Merge pull request #58 from Luro02/const_generics

Use const-generics to implement FromHex trait

src/lib.rs

@@ -196,44 +196,15 @@ impl FromHex for Vec<u8> {
     }
 }
 
-// Helper macro to implement the trait for a few fixed sized arrays. Once Rust
-// has type level integers, this should be removed.
-macro_rules! from_hex_array_impl {
-    ($($len:expr)+) => {$(
-        impl FromHex for [u8; $len] {
-            type Error = FromHexError;
-
-            fn from_hex<T: AsRef<[u8]>>(hex: T) -> Result<Self, Self::Error> {
-                let mut out = [0_u8; $len];
-                decode_to_slice(hex, &mut out as &mut [u8])?;
-                Ok(out)
-            }
-        }
-    )+}
-}
-
-from_hex_array_impl! {
-    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
-    17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
-    33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
-    49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
-    65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
-    81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96
-    97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
-    113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128
-    160 192 200 224 256 384 512 768 1024 2048 4096 8192 16384 32768
-}
+impl<const N: usize> FromHex for [u8; N] {
+    type Error = FromHexError;
 
-#[cfg(any(target_pointer_width = "32", target_pointer_width = "64"))]
-from_hex_array_impl! {
-    65536 131072 262144 524288 1048576 2097152 4194304 8388608
-    16777216 33554432 67108864 134217728 268435456 536870912
-    1073741824 2147483648
-}
+    fn from_hex<T: AsRef<[u8]>>(hex: T) -> Result<Self, Self::Error> {
+        let mut out = [0_u8; N];
+        decode_to_slice(hex, &mut out as &mut [u8])?;
 
-#[cfg(target_pointer_width = "64")]
-from_hex_array_impl! {
-    4294967296
+        Ok(out)
+    }
 }
 
 /// Encodes `data` as hex string using lowercase characters.