some old java code that happens to be in ruby

strategies.rb

#
#  strategies.rb
#  reframeit-testing
#
#  Created by Ben Taitelbaum on 2/25/08.
#  Copyright (c) 2008 __MyCompanyName__. All rights reserved.
#
module ActiveThrift

  class CompoundStrategy
    def initialize(&block)
      @strategy = block || Proc.new {|arg, opts| false }
    end

    def execute(*opts)
      @strategy.call(*opts)
    end
    
    # chains this strategy with the next one so that the next
    # one executes only if this one evaluates to true
    def &(compound_strategy)
      CompoundStrategy.new do |*opts|
        @strategy.call(*opts) && compound_strategy.strategy.call(*opts)
      end
    end

    # chains this strategy with the next one, where each will be executed
    # and the result ignored
    def +(compound_strategy)
      CompoundStrategy.new do |*opts|
        @strategy.call(*opts)
        compound_strategy.strategy.call(*opts)
      end
    end

    # chains this strategy with the next one, where the output of this
    # is passed as the first argument to the next
    #
    # this requires that the strategy takes at least one argument, where the
    # first is used as the piped arg
    def |(compound_strategy)
      CompoundStrategy.new do |arg, *opts|
        ret = @strategy.call(arg, *opts)
        compound_strategy.strategy.call(ret, *opts)
      end
    end
    
    protected
    attr_accessor :strategy
  end

  class SingletonStrategy < CompoundStrategy
    def self.instance
      @instance ||= self.send(:new)
      return @instance
    end
  end

  class TrueStrategy < SingletonStrategy
    private
    def initialize
      super{true}
    end
  end

  class FalseStrategy < SingletonStrategy
    private
    def initialize
      super{false}
    end
  end

  class IdentityStrategy < SingletonStrategy
    private
    def initialize
      super{|arg, opts| arg}
    end
  end

  class VoidStrategy < SingletonStrategy
    private
    def initialize
      super{}
    end
  end


end