Relative-Lempel Ziv (RLZ) Crates.io Docs.rs MIT licensed

A Relative-Lempel Ziv (RLZ) based LZ compressor that compresses against a large static dictionary.

This code implements the RLZ compressor, as described in:

bibtex @article{DBLP:journals/pvldb/HoobinPZ11, author = {Christopher Hoobin and Simon J. Puglisi and Justin Zobel}, title = {Relative Lempel-Ziv Factorization for Efficient Storage and Retrieval of Web Collections}, journal = {Proc. {VLDB} Endow.}, volume = {5}, number = {3}, pages = {265--273}, year = {2011}, }

bibtex @article{DBLP:journals/corr/PetriMNW16, author = {Matthias Petri and Alistair Moffat and P. C. Nagesh and Anthony Wirth}, title = {Access Time Tradeoffs in Archive Compression}, journal = {CoRR}, volume = {abs/1602.08829}, year = {2016}, url = {http://arxiv.org/abs/1602.08829}, eprinttype = {arXiv}, }

bibtex @inproceedings{DBLP:conf/www/LiaoPMW16, author = {Kewen Liao and Matthias Petri and Alistair Moffat and Anthony Wirth}, title = {Effective Construction of Relative Lempel-Ziv Dictionaries}, booktitle = {Proceedings of the 25th International Conference on World Wide Web, {WWW} 2016, Montreal, Canada, April 11 - 15, 2016}, }

What is RLZ (taken from the paper)

The Relative Lempel-Ziv (RLZ) scheme is a hybrid of several phrase-based compression mechanisms. Encoding is based on a fixed-text dictionary, with all substrings within the dictionary available for use as factors, in the style of LZ77. But the dictionary is constructed in a semi-static manner, and hence needs to be representative of the entire text being coded if compression effectiveness is not to be compromised. Furthermore, because RLZ is intended for large web-based archives when constructing the dictionary, it is infeasible to have the whole input text in memory.

Usage

```rust use rlz::RlzCompressor;

let dict = Dictionary::from(b"banana");

let rlzcompressor = RlzCompressor::builder().buildfrom_dict(dict);

let mut output = Vec::new();

let encodedlen = rlzcompressor.encode(&text[..],&mut output)?; asserteq!(encodedlen,output.len());

let mut storeddecoder = Vec::new(); rlzcompressor.store(&mut stored_decoder)?;

let loadeddecoder = RlzCompressor::load(&storeddecoder[..])?;

let mut recovered = Vec::new(); loaded_decoder.decode(&output[..],&mut recovered)?;

assert_eq!(recovered,text); ```

License

MIT