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#![cfg(feature = "alloc")]
#![allow(missing_docs)]
use crate::exception::Exception;
use alloc::boxed::Box;
use alloc::string::{String, ToString};
use core::fmt::Display;
use core::ptr::{self, NonNull};
use core::result::Result as StdResult;
use core::slice;
use core::str;
#[repr(C)]
#[derive(Copy, Clone)]
pub struct PtrLen {
pub ptr: NonNull<u8>,
pub len: usize,
}
#[repr(C)]
pub union Result {
err: PtrLen,
ok: *const u8, // null
}
pub unsafe fn r#try<T, E>(ret: *mut T, result: StdResult<T, E>) -> Result
where
E: Display,
{
match result {
Ok(ok) => {
unsafe { ptr::write(ret, ok) }
Result { ok: ptr::null() }
}
Err(err) => unsafe { to_c_error(err.to_string()) },
}
}
unsafe fn to_c_error(msg: String) -> Result {
let mut msg = msg;
unsafe { msg.as_mut_vec() }.push(b'\0');
let ptr = msg.as_ptr();
let len = msg.len();
extern "C" {
#[link_name = "cxxbridge1$error"]
fn error(ptr: *const u8, len: usize) -> NonNull<u8>;
}
let copy = unsafe { error(ptr, len) };
let err = PtrLen { ptr: copy, len };
Result { err }
}
impl Result {
pub unsafe fn exception(self) -> StdResult<(), Exception> {
unsafe {
if self.ok.is_null() {
Ok(())
} else {
let err = self.err;
let slice = slice::from_raw_parts_mut(err.ptr.as_ptr(), err.len);
let s = str::from_utf8_unchecked_mut(slice);
Err(Exception {
what: Box::from_raw(s),
})
}
}
}
}
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