From e36c4e597fbeea538f1315dd5b1246ca6f80eb07 Mon Sep 17 00:00:00 2001
From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
Date: Thu, 3 Dec 2020 19:56:48 +0000
Subject: [PATCH] layout: Remove the little abomination of view change promise

It didn't make anything more testable due to being tightly coupled to Layout.
With the last place needing the curent form abolished, it's no longer needed.

No attempt to make it more stateless and unit-testable was made though.
---
 src/layout.rs | 39 ++++++++++++---------------------------
 1 file changed, 12 insertions(+), 27 deletions(-)

diff --git a/src/layout.rs b/src/layout.rs
index b84ddd6b..bc05b07e 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -837,14 +837,13 @@ impl Layout {
             self.view_latched,
         );
 
-        self.view_latched = new_latched;
         match transition {
-            ViewTransition::UnlatchAll => unstick_locks(self).apply(),
-            ViewTransition::ChangeTo(view) => {
-                try_set_view(self, view.into());
-            },
+            ViewTransition::UnlatchAll => unstick_locks(self),
+            ViewTransition::ChangeTo(view) => try_set_view(self, view.into()),
             ViewTransition::NoChange => {},
         };
+
+        self.view_latched = new_latched;
     }
 
     /// Last bool is new latch state.
@@ -907,31 +906,18 @@ fn try_set_view(layout: &mut Layout, view_name: String) {
         );
 }
 
-/// A vessel holding an obligation to switch view.
-/// Use with #[must_use]
-struct ViewChange<'a> {
-    layout: &'a mut Layout,
-    view_name: Option<String>,
-}
-
-impl<'a> ViewChange<'a> {
-    fn apply(self) {
-        if let Some(name) = self.view_name {
-            try_set_view(self.layout, name);
-        }
-    }
-}
-
 /// Find all impermanent view changes and undo them in an arbitrary order.
-/// Return an obligation to actually switch the view.
 /// The final view is the "unlock" view
-/// from one of the currently stuck keys.
+/// from one of the currently latched keys.
 // As long as only one stuck button is used, this should be fine.
 // This is guaranteed because pressing a lock button unlocks all others.
 // TODO: Make some broader guarantee about the resulting view,
 // e.g. by maintaining a stack of stuck keys.
-#[must_use]
-fn unstick_locks(layout: &mut Layout) -> ViewChange {
+fn unstick_locks(layout: &mut Layout) {
+    if !layout.view_latched {
+        return;
+    }
+
     let mut new_view = None;
     for key in layout.get_locked_keys().clone() {
         let key: &Rc<RefCell<KeyState>> = key.borrow();
@@ -948,9 +934,8 @@ fn unstick_locks(layout: &mut Layout) -> ViewChange {
         };
     }
     
-    ViewChange {
-        layout,
-        view_name: new_view,
+    if let Some(name) = new_view {
+        try_set_view(layout, name);
     }
 }