# trie-rs

KV capable prefix trie library based on LOUDS.

This is a fork of https://laysakura.github.io/trie-rs/trie_rs.

## Quickstart

To use trie-rs, add the following to your `Cargo.toml` file:

```toml
[dependencies]
trie-rs = "0.1"  # NOTE: Replace to latest minor version.
```

### Usage Overview
```rust
use std::str;
use trie_rs::TrieBuilder;

let mut builder = TrieBuilder::new();  // Inferred `TrieBuilder<u8>` automatically
builder.push("すし", 1);
builder.push("すしや", 2);
builder.push("すしだね", 3);
builder.push("すしづめ", 4);
builder.push("すしめし", 5);
builder.push("すしをにぎる", 6);
builder.push("すし", 7);  // Word `push`ed twice is just ignored.
builder.push("🍣", 8);

let mut trie = builder.build();

// exact_match(): Find a word exactly match to query.
assert_eq!(trie.exact_match("すし"), true);
assert_eq!(trie.exact_match("🍣"), true);
assert_eq!(trie.exact_match("🍜"), false);

// predictive_search(): Find words which include `query` as their prefix.
let results_in_u8s: Vec<Vec<u8>> = trie.predictive_search("すし");
let results_in_str: Vec<&str> = results_in_u8s
    .iter()
    .map(|u8s| str::from_utf8(u8s).unwrap())
    .collect();
assert_eq!(
    results_in_str,
    vec![
        "すし",
        "すしだね",
        "すしづめ",
        "すしめし",
        "すしや",
        "すしをにぎる"
    ]  // Sorted by `Vec<u8>`'s order
);

// common_prefix_search(): Find words which is included in `query`'s prefix.
let results_in_u8s: Vec<Vec<u8>> = trie.common_prefix_search("すしや");
let results_in_str: Vec<&str> = results_in_u8s
    .iter()
    .map(|u8s| str::from_utf8(u8s).unwrap())
    .collect();
assert_eq!(
    results_in_str,
    vec![
        "すし",
        "すしや",
    ]  // Sorted by `Vec<u8>`'s order
);

// common_prefix_search_with_value(): Find words which is included in `query`'s prefix and return their values.
let results_in_u8s: Vec<(Vec<u8>, u8)> = trie.common_prefix_search_with_values("すしや");
let results_in_str: Vec<(&str, u8)> = results_in_u8s
   .iter()
   .map(|(u8s, v)| (str::from_utf8(u8s).unwrap(), *v))
   .collect();

   assert_eq!(
   results_in_str,
   vec![
   ("すし", 1),
   ("すしや", 2),
   ]  // Sorted by `Vec<u8>`'s order
   );

// get_value(): Get value of a word.
assert_eq!(trie.get("すし"), Some(&1));

// set value in a built trie.
trie.set("すし", 9);
assert_eq!(trie.get("すし"), Some(&9));

```

### Using with Various Data Types
`TrieBuilder` is implemented using generic type like following:

```
impl<Label: Ord + Clone> TrieBuilder<Label> {
    ...
    pub fn push<Arr: AsRef<[Label]>>(&mut self, word: Arr) { ... }
    ...
}
```

In the above `Usage Overview` example, we used `Label=u8, Arr=&str`.

Here shows other `Label` and `Arr` type examples.

#### `Label=&str, Arr=Vec<&str>`
Say `Label` is English words and `Arr` is English phrases.

```rust
use trie_rs::TrieBuilder;

let mut builder = TrieBuilder::new();
builder.push(vec!["a", "woman"], 0 );
builder.push(vec!["a", "woman", "on", "the", "beach"], 1);
builder.push(vec!["a", "woman", "on", "the", "run"], 2);

let trie = builder.build();

assert_eq!(
    trie.exact_match(vec!["a", "woman", "on", "the", "beach"]),
    true
);
assert_eq!(
    trie.predictive_search(vec!["a", "woman", "on"]),
    vec![
        ["a", "woman", "on", "the", "beach"],
        ["a", "woman", "on", "the", "run"],
    ],
);
assert_eq!(
    trie.common_prefix_search(vec!["a", "woman", "on", "the", "beach"]),
    vec![vec!["a", "woman"], vec!["a", "woman", "on", "the", "beach"]],
);
```

