Add support for [T] and &[mut] [T]

Author: HadrienG2

src/lib.rs

@@ -429,19 +429,37 @@ tuple_abomonate!(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA AB AC AD
 tuple_abomonate!(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA AB AC AD AE);
 tuple_abomonate!(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA AB AC AD AE AF);
 
+unsafe impl<T: Abomonation> Abomonation for [T] {
+    unsafe fn entomb<W: Write>(&self, write: &mut W) ->  IOResult<()> {
+        for element in self { T::entomb(element, write)?; }
+        Ok(())
+    }
+
+    unsafe fn exhume<'a>(self_: NonNull<Self>, bytes: &'a mut[u8]) -> Option<&'a mut [u8]> {
+        // FIXME: This constructs an &[T] to invalid data, which is UB.
+        //        I'm not sure if this can be fully resolved without relying on slice implementation details.
+        let self_len = self_.as_ref().len();
+        exhume_slice(self_.as_ptr() as *mut T, self_len, bytes)
+    }
+
+    fn extent(&self) -> usize {
+        self.iter().map(T::extent).sum()
+    }
+}
+
 macro_rules! array_abomonate {
     ($size:expr) => (
         unsafe impl<T: Abomonation> Abomonation for [T; $size] {
             unsafe fn entomb<W: Write>(&self, write: &mut W) ->  IOResult<()> {
-                entomb_slice(&self[..], write)
+                <[T]>::entomb(&self[..], write)
             }
 
             unsafe fn exhume<'a>(self_: NonNull<Self>, bytes: &'a mut[u8]) -> Option<&'a mut [u8]> {
                 exhume_slice(self_.as_ptr() as *mut T, $size, bytes)
             }
 
             fn extent(&self) -> usize {
-                slice_extent(&self[..])
+                <[T]>::extent(&self[..])
             }
         }
     )
@@ -541,30 +559,64 @@ unsafe impl Abomonation for String {
     }
 }
 
-unsafe impl<T: Abomonation> Abomonation for Vec<T> {
+unsafe impl<T: Abomonation> Abomonation for &'_ [T] {
     unsafe fn entomb<W: Write>(&self, write: &mut W) -> IOResult<()> {
         write.write_all(typed_to_bytes(&self[..]))?;
-        entomb_slice(&self[..], write)
+        <[T]>::entomb(&self[..], write)
+    }
+
+    #[inline]
+    unsafe fn exhume<'a>(self_: NonNull<Self>, bytes: &'a mut [u8]) -> Option<&'a mut [u8]> {
+        // FIXME: This (briefly) constructs an &[T] to invalid data, which is UB.
+        //        I'm not sure if this can be fully resolved without relying on slice implementation details.
+        let self_len = self_.as_ref().len();
+        let (s, rest) = exhume_slice_ref(self_len, bytes)?;
+        self_.as_ptr().write(s.as_ref());
+        Some(rest)
+    }
+
+    fn extent(&self) -> usize {
+        mem::size_of::<T>() * self.len() + <[T]>::extent(&self[..])
+    }
+}
+
+unsafe impl<T: Abomonation> Abomonation for &'_ mut [T] {
+    unsafe fn entomb<W: Write>(&self, write: &mut W) -> IOResult<()> {
+        <&[T]>::entomb(&&self[..], write)
+    }
+
+    #[inline]
+    unsafe fn exhume<'a>(self_: NonNull<Self>, bytes: &'a mut [u8]) -> Option<&'a mut [u8]> {
+        // FIXME: This (briefly) constructs an &mut [T] to invalid data, which is UB.
+        //        I'm not sure if this can be fully resolved without relying on slice implementation details.
+        let self_len = self_.as_ref().len();
+        let (mut s, rest) = exhume_slice_ref(self_len, bytes)?;
+        self_.as_ptr().write(s.as_mut());
+        Some(rest)
+    }
+
+    fn extent(&self) -> usize {
+        <&[T]>::extent(&&self[..])
+    }
+}
+
+unsafe impl<T: Abomonation> Abomonation for Vec<T> {
+    unsafe fn entomb<W: Write>(&self, write: &mut W) -> IOResult<()> {
+        <&[T]>::entomb(&&self[..], write)
     }
 
     #[inline]
     unsafe fn exhume<'a>(self_: NonNull<Self>, bytes: &'a mut [u8]) -> Option<&'a mut [u8]> {
         // FIXME: This (briefly) constructs an &Vec<T> to invalid data, which is UB.
         //        I'm not sure if this can be fully resolved without relying on Vec implementation details.
         let self_len = self_.as_ref().len();
-        let binary_len = self_len * mem::size_of::<T>();
-        if binary_len > bytes.len() { None }
-        else {
-            let (mine, mut rest) = bytes.split_at_mut(binary_len);
-            let first_ptr = mine.as_mut_ptr() as *mut T;
-            rest = exhume_slice(first_ptr, self_len, rest)?;
-            self_.as_ptr().write(Vec::from_raw_parts(first_ptr, self_len, self_len));
-            Some(rest)
-        }
+        let (mut s, rest) = exhume_slice_ref(self_len, bytes)?;
+        self_.as_ptr().write(Vec::from_raw_parts(s.as_mut().as_mut_ptr(), self_len, self_len));
+        Some(rest)
     }
 
     fn extent(&self) -> usize {
-        mem::size_of::<T>() * self.len() + slice_extent(&self[..])
+        <&[T]>::extent(&&self[..])
     }
 }
 
