issue/77 Added managed directory

src/core/segment_component.rs

@@ -10,5 +10,20 @@ pub enum SegmentComponent {
     DELETE
 }
 
-
-    
+impl SegmentComponent {
+    
+    pub fn iterator() -> impl Iterator<Item=&'static SegmentComponent> {
+        static SEGMENT_COMPONENTS: [SegmentComponent;  8] = [
+            SegmentComponent::INFO,
+            SegmentComponent::POSTINGS,
+            SegmentComponent::POSITIONS,
+            SegmentComponent::FASTFIELDS,
+            SegmentComponent::FIELDNORMS,
+            SegmentComponent::TERMS,
+            SegmentComponent::STORE,
+            SegmentComponent::DELETE
+        ];
+        SEGMENT_COMPONENTS.into_iter()
+    }
+    
+}