Holy Hash

holy_hash_search.rb

require 'set'

def search(&block)
  query_config = Object.new 
  class << query_config
    def method_missing method_name, *args, &block
      sym_variable = "@#{method_name}".to_sym
      return dynamic_set("@#{$1}", args.first) if method_name.to_s =~ /(.*)=$/
      return dynamic_get(sym_variable) if user_variables.include? sym_variable
      super
    end
  
    def dynamic_set var_name, val
      instance_variable_set var_name, val
      user_variables << var_name.to_sym
    end

    def dynamic_get var_name
      instance_variable_get var_name
    end

    def user_variables
      @user_variables ||= Set.new
    end

    def cursor &block
      @cursor = block
    end 

    def next &block
      @next = block      
    end

    def catch &block
      @catch = block
    end
  end
  def configurer block
   Proc.new do |query_config|
      block.call query_config
      query_config
   end 
  end
  configured =  configurer(block).call query_config
  configured.extend(Module.new do
    attr_accessor :haystack
    def invoke haystack
      @haystack = haystack 
      while @target = @cursor.()
        unless @catch.nil?
          return @target if @catch.(@target)
        end 
        @next.()
      end
    end
  end)
  configured
end

holy_hash_use.rb

sample = [
  {
    :name => "john",
    :likes => ["fishing", "boating"]
  },
  {
    :name => "tom",
    :likes => ["biking", "hiking"]
  },
  {
    :name => "chris",
    :likes => ["searching", "boating"]
  },
  {
    :name => "fox",
    :likes => ["canoeing", "boating"]
  }
]

require './holy_hash_search'

query = search do |sniffer|
  sniffer.i = 0

  sniffer.cursor do 
    sniffer.haystack[sniffer.i]
  end

  sniffer.next do
    sniffer.i += 1
  end

  sniffer.catch do |cursor|
    cursor[:likes].include? "hiking"
  end
end

p query.invoke(sample) # => [:name => "tom", :likes => ["biking", "hiking"]