Clean up some pointer shuffling stuff

appkit/src/utils.rs

@@ -2,6 +2,8 @@
 //! belong to. These are typically internal, and if you rely on them... well, don't be surprised if
 //! they go away one day.
 
+use std::rc::Rc;
+use std::cell::RefCell;
 use std::{slice, str};
 use std::os::raw::c_char;
 
@@ -9,6 +11,7 @@ use cocoa::base::id;
 use cocoa::foundation::NSString;
 
 use objc::{msg_send, sel, sel_impl};
+use objc::runtime::Object;
 
 /// A utility method for taking an `NSString` and bridging it to a Rust `&str`.
 pub fn str_from(nsstring: id) -> &'static str {
@@ -23,3 +26,14 @@ pub fn str_from(nsstring: id) -> &'static str {
         str::from_utf8(bytes).unwrap()
     }
 }
+
+/// Used for moving a pointer back into an Rc, so we can work with the object held behind it. Note
+/// that it's very important to make sure you reverse this when you're done (using
+/// `Rc::into_raw()`) otherwise you'll cause problems due to the `Drop` logic.
+pub fn load<T>(this: &Object, ptr: &str) -> Rc<RefCell<T>> {
+    unsafe {
+        let ptr: usize = *this.get_ivar(ptr);
+        let view_ptr = ptr as *const RefCell<T>;
+        Rc::from_raw(view_ptr)
+    }
+}

appkit/src/view/class.rs

@@ -7,7 +7,6 @@
 //! for in the modern era. It also implements a few helpers for things like setting a background
 //! color, and enforcing layer backing by default.
 
-use std::cell::RefCell;
 use std::rc::Rc;
 use std::sync::Once;
 
@@ -22,6 +21,8 @@ use objc_id::Id;
 use crate::constants::{BACKGROUND_COLOR, VIEW_CONTROLLER_PTR};
 use crate::dragdrop::DragInfo;
 use crate::view::traits::ViewController;
+use crate::utils::load;
+
 
 /// Enforces normalcy, or: a needlessly cruel method in terms of the name. You get the idea though.
 extern fn enforce_normalcy(_: &Object, _: Sel) -> BOOL {
@@ -42,106 +43,84 @@ extern fn update_layer(this: &Object, _: Sel) {
 
 /// Called when a drag/drop operation has entered this view.
 extern fn dragging_entered<T: ViewController>(this: &mut Object, _: Sel, info: id) -> NSUInteger {
-    unsafe {
-        let ptr: usize = *this.get_ivar(VIEW_CONTROLLER_PTR);
-        let view_ptr = ptr as *const RefCell<T>;
-        let view = Rc::from_raw(view_ptr);
+    let view = load::<T>(this, VIEW_CONTROLLER_PTR);
 
-        let response = {
-            let v = view.borrow();
+    let response = {
+        let v = view.borrow();
 
-            (*v).dragging_entered(DragInfo {
-                info: Id::from_ptr(info)
-            }).into()
-        };
+        (*v).dragging_entered(DragInfo {
+            info: unsafe { Id::from_ptr(info) }
+        }).into()
+    };
 
-        Rc::into_raw(view); 
-        response
-    }
+    Rc::into_raw(view);
+    response
 }
 
 /// Called when a drag/drop operation has entered this view.
 extern fn prepare_for_drag_operation<T: ViewController>(this: &mut Object, _: Sel, info: id) -> BOOL {
-    unsafe {
-        let ptr: usize = *this.get_ivar(VIEW_CONTROLLER_PTR);
-        let view_ptr = ptr as *const RefCell<T>;
-        let view = Rc::from_raw(view_ptr);
+    let view = load::<T>(this, VIEW_CONTROLLER_PTR);
     
-        let response = {
-            let v = view.borrow();
+    let response = {
+        let v = view.borrow();
         
-            match (*v).prepare_for_drag_operation(DragInfo {
-                info: Id::from_ptr(info)
-            }) {
-                true => YES,
-                false => NO
-            }
-        };
+        match (*v).prepare_for_drag_operation(DragInfo {
+            info: unsafe { Id::from_ptr(info) }
+        }) {
+            true => YES,
+            false => NO
+        }
+    };
 
-        Rc::into_raw(view); 
-        response
-    }
+    Rc::into_raw(view); 
+    response
 }
 
