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/*!
Functionality for declaring Objective-C classes.
Classes can be declared using the `ClassDecl` struct. Instance variables and
methods can then be added before the class is ultimately registered.
# Example
The following example demonstrates declaring a class named `MyNumber` that has
one ivar, a `u32` named `_number` and a `number` method that returns it:
``` no_run
# #[macro_use] extern crate objc;
# use objc::declare::ClassDecl;
# use objc::runtime::{Class, Object, Sel};
# fn main() {
let superclass = class!(NSObject);
let mut decl = ClassDecl::new("MyNumber", superclass).unwrap();
// Add an instance variable
decl.add_ivar::<u32>("_number");
// Add an ObjC method for getting the number
extern fn my_number_get(this: &Object, _cmd: Sel) -> u32 {
unsafe { *this.get_ivar("_number") }
}
unsafe {
decl.add_method(sel!(number),
my_number_get as extern fn(&Object, Sel) -> u32);
}
decl.register();
# }
```
*/
use std::ffi::CString;
use std::mem;
use std::ptr;
use runtime::{BOOL, Class, Imp, NO, Object, Protocol, Sel, self};
use {Encode, EncodeArguments, Encoding, Message};
/// Types that can be used as the implementation of an Objective-C method.
pub trait MethodImplementation {
/// The callee type of the method.
type Callee: Message;
/// The return type of the method.
type Ret: Encode;
/// The argument types of the method.
type Args: EncodeArguments;
/// Returns self as an `Imp` of a method.
fn imp(self) -> Imp;
}
macro_rules! method_decl_impl {
(-$s:ident, $r:ident, $f:ty, $($t:ident),*) => (
impl<$s, $r $(, $t)*> MethodImplementation for $f
where $s: Message, $r: Encode $(, $t: Encode)* {
type Callee = $s;
type Ret = $r;
type Args = ($($t,)*);
fn imp(self) -> Imp {
unsafe { mem::transmute(self) }
}
}
);
($($t:ident),*) => (
method_decl_impl!(-T, R, extern fn(&T, Sel $(, $t)*) -> R, $($t),*);
method_decl_impl!(-T, R, extern fn(&mut T, Sel $(, $t)*) -> R, $($t),*);
);
}
method_decl_impl!();
method_decl_impl!(A);
method_decl_impl!(A, B);
method_decl_impl!(A, B, C);
method_decl_impl!(A, B, C, D);
method_decl_impl!(A, B, C, D, E);
method_decl_impl!(A, B, C, D, E, F);
method_decl_impl!(A, B, C, D, E, F, G);
method_decl_impl!(A, B, C, D, E, F, G, H);
method_decl_impl!(A, B, C, D, E, F, G, H, I);
method_decl_impl!(A, B, C, D, E, F, G, H, I, J);
method_decl_impl!(A, B, C, D, E, F, G, H, I, J, K);
method_decl_impl!(A, B, C, D, E, F, G, H, I, J, K, L);
fn count_args(sel: Sel) -> usize {
sel.name().chars().filter(|&c| c == ':').count()
}
fn method_type_encoding(ret: &Encoding, args: &[Encoding]) -> CString {
let mut types = ret.as_str().to_owned();
// First two arguments are always self and the selector
types.push_str(<*mut Object>::encode().as_str());
types.push_str(Sel::encode().as_str());
types.extend(args.iter().map(|e| e.as_str()));
CString::new(types).unwrap()
}
fn log2_align_of<T>() -> u8 {
let align = mem::align_of::<T>();
// Alignments are required to be powers of 2
debug_assert!(align.count_ones() == 1);
// log2 of a power of 2 is the number of trailing zeros
align.trailing_zeros() as u8
}
/// A type for declaring a new class and adding new methods and ivars to it
/// before registering it.
pub struct ClassDecl {
cls: *mut Class,
}
impl ClassDecl {
fn with_superclass(name: &str, superclass: Option<&Class>)
-> Option<ClassDecl> {
let name = CString::new(name).unwrap();
let super_ptr = superclass.map_or(ptr::null(), |c| c);
let cls = unsafe {
runtime::objc_allocateClassPair(super_ptr, name.as_ptr(), 0)
};
if cls.is_null() {
None
} else {
Some(ClassDecl { cls: cls })
}
}
/// Constructs a `ClassDecl` with the given name and superclass.
/// Returns `None` if the class couldn't be allocated.
pub fn new(name: &str, superclass: &Class) -> Option<ClassDecl> {
ClassDecl::with_superclass(name, Some(superclass))
}
/**
Constructs a `ClassDecl` declaring a new root class with the given name.
Returns `None` if the class couldn't be allocated.
An implementation for `+initialize` must also be given; the runtime calls
this method for all classes, so it must be defined on root classes.
Note that implementing a root class is not a simple endeavor.
For example, your class probably cannot be passed to Cocoa code unless
the entire `NSObject` protocol is implemented.
Functionality it expects, like implementations of `-retain` and `-release`
used by ARC, will not be present otherwise.
*/
pub fn root(name: &str, intitialize_fn: extern fn(&Class, Sel))
-> Option<ClassDecl> {
let mut decl = ClassDecl::with_superclass(name, None);
if let Some(ref mut decl) = decl {
unsafe {
decl.add_class_method(sel!(initialize), intitialize_fn);
}
}
decl
}
/// Adds a method with the given name and implementation to self.
/// Panics if the method wasn't sucessfully added
/// or if the selector and function take different numbers of arguments.
