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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 }; #if !USE_RVARGC /** * This is an enum because GDB wants it (rather than a macro). People need not * bother. */ enum ruby_robject_consts { /** Max possible number of instance variables that can be embedded. */ ROBJECT_EMBED_LEN_MAX = RBIMPL_EMBED_LEN_MAX_OF(VALUE) }; #endif 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; #if USE_RVARGC /* 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]; #else /** * Embedded instance variables. When an object is small enough, it * uses this area to store the instance variables. */ VALUE ary[ROBJECT_EMBED_LEN_MAX]; #endif } as; }; /* Offsets for YJIT */ #ifndef __cplusplus static const int32_t ROBJECT_OFFSET_AS_HEAP_IVPTR = offsetof(struct RObject, as.heap.ivptr); static const int32_t ROBJECT_OFFSET_AS_HEAP_IV_INDEX_TBL = offsetof(struct RObject, as.heap.iv_index_tbl); static const int32_t ROBJECT_OFFSET_AS_ARY = offsetof(struct RObject, as.ary); #endif 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 */