Move Set::isDirected() helper to new Algorithm\Directed

CHANGELOG.md

@@ -10,6 +10,7 @@ you spot any mistakes.
 * BC break: Move `Set::getWeight()`, `Set::getWeightFlow()`, `Set::getWeightMin()` and `Set::isWeighted()` to new `Algorithm\Weight` (#33)
 * BC break: Move `Graph::getDegree()`, `Graph::getDegreeMin()`, `Graph::getDegreeMax()`, `Graph::isRegular()` and `Graph::isBalanced()` to new `Algorithm\Degree` (#29)
 * BC break: Move `Graph::getBalance()` and `Graph::isBalancedFlow()` to new `Algorithm\Balance` (#30)
+* BC break: Move `Set::isDirected()` to new `Algorithm\Directed` (#34)
 * Feature: `Graph::createVertices()` now also accepts an array of vertex IDs (#19)
 * Fix: Various issues with `Vertex`/`Edge` layout attributes (#32)
 

lib/Fhaculty/Graph/Algorithm/Directed.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace Fhaculty\Graph\Algorithm;
+
+use Fhaculty\Graph\Set;
+use Fhaculty\Graph\Algorithm\Base;
+use Fhaculty\Graph\Edge\Directed as EdgeDirected;
+use Fhaculty\Graph\Graph;
+use Fhaculty\Graph\Walk;
+
+/**
+ * Basic algorithms for working with the undirected or directed Graphs (digraphs) / Walks.
+ *
+ * @link http://en.wikipedia.org/wiki/Glossary_of_graph_theory#Direction
+ * @link http://en.wikipedia.org/wiki/Digraph_%28mathematics%29
+ */
+class Directed extends Base
+{
+    /**
+     * Graph/Walk to operate on
+     *
+     * @var Set
+     */
+    private $set;
+
+    /**
+     * instanciate new directed algorithm
+     *
+     * @param Set|Graph|Walk $graphOrWalk either the Graph or Walk to operate on (or the common base class Set)
+     */
+    public function __construct(Set $graphOrWalk)
+    {
+        $this->set = $graphOrWalk;
+    }
+
+    /**
+     * checks whether the graph has any directed edges (aka digraph)
+     *
+     * @return boolean
+     */
+    public function isDirected()
+    {
+        foreach ($this->set->getEdges() as $edge) {
+            if ($edge instanceof EdgeDirected) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}

lib/Fhaculty/Graph/Algorithm/MaximumMatching/Flow.php

@@ -2,6 +2,8 @@
 
 namespace Fhaculty\Graph\Algorithm\MaximumMatching;
 
+use Fhaculty\Graph\Algorithm\Directed;
+
 use Fhaculty\Graph\Exception\LogicException;
 
 use Fhaculty\Graph\Exception\UnexpectedValueException;
@@ -14,7 +16,8 @@ class Flow extends Base
 {
     public function getEdges()
     {
-        if ($this->graph->isDirected()) {
+        $alg = new Directed($this->graph);
+        if ($alg->isDirected()) {
             throw new UnexpectedValueException('Input graph contains directed edges');
         }
 

lib/Fhaculty/Graph/GraphViz.php

@@ -2,6 +2,7 @@
 
 namespace Fhaculty\Graph;
 
+use Fhaculty\Graph\Algorithm\Directed;
 use Fhaculty\Graph\Algorithm\Groups;
 use Fhaculty\Graph\Exception\UnexpectedValueException;
 use Fhaculty\Graph\Exception\InvalidArgumentException;
@@ -269,13 +270,14 @@ public function createImageFile()
      * create graphviz script representing this graph
      *
      * @return string
-     * @uses Graph::isDirected()
+     * @uses Directed::isDirected()
      * @uses Graph::getVertices()
      * @uses Graph::getEdges()
      */
     public function createScript()
     {
-        $directed = $this->graph->isDirected();
+        $alg = new Directed($this->graph);
+        $directed = $alg->isDirected();
 
         $script = ($directed ? 'di':'') . 'graph G {' . self::EOL;
 

lib/Fhaculty/Graph/Set.php

@@ -3,7 +3,6 @@
 namespace Fhaculty\Graph;
 
 use Fhaculty\Graph\Edge\Base as Edge;
-use Fhaculty\Graph\Edge\Directed as EdgeDirected;
 
 /**
  *
@@ -65,22 +64,6 @@ public function getNumberOfEdges()
         return count($this->edges);
     }
 
-    /**
-     * checks whether the graph has any directed edges (aka digraph)
-     *
-     * @return boolean
-     */
-    public function isDirected()
-    {
-        foreach ($this->edges as $edge) {
-            if ($edge instanceof EdgeDirected) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
     /**
      * check if this graph has any flow set (any edge has a non-NULL flow)
      *

tests/Fhaculty/Graph/Algorithm/DirectedTest.php

@@ -0,0 +1,50 @@
+<?php
+
+use Fhaculty\Graph\Algorithm\Directed as AlgorithmDirected;
+use Fhaculty\Graph\Graph;
+
+class DirectedTest extends TestCase
+{
+    public function testGraphEmpty()
+    {
+        $graph = new Graph();
+
+        $alg = new AlgorithmDirected($graph);
+
+        $this->assertFalse($alg->isDirected());
+    }
+
+    public function testGraphUndirected()
+    {
+        // 1 -- 2
+        $graph = new Graph();
+        $graph->createVertex(1)->createEdge($graph->createVertex(2));
+
+        $alg = new AlgorithmDirected($graph);
+
+        $this->assertFalse($alg->isDirected());
+    }
+
+    public function testGraphDirected()
+    {
+        // 1 -> 2
+        $graph = new Graph();
+        $graph->createVertex(1)->createEdgeTo($graph->createVertex(2));
+
+        $alg = new AlgorithmDirected($graph);
+
+        $this->assertTrue($alg->isDirected());
+    }
+
+    public function testGraphMixed()
+    {
+        // 1 -- 2 -> 3
+        $graph = new Graph();
+        $graph->createVertex(1)->createEdge($graph->createVertex(2));
+        $graph->getVertex(2)->createEdgeTo($graph->createVertex(3));
+
+        $alg = new AlgorithmDirected($graph);
+
+        $this->assertTrue($alg->isDirected());
+    }
+}

tests/Fhaculty/Graph/Loader/CompleteGraphTest.php

@@ -1,5 +1,7 @@
 <?php
 
+use Fhaculty\Graph\Algorithm\Directed;
+
 use Fhaculty\Graph\Graph;
 
 use Fhaculty\Graph\Loader\CompleteGraph;
@@ -38,7 +40,10 @@ public function testDirected()
 
         $this->assertEquals($n, $graph->getNumberOfVertices());
         $this->assertEquals($n*($n-1), $graph->getNumberOfEdges()); // n*(n-1) for directed graphs
-        $this->assertTrue($graph->isDirected());
+
+        $alg = new Directed($graph);
+        $this->assertTrue($alg->isDirected());
+
         $this->assertTrue($graph->isComplete());
     }
 }