tesseract_swift_utils/future/
cfuture.rs

1use super::from::CFutureWrapper;
2use crate::error::CError;
3use crate::ptr::*;
4use crate::response::COptionResponseResult;
5use crate::result::Result;
6use crate::Void;
7use std::future::Future;
8use std::mem::{ManuallyDrop, MaybeUninit};
9
10pub type CFutureOnCompleteCallback<V> = unsafe extern "C" fn(
11    context: SyncPtr<Void>,
12    value: *mut ManuallyDrop<V>,
13    error: *mut ManuallyDrop<CError>,
14);
15
16#[repr(C)]
17pub struct CFuture<V: 'static> {
18    ptr: CAnyDropPtr,
19    set_on_complete: unsafe extern "C" fn(
20        future: &CFuture<V>,
21        context: SyncPtr<Void>,
22        value: *mut ManuallyDrop<V>,
23        error: *mut ManuallyDrop<CError>,
24        cb: CFutureOnCompleteCallback<V>
25    ) -> COptionResponseResult,
26}
27
28struct CFutureContext<V: 'static> {
29    _future: CFuture<V>,
30    closure: Option<Box<dyn FnOnce(Result<V>)>>,
31}
32
33impl<V: 'static> CFutureContext<V> {
34    fn new<F: 'static + FnOnce(Result<V>)>(future: CFuture<V>, closure: F) -> Self {
35        Self {
36            _future: future,
37            closure: Some(Box::new(closure)),
38        }
39    }
40
41    fn resolve(&mut self, result: Result<V>) {
42        (self.closure.take().unwrap())(result);
43    }
44
45    unsafe fn from_raw(mut ptr: SyncPtr<Void>) -> Self {
46        ptr.take_typed()
47    }
48
49    fn into_raw(self) -> SyncPtr<Void> {
50        SyncPtr::new(self).as_void()
51    }
52}
53
54impl<V: 'static> CFuture<V> {
55    pub fn new(
56        ptr: CAnyDropPtr,
57        set_on_complete: unsafe extern "C" fn(
58            future: &CFuture<V>,
59            context: SyncPtr<Void>,
60            value: *mut ManuallyDrop<V>,
61            error: *mut ManuallyDrop<CError>,
62            cb: CFutureOnCompleteCallback<V>
63        ) -> COptionResponseResult,
64    ) -> Self {
65        Self {
66            ptr,
67            set_on_complete,
68        }
69    }
70
71    pub fn on_complete<F: 'static + FnOnce(Result<V>)>(self, cb: F) -> Option<Result<V>> {
72        let set_on_complete = self.set_on_complete;
73        let reference = &self as *const Self; // this is ok. It passed as ref into set_on_complete call only
74        let context = CFutureContext::new(self, cb).into_raw().ptr();
75
76        let mut value: MaybeUninit<ManuallyDrop<V>> = MaybeUninit::uninit();
77        let mut error: MaybeUninit<ManuallyDrop<CError>> = MaybeUninit::uninit();
78        let result = unsafe {
79            set_on_complete(
80                reference.as_ref().unwrap(),
81                SyncPtr::raw(context),
82                value.as_mut_ptr(), error.as_mut_ptr(),
83                Self::on_complete_handler
84            )
85        };
86
87        let value = unsafe { match result {
88            COptionResponseResult::None => None,
89            COptionResponseResult::Error =>
90                Some(Err(ManuallyDrop::into_inner(error.assume_init()))),
91            COptionResponseResult::Some =>
92                Some(Ok(ManuallyDrop::into_inner(value.assume_init())))
93        }};
94        if value.is_some() {
95            // Context is non-needed. Callback never will be called
96            let _ = unsafe { CFutureContext::<V>::from_raw(SyncPtr::raw(context)) };
97        }
98        value
99    }
100
101    pub fn ptr(&self) -> &CAnyDropPtr {
102        &self.ptr
103    }
104
105    pub fn try_into_future(self) -> Result<impl Future<Output = Result<V>>> {
106        CFutureWrapper::try_from(self)
107    }
108
109    unsafe extern "C" fn on_complete_handler(
110        context: SyncPtr<Void>,
111        value: *mut ManuallyDrop<V>,
112        error: *mut ManuallyDrop<CError>,
113    ) {
114        let mut context = CFutureContext::from_raw(context);
115        if error.is_null() {
116            context.resolve(Ok(ManuallyDrop::take(value.as_mut().unwrap())));
117        } else {
118            context.resolve(Err(ManuallyDrop::take(error.as_mut().unwrap())));
119        }
120    }
121}
tesseract_swift_utils/future/cfuture.rs

tesseract_swift_utils/future/
cfuture.rs
