Fixed the slice code, too

therm_util/src/reader.rs

@@ -8,10 +8,10 @@ pub struct ByteReader<Rd> {
 
 #[test]
 fn reader_tests() {
-    assert!(ByteReader::from_vec(vec![0x00]).read_twip() == Ok(-32.0));
-    assert!(ByteReader::from_vec(vec![0x00]).read_prefix_int() == Ok(0x00));
-    assert!(ByteReader::from_vec(vec![0x7f]).read_prefix_int() == Ok(0x7f));
-    assert!(ByteReader::from_vec(vec![0x80,0xff]).read_prefix_int() == Ok(0xff));
+    assert!(ByteReader::from_slice(&[0x00]).read_twip() == Ok(-32.0));
+    assert!(ByteReader::from_slice(&[0x00]).read_prefix_int() == Ok(0x00));
+    assert!(ByteReader::from_slice(&[0x7f]).read_prefix_int() == Ok(0x7f));
+    assert!(ByteReader::from_slice(&[0x80,0xff]).read_prefix_int() == Ok(0xff));
 }
 
 const MK_OK: &'static Fn(io::Result<u8>) -> Option<u8> = &|s| s.ok();
@@ -44,9 +44,12 @@ impl ByteReader<vec::IntoIter<u8>> {
     }
 }
 
-impl<'a> ByteReader<slice::Iter<'a, u8>> {
+const DEREF: &'static Fn(&u8) -> u8 = &|s| *s;
+
+impl<'a> ByteReader<iter::Map<slice::Iter<'a, u8>, &'static Fn(&u8) -> u8>> {
+    /// Create a reader from a borrowed slice, with a copy on each access
     pub fn from_slice(lst: &'a [u8]) -> Self {
-        ByteReader { bytes: lst.iter() }
+        ByteReader { bytes: lst.iter().map(DEREF) }
     }
 }