bam/record/data/field/value: Add byte reader

noodles-bam/src/record/data/field/value.rs

@@ -12,9 +12,9 @@ use self::array::decode_array;
 
 pub(crate) fn decode_value<'a>(src: &mut &'a [u8], ty: Type) -> io::Result<Value<'a>> {
     match ty {
-        Type::Character => decode_character(src),
-        Type::Int8 => decode_i8(src),
-        Type::UInt8 => decode_u8(src),
+        Type::Character => read_u8(src).map(Value::Character),
+        Type::Int8 => read_u8(src).map(|n| Value::Int8(n as i8)),
+        Type::UInt8 => read_u8(src).map(Value::UInt8),
         Type::Int16 => decode_i16(src),
         Type::UInt16 => decode_u16(src),
         Type::Int32 => decode_i32(src),
@@ -26,18 +26,6 @@ pub(crate) fn decode_value<'a>(src: &mut &'a [u8], ty: Type) -> io::Result<Value
     }
 }
 
-fn decode_character<'a>(src: &mut &'a [u8]) -> io::Result<Value<'a>> {
-    src.read_u8().map(Value::Character)
-}
-
-fn decode_i8<'a>(src: &mut &'a [u8]) -> io::Result<Value<'a>> {
-    src.read_i8().map(Value::Int8)
-}
-
-fn decode_u8<'a>(src: &mut &'a [u8]) -> io::Result<Value<'a>> {
-    src.read_u8().map(Value::UInt8)
-}
-
 fn decode_i16<'a>(src: &mut &'a [u8]) -> io::Result<Value<'a>> {
     src.read_i16::<LittleEndian>().map(Value::Int16)
 }
@@ -77,6 +65,16 @@ fn decode_hex<'a>(src: &mut &'a [u8]) -> io::Result<Value<'a>> {
     decode_string(src).map(Value::Hex)
 }
 
+fn read_u8(src: &mut &[u8]) -> io::Result<u8> {
+    let Some((n, rest)) = src.split_first() else {
+        return Err(io::Error::from(io::ErrorKind::UnexpectedEof));
+    };
+
+    *src = rest;
+
+    Ok(*n)
+}
+
 #[cfg(test)]
 mod tests {
     use noodles_sam::alignment::record::data::field::value::Array;