Add id_msg_send to help with following memory management rules

Author: madsmtm

objc2-foundation/src/data.rs

@@ -5,10 +5,10 @@ use core::slice::{self, SliceIndex};
 use core::{ffi::c_void, ptr::NonNull};
 
 use super::{INSCopying, INSMutableCopying, INSObject, NSRange};
-use objc2::msg_send;
 use objc2::rc::{DefaultId, Id, Owned, Ownership, Shared};
+use objc2::{id_msg_send, msg_send};
 
-pub unsafe trait INSData: INSObject {
+pub unsafe trait INSData: INSObject + Sized {
     type Ownership: Ownership;
 
     unsafe_def_fn!(fn new -> Self::Ownership);
@@ -35,13 +35,12 @@ pub unsafe trait INSData: INSObject {
         let cls = Self::class();
         let bytes_ptr = bytes.as_ptr() as *const c_void;
         unsafe {
-            let obj: *mut Self = msg_send![cls, alloc];
-            let obj: *mut Self = msg_send![
+            let obj: Id<Self, Self::Ownership> = id_msg_send![cls, alloc];
+            id_msg_send![
                 obj,
                 initWithBytes: bytes_ptr,
                 length: bytes.len(),
-            ];
-            Id::new(NonNull::new_unchecked(obj))
+            ]
         }
     }
 
@@ -80,14 +79,13 @@ pub unsafe trait INSData: INSObject {
         let mut bytes = ManuallyDrop::new(bytes);
 
         unsafe {
-            let obj: *mut Self = msg_send![cls, alloc];
-            let obj: *mut Self = msg_send![
+            let obj: Id<Self, Self::Ownership> = id_msg_send![cls, alloc];
+            id_msg_send![
                 obj,
                 initWithBytesNoCopy: bytes.as_mut_ptr() as *mut c_void,
                 length: bytes.len(),
                 deallocator: dealloc,
-            ];
-            Id::new(NonNull::new_unchecked(obj))
+            ]
         }
     }
 }

objc2-foundation/tests/objc_id_retain_autoreleased.rs

@@ -1,8 +1,7 @@
 use std::ffi::c_void;
-use std::ptr::NonNull;
 
-use objc2::msg_send;
 use objc2::rc::{autoreleasepool, Id, Shared};
+use objc2::{id_msg_send, msg_send};
 use objc2_foundation::{INSObject, NSData};
 
 fn retain_count(obj: &NSData) -> usize {
@@ -12,14 +11,11 @@ fn retain_count(obj: &NSData) -> usize {
 fn create_data(bytes: &[u8]) -> Id<NSData, Shared> {
     let bytes_ptr = bytes.as_ptr() as *const c_void;
     unsafe {
-        // All code between the `msg_send!` and the `retain_autoreleased` must
-        // be able to be optimized away for this to work.
-        let obj: *mut NSData = msg_send![
+        id_msg_send![
             NSData::class(),
             dataWithBytes: bytes_ptr,
             length: bytes.len(),
-        ];
-        Id::retain_autoreleased(NonNull::new_unchecked(obj))
+        ]
     }
 }
 

objc2/examples/introspection.rs

@@ -1,8 +1,6 @@
-use core::ptr::NonNull;
-
 use objc2::rc::{Id, Owned};
 use objc2::runtime::{Class, Object};
-use objc2::{class, msg_send};
+use objc2::{class, id_msg_send, msg_send};
 #[cfg(feature = "malloc")]
 use objc2::{sel, Encode};
 
