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Due to rust monophormisation, there is no need for double indirection

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This commit is contained in:
gwenn
2017-04-27 18:05:12 +02:00
parent 63a444a95f
commit 3e6fffaf94
3 changed files with 12 additions and 14 deletions
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18
src/hooks.rs
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@@ -130,7 +130,8 @@ impl InnerConnection {
use std::ffi::CStr;
use std::str;
let boxed_hook: &mut Box<F> = mem::transmute(p_arg);
let boxed_hook: *mut F = mem::transmute(p_arg);
assert!(!boxed_hook.is_null(), "Internal error - null function pointer");
let action = Action::from(action_code);
let db_name = {
@@ -142,15 +143,15 @@ impl InnerConnection {
str::from_utf8_unchecked(c_slice)
};
boxed_hook(action, db_name, tbl_name, row_id);
(*boxed_hook)(action, db_name, tbl_name, row_id);
}
let previous_hook = {
let boxed_hook: Box<Box<FnMut(Action, &str, &str, i64)>> = Box::new(Box::new(hook));
let boxed_hook: *mut F = Box::into_raw(Box::new(hook));
unsafe {
ffi::sqlite3_update_hook(self.db(),
Some(call_boxed_closure::<F>),
Box::into_raw(boxed_hook) as *mut _)
boxed_hook as *mut _)
}
};
free_boxed_update_hook(previous_hook);
@@ -164,14 +165,9 @@ impl InnerConnection {
}
fn free_boxed_update_hook(hook: *mut c_void) {
/*
http://stackoverflow.com/questions/32270030/how-do-i-convert-a-rust-closure-to-a-c-style-callback
Double indirection (i.e. Box<Box<...>>) is necessary
because Box<Fn(..) -> ..> is a trait object and therefore a fat pointer,
incompatible with *mut c_void because of different size.
*/
if !hook.is_null() {
let _: Box<Box<FnMut(Action, &str, &str, i64)>> = unsafe { Box::from_raw(hook as *mut _) };
// TODO make sure that size_of::<*mut F>() is always equal to size_of::<*mut c_void>()
let _: Box<*mut c_void> = unsafe { Box::from_raw(hook as *mut _) };
}
}