add Rle CompressionScheme and tests

src/rle.rs

@@ -1,3 +1,37 @@
+use std::io::Read;
+
+use bitvec::{slice::BitSlice, vec::BitVec};
+
+use crate::CompressionScheme;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Rle;
+
+impl CompressionScheme for Rle {
+    type Header = ();
+
+    fn encode(src: &[u8], buf: &mut BitVec) -> Self::Header {
+        for Run { count, byte } in Encoder::new(src) {
+            // TODO: surely this can be expressed better
+            buf.extend_from_bitslice(BitSlice::<u8>::from_slice(&[count, byte]));
+        }
+    }
+
+    fn decode(src: &BitSlice, (): &Self::Header, buf: &mut Vec<u8>) {
+        #[allow(clippy::unbuffered_bytes)]
+        let mut bytes = src.bytes();
+        while let (Some(Ok(count)), Some(Ok(byte))) = (bytes.next(), bytes.next()) {
+            for _ in 0..count {
+                buf.push(byte);
+            }
+        }
+    }
+
+    fn header_size((): &Self::Header) -> usize {
+        0
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Run {
     pub count: u8,

src/test.rs

@@ -4,6 +4,12 @@ use crate::{CompressionScheme, Freq, Rle};
 
 #[allow(clippy::needless_pass_by_value)]
 #[quickcheck]
-fn freq_roundtrip(src: Vec<u8>) -> bool {
+fn roundtrip_freq(src: Vec<u8>) -> bool {
     Freq::idempotent_on(&src)
 }
+
+#[allow(clippy::needless_pass_by_value)]
+#[quickcheck]
+fn roundtrip_rle(src: Vec<u8>) -> bool {
+    Rle::idempotent_on(&src)
+}