@@ -22,9 +20,8 @@ fn main() {
 
     // Allocate an instance
     let obj: Id<Object, Owned> = unsafe {
-        let obj: *mut Object = msg_send![cls, alloc];
-        let obj: NonNull<Object> = msg_send![obj, init];
-        Id::new(obj)
+        let obj: Id<Object, Owned> = id_msg_send![cls, alloc];
+        id_msg_send![obj, init]
     };
     println!("NSObject address: {:p}", obj);
 

objc2/src/lib.rs

@@ -30,16 +30,14 @@
 #![cfg_attr(apple, doc = "```")]
 #![cfg_attr(not(apple), doc = "```no_run")]
 //! use core::ptr::NonNull;
-//! use objc2::{class, msg_send};
+//! use objc2::{class, id_msg_send, msg_send};
 //! use objc2::ffi::NSUInteger;
 //! use objc2::rc::{Id, Owned};
 //! use objc2::runtime::{Bool, Object};
 //!
 //! // Creation
 //! let cls = class!(NSObject);
-//! let obj: *mut Object = unsafe { msg_send![cls, new] };
-//! let obj = NonNull::new(obj).expect("Failed allocating object");
-//! let obj: Id<Object, Owned> = unsafe { Id::new(obj) };
+//! let obj: Id<Object, Owned> = unsafe { id_msg_send![cls, new] }; // .expect("Failed allocating object")
 //!
 //! // Usage
 //! let hash: NSUInteger = unsafe { msg_send![obj, hash] };
@@ -150,6 +148,8 @@ pub use crate::message::{Message, MessageArguments, MessageError, MessageReceive
 pub use crate::cache::CachedClass as __CachedClass;
 pub use crate::cache::CachedSel as __CachedSel;
 
+pub use crate::macros::__starts_with_str;
+
 #[macro_use]
 mod macros;
 

objc2/src/macros.rs

@@ -172,3 +172,75 @@ macro_rules! msg_send {
         result
     });
 }
+
+/// TODO
+#[macro_export]
+macro_rules! id_msg_send {
+    ($obj:expr, $name:ident) => ({
+        const NAME: &[u8] = stringify!($name).as_bytes();
+        $crate::id_msg_send!(@ $obj, NAME, $name)
+    });
+    ($obj:expr, $($name:ident: $arg:expr),+ $(,)?) => ({
+        const NAME: &[u8] = concat!($(stringify!($name), ':'),+).as_bytes();
+        $crate::id_msg_send!(@ $obj, NAME, $($name: $arg),+)
+    });
+    (@ $obj:expr, $name:ident, $($sel:tt)+) => {{
+        const IS_INIT: bool = $crate::__starts_with_str($name, b"init");
+        const IS_RETAINED: bool = {
+            $crate::__starts_with_str($name, b"alloc")
+                || $crate::__starts_with_str($name, b"new")
+                || $crate::__starts_with_str($name, b"copy")
+                || $crate::__starts_with_str($name, b"mutableCopy")
+                || $crate::__starts_with_str($name, b"init")
+        };
+
+        ::std::println!("IS_INIT: {}", IS_INIT);
+        ::std::println!("IS_RETAINED: {}", IS_RETAINED);
+
+        let result = if IS_INIT {
+            // TODO: Ensure `obj` is Id here
+            let obj = ::core::mem::ManuallyDrop::new($obj);
+            $crate::msg_send![obj, $($sel)+]
+        } else {
+            $crate::msg_send![$obj, $($sel)+]
+        };
+        if IS_RETAINED {
+            $crate::rc::Id::new(result)
+        } else {
+            // All code between the `msg_send!` and the `retain_autoreleased` must
+            // be able to be optimized away for this to work.
+            $crate::rc::Id::retain_autoreleased(result)
+        }
+    }};
+}
+
+#[doc(hidden)]
+pub const fn __starts_with_str(haystack: &[u8], needle: &[u8]) -> bool {
+    if needle.len() > haystack.len() {
+        return false;
+    }
+    let mut i = 0;
+    while i < needle.len() {
+        if needle[i] != haystack[i] {
+            return false;
+        }
+        i += 1;
+    }
+    true
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_starts_with_str() {
+        assert!(__starts_with_str(b"abcdef", b"abc"));
+        assert!(__starts_with_str(b"a", b""));
+        assert!(__starts_with_str(b"", b""));
+
+        assert!(!__starts_with_str(b"abcdef", b"def"));
+        assert!(!__starts_with_str(b"abcdef", b"abb"));
+        assert!(!__starts_with_str(b"", b"a"));
+    }
+}