cxx/
result.rs

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1#![cfg(feature = "alloc")]
2#![allow(missing_docs)]
3
4use crate::exception::Exception;
5use alloc::boxed::Box;
6use alloc::string::{String, ToString};
7use core::fmt::Display;
8use core::ptr::{self, NonNull};
9use core::result::Result as StdResult;
10use core::slice;
11use core::str;
12
13#[repr(C)]
14#[derive(Copy, Clone)]
15pub(crate) struct PtrLen {
16    pub ptr: NonNull<u8>,
17    pub len: usize,
18}
19
20#[repr(C)]
21pub union Result {
22    err: PtrLen,
23    ok: *const u8, // null
24}
25
26pub unsafe fn r#try<T, E>(ret: *mut T, result: StdResult<T, E>) -> Result
27where
28    E: Display,
29{
30    match result {
31        Ok(ok) => {
32            unsafe { ptr::write(ret, ok) }
33            Result { ok: ptr::null() }
34        }
35        Err(err) => unsafe { to_c_error(err.to_string()) },
36    }
37}
38
39unsafe fn to_c_error(msg: String) -> Result {
40    let mut msg = msg;
41    unsafe { msg.as_mut_vec() }.push(b'\0');
42    let ptr = msg.as_ptr();
43    let len = msg.len();
44
45    extern "C" {
46        #[link_name = "cxxbridge1$error"]
47        fn error(ptr: *const u8, len: usize) -> NonNull<u8>;
48    }
49
50    let copy = unsafe { error(ptr, len) };
51    let err = PtrLen { ptr: copy, len };
52    Result { err }
53}
54
55impl Result {
56    pub unsafe fn exception(self) -> StdResult<(), Exception> {
57        unsafe {
58            if self.ok.is_null() {
59                Ok(())
60            } else {
61                let err = self.err;
62                let slice = slice::from_raw_parts_mut(err.ptr.as_ptr(), err.len);
63                let s = str::from_utf8_unchecked_mut(slice);
64                Err(Exception {
65                    what: Box::from_raw(s),
66                })
67            }
68        }
69    }
70}
cxx/result.rs

cxx/
result.rs
