From 67d7885ef318e2008b635c9511d46b4c32c891f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Charlotte=20=F0=9F=A6=9D=20Delenk?= <lotte@chir.rs>
Date: Fri, 8 Jul 2022 15:42:32 +0100
Subject: [PATCH] add NonNull<T>

---
 lib/tinyptr/src/ptr/mod.rs      |   2 +
 lib/tinyptr/src/ptr/non_null.rs | 155 ++++++++++++++++++++++++++++++++
 2 files changed, 157 insertions(+)
 create mode 100644 lib/tinyptr/src/ptr/non_null.rs

diff --git a/lib/tinyptr/src/ptr/mod.rs b/lib/tinyptr/src/ptr/mod.rs
index 55e8033..4c42cec 100644
--- a/lib/tinyptr/src/ptr/mod.rs
+++ b/lib/tinyptr/src/ptr/mod.rs
@@ -5,3 +5,5 @@ mod const_ptr;
 pub use const_ptr::*;
 mod mut_ptr;
 pub use mut_ptr::*;
+mod non_null;
+pub use non_null::*;
diff --git a/lib/tinyptr/src/ptr/non_null.rs b/lib/tinyptr/src/ptr/non_null.rs
new file mode 100644
index 0000000..c178670
--- /dev/null
+++ b/lib/tinyptr/src/ptr/non_null.rs
@@ -0,0 +1,155 @@
+use core::{num::NonZeroU16, marker::{PhantomData, Unsize}, ops::CoerceUnsized, fmt, cmp::Ordering, hash};
+
+use crate::Pointable;
+
+use super::MutPtr;
+
+/// `*mut T` but non-zero and covariant
+pub struct NonNull<T: Pointable + ?Sized, const BASE: usize> {
+    pub(crate) ptr: NonZeroU16,
+    pub(crate) meta: <T as Pointable>::PointerMetaTiny,
+    pub(crate) _marker: PhantomData<MutPtr<T, BASE>>
+}
+
+impl<T: Pointable<PointerMetaTiny = ()> + Sized, const BASE: usize> NonNull<T, BASE> {
+    /// Creates a dangling but well-aligned `NonNull`
+    pub const fn dangling() -> Self {
+        // SAFE: align_of is never 0
+        unsafe {
+            Self::new_unchecked(MutPtr::from_raw_parts(core::mem::align_of::<T>() as u16, ()))
+        }
+    }
+    // TODO: as_uninit_ref
+    // TODO: as_uninit_mut
+}
+impl<T: Pointable + ?Sized, const BASE: usize> NonNull<T, BASE> {
+    pub const unsafe fn new_unchecked(ptr: MutPtr<T, BASE>) -> Self {
+        NonNull {
+            ptr: NonZeroU16::new_unchecked(ptr.ptr),
+            meta: ptr.meta,
+            _marker: PhantomData
+        }
+    }
+    pub const fn new(ptr: MutPtr<T, BASE>) -> Option<Self> {
+        if ptr.is_null() {
+            None
+        } else {
+            // SAFETY: Just checked for null
+            unsafe {
+                Some(Self::new_unchecked(ptr))
+            }
+        }
+    }
+    pub const fn from_raw_parts(
+        data_address: NonNull<(), BASE>,
+        metadata: <T as Pointable>::PointerMetaTiny
+    ) -> Self {
+        unsafe {
+            Self::new_unchecked(MutPtr::from_raw_parts(data_address.as_ptr().addr(), metadata))
+        }
+    }
+    pub const fn to_raw_parts(self) -> (NonNull<(), BASE>, <T as Pointable>::PointerMetaTiny) {
+        (self.cast(), self.meta)
+    }
+    pub const fn addr(self) -> NonZeroU16 {
+        self.ptr
+    }
+    pub const fn with_addr(self, addr: NonZeroU16) -> Self
+    where
+        T: Sized
+    {
+        Self {
+            ptr: addr,
+            meta: self.meta,
+            _marker: PhantomData
+        }
+    }
+    pub fn map_addr(self, f: impl FnOnce(NonZeroU16) -> NonZeroU16) -> Self
+    where T: Sized
+    {
+        self.with_addr(f(self.addr()))
+    }
+    pub const fn as_ptr(self) -> MutPtr<T, BASE> {
+        MutPtr::from_raw_parts(self.ptr.get(), self.meta)
+    }
+    // TODO: as_ref
+    // TODO: as_mut
+    pub const fn cast<U>(self) -> NonNull<U, BASE>
+    where U: Pointable<PointerMetaTiny = ()>
+    {
+        NonNull {
+            ptr: self.ptr,
+            meta: (),
+            _marker: PhantomData
+        }
+    }
+}
+
+impl<T: Pointable<PointerMetaTiny = ()>, const BASE: usize> NonNull<[T], BASE> {
+    pub const fn slice_from_raw_parts(data: NonNull<T, BASE>, len: u16) -> Self {
+        Self {
+            ptr: data.ptr,
+            meta: len,
+            _marker: PhantomData
+        }
+    }
+    pub const fn len(self) -> u16 {
+        self.meta
+    }
+    pub const fn as_non_null_ptr(self) -> NonNull<T, BASE> {
+        NonNull {
+            ptr: self.ptr,
+            meta: (),
+            _marker: PhantomData
+        }
+    }
+    pub const fn as_mut_ptr(self) -> MutPtr<T, BASE> {
+        self.as_non_null_ptr().as_ptr()
+    }
+    // TODO: as_uninit_slice
+    // TODO: as_uninit_slice_mut
+}
+
+impl<T: Pointable + ?Sized, const BASE: usize> Clone for NonNull<T, BASE> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<T: Pointable + ?Sized, const BASE: usize> Copy for NonNull<T, BASE> {}
+impl<T: Pointable + ?Sized, U: Pointable + ?Sized, const BASE: usize> CoerceUnsized<NonNull<U, BASE>> for NonNull<T, BASE> where T: Unsize<U>, <T as Pointable>::PointerMetaTiny: CoerceUnsized<<U as Pointable>::PointerMetaTiny> {}
+
+impl<T: Pointable + ?Sized, const BASE: usize> fmt::Debug for NonNull<T, BASE> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Pointer::fmt(&self.as_ptr(), f)
+    }
+}
+impl<T: Pointable + ?Sized, const BASE: usize> fmt::Pointer for NonNull<T, BASE> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Pointer::fmt(&self.as_ptr(), f)
+    }
+}
+impl<T: Pointable + ?Sized, const BASE: usize> Eq for NonNull<T, BASE> {}
+impl<T: Pointable + ?Sized, const BASE: usize> PartialEq for NonNull<T, BASE> {
+    fn eq(&self, other: &Self) -> bool {
+        self.as_ptr() == other.as_ptr()
+    }
+}
+impl<T: Pointable + ?Sized, const BASE: usize> Ord for NonNull<T, BASE> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.as_ptr().cmp(&other.as_ptr())
+    }
+}
+impl<T: Pointable + ?Sized, const BASE: usize> PartialOrd for NonNull<T, BASE> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.as_ptr().partial_cmp(&other.as_ptr())
+    }
+}
+impl<T: Pointable + ?Sized, const BASE: usize> hash::Hash for NonNull<T, BASE> {
+    fn hash<H: hash::Hasher>(&self, state: &mut H) {
+        self.as_ptr().hash(state)
+    }
+}
+// TODO: From<Unique<T>>
+// TODO: From<RefMut<T>>
+// TODO: From<Ref<T>>