pipeline builders for sequence to grid with simple horizontal / vertical layout

nested/src/index/map_key.rs

@@ -14,7 +14,8 @@ pub use {
             InnerViewPort,
             OuterViewPort
         },
-        index::{IndexView}
+        index::{IndexView},
+        grid::{GridView}
     }
 };
 
@@ -40,6 +41,24 @@ where SrcKey: Clone + Send + Sync + 'static,
     }
 }
 
+impl<Item> OuterViewPort<dyn IndexView<usize, Item = Item>>
+where Item: 'static
+{
+    pub fn to_grid_horizontal(&self) -> OuterViewPort<dyn GridView<Item = Item>> {
+        self.map_key(
+            |idx| cgmath::Point2::new(*idx as i16, 0),
+            |pt| if pt.y == 0 { Some(pt.x as usize) } else { None }
+        )
+    }
+
+    pub fn to_grid_vertical(&self) -> OuterViewPort<dyn GridView<Item = Item>> {
+        self.map_key(
+            |idx| cgmath::Point2::new(0, *idx as i16),
+            |pt| if pt.x == 0 { Some(pt.y as usize) } else { None }
+        )        
+    }
+}
+
 pub struct MapIndexKey<DstKey, SrcKey, SrcView, F1, F2>
 where DstKey: Clone + Send + Sync,
       SrcKey: Clone + Send + Sync,

nested/src/sequence/seq2idx.rs

@@ -9,7 +9,8 @@ use {
             ViewPort, InnerViewPort, OuterViewPort
         },
         sequence::SequenceView,
-        index::IndexView
+        index::IndexView,
+        grid::GridView
     }
 };
 
@@ -43,6 +44,14 @@ impl<Item: 'static> OuterViewPort<dyn SequenceView<Item = Item>> {
         self.add_observer(Sequence2Index::new(port.inner()));
         port.into_outer()
     }
+
+    pub fn to_grid_horizontal(&self) -> OuterViewPort<dyn GridView<Item = Item>> {
+        self.to_index().to_grid_horizontal()
+    }
+
+    pub fn to_grid_vertical(&self) -> OuterViewPort<dyn GridView<Item = Item>> {
+        self.to_index().to_grid_vertical()
+    }
 }
 
 impl<SrcView> View for Sequence2Index<SrcView>