Class: BinData::DSLMixin::DSLBigAndLittleEndianHandler

Inherits:
Object
  • Object
show all
Defined in:
lib/bindata/dsl.rb

Overview

Handles the :big_and_little endian option. This option creates two subclasses, each handling :big or :little endian.

Class Method Summary collapse

Class Method Details

.class_with_endian(class_name, endian) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 332

def class_with_endian(class_name, endian)
  hints = {
    :endian => endian,
    :search_prefix => class_name.dsl_parser.search_prefix,
  }
  RegisteredClasses.lookup(class_name, hints)
end

.create_subclasses_with_endian(bnl_class) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 278

def create_subclasses_with_endian(bnl_class)
  instance_eval "class ::#{bnl_class}Be < ::#{bnl_class}; endian :big; end"
  instance_eval "class ::#{bnl_class}Le < ::#{bnl_class}; endian :little; end"
end

.delegate_field_creation(bnl_class) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 299

def delegate_field_creation(bnl_class)
  endian_classes = {
    :big    => class_with_endian(bnl_class, :big),
    :little => class_with_endian(bnl_class, :little),
  }

  parser = bnl_class.dsl_parser
  parser.define_singleton_method(:parse_and_append_field) do |*args, &block|
    endian_classes[:big].send(*args, &block)
    endian_classes[:little].send(*args, &block)
  end
end

.fixup_subclass_hierarchy(bnl_class) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 312

def fixup_subclass_hierarchy(bnl_class)
  parent = bnl_class.superclass
  if obj_attribute(parent, :endian) == :big_and_little
    be_subclass = class_with_endian(bnl_class, :big)
    be_parent   = class_with_endian(parent, :big)
    be_fields   = obj_attribute(be_parent, :fields)

    le_subclass = class_with_endian(bnl_class, :little)
    le_parent   = class_with_endian(parent, :little)
    le_fields   = obj_attribute(le_parent, :fields)

    be_subclass.dsl_parser.define_singleton_method(:parent_fields) do
      be_fields
    end
    le_subclass.dsl_parser.define_singleton_method(:parent_fields) do
      le_fields
    end
  end
end

.handle(bnl_class) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 266

def handle(bnl_class)
  make_class_abstract(bnl_class)
  create_subclasses_with_endian(bnl_class)
  override_new_in_class(bnl_class)
  delegate_field_creation(bnl_class)
  fixup_subclass_hierarchy(bnl_class)
end

.make_class_abstract(bnl_class) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 274

def make_class_abstract(bnl_class)
  bnl_class.send(:unregister_self)
end

.obj_attribute(obj, attr) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 340

def obj_attribute(obj, attr)
  obj.dsl_parser.send(attr)
end

.override_new_in_class(bnl_class) ⇒ Object 



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# File 'lib/bindata/dsl.rb', line 283

def override_new_in_class(bnl_class)
  endian_classes = {
    :big    => class_with_endian(bnl_class, :big),
    :little => class_with_endian(bnl_class, :little),
  }
  bnl_class.define_singleton_method(:new) do |*args|
    if self == bnl_class
      _, options, _ = arg_processor.separate_args(self, args)
      delegate = endian_classes[options[:endian]]
      return delegate.new(*args) if delegate
    end

    super(*args)
  end
end