IdView: skip view if borrowing fails.

Fixes #144

src/view/mod.rs

@@ -114,15 +114,15 @@ pub trait View {
     /// Draws the view with the given printer (includes bounds) and focus.
     fn draw(&self, printer: &Printer);
 
-    /// Finds the view identified by the given selector.
+    /// Runs a closure on the view identified by the given selector.
     ///
     /// See [`Finder::call_on`] for a nicer interface, implemented for all views.
     ///
     /// [`Finder::call_on`]: trait.Finder.html#method.call_on
     ///
-    /// Returns None if the path doesn't lead to a view.
+    /// If the selector doesn't find a match, the closure will not be run.
     ///
-    /// Default implementation always return `None`.
+    /// Default implementation is a no-op.
     fn call_on_any<'a>(&mut self, _: &Selector, _: Box<FnMut(&mut Any) + 'a>) {
         // TODO: FnMut -> FnOnce once it works
     }
@@ -130,6 +130,8 @@ pub trait View {
     /// Moves the focus to the view identified by the given selector.
     ///
     /// Returns `Ok(())` if the view was found and selected.
+    ///
+    /// Default implementation simply returns `Err(())`.
     fn focus_view(&mut self, &Selector) -> Result<(), ()> {
         Err(())
     }

src/views/id_view.rs

@@ -30,14 +30,18 @@ impl<V: View> IdView<V> {
     /// Gets mutable access to the inner view.
     ///
     /// This returns a `ViewRef<V>`, which implement `DerefMut<Target = V>`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if another reference for this view already exists.
     pub fn get_mut(&mut self) -> ViewRef<V> {
-        // TODO: return a standalone item (not tied to our lifetime)
-        // that bundles `self.view.clone()` and allow mutable reference to
-        // the inner view.
         let cell_ref = RcRef::new(self.view.clone());
 
-        OwningHandle::new(cell_ref,
+        // The unsafe part here is tied to OwningHandle's limitation.
-                          |x| unsafe { x.as_ref() }.unwrap().borrow_mut())
+        OwningHandle::new(
+            cell_ref,
+            |x| unsafe { x.as_ref() }.unwrap().borrow_mut(),
+        )
     }
 }
 
@@ -45,35 +49,43 @@ impl<T: View + 'static> ViewWrapper for IdView<T> {
     type V = T;
 
     fn with_view<F, R>(&self, f: F) -> Option<R>
-        where F: FnOnce(&Self::V) -> R
+    where
+        F: FnOnce(&Self::V) -> R,
     {
-        self.view
+        self.view.try_borrow().ok().map(|v| f(&*v))
-            .try_borrow()
-            .ok()
-            .map(|v| f(&*v))
     }
 
     fn with_view_mut<F, R>(&mut self, f: F) -> Option<R>
-        where F: FnOnce(&mut Self::V) -> R
+    where
+        F: FnOnce(&mut Self::V) -> R,
     {
-        self.view
+        self.view.try_borrow_mut().ok().map(|mut v| f(&mut *v))
-            .try_borrow_mut()
-            .ok()
-            .map(|mut v| f(&mut *v))
     }
 
-    fn wrap_call_on_any<'a>(&mut self, selector: &Selector,
+    fn wrap_call_on_any<'a>(
-                         mut callback: Box<for<'b> FnMut(&'b mut Any) + 'a>) {
+        &mut self, selector: &Selector,
+        mut callback: Box<for<'b> FnMut(&'b mut Any) + 'a>
+    ) {
         match selector {
             &Selector::Id(id) if id == self.id => callback(self),
-            s => self.view.borrow_mut().call_on_any(s, callback),
+            s => {
+                self.view.try_borrow_mut().ok().map(|mut v| {
+                    v.call_on_any(s, callback)
+                });
+            }
         }
     }
 
     fn wrap_focus_view(&mut self, selector: &Selector) -> Result<(), ()> {
         match selector {
             &Selector::Id(id) if id == self.id => Ok(()),
-            s => self.view.borrow_mut().focus_view(s),
+            s => {
+                self.view.try_borrow_mut().map_err(|_| ()).and_then(
+                    |mut v| {
+                        v.focus_view(s)
+                    },
+                )
+            }
         }
     }
 }