 /// Called when a drag/drop operation has entered this view.
 extern fn perform_drag_operation<T: ViewController>(this: &mut Object, _: Sel, info: id) -> BOOL {
-    unsafe {
-        let ptr: usize = *this.get_ivar(VIEW_CONTROLLER_PTR);
-        let view_ptr = ptr as *const RefCell<T>;
-        let view = Rc::from_raw(view_ptr);
+    let view = load::<T>(this, VIEW_CONTROLLER_PTR);
         
-        let response = {
-            let v = view.borrow();
+    let response = {
+        let v = view.borrow();
         
-            match (*v).perform_drag_operation(DragInfo {
-                info: Id::from_ptr(info)
-            }) {
-                true => YES,
-                false => NO
-            }
-        };
+        match (*v).perform_drag_operation(DragInfo {
+            info: unsafe { Id::from_ptr(info) }
+        }) {
+            true => YES,
+            false => NO
+        }
+    };
 
-        Rc::into_raw(view); 
-        response
-    }
+    Rc::into_raw(view); 
+    response
 }
 
 /// Called when a drag/drop operation has entered this view.
 extern fn conclude_drag_operation<T: ViewController>(this: &mut Object, _: Sel, info: id) {
-    unsafe {
-        let ptr: usize = *this.get_ivar(VIEW_CONTROLLER_PTR);
-        let view_ptr = ptr as *const RefCell<T>;
-        let view = Rc::from_raw(view_ptr);
+    let view = load::<T>(this, VIEW_CONTROLLER_PTR);
 
-        let response = {
-            let v = view.borrow();
-            (*v).conclude_drag_operation(DragInfo {
-                info: Id::from_ptr(info)
-            });           
-        };
-
-        Rc::into_raw(view); 
-        response
+    {
+        let v = view.borrow();
+        (*v).conclude_drag_operation(DragInfo {
+            info: unsafe { Id::from_ptr(info) }
+        });           
     }
+
+    Rc::into_raw(view); 
 }
 
 /// Called when a drag/drop operation has entered this view.
 extern fn dragging_exited<T: ViewController>(this: &mut Object, _: Sel, info: id) {
-    unsafe {
-        let ptr: usize = *this.get_ivar(VIEW_CONTROLLER_PTR);
-        let view_ptr = ptr as *const RefCell<T>;
-        let view = Rc::from_raw(view_ptr);
+    let view = load::<T>(this, VIEW_CONTROLLER_PTR);
         
-        let response = {
-            let v = view.borrow();
-            (*v).dragging_exited(DragInfo {
-                info: Id::from_ptr(info)
-            });
-        };
-
-        Rc::into_raw(view); 
-        response
+    {
+        let v = view.borrow();
+        (*v).dragging_exited(DragInfo {
+            info: unsafe { Id::from_ptr(info) }
+        });
     }
+
+    Rc::into_raw(view); 
 }
 
 /// Injects an `NSView` subclass, with some callback and pointer ivars for what we

appkit/src/window/controller.rs

@@ -1,6 +1,7 @@
 //! Everything useful for the `WindowController`. Handles injecting an `NSWindowController` subclass
 //! into the Objective C runtime, which loops back to give us lifecycle methods.
 
+use std::rc::Rc;
 use std::sync::Once;
 
 use cocoa::base::id;
@@ -9,18 +10,21 @@ use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
 use objc::{class, sel, sel_impl};
 
+use crate::constants::WINDOW_CONTROLLER_PTR;
+use crate::utils::load;
 use crate::window::WindowController;
 
-static WINDOW_CONTROLLER_PTR: &str = "rstWindowController";
-
 /// Called when an `NSWindow` receives a `windowWillClose:` event.
 /// Good place to clean up memory and what not.
 extern fn will_close<T: WindowController>(this: &Object, _: Sel, _: id) {
-    unsafe {
-        let window_ptr: usize = *this.get_ivar(WINDOW_CONTROLLER_PTR);
-        let window = window_ptr as *const T;
+    let window = load::<T>(this, WINDOW_CONTROLLER_PTR);
+
+    {
+        let window = window.borrow();
         (*window).will_close();
     }
+
+    Rc::into_raw(window);
 }
 
 /// Injects an `NSWindowController` subclass, with some callback and pointer ivars for what we

appkit/src/window/window.rs

@@ -4,8 +4,7 @@
 use std::rc::Rc;
 use std::cell::RefCell;
 
-use cocoa::base::{id, nil, YES, NO};
-use cocoa::foundation::{NSSize, NSString};
+use cocoa::base::{id, nil};
 
 use objc::{msg_send, sel, sel_impl};
 use objc_id::ShareId;