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#ifndef RBIMPL_ROBJECT_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_ROBJECT_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief Defines struct ::RObject.
*/
#include "ruby/internal/config.h"
#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif
#include "ruby/internal/attr/artificial.h"
#include "ruby/internal/attr/deprecated.h"
#include "ruby/internal/attr/pure.h"
#include "ruby/internal/cast.h"
#include "ruby/internal/fl_type.h"
#include "ruby/internal/value.h"
#include "ruby/internal/value_type.h"
/**
* Convenient casting macro.
*
* @param obj An object, which is in fact an ::RObject.
* @return The passed object casted to ::RObject.
*/
#define ROBJECT(obj) RBIMPL_CAST((struct RObject *)(obj))
/** @cond INTERNAL_MACRO */
#define ROBJECT_EMBED_LEN_MAX ROBJECT_EMBED_LEN_MAX
#define ROBJECT_EMBED ROBJECT_EMBED
#define ROBJECT_IV_CAPACITY ROBJECT_IV_CAPACITY
#define ROBJECT_IVPTR ROBJECT_IVPTR
/** @endcond */
/**
* @private
*
* Bits that you can set to ::RBasic::flags.
*/
enum ruby_robject_flags {
/**
* This flag has something to do with memory footprint. If the object is
* "small" enough, ruby tries to be creative to abuse padding bits of
* struct ::RObject for storing instance variables. This flag denotes that
* situation.
*
* @warning This bit has to be considered read-only. Setting/clearing
* this bit without corresponding fix up must cause immediate
* SEGV. Also, internal structures of an object change
* dynamically and transparently throughout of its lifetime.
* Don't assume it being persistent.
*
* @internal
*
* 3rd parties must not be aware that there even is more than one way to
* store instance variables. Might better be hidden.
*/
ROBJECT_EMBED = RUBY_FL_USER1
};
struct st_table;
/**
* Ruby's ordinal objects. Unless otherwise special cased, all predefined and
* user-defined classes share this struct to hold their instances.
*/
struct RObject {
/** Basic part, including flags and class. */
struct RBasic basic;
/** Object's specific fields. */
union {
/**
* Object that use separated memory region for instance variables use
* this pattern.
*/
struct {
/** Pointer to a C array that holds instance variables. */
VALUE *ivptr;
/**
* This is a table that holds instance variable name to index
* mapping. Used when accessing instance variables using names.
*
* @internal
*
* This is a shortcut for `RCLASS_IV_INDEX_TBL(rb_obj_class(obj))`.
*/
struct rb_id_table *iv_index_tbl;
} heap;
/* Embedded instance variables. When an object is small enough, it
* uses this area to store the instance variables.
*
* This is a length 1 array because:
* 1. GCC has a bug that does not optimize C flexible array members
* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102452)
* 2. Zero length arrays are not supported by all compilers
*/
VALUE ary[1];
} as;
};
RBIMPL_ATTR_PURE_UNLESS_DEBUG()
RBIMPL_ATTR_ARTIFICIAL()
/**
* Queries the instance variables.
*
* @param[in] obj Object in question.
* @return Its instance variables, in C array.
* @pre `obj` must be an instance of ::RObject.
*
* @internal
*
* @shyouhei finds no reason for this to be visible from extension libraries.
*/
static inline VALUE *
ROBJECT_IVPTR(VALUE obj)
{
RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
struct RObject *const ptr = ROBJECT(obj);
if (RB_FL_ANY_RAW(obj, ROBJECT_EMBED)) {
return ptr->as.ary;
}
else {
return ptr->as.heap.ivptr;
}
}
#endif /* RBIMPL_ROBJECT_H */
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