https://github.com/codeplea/ahocorasickphp

Aho-Corasick multi-keyword string searching library in PHP.
https://github.com/codeplea/ahocorasickphp

aho-corasick ahocorasick algorithm php search-algorithm string-search

Last synced: 2 months ago
JSON representation

Aho-Corasick multi-keyword string searching library in PHP.

• Host: GitHub
• URL: https://github.com/codeplea/ahocorasickphp
• Owner: codeplea
• License: zlib
• Created: 2018-07-21T20:53:40.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2018-10-01T16:29:59.000Z (over 6 years ago)
• Last Synced: 2023-11-07T17:11:43.495Z (about 1 year ago)
• Topics: aho-corasick, ahocorasick, algorithm, php, search-algorithm, string-search
• Language: PHP
• Homepage:
• Size: 234 KB
• Stars: 176
• Watchers: 10
• Forks: 15
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        

# Aho Corasick in PHP

This is a small library which implements the [Aho-Corasick string

search

algorithm](https://en.wikipedia.org/wiki/Aho%E2%80%93Corasick_algorithm).

It's coded in pure PHP and self-contained in a single file, `ahocorasick.php`.

It's useful when you want to search for many keywords all at once. It's faster

than simply calling `strpos` many times, and it's much faster than calling

`preg_match_all` with something like `/keyword1|keyword2|...|keywordn/`.

I originally wrote this to use with [F5Bot](https://f5bot.com), since it's

searching for the same set of a few thousand keywords over and over again.

# Usage

It's designed to be really easy to use. You create the `ahocorasick` object,

add your keywords, call `finalize()` to finish setup, and then search your

text. It'll return an array of the keywords found and their position in the

search text.

Create, add keywords, and `finalize()`:

```php

require('ahocorasick.php');

$ac = new ahocorasick();

$ac->add_needle('art');

$ac->add_needle('cart');

$ac->add_needle('ted');

$ac->finalize();

```

Call `search()` to preform the actual search. It'll return an array of matches.

```php

$found = $ac->search('a carted mart lot one blue ted');

print_r($found);

```

`$found` will be an array with these elements:

```

[0] => Array

    (

        [0] => cart

        [1] => 2

    )

[1] => Array

    (

        [0] => art

        [1] => 3

    )

[2] => Array

    (

        [0] => ted

        [1] => 5

    )

[3] => Array

    (

        [0] => art

        [1] => 10

    )

[4] => Array

    (

        [0] => ted

        [1] => 27

    )

```

See `example.php` for a complete example.

# Speed

A simple benchmarking program is included which compares various alternatives.

```

$ php benchmark.php

Loaded 3000 keywords to search on a text of 19377 characters.

Searching with strpos...

time: 0.38440799713135

Searching with preg_match...

time: 5.6817619800568

Searching with preg_match_all...

time: 5.0735609531403

Searching with aho corasick...

time: 0.054709911346436

```

Note: the regex solutions are actually slightly broken. They won't work if you

have a keyword that is a prefix or suffix of another. But hey, who really uses

regex when it's not slightly broken?

Also keep in mind that building the search tree (the `add_needle()` and

`finalize()` calls) takes time. So you'll get the best speed-up if you're

reusing the same keywords and calling `search()` many times.