From 66602c9dd78deafad117301db652b5271d7c70d0 Mon Sep 17 00:00:00 2001
From: Paul Chiusano <paul.chiusano@gmail.com>
Date: Fri, 12 Dec 2014 15:37:08 -0500
Subject: [PATCH] Using common movement manipulation functions

---
 editor/Elmz/Signal.elm  |  3 +++
 editor/Main.elm         | 20 ++++++--------------
 editor/Unison/Scope.elm | 11 +++++++++++
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/editor/Elmz/Signal.elm b/editor/Elmz/Signal.elm
index 7fb9f09d7..48f2e52df 100644
--- a/editor/Elmz/Signal.elm
+++ b/editor/Elmz/Signal.elm
@@ -123,6 +123,9 @@ toggle s =
   let t = lift (always True) s
   in xor <~ t ~ delay False t
 
+tuple2 : Signal a -> Signal b -> Signal (a,b)
+tuple2 s s2 = (,) <~ s ~ s2
+
 {-| Spikes `False` for one tick when `a` event fires, otherwise is `True`. -}
 unchanged : Signal a -> Signal Bool
 unchanged a = lift not (changed a)
diff --git a/editor/Main.elm b/editor/Main.elm
index aa0f91d7b..54fb5ba2c 100644
--- a/editor/Main.elm
+++ b/editor/Main.elm
@@ -72,20 +72,12 @@ full = E.Lit (E.Distance (Distance.Fraction 1.0))
 
 resolvedPath : Signal E.Term -> Signal (Maybe Path) -> Signal (Maybe Scope)
 resolvedPath e pathUnderPtr =
-  let nonzero {x,y} = x /= 0 || y /= 0
-      edit {x,y} e =
-        (if y == 1 then Scope.up else identity) >>
-        (if y == -1 then Scope.down e else identity) >>
-        (if x == 1 then Scope.right e else identity) >>
-        (if x == -1 then Scope.left e else identity)
-      edits = edit <~ Signals.repeatAfterIf (300*millisecond) 20 nonzero Keyboard.arrows ~ e
-      defaultScope = lift (Maybe.map Scope.scope) pathUnderPtr
-      shifted = Signals.foldpBetween'
-                  Mouse.position
-                  (\edit p -> Maybe.map edit p)
-                  defaultScope
-                  edits
-  in Signals.fromMaybe defaultScope shifted
+  let defaultScope = lift (Maybe.map Scope.scope) pathUnderPtr
+      shifted = Movement.moveD2 Scope.movements
+                                Mouse.position
+                                (Signals.tuple2 e defaultScope)
+                                (Movement.repeatD2 (Movement.d2' Keyboard.arrows))
+  in Signals.fromMaybe defaultScope (Maybe.map snd <~ shifted)
 
 terms : Signal E.Term
 terms = constant expr
diff --git a/editor/Unison/Scope.elm b/editor/Unison/Scope.elm
index 5c0e25543..0c473447e 100644
--- a/editor/Unison/Scope.elm
+++ b/editor/Unison/Scope.elm
@@ -1,5 +1,6 @@
 module Unison.Scope where
 
+import Maybe
 import Unison.Path as Path
 
 import Unison.Term (Term)
@@ -36,3 +37,13 @@ right e {focus,ups,downs} =
   let p = Term.siblingR e focus
   in if p == focus then Scope focus ups downs
      else Scope p [] []
+
+movements : { up : (Term, Maybe Scope) -> (Term, Maybe Scope)
+            , down : (Term, Maybe Scope) -> (Term, Maybe Scope)
+            , left : (Term, Maybe Scope) -> (Term, Maybe Scope)
+            , right : (Term, Maybe Scope) -> (Term, Maybe Scope) }
+movements =
+  { up (e,s) = (e, Maybe.map up s)
+  , down (e,s) = (e, Maybe.map (down e) s)
+  , left (e,s) = (e, Maybe.map (left e) s)
+  , right (e,s) = (e, Maybe.map (right e) s) }