Updating from_hex to accept a &str instead of an ArrayString

2 files changed, 13 insertions, 11 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 71f5206..2db7476 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -177,12 +177,18 @@ impl Hash {
         s
     }
 
-    /// Parse a fixed-length hexidecimal string and return the resulting Hash.
+    /// Parse a hexidecimal string and return the resulting Hash.
     ///
-    /// [`ArrayString`]: https://docs.rs/arrayvec/0.5.1/arrayvec/struct.ArrayString.html
-    pub fn from_hex(hex: ArrayString<[u8; 2 * OUT_LEN]>) -> Result<Self, ParseError> {
+    /// The string must be 64 characters long, producting a 32 byte digest.
+    /// All other string length will return a `ParseError::InvalidLen`.
+    pub fn from_hex(hex: &str) -> Result<Self, ParseError> {
+        let str_bytes = hex.as_bytes();
+        if str_bytes.len() != OUT_LEN * 2 {
+            return Err(ParseError::InvalidLen);
+        }
+
         let mut bytes: [u8; OUT_LEN] = [0; OUT_LEN];
-        for (i, pair) in hex.as_str().as_bytes().chunks(2).enumerate() {
+        for (i, pair) in str_bytes.chunks(2).enumerate() {
             bytes[i] = hex_val(pair[0])? << 4 | hex_val(pair[1])?;
         }
 
@@ -217,9 +223,7 @@ impl core::str::FromStr for Hash {
     type Err = ParseError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let string =
-            ArrayString::<[u8; OUT_LEN * 2]>::from(s).map_err(|_| ParseError::InvalidLen)?;
-        Hash::from_hex(string)
+        Hash::from_hex(s)
     }
 }
 
diff --git a/src/test.rs b/src/test.rs
index d1f73a9..6883c91 100644
--- a/src/test.rs
+++ b/src/test.rs
@@ -459,12 +459,10 @@ fn test_hex_encoding_decoding() {
     assert_eq!(digest.to_hex().as_str(), digest_str);
 
     // Test round trip
-    let input = arrayvec::ArrayString::from(digest_str).unwrap();
-    assert_eq!(digest.to_hex().as_str(), digest_str);
-    let digest = crate::Hash::from_hex(input).unwrap();
+    let digest = crate::Hash::from_hex(digest_str).unwrap();
     assert_eq!(digest.to_hex().as_str(), digest_str);
 
-    // Test string parsing
+    // Test string parsing via FromStr
     let digest: crate::Hash = digest_str.parse().unwrap();
     assert_eq!(digest.to_hex().as_str(), digest_str);
 }