ruby/internal/class.h

#ifndef INTERNAL_CLASS_H                                 /*-*-C-*-vi:se ft=c:*/
#define INTERNAL_CLASS_H
/**
 * @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.
 * @brief      Internal header for Class.
 */
#include "id.h"
#include "id_table.h"           /* for struct rb_id_table */
#include "internal/box.h"
#include "internal/serial.h"    /* for rb_serial_t */
#include "internal/static_assert.h"
#include "internal/variable.h"  /* for rb_class_ivar_set */
#include "ruby/internal/stdbool.h"     /* for bool */
#include "ruby/intern.h"        /* for rb_alloc_func_t */
#include "ruby/ruby.h"          /* for struct RBasic */
#include "shape.h"
#include "ruby_assert.h"
#include "vm_core.h"
#include "vm_sync.h"
#include "method.h"             /* for rb_cref_t */

#ifdef RCLASS_SUPER
# undef RCLASS_SUPER
#endif

struct rb_cvar_class_tbl_entry {
    VALUE imemo_flags;
    uint32_t index;
    rb_serial_t global_cvar_state;
    const rb_cref_t *cref;
    VALUE class_value;
};

struct rb_classext_struct {
    const rb_box_t *box;
    VALUE super;
    VALUE fields_obj; // Fields are either ivar or other internal properties stored inline
    VALUE classpath;
    struct rb_id_table *m_tbl;
    struct rb_id_table *const_tbl;
    struct rb_id_table *callable_m_tbl;
    VALUE cc_tbl; /* { ID => { cme, [cc1, cc2, ...] }, ... } */
    VALUE cvc_tbl;
    VALUE *superclasses;
    /**
     * imemo_subclasses VALUE tracking this class's subclasses.
     * Only used in prime classext. Lazily allocated on first subclass addition.
     */
    VALUE subclasses;

    const VALUE origin_;
    const VALUE refined_class;
    union {
        struct {
            rb_alloc_func_t allocator;
        } class;
        struct {
            VALUE attached_object;
        } singleton_class;
        struct {
            const VALUE includer;
        } iclass;
    } as;
    uint16_t superclass_depth;
    attr_index_t max_iv_count;
    uint8_t variation_count;
    bool permanent_classpath : 1;
    bool shared_const_tbl : 1;
    bool iclass_is_origin : 1;
    bool iclass_origin_shared_mtbl : 1;
    bool superclasses_with_self : 1;
    bool expect_no_ivar : 1;
};
typedef struct rb_classext_struct rb_classext_t;

STATIC_ASSERT(shape_max_variations, SHAPE_MAX_VARIATIONS < (1 << (sizeof(((rb_classext_t *)0)->variation_count) * CHAR_BIT)));

struct RClass {
    struct RBasic basic;
    VALUE object_id;
    /*
     * If box_classext_tbl is NULL, then the prime classext is readable (because no other classext exists).
     * For the check whether writable or not, check flag RCLASS_PRIME_CLASSEXT_WRITABLE
     */
};

struct RClass_and_rb_classext_t {
    struct RClass rclass;
    rb_classext_t classext;
};

#if SIZEOF_VALUE >= SIZEOF_LONG_LONG
// Assert that classes can be embedded in heaps[3] (256B slot size on 64-bit).
// On 32bit platforms there is no variable width allocation so it doesn't matter.
STATIC_ASSERT(sizeof_rb_classext_t, sizeof(struct RClass_and_rb_classext_t) <= 256);
#endif

struct RClass_boxable {
    struct RClass_and_rb_classext_t base;
    st_table *box_classext_tbl; // box_object -> (rb_classext_t *)
};

static const uint16_t RCLASS_MAX_SUPERCLASS_DEPTH = ((uint16_t)-1);

static inline bool RCLASS_SINGLETON_P(VALUE klass);

static inline bool RCLASS_PRIME_CLASSEXT_READABLE_P(VALUE obj);
static inline bool RCLASS_PRIME_CLASSEXT_WRITABLE_P(VALUE obj);
static inline void RCLASS_SET_PRIME_CLASSEXT_WRITABLE(VALUE obj, bool writable);

