https://github.com/mscdex/streamsearch

Streaming Boyer-Moore-Horspool searching for node.js
https://github.com/mscdex/streamsearch

Last synced: 7 days ago
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Streaming Boyer-Moore-Horspool searching for node.js

• Host: GitHub
• URL: https://github.com/mscdex/streamsearch
• Owner: mscdex
• License: mit
• Created: 2012-12-11T17:01:03.000Z (about 12 years ago)
• Default Branch: master
• Last Pushed: 2023-10-16T13:35:05.000Z (about 1 year ago)
• Last Synced: 2024-12-21T14:39:18.508Z (13 days ago)
• Language: JavaScript
• Size: 24.4 KB
• Stars: 70
• Watchers: 8
• Forks: 17
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
Description

===========

streamsearch is a module for [node.js](http://nodejs.org/) that allows searching a stream using the Boyer-Moore-Horspool algorithm.

This module is based heavily on the Streaming Boyer-Moore-Horspool C++ implementation by Hongli Lai [here](https://github.com/FooBarWidget/boyer-moore-horspool).

Requirements

============

* [node.js](http://nodejs.org/) -- v10.0.0 or newer

Installation

============

    npm install streamsearch

Example

=======

```js

  const { inspect } = require('util');

  const StreamSearch = require('streamsearch');

  const needle = Buffer.from('\r\n');

  const ss = new StreamSearch(needle, (isMatch, data, start, end) => {

    if (data)

      console.log('data: ' + inspect(data.toString('latin1', start, end)));

    if (isMatch)

      console.log('match!');

  });

  const chunks = [

    'foo',

    ' bar',

    '\r',

    '\n',

    'baz, hello\r',

    '\n world.',

    '\r\n Node.JS rules!!\r\n\r\n',

  ];

  for (const chunk of chunks)

    ss.push(Buffer.from(chunk));

  // output:

  //

  // data: 'foo'

  // data: ' bar'

  // match!

  // data: 'baz, hello'

  // match!

  // data: ' world.'

  // match!

  // data: ' Node.JS rules!!'

  // match!

  // data: ''

  // match!

```

API

===

Properties

----------

* **maxMatches** - < _integer_ > - The maximum number of matches. Defaults to `Infinity`.

* **matches** - < _integer_ > - The current match count.

Functions

---------

* **(constructor)**(< _mixed_ >needle, < _function_ >callback) - Creates and returns a new instance for searching for a _Buffer_ or _string_ `needle`. `callback` is called any time there is non-matching data and/or there is a needle match. `callback` will be called with the following arguments:

  1. `isMatch` - _boolean_ - Indicates whether a match has been found

  2. `data` - _mixed_ - If set, this contains data that did not match the needle.

  3. `start` - _integer_ - The index in `data` where the non-matching data begins (inclusive).

  4. `end` - _integer_ - The index in `data` where the non-matching data ends (exclusive).

  5. `isSafeData` - _boolean_ - Indicates if it is safe to store a reference to `data` (e.g. as-is or via `data.slice()`) or not, as in some cases `data` may point to a Buffer whose contents change over time.

* **destroy**() - _(void)_ - Emits any last remaining unmatched data that may still be buffered and then resets internal state.

* **push**(< _Buffer_ >chunk) - _integer_ - Processes `chunk`, searching for a match. The return value is the last processed index in `chunk` + 1.

* **reset**() - _(void)_ - Resets internal state. Useful for when you wish to start searching a new/different stream for example.