Structures_Graph class
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*
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* @see Structures_Graph
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* @package Structures_Graph
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*/
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/* dependencies {{{ */
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/** PEAR base classes */
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require_once 'PEAR.php';
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/** Graph Node */
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require_once 'Structures/Graph/Node.php';
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/* }}} */
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define('STRUCTURES_GRAPH_ERROR_GENERIC', 100);
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/* class Structures_Graph {{{ */
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/**
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* The Structures_Graph class represents a graph data structure.
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*
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* A Graph is a data structure composed by a set of nodes, connected by arcs.
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* Graphs may either be directed or undirected. In a directed graph, arcs are
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* directional, and can be traveled only one way. In an undirected graph, arcs
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* are bidirectional, and can be traveled both ways.
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*
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* @author Sérgio Carvalho <sergio.carvalho@portugalmail.com>
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* @copyright (c) 2004 by Sérgio Carvalho
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* @package Structures_Graph
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*/
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/* }}} */
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class Structures_Graph {
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/* fields {{{ */
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/**
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* @access private
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*/
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var $_nodes = array();
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/**
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* @access private
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*/
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var $_directed = false;
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/* }}} */
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/* Constructor {{{ */
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/**
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*
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* Constructor
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*
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* @param boolean Set to true if the graph is directed. Set to false if it is not directed. (Optional, defaults to true)
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* @access public
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*/
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function __construct($directed = true) {
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$this->_directed = $directed;
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}
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/* }}} */
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/* isDirected {{{ */
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/**
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*
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* Return true if a graph is directed
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*
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* @return boolean true if the graph is directed
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* @access public
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*/
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function isDirected() {
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return (boolean) $this->_directed;
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}
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/* }}} */
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/* addNode {{{ */
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/**
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*
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* Add a Node to the Graph
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*
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* @param Structures_Graph_Node The node to be added.
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* @access public
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*/
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function addNode(&$newNode) {
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// We only add nodes
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if (!is_a($newNode, 'Structures_Graph_Node')) return Pear::raiseError('Structures_Graph::addNode received an object that is not a Structures_Graph_Node', STRUCTURES_GRAPH_ERROR_GENERIC);
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// Graphs are node *sets*, so duplicates are forbidden. We allow nodes that are exactly equal, but disallow equal references.
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foreach($this->_nodes as $key => $node) {
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/*
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ZE1 equality operators choke on the recursive cycle introduced by the _graph field in the Node object.
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So, we'll check references the hard way (change $this->_nodes[$key] and check if the change reflects in
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$node)
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*/
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$savedData = $this->_nodes[$key];
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$referenceIsEqualFlag = false;
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$this->_nodes[$key] = true;
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if ($node === true) {
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$this->_nodes[$key] = false;
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if ($node === false) $referenceIsEqualFlag = true;
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}
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$this->_nodes[$key] = $savedData;
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if ($referenceIsEqualFlag) return Pear::raiseError('Structures_Graph::addNode received an object that is a duplicate for this dataset', STRUCTURES_GRAPH_ERROR_GENERIC);
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}
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$this->_nodes[] =& $newNode;
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$newNode->setGraph($this);
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}
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/* }}} */
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/* removeNode (unimplemented) {{{ */
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/**
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*
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* Remove a Node from the Graph
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*
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* @todo This is unimplemented
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* @param Structures_Graph_Node The node to be removed from the graph
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* @access public
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*/
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function removeNode(&$node) {
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}
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/* }}} */
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/* getNodes {{{ */
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/**
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*
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* Return the node set, in no particular order. For ordered node sets, use a Graph Manipulator insted.
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*
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* @access public
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* @see Structures_Graph_Manipulator_TopologicalSorter
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* @return array The set of nodes in this graph
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*/
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function &getNodes() {
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return $this->_nodes;
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}
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/* }}} */
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}
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?>
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