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use std::fmt;
use std::hash::{Hash, Hasher};
use std::marker::PhantomData;
use std::mem::{size_of, uninitialized};
pub struct TagWrapper<V: ?Sized, TM>(PhantomData<TM>, pub V);
impl<TM, V: Clone> Clone for TagWrapper<V, TM> {
fn clone(&self) -> Self {
TagWrapper(PhantomData, self.1.clone())
}
fn clone_from(&mut self, source: &Self) {
self.1.clone_from(&source.1)
}
}
impl<TM, V: Copy> Copy for TagWrapper<V, TM> {}
impl<TM, V: fmt::Debug> fmt::Debug for TagWrapper<V, TM> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{:?}", self.1)
}
}
impl<TM, V: Hash> Hash for TagWrapper<V, TM> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.1.hash(state);
}
}
pub trait TagOptions: Copy+Eq+fmt::Debug {}
#[derive(Clone,Copy,Debug,PartialEq,Eq,PartialOrd,Ord,Hash)]
pub enum One {
Untagged,
Tagged,
}
impl TagOptions for One {}
#[derive(Clone,Copy,Debug,PartialEq,Eq,PartialOrd,Ord,Hash)]
pub enum Two {
Option0,
Option1,
}
impl TagOptions for Two {}
pub unsafe trait TaggableValue<TM, Count: TagOptions> {
#[inline]
fn untag(v: TagWrapper<Self, TM>) -> Self;
#[inline]
fn untag_in_place(v: &mut TagWrapper<Self, TM>);
#[inline]
fn get_tag(v: &TagWrapper<Self, TM>) -> Count;
#[inline]
fn tag(v: Self, o: Count) -> TagWrapper<Self, TM>;
#[inline]
fn tag_in_place(v: &mut TagWrapper<Self, TM>, o: Count);
#[inline]
fn change_tag(v: &mut TagWrapper<Self, TM>, o: Count);
#[inline]
unsafe fn uninitialized_from_tag(o: Count) -> TagWrapper<Self, TM>;
#[inline]
fn fmt_untagged(v: &TagWrapper<Self, TM>, f: &mut fmt::Formatter) -> fmt::Result
where Self: fmt::Debug;
#[inline]
fn eq(a: &TagWrapper<Self, TM>, b: &TagWrapper<Self, TM>) -> bool
where Self: PartialEq;
#[inline]
fn ne(a: &TagWrapper<Self, TM>, b: &TagWrapper<Self, TM>) -> bool
where Self: PartialEq;
}
pub unsafe trait UntaggedZero<TM, Count: TagOptions>: TaggableValue<TM, Count> {}
unsafe impl<T, TM> TaggableValue<TM, One> for T
where T: UntaggedZero<TM, Two> {
#[inline]
fn untag(v: TagWrapper<T, TM>) -> T {
TaggableValue::<TM, Two>::untag(v)
}
#[inline]
fn untag_in_place(v: &mut TagWrapper<T, TM>) {
TaggableValue::<TM, Two>::untag_in_place(v)
}
#[inline]
fn get_tag(v: &TagWrapper<T, TM>) -> One {
match TaggableValue::<TM, Two>::get_tag(v) {
Two::Option0 => One::Untagged,
Two::Option1 => One::Tagged,
}
}
#[inline]
fn tag(v: Self, o: One) -> TagWrapper<T, TM> {
let o = match o {
One::Untagged => Two::Option0,
One::Tagged => Two::Option1,
};
TaggableValue::<TM, Two>::tag(v, o)
}
#[inline]
fn tag_in_place(v: &mut TagWrapper<T, TM>, o: One) {
let o = match o {
One::Untagged => Two::Option0,
One::Tagged => Two::Option1,
};
TaggableValue::<TM, Two>::tag_in_place(v, o)
}
#[inline]
fn change_tag(v: &mut TagWrapper<T, TM>, o: One) {
let o = match o {
One::Untagged => Two::Option0,
One::Tagged => Two::Option1,
};
TaggableValue::<TM, Two>::change_tag(v, o)
}
#[inline]
unsafe fn uninitialized_from_tag(o: One) -> TagWrapper<T, TM> {
let o = match o {
One::Untagged => Two::Option0,
One::Tagged => Two::Option1,
};
TaggableValue::<TM, Two>::uninitialized_from_tag(o)
}
#[inline]
fn fmt_untagged(v: &TagWrapper<T, TM>, f: &mut fmt::Formatter) -> fmt::Result
where Self: fmt::Debug {
TaggableValue::<TM, Two>::fmt_untagged(v, f)
}
#[inline]
fn eq(a: &TagWrapper<T, TM>, b: &TagWrapper<T, TM>) -> bool
where Self: PartialEq {
TaggableValue::<TM, Two>::eq(a, b)
}
#[inline]
fn ne(a: &TagWrapper<T, TM>, b: &TagWrapper<T, TM>) -> bool
where Self: PartialEq {
TaggableValue::<TM, Two>::ne(a, b)
}
}
#[derive(Clone,Copy,Debug,PartialEq,Eq,PartialOrd,Ord,Hash)]
pub struct TagMSB;
macro_rules! msb_set { ($t:ty) => {1 << (8*size_of::<$t>() - 1)} }
macro_rules! tag_msb { ($($t:ty)+) => {$(
unsafe impl UntaggedZero<TagMSB, Two> for $t{}
unsafe impl TaggableValue<TagMSB, Two> for $t {
#[inline]
fn untag(v: TagWrapper<$t, TagMSB>) -> $t { v.1 & !msb_set!($t) }
#[inline]
fn untag_in_place(v: &mut TagWrapper<$t, TagMSB>) { v.1 &= !msb_set!($t) }
#[inline]
fn get_tag(v: &TagWrapper<$t, TagMSB>) -> Two {
if v.1 < msb_set!($t) { Two::Option0 } else { Two::Option1 }
}
#[inline]
fn tag(v: Self, o: Two) -> TagWrapper<$t, TagMSB> {
match o {
Two::Option0 => TagWrapper(PhantomData, v & !msb_set!($t)),
Two::Option1 => TagWrapper(PhantomData, v | msb_set!($t)),
}
}
#[inline]
fn tag_in_place(v: &mut TagWrapper<$t, TagMSB>, o: Two) {
match o {
Two::Option0 => v.1 &= !msb_set!($t),
Two::Option1 => v.1 |= msb_set!($t),
}
}
#[inline]
fn change_tag(v: &mut TagWrapper<$t, TagMSB>, o: Two) {
Self::tag_in_place(v, o)
}
#[inline]
unsafe fn uninitialized_from_tag(o: Two) -> TagWrapper<$t, TagMSB> {
Self::tag(uninitialized(), o)
}
#[inline]
fn fmt_untagged(v: &TagWrapper<$t, TagMSB>, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{:?}", TaggableValue::<TagMSB, Two>::untag(*v))
}
#[inline]
fn eq(a: &TagWrapper<$t, TagMSB>, b: &TagWrapper<$t, TagMSB>) -> bool { a.1.eq(&b.1) }
#[inline]
fn ne(a: &TagWrapper<$t, TagMSB>, b: &TagWrapper<$t, TagMSB>) -> bool { a.1.ne(&b.1) }
}
)+}}
tag_msb!{u8 u16 u32 u64 usize}