#define RCLASS_EXT_PRIME(c) (&((struct RClass_and_rb_classext_t*)(c))->classext)
#define RCLASS_EXT_PRIME_P(ext, c) (&((struct RClass_and_rb_classext_t*)(c))->classext == ext)

static inline rb_classext_t * RCLASS_EXT_READABLE_IN_BOX(VALUE obj, const rb_box_t *box);
static inline rb_classext_t * RCLASS_EXT_READABLE(VALUE obj);
static inline rb_classext_t * RCLASS_EXT_WRITABLE_IN_BOX(VALUE obj, const rb_box_t *box);
static inline rb_classext_t * RCLASS_EXT_WRITABLE(VALUE obj);

// Raw accessor
#define RCLASSEXT_BOX(ext) (ext->box)
#define RCLASSEXT_SUPER(ext) (ext->super)
#define RCLASSEXT_FIELDS(ext) (ext->fields_obj ? ROBJECT_FIELDS(ext->fields_obj) : NULL)
#define RCLASSEXT_FIELDS_OBJ(ext) (ext->fields_obj)
#define RCLASSEXT_M_TBL(ext) (ext->m_tbl)
#define RCLASSEXT_CONST_TBL(ext) (ext->const_tbl)
#define RCLASSEXT_CALLABLE_M_TBL(ext) (ext->callable_m_tbl)
#define RCLASSEXT_CC_TBL(ext) (ext->cc_tbl)
#define RCLASSEXT_CVC_TBL(ext) (ext->cvc_tbl)
#define RCLASSEXT_SUPERCLASS_DEPTH(ext) (ext->superclass_depth)
#define RCLASSEXT_SUPERCLASSES(ext) (ext->superclasses)
#define RCLASSEXT_SUBCLASSES(ext) (ext->subclasses)
#define RCLASSEXT_ORIGIN(ext) (ext->origin_)
#define RCLASSEXT_REFINED_CLASS(ext) (ext->refined_class)
// class.allocator/singleton_class.attached_object are not accessed directly via RCLASSEXT_*
#define RCLASSEXT_INCLUDER(ext) (ext->as.iclass.includer)
#define RCLASSEXT_PERMANENT_CLASSPATH(ext) (ext->permanent_classpath)
#define RCLASSEXT_SHARED_CONST_TBL(ext) (ext->shared_const_tbl)
#define RCLASSEXT_ICLASS_IS_ORIGIN(ext) (ext->iclass_is_origin)
#define RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(ext) (ext->iclass_origin_shared_mtbl)
#define RCLASSEXT_SUPERCLASSES_WITH_SELF(ext) (ext->superclasses_with_self)
#define RCLASSEXT_CLASSPATH(ext) (ext->classpath)

static inline void RCLASSEXT_SET_ORIGIN(rb_classext_t *ext, VALUE klass, VALUE origin);
static inline void RCLASSEXT_SET_INCLUDER(rb_classext_t *ext, VALUE klass, VALUE includer);

/* Prime classext entry accessor for very specific reason */
#define RCLASS_PRIME_BOX(c) (RCLASS_EXT_PRIME(c)->box)
// To invalidate CC by inserting&invalidating method entry into tables containing the target cme
// See clear_method_cache_by_id_in_class()
#define RCLASS_PRIME_FIELDS_OBJ(c) (RCLASS_EXT_PRIME(c)->fields_obj)
#define RCLASS_PRIME_M_TBL(c) (RCLASS_EXT_PRIME(c)->m_tbl)
#define RCLASS_PRIME_CONST_TBL(c) (RCLASS_EXT_PRIME(c)->const_tbl)
#define RCLASS_PRIME_CALLABLE_M_TBL(c) (RCLASS_EXT_PRIME(c)->callable_m_tbl)
#define RCLASS_PRIME_CC_TBL(c) (RCLASS_EXT_PRIME(c)->cc_tbl)
#define RCLASS_M_TBL_NOT_PRIME_P(c, tbl) (RCLASS_EXT_PRIME(c)->m_tbl != tbl)
#define RCLASS_CALLABLE_M_TBL_NOT_PRIME_P(c, tbl) (RCLASS_EXT_PRIME(c)->callable_m_tbl != tbl)
#define RCLASS_CC_TBL_NOT_PRIME_P(c, tbl) (RCLASS_EXT_PRIME(c)->cc_tbl != tbl)

