proc_macro/bridge/
closure.rs

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1//! Closure type (equivalent to `&mut dyn FnMut(A) -> R`) that's `repr(C)`.
2
3use std::marker::PhantomData;
4
5#[repr(C)]
6pub(super) struct Closure<'a, A, R> {
7    call: unsafe extern "C" fn(*mut Env, A) -> R,
8    env: *mut Env,
9    // Prevent Send and Sync impls. `!Send`/`!Sync` is the usual way of doing
10    // this, but that requires unstable features. rust-analyzer uses this code
11    // and avoids unstable features.
12    //
13    // The `'a` lifetime parameter represents the lifetime of `Env`.
14    _marker: PhantomData<*mut &'a mut ()>,
15}
16
17struct Env;
18
19impl<'a, A, R, F: FnMut(A) -> R> From<&'a mut F> for Closure<'a, A, R> {
20    fn from(f: &'a mut F) -> Self {
21        unsafe extern "C" fn call<A, R, F: FnMut(A) -> R>(env: *mut Env, arg: A) -> R {
22            unsafe { (*(env as *mut _ as *mut F))(arg) }
23        }
24        Closure { call: call::<A, R, F>, env: f as *mut _ as *mut Env, _marker: PhantomData }
25    }
26}
27
28impl<'a, A, R> Closure<'a, A, R> {
29    pub(super) fn call(&mut self, arg: A) -> R {
30        unsafe { (self.call)(self.env, arg) }
31    }
32}
proc_macro/bridge/closure.rs

proc_macro/bridge/
closure.rs
