Mruby

• Light weight ruby
• Repository URL
• emscripten changes
• mruby to c parser
• related projects

Exceptions

• Uses longjmp/setjmp internally.
• When C++ code is mixed it will use C++ exception instead.
  • Exception patch that was used in emscripten(removed since longjmp/setjmp was supported now).

PNaCl/Emscripten

• Primitive boxing.
  • Use primitive type as mrb_value.

mruby-require

• iij version
  • requires mruby-env/io/dir/tempfile
  • only supports script loading
• mattn version
  • supports dynamic library loading

user defined object allocation

• use MRB_SET_INSTANCE_TT
  • equivalent to rb_define_alloc_func
  • though it just sets allocating ruby object type
• need to allocate data if MRB_TT_DATA is set.
  • type and pointer must be set
  • DATA_PTR and DATA_TYPE is just a macro so the return of it can be assigned

mrbgems

• document
• enabling
• mgem
  • how to use
  • command to add mrbgems
  • mgem-list
• MRuby::Build#gem
  • String is treated as mrbgem path
  • Hash(order is the priority)
    • :core : mrbgem path "${MRUBY_ROOT}/mrbgems/#{value of :core}"
      • example "conf.gem :core => 'mruby-time'"
    • :github : git url of "https://github.com/#{value of :github}.git"
      • example "conf.gem :github => 'take-cheeze/mruby-msgpack'"
    • :bitbucket: git url of "https://bitbucket.org/#{value of :bitbucket}"
      • example "conf.gem :bitbucket => 'masahino/mruby-skkdic'"
    • :git : git url. cloned when cleaned
      • example "conf.gem :git => 'https://github.com/take-cheeze/mruby-msgpack.git'"
    • :branch : used with repository URL. specifies with branch to use in repository
  • If a block is passed it will be called after the gem spec's block
• MRuby::Build#gembox
  • mrbgem set to import multiple mrbgems
  • by default 'default' and 'full-core' is available
    • 'default': default gembox. mruby-strintg-utf8 is not included in this
    • 'full-core': gembox of all gems that can be added with ":core"

gems

• mruby zlib
  • zlib binding
  • Zlib.inflate/deflate

Block

• One of the most powerful feature of ruby.
• to call given block to function use **yield**.

Garbage Collector

• root_scan_phase scans marks root
• "mrb_iv_set"ed children(is in iv_tbl) will be marked if parent is marked
• All the mrb_value in RStruct will be marked.
• to mark mrb_value use mrb_gc_mark_value
• to mart RBasic* use mrb_gv_mark
• built-in type(e.g. int, float) is ignored
• Unable to have mark function(currently)

Data type

• mrb_sym
  • string reference like flyweight pattern. pooled string pointer
  • get it from mrb_intern(mrb, sym_str)
  • mrb_intern2 has string length argument
• mrb_irep
  • VM codes of mruby? Symbol table?
  • mrb_dump_irep/mrb_bdump_irep outputs mruby binary
  • mrb_cdump_irep outputs C code
  • to load binary outputed by "mrb -B" use mrb_read_irep, use mrb_load_irep to load if "-C","-B" wasn't passed.

mrb_get_args() format

char	mruby type	C type
o	Object	mrb_value
S	String	mrb_value
A	Array	mrb_value
H	Hash	mrb_value
s	String	char*, int
z	String	char*
a	Array	mrb_value*, mrb_int
f	Float	mrb_float
i	integer	mrb_int
b	boolean	mrb_bool
n	Symbol	mrb_sym
d	Data	void*, mrb_data_type
&	Block	mrb_value
*	rest argument	mrb_value*, int
｜	optional	after this character the following argument will be optional
?	optional argument retrieved	mrb_bool

Built-in Classes

• RBasic
  • base of all built-in classes
  • use RBASIC to get pointer from mrb_value
  • To create mrb_value use mrb_obj_value(p)
• RStruct
  • Tuple
  • able to access with index and symbol
• RData
  • C struct wrapper.
  • pointer getting
    • mrb_get_datatype: if error returns NULL
    • mrb_check_datatype: if error throws exception

C language translater

• How to use.
• mrbc -C${symbol} ${file}.rb: outputs C function
  • ${file}.c: extern void ${symbol}(mrb_state* mrb) {}
• mrbc -B${symbol} ${file}.rb: outputs C array mruby binary
  • ${file}.c: extern const char hello[] = {}
• mrbc ${file}.rb: outputs mruby binary
  • ${file}.mrb: mruby binary

Native Client

• How to build mruby

Fiber

• Not implemented
• CRuby Fiber API
• If single argument is passed to Fiber.yield that argument is returned.
• When multiple arguments is passed to Fiber.yield array of arguments is returned.
• impelemented

Weak Reference

• Seems not implemented.
• CRuby implemetation
• In ruby 1.9 there is weak map so no special code is needed now.
• weakref implementation using c++ shared_ptr/weak_ptr
  • don't know how much it's safe from GC.

Native Client

• Example
• Use with cmake will be better

Emscripten

• webruby
• patch to replace longjmp with exception throwing