#### `Label=u8, Arr=[u8; n]`
Say `Label` is a digit in Pi (= 3.14...) and Arr is a window to separate pi's digit by 10.

```rust
use trie_rs::TrieBuilder;

let mut builder = TrieBuilder::<u8, u8>::new(); // Pi = 3.14...

builder.push([1, 4, 1, 5, 9, 2, 6, 5, 3, 5], 1);
builder.push([8, 9, 7, 9, 3, 2, 3, 8, 4, 6], 2);
builder.push([2, 6, 4, 3, 3, 8, 3, 2, 7, 9], 3);
builder.push([6, 9, 3, 9, 9, 3, 7, 5, 1, 0], 4);
builder.push([5, 8, 2, 0, 9, 7, 4, 9, 4, 4], 5);
builder.push([5, 9, 2, 3, 0, 7, 8, 1, 6, 4], 6);
builder.push([0, 6, 2, 8, 6, 2, 0, 8, 9, 9], 7);
builder.push([8, 6, 2, 8, 0, 3, 4, 8, 2, 5], 8);
builder.push([3, 4, 2, 1, 1, 7, 0, 6, 7, 9], 9);
builder.push([8, 2, 1, 4, 8, 0, 8, 6, 5, 1], 10);
builder.push([3, 2, 8, 2, 3, 0, 6, 6, 4, 7], 11);
builder.push([0, 9, 3, 8, 4, 4, 6, 0, 9, 5], 12);
builder.push([5, 0, 5, 8, 2, 2, 3, 1, 7, 2], 13);
builder.push([5, 3, 5, 9, 4, 0, 8, 1, 2, 8], 14);

let trie = builder.build();

assert_eq!(trie.exact_match([5, 3, 5, 9, 4, 0, 8, 1, 2, 8]), true);
assert_eq!(
    trie.predictive_search([3]),
    vec![
        [3, 2, 8, 2, 3, 0, 6, 6, 4, 7],
        [3, 4, 2, 1, 1, 7, 0, 6, 7, 9],
    ],
);
assert_eq!(
    trie.common_prefix_search([1, 4, 1, 5, 9, 2, 6, 5, 3, 5]),
    vec![[1, 4, 1, 5, 9, 2, 6, 5, 3, 5]],
);
```

## Features
- **Generic type support**: As the above examples show, trie-rs can be used for searching not only UTF-8 string but also other data types.
- **Based on [louds-rs](https://crates.io/crates/louds-rs)**, which is fast, parallelized, and memory efficient.
- **Latest benchmark results are always accessible**: trie-rs is continuously benchmarked in Travis CI using [Criterion.rs](https://crates.io/crates/criterion). Graphical benchmark results are published [here](https://laysakura.github.io/trie-rs/criterion/report/).

## Acknowledgments
[`edict.furigana`](https://github.com/laysakura/trie-rs/blob/master/benches/edict.furigana) is used for benchmark.
This file is constructed in the following step:

1. Download `edict.gz` from [EDICT](http://www.edrdg.org/jmdict/edict.html).
2. Convert it from original EUC into UTF-8.
3. Translate it into CSV file with [edict-to-csv](https://pypi.org/project/edict-to-csv/).
4. Extract field $1 for Hiragana/Katakana words, and field $3 for other (like Kanji) words.
5. Translate Katakana into Hiragana with [kana2hira](https://github.com/ShellShoccar-jpn/misc-tools/blob/master/kata2hira).

Many thanks for these dictionaries and tools.

## Versions
trie-rs uses [semantic versioning](http://semver.org/spec/v2.0.0.html).

Since current major version is _0_, minor version update might involve breaking public API change (although it is carefully avoided).

## Rust Version Supports

trie-rs is continuously tested with these Rust versions in Travis CI:

- 1.33.0
- Latest stable version

So it expectedly works with Rust 1.33.0 and any newer versions.

Older versions may also work, but are not tested or guaranteed.

## Contributing

Any kind of pull requests are appreciated.

### Guidelines

- `README.md` is generated from `$ cargo readme` command. Do not manually update `README.md` but edit `src/lib.rs` and then `$ cargo readme > README.md`.
- Travis CI automatically does the following commit & push to your pull-requests:
    - `$ cargo readme > README.md`
    - `$ cargo fmt --all`

## License

MIT OR Apache-2.0