@@ -622,14 +674,8 @@ unsafe fn typed_to_bytes<T>(slice: &[T]) -> &[u8] {
     std::slice::from_raw_parts(slice.as_ptr() as *const u8, slice.len() * mem::size_of::<T>())
 }
 
-// Common subset of "entomb" for all [T]-like types
-unsafe fn entomb_slice<T: Abomonation, W: Write>(slice: &[T], write: &mut W) ->  IOResult<()> {
-    for element in slice { T::entomb(element, write)?; }
-    Ok(())
-}
-
 // Common subset of "exhume" for all [T]-like types
-// (I'd gladly take a NonNull<[T]>, but it is too difficult to build raw pointers to slices)
+// (I'd gladly move this to [T]::extent, but building a NonNull<[T]> is currently too difficult)
 #[inline]
 unsafe fn exhume_slice<'a, T: Abomonation>(first_ptr: *mut T, length: usize, mut bytes: &'a mut [u8]) -> Option<&'a mut [u8]> {
     for i in 0..length {
@@ -639,9 +685,17 @@ unsafe fn exhume_slice<'a, T: Abomonation>(first_ptr: *mut T, length: usize, mut
     Some(bytes)
 }
 
-// Common subset of "extent" for all [T]-like types
-fn slice_extent<T: Abomonation>(slice: &[T]) -> usize {
-    slice.iter().map(T::extent).sum()
+// Common subset of "exhume" for all &[T]-like types
+#[inline]
+unsafe fn exhume_slice_ref<'a, T:Abomonation>(length: usize, bytes: &'a mut [u8]) -> Option<(NonNull<[T]>, &'a mut [u8])> {
+    let binary_len = length * mem::size_of::<T>();
+    if binary_len > bytes.len() { None }
+    else {
+        let (mine, mut rest) = bytes.split_at_mut(binary_len);
+        let first_ptr = mine.as_mut_ptr() as *mut T;
+        rest = exhume_slice(first_ptr, length, rest)?;
+        Some((std::slice::from_raw_parts_mut(first_ptr, length).into(), rest))
+    }
 }
 
 // Common subset of "exhume" for all NonNull<T>-like types

tests/tests.rs

@@ -17,13 +17,15 @@ use std::fmt::Debug;
 #[test] fn test_vec_u_s_pass() { _test_pass(vec![vec![(0u64, format!("grawwwwrr!")); 32]; 32]); }
 #[test] fn test_ref_u64_pass() { _test_pass(vec![Some(&42u64); 1024]); }
 #[test] fn test_str_pass() { _test_pass(vec![&"grawwwwrr!"; 1024]); }
+#[test] fn test_slice_pass() { _test_pass(vec![&[0, 1, 2]; 1024]); }
 
 #[test] fn test_u64_fail() { _test_fail(vec![0u64; 1024]); }
 #[test] fn test_u128_fail() { _test_fail(vec![0u128; 1024]); }
 #[test] fn test_string_fail() { _test_fail(vec![format!("grawwwwrr!"); 1024]); }
 #[test] fn test_vec_u_s_fail() { _test_fail(vec![vec![(0u64, format!("grawwwwrr!")); 32]; 32]); }
 #[test] fn test_ref_u64_fail() { _test_fail(vec![Some(&42u64); 1024]); }
 #[test] fn test_str_fail() { _test_fail(vec![&"grawwwwrr!"; 1024]); }
+#[test] fn test_slice_fail() { _test_fail(vec![&[0, 1, 2]; 1024]); }
 
 #[test] fn test_array_size() { _test_size(vec![[0, 1, 2]; 1024]); }
 #[test] fn test_opt_vec_size() { _test_size(vec![Some(vec![0,1,2]), None]); }
@@ -38,6 +40,7 @@ use std::fmt::Debug;
 #[test] fn test_vec_u_s_size() { _test_size(vec![vec![(0u64, format!("grawwwwrr!")); 32]; 32]); }
 #[test] fn test_ref_u64_size() { _test_size(vec![Some(&42u64); 1024]); }
 #[test] fn test_str_size() { _test_size(vec![&"grawwwwrr!"; 1024]); }
+#[test] fn test_slice_size() { _test_fail(vec![&[0, 1, 2]; 1024]); }
 
 #[test]
 fn test_phantom_data_for_non_abomonatable_type() {