First TwoPlayerTrueSkillCalculator unit test passed

PHPSkills/PairwiseComparison.php

@@ -0,0 +1,27 @@
+<?php
+namespace Moserware\Skills;
+
+/**
+ * Represents a comparison between two players.
+ * @internal The actual values for the enum were chosen so that the also correspond to the multiplier for updates to means.
+ */
+class PairwiseComparison
+{
+    const WIN = 1;
+    const DRAW = 0;
+    const LOSE = -1;
+
+    public static function getRankFromComparison($comparison)
+    {
+        switch ($comparison) {
+            case PairwiseComparison::WIN:
+                return array(1,2);
+            case PairwiseComparison::LOSE:
+                return array(2,1);
+            default:
+                return array(1,1);
+        }
+    }
+}
+
+?>