From 272b2004027e50d3d913290ff8d5a3b4a46d574d Mon Sep 17 00:00:00 2001
From: Jorge Leitao <jorgecarleitao@gmail.com>
Date: Wed, 29 Sep 2021 08:06:53 +0100
Subject: [PATCH] Fixed error in reading zero-width bit from hybrid RLE. (#53)

---
 src/encoding/hybrid_rle/decoder.rs |  1 +
 src/encoding/hybrid_rle/mod.rs     | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/encoding/hybrid_rle/decoder.rs b/src/encoding/hybrid_rle/decoder.rs
index 8b240ff5e..403b1f0bb 100644
--- a/src/encoding/hybrid_rle/decoder.rs
+++ b/src/encoding/hybrid_rle/decoder.rs
@@ -14,6 +14,7 @@ impl<'a> Decoder<'a> {
     }
 
     /// Returns the number of bits being used by this decoder.
+    #[inline]
     pub fn num_bits(&self) -> u32 {
         self.num_bits
     }
diff --git a/src/encoding/hybrid_rle/mod.rs b/src/encoding/hybrid_rle/mod.rs
index 30c72b957..38b1e2a73 100644
--- a/src/encoding/hybrid_rle/mod.rs
+++ b/src/encoding/hybrid_rle/mod.rs
@@ -18,6 +18,7 @@ pub enum HybridEncoded<'a> {
 }
 
 enum State<'a> {
+    None,
     Bitpacked(bitpacking::Decoder<'a>),
     Rle(std::iter::Take<std::iter::Repeat<u32>>),
 }
@@ -29,7 +30,12 @@ pub struct HybridRleDecoder<'a> {
     remaining: usize,
 }
 
+#[inline]
 fn read_next<'a, 'b>(decoder: &'b mut Decoder<'a>, remaining: usize) -> State<'a> {
+    if decoder.num_bits() == 0 {
+        return State::None;
+    };
+
     let state = decoder.next().unwrap();
     match state {
         HybridEncoded::Bitpacked(packed) => {
@@ -71,6 +77,7 @@ impl<'a> Iterator for HybridRleDecoder<'a> {
         let result = match &mut self.state {
             State::Bitpacked(decoder) => decoder.next(),
             State::Rle(iter) => iter.next(),
+            State::None => Some(0),
         };
         if let Some(result) = result {
             self.remaining -= 1;
@@ -203,4 +210,17 @@ mod tests {
 
         assert_eq!(result, &[2]);
     }
+
+    #[test]
+    fn zero_bit_width() {
+        let data = vec![3];
+
+        let num_bits = 0;
+
+        let decoder = HybridRleDecoder::new(&data, num_bits as u32, 2);
+
+        let result = decoder.collect::<Vec<_>>();
+
+        assert_eq!(result, &[0, 0]);
+    }
 }