Start of factor graph port. Things don't work yet, but a lot of syntax updates towards PHP

PHPSkills/TrueSkill/Layers/PlayerPriorValuesToSkillsLayer.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace Moserware\Skills\TrueSkill\Layers;
+
+// We intentionally have no Posterior schedule since the only purpose here is to
+class PlayerPriorValuesToSkillsLayer extends TrueSkillFactorGraphLayer
+{
+    private $_teams;
+
+    public function __construct(TrueSkillFactorGraph $parentGraph, $teams)
+    {
+        parent::__construct($parentGraph);
+        $this->_teams = $teams;
+    }
+
+    public function buildLayer()
+    {
+        foreach ($this->_teams as $currentTeam)
+        {
+            $currentTeamSkills = array();
+
+            foreach ($currentTeam as $currentTeamPlayer)
+            {
+                $playerSkill = $this->createSkillOutputVariable($currentTeamPlayer.Key);
+                $this->addLayerFactor($this->createPriorFactor($currentTeamPlayer.Key, $currentTeamPlayer.Value, $playerSkill));
+                $currentTeamSkills[] = $playerSkill;
+            }
+
+            OutputVariablesGroups.Add(currentTeamSkills);
+        }
+    }
+
+    public function createPriorSchedule()
+    {
+        return $this->scheduleSequence(
+                array_map(
+                        function($prior)
+                        {
+                            return new ScheduleStep("Prior to Skill Step", $prior, 0);
+                        },
+                        $this->getLocalFactors()),
+                 "All priors");
+    }
+
+    private function createPriorFactor($player, $priorRating, $skillsVariable)
+    {
+        return new GaussianPriorFactor($priorRating->getMean(),
+                                       square($priorRating->getStandardDeviation()) +
+                                       square($this->getParentFactorGraph()->getGameInfo()->getDynamicsFactor()),
+                                       $skillsVariable);
+    }
+
+    private function createSkillOutputVariable($key)
+    {
+        return $this->getParentFactorGraph()->getVariableFactory()->createKeyedVariable($key, "{0}'s skill", $key);
+    }
+}
+
+?>