From: Avdi Grimm <avdi@...>
Date: 2008-12-02T00:53:45+09:00
Subject: Multi-Index Containers

Does anyone know of a multi-index container library for Ruby?  I just
want to check before I put it on my personal TODO list.

By multi-index, I mean a container which will index its contained
objects by more than one attribute.  E.g. something along these lines:

  mi = MultiIndex.new
  mi.add_index(:prefix) {|val| val[0,3]}
  mi.add_index(:size)

  mi << "foobar"
  mi << "foobaz"
  mi << "fuzz"
  mi << "fuzzbizz"

  mi.by_prefix("foo") # => ["foobar", "foobaz"]
  mi.by_prefix("fuz") # => ["fuzz", "fuzzbizz"]
  mi.by_size(4) # => ["fuzz"]
  mi.by_size(8) #= ["fuzzbizz"]

Yes, I know I can just uses #select on Ruby's existing containers, but
the idea here is that a MultiIndex would index each attribute on
insert, making lookups faster than using a #select.

So: does this exist?

-- 
Avdi

Home: http://avdi.org
Developer Blog: http://avdi.org/devblog/
Twitter: http://twitter.com/avdi
Journal: http://avdi.livejournal.com