In Memory Lucene Index in CRuby - ported from http://ikaisays.com/2010/04/25/jruby-in-memory-search-example-with-lucene-3-0-1/

in_memory.rb

$:.unshift './lib'

require 'rubygems'
require 'rjb'
require 'rjbextension'

Document          = Rjb::import('org.apache.lucene.document.Document')
StandardAnalyzer  = Rjb::import('org.apache.lucene.analysis.standard.StandardAnalyzer')
Field             = Rjb::import('org.apache.lucene.document.Field')
IndexWriter       = Rjb::import('org.apache.lucene.index.IndexWriter')
IndexWriterConfig = Rjb::import('org.apache.lucene.index.IndexWriterConfig')
ParseException    = Rjb::import('org.apache.lucene.queryParser.ParseException')
QueryParser       = Rjb::import('org.apache.lucene.queryParser.QueryParser')
RAMDirectory      = Rjb::import('org.apache.lucene.store.RAMDirectory')
IndexSearcher     = Rjb::import('org.apache.lucene.search.IndexSearcher')

Store       = Rjb::import 'org.apache.lucene.document.Field$Store'
Index       = Rjb::import 'org.apache.lucene.document.Field$Index'
Resolution  = Rjb::import 'org.apache.lucene.document.DateTools$Resolution'

VERSION = org.apache.lucene.util.Version.LUCENE_33

load_jvm(['-Xms128m', '-Xmx512m'])

def create_document(title, content)
  doc = Document.new
  doc.add Field.new("title", title, Store.YES, Index.NO)
  doc.add Field.new("content", content, Store.YES, Index.ANALYZED)
  doc
end

def create_index
  idx     = RAMDirectory.new
  config = IndexWriterConfig.new(VERSION,  StandardAnalyzer.new(VERSION))
  writer  = IndexWriter.new(idx, config)

  writer.add_document(create_document("Theodore Roosevelt",
          "It behooves every man to remember that the work of the " +
                  "critic, is of altogether secondary importance, and that, " +
                  "in the end, progress is accomplished by the man who does " +
                  "things."))
  writer.add_document(create_document("Friedrich Hayek",
          "The case for individual freedom rests largely on the " +
                  "recognition of the inevitable and universal ignorance " +
                  "of all of us concerning a great many of the factors on " +
                  "which the achievements of our ends and welfare depend."))
  writer.add_document(create_document("Ayn Rand",
          "There is nothing to take a man's freedom away from " +
                  "him, save other men. To be free, a man must be free " +
                  "of his brothers."))
  writer.add_document(create_document("Mohandas Gandhi",
          "Freedom is not worth having if it does not connote " +
                  "freedom to err."))

  writer.optimize
  writer.close
  idx
end

def search(searcher, query_string)
  parser = QueryParser.new(VERSION, "content", StandardAnalyzer.new(VERSION))

  puts "Searching for #{query_string}"
  query = parser.parse(query_string)

  hits = searcher.search(query, 10)

  hit_count = hits.totalHits

  if hit_count.zero?
    puts "No matching documents."
  else
    puts "%d total matching documents" % hit_count

    puts "Hits for %s were found in quotes by:" % query_string

    hits.scoreDocs.each_with_index do |score_doc, i|
      doc_id = score_doc.doc
      doc_score = score_doc.score

      puts "doc_id: %s \t score: %s" % [doc_id, doc_score]

      doc = searcher.doc(doc_id)
      puts "%d. %s" % [i, doc.get("title")]
      puts "Content: %s" % doc.get("content")
      puts

    end

  end

end

def main
  index = create_index
  searcher = IndexSearcher.new(index)

  search(searcher, "freedom")
  search(searcher, "free");
  search(searcher, "progress or achievements");
  search(searcher, "wibble")

  searcher.close
end

main()