Description

Node.js event based module for searching streams using the Boyer–Moore–Horspool algorithm.

Requirements

Node.js 6.14.3 or higher is required.

Installation

npm i @slaviczavik/stream-search

Example

Code

const StreamSearch = require('@slaviczavik/stream-search')
const search = StreamSearch('AQD')

search.on('part', function (obj) {
  const isMatch = obj['isMatch']
  const start = obj['start']
  const end = obj['end']
  const data = obj['data']

  if (isMatch) {
    console.log(`Found! [${start} - ${end}]`)
  }
  else {
    console.log(`Not found!`)
  }

  if (data) {
    console.log(data.toString('ascii'))
  }
})

search.add('--AQD-QDD-DQD--')
search.end()

Output

> Found! [2 - 4]
> --AQD
> Not found!
> -QDD-DQD--

API

Constructor

StreamSearch(needle, limit)

Name	Required	Type	Description	Default
needle	true	string, buffer	The needle what we are searching for.	none
limit	false	integer	The maximum number of matches.	Infinity

Number of matches is reseted after the end method calling.

Methods

add(haystack)

Call this method every time you receive a new stream data. If there were some unprocessed data in the previous request, this data will be processed with this new data.

Parameter	Required	Type	Description
haystack	true	string, buffer	Your data you want to search.

end()

Calling this method you signals that no more data will be passed. If there are some trailing data (too few to run the algorithm), this data will be emitted back to user.

Events

part(object)

Emitted every time a match was or was not made. In both case, a processed chunk of data is available. If match was made, the needle is between start (inclusive) and end (inclusive).

The object contains following properties:

Property	Type	Description
isMatch	boolean	Bool value that data contains the needle.
data	buffer	Returned data from the haystack.
start	integer, undefined	Start position of needle (if any) in the haystack (inclusive).
end	integer, undefined	End position of needle (if any) in the haystack (inclusive).

The property end also indicates the end of the data.