dispatchr 1.0.0

Drew's Rust bindings for libdispatch, a.k.a. GCD
Documentation 
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// SPDX-License-Identifier: MIT OR Apache-2.0

//! `https://clang.llvm.org/docs/Block-ABI-Apple.html#high-level`

use std::os::raw::{c_int};
use crate::data::Unmanaged;

use blocksr::once_escaping;
once_escaping!(pub(crate) ReadEscapingBlock(data: *const Unmanaged, error: c_int) -> ());

once_escaping!(pub(crate) WriteEscapingBlock(data: Option<&Unmanaged>, error: c_int) -> ());

//all arguments to this one passed in via closure
once_escaping!(pub(crate) DropBlock() -> ());

///A block that will drop the receiver.  This can be used to transfer
/// ownership of the receiver into dispatch.
///
/// # Safety
/// You must verify that
//  * Block will execute exactly once:
//      * If ObjC executes the block several times, it's UB
//      * If ObjC executes the block less than once, it is not UB, but it will leak.
pub(crate) unsafe fn drop_block<T: Send + 'static>(t: T) -> DropBlock {
    DropBlock::new(move || {
        std::mem::drop(t)
    })
}