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use core::{ fmt, mem };
use core::cmp::{ self, Ordering };
use memsec::{ memeq, memcmp };
pub struct CmpKey<T: ?Sized + 'static>(pub T);
impl<T: ?Sized> CmpKey<T> {
pub fn from(t: &T) -> &CmpKey<T> {
unsafe { mem::transmute(t) }
}
}
impl<T: ?Sized> fmt::Debug for CmpKey<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("CmpKey")
.field(&format_args!("{:p}", &self.0))
.finish()
}
}
impl<T: ?Sized> PartialEq<T> for CmpKey<T> {
fn eq(&self, rhs: &T) -> bool {
let len1 = mem::size_of_val(&self.0);
let len2 = mem::size_of_val(rhs);
let r = unsafe { memeq(
&self.0 as *const T as *const u8,
rhs as *const T as *const u8,
cmp::min(len1, len2)
) };
len1 == len2 && r
}
}
impl<T: ?Sized> PartialEq<CmpKey<T>> for CmpKey<T> {
fn eq(&self, &CmpKey(ref rhs): &CmpKey<T>) -> bool {
self.eq(rhs)
}
}
impl<T: ?Sized> Eq for CmpKey<T> {}
impl<T: ?Sized> PartialOrd<T> for CmpKey<T> {
fn partial_cmp(&self, rhs: &T) -> Option<Ordering> {
self.partial_cmp(CmpKey::from(rhs))
}
}
impl<T: ?Sized> PartialOrd<CmpKey<T>> for CmpKey<T> {
fn partial_cmp(&self, rhs: &CmpKey<T>) -> Option<Ordering> {
Some(self.cmp(rhs))
}
}
impl<T: ?Sized> Ord for CmpKey<T> {
fn cmp(&self, &CmpKey(ref rhs): &CmpKey<T>) -> Ordering {
let len1 = mem::size_of_val(&self.0);
let len2 = mem::size_of_val(rhs);
let order = unsafe { memcmp(
&self.0 as *const T as *const u8,
rhs as *const T as *const u8,
cmp::min(len1, len2))
};
let r = len1.cmp(&len2);
match order.cmp(&0) {
Ordering::Equal => r,
order => order
}
}
}