const generics

src/hasher.rs

@@ -41,7 +41,7 @@ pub trait Digest<const S: usize>:
         use unsigned_varint::io::read_u64;
 
         let size = read_u64(&mut r)?;
-        if size > S as u64 || size > u8::max_value() as u64 {
+        if size > S as u64 || size > u16::MAX as u64 {
             return Err(Error::InvalidSize(size));
         }
         let mut digest = [0; S];

src/hasher_impl.rs

@@ -5,7 +5,7 @@ use core::convert::TryFrom;
 macro_rules! derive_digest {
     ($name:ident) => {
         /// Multihash digest.
-        #[derive(Clone, Debug, Eq, Hash, PartialEq)]
+        #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
         pub struct $name<const S: usize>([u8; S]);
 
         impl<const S: usize> Default for $name<S> {
@@ -205,12 +205,10 @@ macro_rules! derive_hasher_sha {
 
             fn finalize(&self) -> Self::Digest {
                 use digest::Digest;
-                // TODO: this extra array seems excessive to convert from a generic array
-                let a = self.state.clone().finalize();
-                let b = a.as_slice();
+                let digest = self.state.clone().finalize();
                 let mut array = [0; $size];
-                array.copy_from_slice(b);
-                Self::Digest::from(array)
+                array.copy_from_slice(digest.as_slice());
+                array.into()
             }
 
             fn reset(&mut self) {
@@ -330,7 +328,7 @@ pub mod identity {
             use unsigned_varint::io::read_u64;
 
             let size = read_u64(&mut r)?;
-            if size > S as u64 || size > u8::max_value() as u64 {
+            if size > S as u64 || size > u16::MAX as u64 {
                 return Err(Error::InvalidSize(size));
             }
             let mut digest = [0; S];

src/multihash.rs

@@ -70,7 +70,7 @@ pub trait MultihashDigest<const S: usize>:
 /// ```
 #[cfg_attr(feature = "serde-codec", derive(serde::Deserialize))]
 #[cfg_attr(feature = "serde-codec", derive(serde::Serialize))]
-#[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
 pub struct Multihash<const S: usize> {
     /// The code of the Multihash.
     code: u64,
@@ -81,8 +81,6 @@ pub struct Multihash<const S: usize> {
     digest: [u8; S],
 }
 
-impl<const S: usize> Copy for Multihash<S> {}
-
 impl<const S: usize> Default for Multihash<S> {
     fn default() -> Self {
         Self {
@@ -249,7 +247,7 @@ where
     let code = read_u64(&mut r)?;
     let size = read_u64(&mut r)?;
 
-    if size > S as u64 || size > u8::MAX as u64 {
+    if size > S as u64 || size > u16::MAX as u64 {
         return Err(Error::InvalidSize(size));
     }