######################################################################
# Jsonify::BlankSlate is based on Jim Weirich's BlankSlate.
#
# Copyright 2004, 2006 by Jim Weirich (jim@weirichhouse.org).
# All rights reserved.
#
# BlankSlate provides an abstract base class with no predefined
# methods (except for <tt>\_\_send__</tt> and <tt>\_\_id__</tt>).
# BlankSlate is useful as a base class when writing classes that
# depend upon <tt>method_missing</tt> (e.g. dynamic proxies).
#
# This Jsonify implementation of BlankSlate is identical; with the
# exception that it does not include the Kernel, Module, and Object
# patches.
#
module Jsonify
  class BlankSlate
    class << self

      # Hide the method named +name+ in the BlankSlate class.  Don't
      # hide +instance_eval+ or any method beginning with "__".
      def hide(name)
        if instance_methods.include?(name.to_s) and
          name !~ /^(__|instance_eval)/
          @hidden_methods ||= {}
          @hidden_methods[name.to_sym] = instance_method(name)
          undef_method name
        end
      end

      def find_hidden_method(name)
        @hidden_methods ||= {}
        @hidden_methods[name] || superclass.find_hidden_method(name)
      end

      # Redefine a previously hidden method so that it may be called on a blank
      # slate object.
      def reveal(name)
        hidden_method = find_hidden_method(name)
        fail "Don't know how to reveal method '#{name}'" unless hidden_method
        define_method(name, hidden_method)
      end
    end

    instance_methods.each { |m| hide(m) }
  end
end
######################################################################
# Since Ruby is very dynamic, methods added to the ancestors of
# BlankSlate <em>after BlankSlate is defined</em> will show up in the
# list of available BlankSlate methods.  We handle this by defining a
# hook in the Object and Kernel classes that will hide any method
# defined after BlankSlate has been loaded.
#
# module Kernel
#   class << self
#     alias_method :blank_slate_method_added, :method_added
# 
#     # Detect method additions to Kernel and remove them in the
#     # BlankSlate class.
#     def method_added(name)
#       result = blank_slate_method_added(name)
#       return result if self != Kernel
#       BlankSlate.hide(name)
#       result
#     end
#   end
# end

######################################################################
# Same as above, except in Object.
#
# class Object
#   class << self
#     alias_method :blank_slate_method_added, :method_added
# 
#     # Detect method additions to Object and remove them in the
#     # BlankSlate class.
#     def method_added(name)
#       result = blank_slate_method_added(name)
#       return result if self != Object
#       BlankSlate.hide(name)
#       result
#     end
# 
#     def find_hidden_method(name)
#       nil
#     end
#   end
# end

######################################################################
# Also, modules included into Object need to be scanned and have their
# instance methods removed from blank slate.  In theory, modules
# included into Kernel would have to be removed as well, but a
# "feature" of Ruby prevents late includes into modules from being
# exposed in the first place.
#
# class Module
#   alias blankslate_original_append_features append_features
#   def append_features(mod)
#     result = blankslate_original_append_features(mod)
#     return result if mod != Object
#     instance_methods.each do |name|
#       BlankSlate.hide(name)
#     end
#     result
#   end
# end