polecat¶ ↑

This is my attempt to build a search library like lucene in native ruby.

The idea formed, when I learned about the rubinius project and it’s ability to tune parts of the ruby code with it’s jit. It’s a bit sad for MRI, that more and more ruby code get’s converted to C, so it would be great, if rbx could be as performant as MRI, even if great parts of a application are written in ruby.

It is easy to use the search. The first thing, you have to do, is building a class, which has to have a method #attributes which has to return an array of all attributes. For every attribute, there as to be a reader, so that the search can read them. A great way to build such a class is by using (virtus) which is part of DM2. The Code can look like this

require 'virtus'

class Document
  include Virtus
  attribute :id, Integer
  attribute :text, String
  attribute :short, String
end

After that, you need an IndexWriter to fill the index with documents.

writer = Polecat::IndexWriter.new 'index/'

After that, fill the index with as much Documents you want and write them to the harddisk. As long, as you did not write them, they are only in the memory and not searchable.

writer.add Document.new(:id => 0, :text => 'foobar', :short => 'foo')
writer.add Document.new(:id => 1, :text => 'Lorem', :short => 'ipsum')
writer.write # write the docs

Now you can get the reader or searcher.

# first way - create a reader with the informations of the writer
reader = writer.create_reader
searcher = Polecat::IndexSearcher.new :reader => reader

# second way - create a new reader
reader = Polecat::IndexReader.new 'index/'
searcher = Polecat::IndexSearcher.new :reader => reader

# third way - create a new searcher and let it handle the reader
searcher = Polecat::IndexSearcher.new :path => 'index/'

Either way, you need a Searcher to go hunting for the documents. For making a search, there is another thing you need, a query.

A Query consists of one or more terms, which contain the match you want, like this.

# create a new Term with the :field, :operator and the :value it should has
# this would generate a id == 0 term
term1 = Term.new(:id, :eq, 0)

# this would generate a id < 1 term
term2 = Term.new(:id, :lt, 1)

Now that we have two terms you need to put them into a Query, which can combine them with an :or operator or with an :and operator, which is the default. You can append multiple terms with add, which returns the query itself.

query = Polecat::Query.new(:or).add(term1).add(term2)

Now, give that to #search of the searcher and you get an array of documents, which should contain one Document in this case.

result = searcher.search(query)

Now, try it out and have some fun. If you find a bug, write a bug report or better, fork it and fix it :D

• Check out the latest master to make sure the feature hasn’t been implemented or the bug hasn’t been fixed yet

• Check out the issue tracker to make sure someone already hasn’t requested it and/or contributed it

• Fork the project

• Start a feature/bugfix branch

• Commit and push until you are happy with your contribution

• Make sure to add tests for it. This is important so I don’t break it in a future version unintentionally.

• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright © 2011 Gibheer. See LICENSE.txt for further details.