/// Unsafe because the caller must ensure that the types match those that
/// are expected when the method is invoked from Objective-C.
pub unsafe fn add_method<F>(&mut self, sel: Sel, func: F)
where F: MethodImplementation<Callee=Object> {
let encs = F::Args::encodings();
let encs = encs.as_ref();
let sel_args = count_args(sel);
assert!(sel_args == encs.len(),
"Selector accepts {} arguments, but function accepts {}",
sel_args, encs.len(),
);
let types = method_type_encoding(&F::Ret::encode(), encs);
let success = runtime::class_addMethod(self.cls, sel, func.imp(),
types.as_ptr());
assert!(success != NO, "Failed to add method {:?}", sel);
}
/// Adds a class method with the given name and implementation to self.
/// Panics if the method wasn't sucessfully added
/// or if the selector and function take different numbers of arguments.
/// Unsafe because the caller must ensure that the types match those that
/// are expected when the method is invoked from Objective-C.
pub unsafe fn add_class_method<F>(&mut self, sel: Sel, func: F)
where F: MethodImplementation<Callee=Class> {
let encs = F::Args::encodings();
let encs = encs.as_ref();
let sel_args = count_args(sel);
assert!(sel_args == encs.len(),
"Selector accepts {} arguments, but function accepts {}",
sel_args, encs.len(),
);
let types = method_type_encoding(&F::Ret::encode(), encs);
let metaclass = (*self.cls).metaclass() as *const _ as *mut _;
let success = runtime::class_addMethod(metaclass, sel, func.imp(),
types.as_ptr());
assert!(success != NO, "Failed to add class method {:?}", sel);
}
/// Adds an ivar with type `T` and the provided name to self.
/// Panics if the ivar wasn't successfully added.
pub fn add_ivar<T>(&mut self, name: &str) where T: Encode {
let c_name = CString::new(name).unwrap();
let encoding = CString::new(T::encode().as_str()).unwrap();
let size = mem::size_of::<T>();
let align = log2_align_of::<T>();
let success = unsafe {
runtime::class_addIvar(self.cls, c_name.as_ptr(), size, align,
encoding.as_ptr())
};
assert!(success != NO, "Failed to add ivar {}", name);
}
/// Adds a protocol to self. Panics if the protocol wasn't successfully
/// added
pub fn add_protocol(&mut self, proto: &Protocol) {
let success = unsafe { runtime::class_addProtocol(self.cls, proto) };
assert!(success != NO, "Failed to add protocol {:?}", proto);
}
/// Registers self, consuming it and returning a reference to the
/// newly registered `Class`.
pub fn register(self) -> &'static Class {
unsafe {
let cls = self.cls;
runtime::objc_registerClassPair(cls);
// Forget self otherwise the class will be disposed in drop
mem::forget(self);
&*cls
}
}
}
impl Drop for ClassDecl {
fn drop(&mut self) {
unsafe {
runtime::objc_disposeClassPair(self.cls);
}
}
}
/// A type for declaring a new protocol and adding new methods to it
/// before registering it.
pub struct ProtocolDecl {
proto: *mut Protocol
}
impl ProtocolDecl {
/// Constructs a `ProtocolDecl` with the given name. Returns `None` if the
/// protocol couldn't be allocated.
pub fn new(name: &str) -> Option<ProtocolDecl> {
let c_name = CString::new(name).unwrap();
let proto = unsafe {
runtime::objc_allocateProtocol(c_name.as_ptr())
};
if proto.is_null() {
None
} else {
Some(ProtocolDecl { proto: proto })
}
}
fn add_method_description_common<Args, Ret>(&mut self, sel: Sel, is_required: bool,
is_instance_method: bool)
where Args: EncodeArguments,
Ret: Encode {
let encs = Args::encodings();
let encs = encs.as_ref();
let sel_args = count_args(sel);
assert!(sel_args == encs.len(),
"Selector accepts {} arguments, but function accepts {}",
sel_args, encs.len(),
);
let types = method_type_encoding(&Ret::encode(), encs);
unsafe {
runtime::protocol_addMethodDescription(
self.proto, sel, types.as_ptr(), is_required as BOOL, is_instance_method as BOOL);
}
}
/// Adds an instance method declaration with a given description to self.
pub fn add_method_description<Args, Ret>(&mut self, sel: Sel, is_required: bool)
where Args: EncodeArguments,
Ret: Encode {
self.add_method_description_common::<Args, Ret>(sel, is_required, true)
}
/// Adds a class method declaration with a given description to self.
pub fn add_class_method_description<Args, Ret>(&mut self, sel: Sel, is_required: bool)
where Args: EncodeArguments,
Ret: Encode {
self.add_method_description_common::<Args, Ret>(sel, is_required, false)
}
/// Adds a requirement on another protocol.
pub fn add_protocol(&mut self, proto: &Protocol) {
unsafe {
runtime::protocol_addProtocol(self.proto, proto);
}
}
/// Registers self, consuming it and returning a reference to the
/// newly registered `Protocol`.
pub fn register(self) -> &'static Protocol {
unsafe {
runtime::objc_registerProtocol(self.proto);
&*self.proto
}
}
}
#[cfg(test)]
mod tests {
use test_utils;
#[test]
fn test_custom_class() {
// Registering the custom class is in test_utils
let obj = test_utils::custom_object();
unsafe {
let _: () = msg_send![obj, setFoo:13u32];
let result: u32 = msg_send![obj, foo];
assert!(result == 13);
}
}
#[test]
fn test_class_method() {
let cls = test_utils::custom_class();
unsafe {
let result: u32 = msg_send![cls, classFoo];
assert!(result == 7);
}
}
}