Add GraphML Exporter

Author: clue

src/Exporter.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Graphp\GraphML;
+
+use Fhaculty\Graph\Exporter\ExporterInterface;
+use Fhaculty\Graph\Graph;
+use SimpleXMLElement;
+use Fhaculty\Graph\Edge\Directed;
+
+class Exporter implements ExporterInterface
+{
+    const SKEL = <<<EOL
+<?xml version="1.0" encoding="UTF-8"?>
+<graphml xmlns="http://graphml.graphdrawing.org/xmlns"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns
+     http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
+</graphml>
+EOL;
+
+    public function getOutput(Graph $graph)
+    {
+        $root = new SimpleXMLElement(self::SKEL);
+
+        $graphElem = $root->addChild('graph');
+        $graphElem['edgeDefault'] = 'undirected';
+
+        foreach ($graph->getVertices()->getMap() as $id => $vertex) {
+            /* @var $vertex Vertex */
+            $vertexElem = $graphElem->addChild('node');
+            $vertexElem['id'] = $id;
+        }
+
+        foreach ($graph->getEdges() as $edge) {
+            /* @var $edge Edge */
+            $edgeElem = $graphElem->addChild('edge');
+            $edgeElem['source'] = $edge->getVertices()->getVertexFirst()->getId();
+            $edgeElem['target'] = $edge->getVertices()->getVertexLast()->getId();
+
+            if ($edge instanceof Directed) {
+                $edgeElem['directed'] = 'true';
+            }
+        }
+
+        return $root->asXML();
+    }
+}

tests/ExporterTest.php

@@ -0,0 +1,64 @@
+<?php
+
+use Fhaculty\Graph\Graph;
+use Graphp\GraphML\Exporter;
+
+class ExporterTest extends TestCase
+{
+    private $exporter;
+
+    public function setUp()
+    {
+        $this->exporter = new Exporter();
+    }
+
+    public function testEmpty()
+    {
+        $graph = new Graph();
+
+        $output = $this->exporter->getOutput($graph);
+        $xml = new SimpleXMLElement($output);
+
+        $this->assertEquals(1, count($xml));
+        $this->assertEquals(1, count($xml->graph));
+        $this->assertEquals(0, count($xml->graph->children()));
+    }
+
+    public function testSimple()
+    {
+        // 1 -- 2
+        $graph = new Graph();
+        $v1 = $graph->createVertex(1);
+        $v2 = $graph->createVertex(2);
+        $v1->createEdge($v2);
+
+        $output = $this->exporter->getOutput($graph);
+        $xml = new SimpleXMLElement($output);
+
+        $this->assertEquals(1, count($xml->graph->edge));
+
+        $edgeElem = $xml->graph->edge;
+        $this->assertEquals('1', (string)$edgeElem['source']);
+        $this->assertEquals('2', (string)$edgeElem['target']);
+        $this->assertFalse(isset($edgeElem['directed']));
+    }
+
+    public function testSimpleDirected()
+    {
+        // 1 -> 2
+        $graph = new Graph();
+        $v1 = $graph->createVertex(1);
+        $v2 = $graph->createVertex(2);
+        $v1->createEdgeTo($v2);
+
+        $output = $this->exporter->getOutput($graph);
+        $xml = new SimpleXMLElement($output);
+
+        $this->assertEquals(1, count($xml->graph->edge));
+
+        $edgeElem = $xml->graph->edge;
+        $this->assertEquals('1', (string)$edgeElem['source']);
+        $this->assertEquals('2', (string)$edgeElem['target']);
+        $this->assertEquals('true', (string)$edgeElem['directed']);
+    }
+}