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//! Sys api.
//!
//! The sys api is exposed by the [SysAPI] trait.
use crate::ffi::collections::NonNullConst;
use crate::ffi::sys::api::SysBinding;
use crate::ffi::Bool;
use crate::fn_caster::FnCaster;
use crate::sys::sync_handler::SyncHandlerAPI;
use std::ffi::CStr;
pub mod sync_handler;
/// Minimal sys api.
pub trait SysAPIMin<'interface> {
/// Execution of the program is stopped abruptly. The error may be logged.
fn panic(&self, error: Option<impl AsRef<CStr>>) -> !;
/// Checks if a function is implemented.
///
/// # Return
///
/// Returns [true] if the function exists, [false] otherwise.
fn has_function<U>(&self) -> bool
where
U: FnCaster;
/// Fetches a function from the interface.
///
/// # Return
///
/// Function casted to the appropriate type.
fn get_function<U>(&self, caster: &U) -> Option<<U as FnCaster>::Type>
where
U: FnCaster;
}
/// Idiomatic sys api.
pub trait SysAPI<'interface>: SysAPIMin<'interface> {
/// Sends a termination signal.
fn shutdown(&mut self) -> !;
/// Fetches the active synchronization handler.
///
/// # Return
///
/// The active synchronization handler.
fn get_sync_handler<U>(&self) -> <U as SyncHandlerAPI<'interface>>::Handler
where
U: SyncHandlerAPI<'interface>;
/// Sets a new synchronization handler.
///
/// The default synchronization handler is used, if `handler` is [Option::None].
///
/// # Uses
///
/// This function can be used by modules, that want to provide a more complex
/// synchronization mechanism than the one presented by the default handler.
///
/// # Swapping
///
/// The swapping occurs in three steps:
///
/// 1. The new synchronization handler is locked.
/// 2. The new synchronization handler is set as the active synchronization handler.
/// 3. The old synchronization handler is unlocked.
///
/// # Safety
///
/// Changing the synchronization handler may break some modules,
/// if they depend on a specific synchronization handler.
unsafe fn set_sync_handler(&mut self, handler: Option<&impl SyncHandlerAPI<'interface>>);
}
impl<'interface, T> SysAPIMin<'interface> for T
where
T: SysBinding,
{
#[inline]
fn panic(&self, error: Option<impl AsRef<CStr>>) -> ! {
unsafe {
<T as SysBinding>::panic(
self,
error.map(|err| NonNullConst::from(err.as_ref().to_bytes_with_nul())),
)
}
}
#[inline]
fn has_function<U>(&self) -> bool
where
U: FnCaster,
{
unsafe { <T as SysBinding>::has_function(self, U::ID) == Bool::True }
}
#[inline]
fn get_function<U>(&self, caster: &U) -> Option<<U as FnCaster>::Type>
where
U: FnCaster,
{
unsafe {
<T as SysBinding>::get_function(self, U::ID)
.to_option()
.map(|func| caster.cast(func))
}
}
}
impl<'interface, T> SysAPI<'interface> for T
where
T: SysBinding,
{
#[inline]
fn shutdown(&mut self) -> ! {
unsafe { <T as SysBinding>::shutdown(self) }
}
#[inline]
fn get_sync_handler<U>(&self) -> <U as SyncHandlerAPI<'interface>>::Handler
where
U: SyncHandlerAPI<'interface>,
{
unsafe { U::from_interface(<T as SysBinding>::get_sync_handler(self)) }
}
#[inline]
unsafe fn set_sync_handler(&mut self, handler: Option<&impl SyncHandlerAPI<'interface>>) {
<T as SysBinding>::set_sync_handler(self, handler.map(|handler| handler.to_interface()))
}
}