Testing nested struct/union Fiddle version 1.0.1

rstring.rb

require 'fiddle/import'
include Fiddle::Importer

# Fiddle v:1.0.1

dlload
typealias 'VALUE', 'unsigned long long'

RBasic = struct [
  'VALUE flags',
  'VALUE klass'
]

Aux = union [
  'long capa',
  'VALUE shared'
]

Heap = struct [
  'long len',
  'char *ptr',
  {aux: Aux}
]

As = union [
  {heap: Heap},
  'char ary[24]'
]

RString = struct [
  {basic: RBasic},
  {as: As}
]

# Heap string.
rs = RString.new dlwrap(RUBY_COPYRIGHT)

p flags: rs.basic.flags
p class: Pointer.new(rs.basic.klass).to_value
p length: rs.as.heap.len
p pointer: rs.as.heap.ptr.to_s 
p capacity: rs.as.heap.aux.capa
p shared: rs.as.heap.aux.shared
p stack: rs.as.ary.pack('C*')

puts "-" * 80

# Stack string.
rs = RString.new dlwrap("ruby")

p flags: rs.basic.flags
p class: Pointer.new(rs.basic.klass).to_value
p length: rs.as.heap.len
p pointer: rs.as.heap.ptr
p capacity: rs.as.heap.aux.capa
p shared: rs.as.heap.aux.shared
p stack: rs.as.ary.pack('C*')

__END__

{:flags=>1082140773}
{:class=>String}
{:length=>49}
{:pointer=>"ruby - Copyright (C) 1993-2020 Yukihiro Matsumoto"}
{:capacity=>49}
{:shared=>49}
{:stack=>"1\x00\x00\x00\x00\x00\x00\x00\x80V\r\xAC\x91\x7F\x00\x001\x00\x00\x00\x00\x00\x00\x00"}
--------------------------------------------------------------------------------
{:flags=>5308421}
{:class=>String}
{:length=>2036495730}
{:pointer=>#<Fiddle::Pointer:0x00005648352bb110 ptr=0x0000000000000000 size=0 free=0x0000000000000000>}
{:capacity=>0}
{:shared=>0}
{:stack=>"ruby\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"}