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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> |
// +-----------------------------------------------------------------------------+
//
/**
* This file contains the definition of the Structures_Graph_Node class
*
* @see Structures_Graph_Node
* @package Structures_Graph
*/
/* dependencies {{{ */
/** */
require_once 'PEAR.php';
/** */
require_once 'Structures/Graph.php';
/* }}} */
/* class Structures_Graph_Node {{{ */
/**
* The Structures_Graph_Node class represents a Node that can be member of a
* graph node set.
*
* A graph node can contain data. Under this API, the node contains default data,
* and key index data. It behaves, thus, both as a regular data node, and as a
* dictionary (or associative array) node.
*
* Regular data is accessed via getData and setData. Key indexed data is accessed
* via getMetadata and setMetadata.
*
* @author Sérgio Carvalho <sergio.carvalho@portugalmail.com>
* @copyright (c) 2004 by Sérgio Carvalho
* @package Structures_Graph
*/
/* }}} */
class Structures_Graph_Node {
/* fields {{{ */
/**
* @access private
*/
var $_data = null;
/** @access private */
var $_metadata = array();
/** @access private */
var $_arcs = array();
/** @access private */
var $_graph = null;
/* }}} */
/* Constructor {{{ */
/**
*
* Constructor
*
* @access public
*/
function Structures_Graph_Node() {
}
/* }}} */
/* getGraph {{{ */
/**
*
* Node graph getter
*
* @return Structures_Graph Graph where node is stored
* @access public
*/
function &getGraph() {
return $this->_graph;
}
/* }}} */
/* setGraph {{{ */
/**
*
* Node graph setter. This method should not be called directly. Use Graph::addNode instead.
*
* @param Structures_Graph Set the graph for this node.
* @see Structures_Graph::addNode()
* @access public
*/
function setGraph(&$graph) {
$this->_graph =& $graph;
}
/* }}} */
/* getData {{{ */
/**
*
* Node data getter.
*
* Each graph node can contain a reference to one variable. This is the getter for that reference.
*
* @return mixed Data stored in node
* @access public
*/
function &getData() {
return $this->_data;
}
/* }}} */
/* setData {{{ */
/**
*
* Node data setter
*
* Each graph node can contain a reference to one variable. This is the setter for that reference.
*
* @return mixed Data to store in node
* @access public
*/
function setData($data) {
$this->_data =& $data;
}
/* }}} */
/* metadataKeyExists {{{ */
/**
*
* Test for existence of metadata under a given key.
*
* Each graph node can contain multiple 'metadata' entries, each stored under a different key, as in an
* associative array or in a dictionary. This method tests whether a given metadata key exists for this node.
*
* @param string Key to test
* @return boolean
* @access public
*/
function metadataKeyExists($key) {
return array_key_exists($key, $this->_metadata);
}
/* }}} */
/* getMetadata {{{ */
/**
*
* Node metadata getter
*
* Each graph node can contain multiple 'metadata' entries, each stored under a different key, as in an
* associative array or in a dictionary. This method gets the data under the given key. If the key does
* not exist, an error will be thrown, so testing using metadataKeyExists might be needed.
*
* @param string Key
* @param boolean nullIfNonexistent (defaults to false).
* @return mixed Metadata Data stored in node under given key
* @see metadataKeyExists
* @access public
*/
function &getMetadata($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 $a;
}
}
}
/* }}} */
/* unsetMetadata {{{ */
/**
*
* Delete metadata by key
*
* Each graph node can contain multiple 'metadata' entries, each stored under a different key, as in an
* associative array or in a dictionary. This method removes any data that might be stored under the provided key.
* If the key does not exist, no error is thrown, so it is safe using this method without testing for key existence.
*
* @param string Key
* @access public
*/
function unsetMetadata($key) {
if (array_key_exists($key, $this->_metadata)) unset($this->_metadata[$key]);
}
/* }}} */
/* setMetadata {{{ */
/**
*
* Node metadata setter
*
* Each graph node can contain multiple 'metadata' entries, each stored under a different key, as in an
* associative array or in a dictionary. This method stores data under the given key. If the key already exists,
* previously stored data is discarded.
*
* @param string Key
* @param mixed Data
* @access public
*/
function setMetadata($key, $data) {
$this->_metadata[$key] =& $data;
}
/* }}} */
/* _connectTo {{{ */
/** @access private */
function _connectTo(&$destinationNode) {
$this->_arcs[] =& $destinationNode;
}
/* }}} */
/* connectTo {{{ */
/**
*
* Connect this node to another one.
*
* If the graph is not directed, the reverse arc, connecting $destinationNode to $this is also created.
*
* @param Structures_Graph_Node Node to connect to
* @access public
*/
function connectTo(&$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 {{{ */
/**
*
* Return nodes connected to this one.
*
* @return array Array of nodes
* @access public
*/
function getNeighbours() {
return $this->_arcs;
}
/* }}} */
/* connectsTo {{{ */
/**
*
* Test wether this node has an arc to the target node
*
* @return boolean True if the two nodes are connected
* @access public
*/
function connectsTo(&$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 = $copy;
return false;
}
/* }}} */
/* inDegree {{{ */
/**
*
* Calculate the in degree of the node.
*
* The indegree for a node is the number of arcs entering the node. For non directed graphs,
* the indegree is equal to the outdegree.
*
* @return integer In degree of the node
* @access public
*/
function inDegree() {
if ($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 $result;
}
/* }}} */
/* outDegree {{{ */
/**
*
* Calculate the out degree of the node.
*
* The outdegree for a node is the number of arcs exiting the node. For non directed graphs,
* the outdegree is always equal to the indegree.
*
* @return integer Out degree of the node
* @access public
*/
function outDegree() {
if ($this->_graph == null) return 0;
return sizeof($this->_arcs);
}
/* }}} */
}
?>
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