# 🦞 Crawdad: ChaRActer-Wise Double-Array Dictionary
[](https://crates.io/crates/crawdad)
[](https://docs.rs/crawdad)

[](https://join.slack.com/t/daac-tools/shared_invite/zt-1pwwqbcz4-KxL95Nam9VinpPlzUpEGyA)
## Overview
Crawdad is a library of natural language dictionaries using character-wise double-array tries.
The implementation is optimized for strings of multibyte-characters,
and you can enjoy fast text processing on strings such as Japanese or Chinese.
For example, on a large Japanese dictionary of IPADIC+Neologd, Crawdad has a better time-space tradeoff than other Rust libraries.

The detailed experimental settings and other results are available on [Wiki](https://github.com/daac-tools/crawdad/wiki/Performance-Comparison).
### What can do
- **Key-value mapping**: Crawdad stores a set of string keys with mapping arbitrary integer values.
- **Exact match**: Crawdad supports a fast lookup for an input key.
- **Common prefix search**: Crawdad supports fast *common prefix search* that can be used to enumerate all keys appearing in a text.
### Data structures
Crawdad contains the two trie implementations:
- `crawdad::Trie` is a standard trie form that often provides the fastest queries.
- `crawdad::MpTrie` is a minimal-prefix trie form that is memory-efficient for long strings.
## Slack
We have a Slack workspace for developers and users to ask questions and discuss a variety of topics.
* https://daac-tools.slack.com/
* Please get an invitation from [here](https://join.slack.com/t/daac-tools/shared_invite/zt-1pwwqbcz4-KxL95Nam9VinpPlzUpEGyA).
## License
Licensed under either of
* Apache License, Version 2.0
([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license
([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
## Acknowledgment
The initial version of this software was developed by LegalOn Technologies, Inc.,
but not an officially supported LegalOn Technologies product.
## Contribution
See [the guidelines](./CONTRIBUTING.md).