From: ara.t.howard@...
Date: 2006-08-14T04:25:33+09:00
Subject: Re: Search objects

On Mon, 14 Aug 2006, Dark Ambient wrote:

> I can use some help here:
>
> I've set up this class and objects and would like to "search" it
> similar to the way I would search a database.  At this point I'm not
> concerned with adding regex for more liberal searches.
> Any suggestions ?
>
> class Composer
>   def initialize( lname, country )
>       @lname    = lname
>       @country  = country
>   end
>       attr_accessor(:lname, :country)
> end
>
> comp1 = Composer.new("Beethoven", "Germany")
> comp2 = Composer.new("DeFalla", "Spain")
> comp3 = Composer.new("Debussy", "France")
>

harp:~ > cat a.rb
require 'weakref'

class Composer
   (ATTRIBUTES = %w( lname country )).each{|a| attr_accessor a}

   INDEX = Hash.new{|h,k| h[k] = []}

   def self.find arg
     pattern =
       case arg
         when Hash
           ATTRIBUTES.map{|a| arg[a] || arg[a.to_s] || arg[a.to_s.intern]}
         when Array
           arg
         else
           raise ArgumentError
       end

     n = pattern.size

     keys = INDEX.keys.select do |key|
       match = []
       n.times do |i|
         pat, k = pattern[i], key[i]
         match <<
           if pat.nil?
             true
           elsif pat.respond_to? 'call'
             pat.call(k) ? true : false
           elsif pat.respond_to? '==='
             pat === k
           elsif pat.respond_to? '=='
             pat == k
           else
             false
           end
       end
       match.all?
     end

     INDEX.values_at(*keys).map{|list| list.map{|weakref| weakref.__getobj__}}.flatten
   end

   def initialize *argv
     ATTRIBUTES.each{|a| send "#{ a }=", argv.shift}
     key = ATTRIBUTES.map{|a| send a}
     val = WeakRef.new self
     INDEX[key] << val
   end

   def to_hash
     ATTRIBUTES.inject({}){|h,k| h.update k => send(k)}
   end

   def inspect
     to_hash.inspect
   end

   def to_s
     inspect
   end
end

comp1 = Composer.new "Beethoven", "Germany"
comp2 = Composer.new "DeFalla", "Spain"
comp3 = Composer.new "Debussy", "France"

found = Composer.find 'lname' => 'Beethoven' 
p found

found = Composer.find 'lname' => %r/^bee|^defal/io
p found

found = Composer.find :country => lambda{|c| c.upcase === 'SPAIN'}
p found

class CaseOf < ::Array
   def ===(other) flatten.compact.map{|pat| pat === other}.any? end
end
def caseof(*a, &b) CaseOf.new(*a, &b) end

found = Composer.find :lname => %r/y$/, :country => caseof(%w[ Spain France ])
p found



harp:~ > ruby a.rb
[{"country"=>"Germany", "lname"=>"Beethoven"}]
[{"country"=>"Germany", "lname"=>"Beethoven"}, {"country"=>"Spain", "lname"=>"DeFalla"}]
[{"country"=>"Spain", "lname"=>"DeFalla"}]
[{"country"=>"France", "lname"=>"Debussy"}]



food for thought.

-a
-- 
to foster inner awareness, introspection, and reasoning is more efficient than
meditation and prayer.
- h.h. the 14th dali lama