1 | <?php |
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2 | /* vim: set expandtab tabstop=4 shiftwidth=4 foldmethod=marker: */ |
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3 | // +-----------------------------------------------------------------------------+ |
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4 | // | Copyright (c) 2003 Sérgio Gonçalves Carvalho | |
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5 | // +-----------------------------------------------------------------------------+ |
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6 | // | This file is part of Structures_Graph. | |
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7 | // | | |
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8 | // | Structures_Graph is free software; you can redistribute it and/or modify | |
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9 | // | it under the terms of the GNU Lesser General Public License as published by | |
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10 | // | the Free Software Foundation; either version 2.1 of the License, or | |
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11 | // | (at your option) any later version. | |
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12 | // | | |
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13 | // | Structures_Graph is distributed in the hope that it will be useful, | |
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14 | // | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
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15 | // | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
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16 | // | GNU Lesser General Public License for more details. | |
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17 | // | | |
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18 | // | You should have received a copy of the GNU Lesser General Public License | |
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19 | // | along with Structures_Graph; if not, write to the Free Software | |
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20 | // | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
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21 | // | 02111-1307 USA | |
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22 | // +-----------------------------------------------------------------------------+ |
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23 | // | Author: Sérgio Carvalho <sergio.carvalho@portugalmail.com> | |
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24 | // +-----------------------------------------------------------------------------+ |
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25 | // |
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26 | /** |
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27 | * The Graph.php file contains the definition of the Structures_Graph class |
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28 | * |
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29 | * @see Structures_Graph |
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30 | * @package Structures_Graph |
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31 | */ |
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32 | |
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33 | /* dependencies {{{ */ |
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34 | /** PEAR base classes */ |
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35 | require_once 'PEAR.php'; |
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36 | /** Graph Node */ |
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37 | require_once 'Structures/Graph/Node.php'; |
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38 | /* }}} */ |
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39 | |
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40 | define('STRUCTURES_GRAPH_ERROR_GENERIC', 100); |
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41 | |
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42 | /* class Structures_Graph {{{ */ |
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43 | /** |
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44 | * The Structures_Graph class represents a graph data structure. |
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45 | * |
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46 | * A Graph is a data structure composed by a set of nodes, connected by arcs. |
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47 | * Graphs may either be directed or undirected. In a directed graph, arcs are |
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48 | * directional, and can be traveled only one way. In an undirected graph, arcs |
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49 | * are bidirectional, and can be traveled both ways. |
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50 | * |
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51 | * @author Sérgio Carvalho <sergio.carvalho@portugalmail.com> |
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52 | * @copyright (c) 2004 by Sérgio Carvalho |
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53 | * @package Structures_Graph |
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54 | */ |
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55 | /* }}} */ |
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56 | class Structures_Graph { |
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57 | /* fields {{{ */ |
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58 | /** |
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59 | * @access private |
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60 | */ |
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61 | var $_nodes = array(); |
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62 | /** |
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63 | * @access private |
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64 | */ |
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65 | var $_directed = false; |
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66 | /* }}} */ |
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67 | |
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68 | /* Constructor {{{ */ |
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69 | /** |
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70 | * |
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71 | * Constructor |
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72 | * |
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73 | * @param boolean Set to true if the graph is directed. Set to false if it is not directed. (Optional, defaults to true) |
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74 | * @access public |
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75 | */ |
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76 | function Structures_Graph($directed = true) { |
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77 | $this->_directed = $directed; |
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78 | } |
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79 | /* }}} */ |
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80 | |
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81 | /* isDirected {{{ */ |
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82 | /** |
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83 | * |
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84 | * Return true if a graph is directed |
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85 | * |
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86 | * @return boolean true if the graph is directed |
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87 | * @access public |
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88 | */ |
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89 | function isDirected() { |
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90 | return (boolean) $this->_directed; |
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91 | } |
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92 | /* }}} */ |
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93 | |
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94 | /* addNode {{{ */ |
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95 | /** |
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96 | * |
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97 | * Add a Node to the Graph |
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98 | * |
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99 | * @param Structures_Graph_Node The node to be added. |
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100 | * @access public |
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101 | */ |
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102 | function addNode(&$newNode) { |
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103 | // We only add nodes |
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104 | if (!is_a($newNode, 'Structures_Graph_Node')) return Pear::raiseError('Structures_Graph::addNode received an object that is not a Structures_Graph_Node', STRUCTURES_GRAPH_ERROR_GENERIC); |
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105 | // Graphs are node *sets*, so duplicates are forbidden. We allow nodes that are exactly equal, but disallow equal references. |
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106 | foreach($this->_nodes as $key => $node) { |
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107 | /* |
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108 | ZE1 equality operators choke on the recursive cycle introduced by the _graph field in the Node object. |
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109 | So, we'll check references the hard way (change $this->_nodes[$key] and check if the change reflects in |
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110 | $node) |
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111 | */ |
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112 | $savedData = $this->_nodes[$key]; |
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113 | $referenceIsEqualFlag = false; |
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114 | $this->_nodes[$key] = true; |
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115 | if ($node === true) { |
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116 | $this->_nodes[$key] = false; |
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117 | if ($node === false) $referenceIsEqualFlag = true; |
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118 | } |
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119 | $this->_nodes[$key] = $savedData; |
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120 | if ($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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121 | } |
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122 | $this->_nodes[] =& $newNode; |
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123 | $newNode->setGraph($this); |
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124 | } |
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125 | /* }}} */ |
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126 | |
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127 | /* removeNode (unimplemented) {{{ */ |
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128 | /** |
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129 | * |
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130 | * Remove a Node from the Graph |
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131 | * |
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132 | * @todo This is unimplemented |
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133 | * @param Structures_Graph_Node The node to be removed from the graph |
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134 | * @access public |
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135 | */ |
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136 | function removeNode(&$node) { |
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137 | } |
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138 | /* }}} */ |
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139 | |
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140 | /* getNodes {{{ */ |
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141 | /** |
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142 | * |
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143 | * Return the node set, in no particular order. For ordered node sets, use a Graph Manipulator insted. |
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144 | * |
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145 | * @access public |
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146 | * @see Structures_Graph_Manipulator_TopologicalSorter |
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147 | * @return array The set of nodes in this graph |
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148 | */ |
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149 | function &getNodes() { |
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150 | return $this->_nodes; |
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151 | } |
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152 | /* }}} */ |
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153 | } |
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154 | ?> |
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