Rename isDirected() to hasDirected() and add hasUndirected(), isMixed()

Author: Christian Lück

src/Directed.php

@@ -4,6 +4,7 @@
 
 use Fhaculty\Graph\Algorithm\BaseGraph;
 use Fhaculty\Graph\Edge\Directed as EdgeDirected;
+use Fhaculty\Graph\Edge\Undirected as EdgeUndirected;
 
 /**
  * Basic algorithms for working with the undirected or directed Graphs (digraphs) / Walks.
@@ -14,11 +15,14 @@
 class Directed extends BaseDual
 {
     /**
-     * checks whether the graph has any directed edges (aka digraph)
+     * checks whether the graph has any directed edges
+     *
+     * This method is intentionally not named "isDirected()" (aka digraph),
+     * because that might be misleading in regards to empty and/or mixed graphs.
      *
      * @return boolean
      */
-    public function isDirected()
+    public function hasDirected()
     {
         foreach ($this->set->getEdges() as $edge) {
             if ($edge instanceof EdgeDirected) {
@@ -28,4 +32,35 @@ public function isDirected()
 
         return false;
     }
+
+    /**
+     * checks whether the graph has any undirected edges
+     *
+     * This method is intentionally not named "isUndirected()",
+     * because that might be misleading in regards to empty and/or mixed graphs.
+     *
+     * @return boolean
+     */
+    public function hasUndirected()
+    {
+        foreach ($this->set->getEdges() as $edge) {
+            if ($edge instanceof EdgeUndirected) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * checks whether this is a mixed graph (contains both directed and undirected edges)
+     *
+     * @return boolean
+     * @uses self::hasDirected()
+     * @uses self::hasUndirected()
+     */
+    public function isMixed()
+    {
+        return ($this->hasDirected() && $this->hasUndirected());
+    }
 }