91 lines
2.6 KiB
Ruby
91 lines
2.6 KiB
Ruby
# An Object is really a hash like structure. It is dynamic and
|
|
# you want to store values by name (instance variable names).
|
|
#
|
|
# One could (like mri), store the names in each object, but that is wasteful
|
|
# Instead we store only the values, and access them by index.
|
|
# The Layout allows the mapping of names to index.
|
|
|
|
# The Layout of an object describes the memory layout of the object
|
|
# The Layout is a simple list of the names of instance variables.
|
|
#
|
|
# As every object has a Layout to describe it, the name "layout" is the
|
|
# first name in the list for every Layout.
|
|
|
|
# But as we want every Object to have a class, the Layout carries that class.
|
|
# So the layout of layout has an entry "object_class"
|
|
|
|
# In other words, the Layout is a list of names that describe
|
|
# the values stored in an actual object.
|
|
# The object is an List of values of length n and
|
|
# the Layout is an List of names of length n
|
|
# Together they turn the object into a hash like structure
|
|
|
|
module Parfait
|
|
class Layout < Object
|
|
include Indexed
|
|
self.offset(0)
|
|
|
|
attribute :object_class
|
|
|
|
def initialize( object_class )
|
|
super()
|
|
self.object_class = object_class
|
|
end
|
|
|
|
def == other
|
|
self.object_id == other.object_id
|
|
end
|
|
|
|
# add the name of an instance variable
|
|
# The index will be returned and can subsequently be searched with index_of
|
|
# The index of the name is the index of the data in the object
|
|
#
|
|
# TODO , later we would need to COPY the layout to keep the old constant
|
|
# but now we are concerned with booting, ie getting a working structure
|
|
def add_instance_variable name
|
|
self.push(1) if self.get_length == 0
|
|
self.push(name)
|
|
self.get_length
|
|
end
|
|
|
|
def object_instance_names
|
|
names = List.new
|
|
index = 3
|
|
while index <= self.get_length
|
|
item = get(index)
|
|
names.push item
|
|
index = index + 1
|
|
end
|
|
names
|
|
end
|
|
|
|
def object_instance_length
|
|
self.get_length - 2
|
|
end
|
|
|
|
alias :list_index :index_of
|
|
# private inheritance is something to think off, we don't really want the list api exported
|
|
def index_of name
|
|
raise "should not rely on layout internal structure, use variable_index"
|
|
end
|
|
|
|
# index of the variable when using internal_object_get
|
|
# (internal_object_get is 1 based and 1 is always the layout)
|
|
def variable_index name
|
|
has = list_index(name)
|
|
return nil unless has
|
|
raise "internal error #{name}:#{has}" if has < 2
|
|
has - 1
|
|
end
|
|
|
|
def inspect
|
|
"Layout[#{inspect_from(3)}]"
|
|
end
|
|
|
|
def sof_reference_name
|
|
"#{self.object_class.name}_Layout"
|
|
end
|
|
|
|
end
|
|
end
|