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Streaming Boyer-Moore-Horspool searching for node.js


streamsearch is a module for node.js 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.



npm install streamsearch


  var StreamSearch = require('streamsearch'),
      inspect = require('util').inspect;
  var needle = new Buffer([13, 10]), // CRLF 
      s = new StreamSearch(needle),
      chunks = [
        new Buffer('foo'),
        new Buffer(' bar'),
        new Buffer('\r'),
        new Buffer('\n'),
        new Buffer('baz, hello\r'),
        new Buffer('\n world.'),
        new Buffer('\r\n Node.JS rules!!\r\n\r\n')
  s.on('info', function(isMatch, data, start, end) {
    if (data)
      console.log('data: ' + inspect(data.toString('ascii', start, end)));
    if (isMatch)
  for (var i = 0, len = chunks.length; i < len; ++i)
  // output: 
  // data: 'foo' 
  // data: ' bar' 
  // match! 
  // data: 'baz, hello' 
  // match! 
  // data: ' world.' 
  // match! 
  // data: ' Node.JS rules!!' 
  // match! 
  // data: '' 
  // match! 


  • info(< boolean >isMatch[, < Buffer >chunk, < integer >start, < integer >end]) - A match may or may not have been made. In either case, a preceding chunk of data may be available that did not match the needle. Data (if available) is in chunk between start (inclusive) and end (exclusive).
  • maxMatches - < integer > - The maximum number of matches. Defaults to Infinity.

  • matches - < integer > - The current match count.

  • (constructor)(< mixed >needle) - Creates and returns a new instance for searching for a Buffer or string needle.

  • push(< Buffer >chunk) - integer - Processes chunk. 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.