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add proptests, and fix bugs found
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@ -22,3 +22,4 @@ bit-vec = "0.6.3"
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[dev-dependencies]
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criterion = { version = "0.4.0", features = ["html_reports"] }
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proptest = "1.0.0"
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76
src/lib.rs
76
src/lib.rs
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@ -102,6 +102,29 @@ impl Huffman {
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let mut tree: Vec<Rc<RefCell<Node>>> = Vec::with_capacity(priority_queue.len() * 2);
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// Handle case where the frequency table has only 1 value.
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if priority_queue.len() == 1 {
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let shared_node = priority_queue.pop().unwrap();
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let mut node = shared_node.borrow_mut();
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node.index = Some(tree.len());
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tree.push(shared_node.clone());
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let parent = Node {
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data: None,
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count: node.count,
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left: node.index,
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right: None,
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parent: None,
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index: Some(tree.len()),
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};
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node.parent = parent.index;
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let parent = Rc::new(RefCell::new(parent));
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tree.push(parent);
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}
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while priority_queue.len() > 1 {
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let shared_node1 = priority_queue.pop().unwrap();
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let shared_node2 = priority_queue.pop().unwrap();
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@ -159,6 +182,10 @@ impl Huffman {
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/// Compresses the provided data.
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pub fn compress(&self, data: &[u8]) -> Vec<u8> {
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if data.is_empty() {
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return Vec::new();
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}
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let mut bits = BitVec::new();
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for b in data.iter() {
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@ -167,7 +194,7 @@ impl Huffman {
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*self
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.indexes
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.get(b)
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.expect("frequency table did not contain this byte"),
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.unwrap_or_else(|| panic!("frequency table did not contain this byte: {:?}", b)),
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None,
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)
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}
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@ -177,6 +204,10 @@ impl Huffman {
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/// Decompresses the provided data.
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pub fn decompress(&self, data: &[u8]) -> Vec<u8> {
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if data.is_empty() {
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return Vec::new();
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}
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let bits = BitVec::from_bytes(data);
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let mut decompressed = Vec::with_capacity(bits.len() * 2);
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let root_index = self.tree.len() - 1;
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@ -187,7 +218,7 @@ impl Huffman {
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for _ in 0..byte_count {
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let mut index = root_index;
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while self.tree[index].right.is_some() {
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while self.tree[index].left.is_some() ||self.tree[index].right.is_some() {
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let bit = bits_iter.next().expect("missing data");
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if bit {
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index = self.tree[index].left.expect("should have left index");
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@ -206,6 +237,7 @@ impl Huffman {
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#[cfg(test)]
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mod tests {
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use super::*;
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use proptest::prelude::*;
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#[test]
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fn compress_decompress() {
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@ -230,4 +262,44 @@ mod tests {
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assert!(compressed.len() < payload.len());
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assert_eq!(&payload[..], decompressed)
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}
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#[test]
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fn create_freq_table() {
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let table = Huffman::calculate_freq_table(&[0]);
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assert_eq!(table.len(), 1);
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assert_eq!(*table.get(&0).unwrap(), 1);
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let table = Huffman::calculate_freq_table(&[0,1,2,2,3,3,3]);
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assert_eq!(table.len(), 4);
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assert_eq!(*table.get(&0).unwrap(), 1);
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assert_eq!(*table.get(&1).unwrap(), 1);
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assert_eq!(*table.get(&2).unwrap(), 2);
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assert_eq!(*table.get(&3).unwrap(), 3);
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}
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#[test]
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fn test_payload_size_1() {
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let payload = &[0u8];
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let huffman = Huffman::new_from_data(payload);
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let compressed = huffman.compress(payload);
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let decompressed = huffman.decompress(&compressed);
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assert_eq!(&payload[..], decompressed)
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}
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proptest! {
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#[test]
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fn proptest_compress_decompress(data: Vec<u8>) {
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let huffman = Huffman::new_from_data(&data);
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let compressed = huffman.compress(&data);
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let decompressed = huffman.decompress(&compressed);
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prop_assert!(compressed.len() <= data.len());
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prop_assert_eq!(data, decompressed);
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}
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}
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}
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