Is Feature Enabled and Feature Variable Accessor APIs

src/Optimizely/Entity/Variation.php

@@ -52,11 +52,7 @@ public function __construct($id = null, $key = null, $variableUsageInstances = [
 
         $this->_variableUsageInstances = ConfigParser::generateMap($variableUsageInstances, null, VariableUsage::class);
 
-        if(!empty($this->_variableUsageInstances)){
-            foreach(array_values($this->_variableUsageInstances) as $variableUsage){
-                $_variableIdToVariableUsageInstanceMap[$variableUsage->getId()] = $variableUsage;
-            }
-        }
+        $this->generateVariableIdToVariableUsageMap();
     }
 
     /**
@@ -91,16 +87,41 @@ public function setKey($key)
         $this->_key = $key;
     }
 
+    /**
+     * @return [VariableUsage] Variable usage instances in this variation
+     */
     public function getVariables(){
         return $this->_variableUsageInstances;
     }
 
+    /**
+     * @param  string Variable ID
+     * 
+     * @return VariableUsage Variable usage instance corresponding to given variable ID
+     */
+    public function getVariableUsageById($variableId){
+        if(isset($this->_variableIdToVariableUsageInstanceMap[$variableId]))
+            return $this->_variableIdToVariableUsageInstanceMap[$variableId];
+        else
+            return null;
+    }
+
+    /**
+     * @param [VariableUsage] array of variable usage instances
+     */
     public function setVariables($variableUsageInstances){
         $this->_variableUsageInstances = ConfigParser::generateMap($variableUsageInstances, null , VariableUsage::class);
+        $this->generateVariableIdToVariableUsageMap();
+    }
 
+    /**
+     * Generates variable ID to Variable usage instance map
+     * from variable usage instances
+     */
+    private function generateVariableIdToVariableUsageMap(){
         if(!empty($this->_variableUsageInstances)){
             foreach(array_values($this->_variableUsageInstances) as $variableUsage){
-                $_variableIdToVariableUsageInstanceMap[$variableUsage->getId()] = $variableUsage;
+                $this->_variableIdToVariableUsageInstanceMap[$variableUsage->getId()] = $variableUsage;
             }
         }
     }

src/Optimizely/Exceptions/InvalidFeatureVariableException.php

@@ -0,0 +1,23 @@
+<?php
+/**
+ * Copyright 2017, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Optimizely\Exceptions;
+
+
+class InvalidFeatureVariableException extends OptimizelyException
+{
+}