// Read accessor, regarding box
#define RCLASS_SUPER(c) (RCLASS_EXT_READABLE(c)->super)
#define RCLASS_M_TBL(c) (RCLASS_EXT_READABLE(c)->m_tbl)
#define RCLASS_CONST_TBL(c) (RCLASS_EXT_READABLE(c)->const_tbl)
/*
 * Both cc_tbl/callable_m_tbl are cache-like and always be changed when referreed,
 * so always those should be writable.
 */
#define RCLASS_CVC_TBL(c) (RCLASS_EXT_READABLE(c)->cvc_tbl)
#define RCLASS_SUBCLASSES(c) (RCLASS_EXT_PRIME(c)->subclasses)
#define RCLASS_ORIGIN(c) (RCLASS_EXT_READABLE(c)->origin_)
#define RICLASS_IS_ORIGIN_P(c) (RCLASS_EXT_READABLE(c)->iclass_is_origin)
#define RCLASS_PERMANENT_CLASSPATH_P(c) (RCLASS_EXT_READABLE(c)->permanent_classpath)
#define RCLASS_CLASSPATH(c) (RCLASS_EXT_READABLE(c)->classpath)

// Superclasses can't be changed after initialization
#define RCLASS_SUPERCLASS_DEPTH(c) (RCLASS_EXT_PRIME(c)->superclass_depth)
#define RCLASS_SUPERCLASSES(c) (RCLASS_EXT_PRIME(c)->superclasses)
#define RCLASS_SUPERCLASSES_WITH_SELF_P(c) (RCLASS_EXT_PRIME(c)->superclasses_with_self)

// Ruby Box doesn't make changes on these refined_class/attached_object/includer
#define RCLASS_REFINED_CLASS(c) (RCLASS_EXT_PRIME(c)->refined_class)
#define RCLASS_ATTACHED_OBJECT(c) (RCLASS_EXT_PRIME(c)->as.singleton_class.attached_object)
#define RCLASS_INCLUDER(c) (RCLASS_EXT_PRIME(c)->as.iclass.includer)

// max IV count and variation count are just hints, so they don't need to be per-box
#define RCLASS_MAX_IV_COUNT(ext) (RCLASS_EXT_PRIME(ext)->max_iv_count)
#define RCLASS_VARIATION_COUNT(ext) (RCLASS_EXT_PRIME(ext)->variation_count)

// Writable classext entries (instead of RCLASS_SET_*) because member data will be operated directly
#define RCLASS_WRITABLE_M_TBL(c) (RCLASS_EXT_WRITABLE(c)->m_tbl)
#define RCLASS_WRITABLE_CONST_TBL(c) (RCLASS_EXT_WRITABLE(c)->const_tbl)
#define RCLASS_WRITABLE_CALLABLE_M_TBL(c) (RCLASS_EXT_WRITABLE(c)->callable_m_tbl)
#define RCLASS_WRITABLE_CC_TBL(c) (RCLASS_EXT_WRITABLE(c)->cc_tbl)
#define RCLASS_WRITABLE_CVC_TBL(c) (RCLASS_EXT_WRITABLE(c)->cvc_tbl)
// Subclasses are only in the prime classext (box-invariant)
#define RCLASS_WRITABLE_SUBCLASSES(c) (RCLASS_EXT_PRIME(c)->subclasses)

static inline void RCLASS_SET_SUPER(VALUE klass, VALUE super);
static inline void RCLASS_WRITE_SUPER(VALUE klass, VALUE super);
static inline void RCLASS_SET_CONST_TBL(VALUE klass, struct rb_id_table *table, bool shared);
static inline void RCLASS_WRITE_CONST_TBL(VALUE klass, struct rb_id_table *table, bool shared);
static inline void RCLASS_WRITE_CALLABLE_M_TBL(VALUE klass, struct rb_id_table *table);
static inline void RCLASS_WRITE_CC_TBL(VALUE klass, VALUE table);
static inline void RCLASS_SET_CVC_TBL(VALUE klass, VALUE table);
static inline void RCLASS_WRITE_CVC_TBL(VALUE klass, VALUE table);

static inline void RCLASS_WRITE_SUPERCLASSES(VALUE klass, size_t depth, VALUE *superclasses, bool with_self);
static inline void RCLASS_SET_SUBCLASSES(VALUE klass, VALUE subclasses);

static inline void RCLASS_SET_ORIGIN(VALUE klass, VALUE origin);
static inline void RCLASS_WRITE_ORIGIN(VALUE klass, VALUE origin);
static inline void RICLASS_SET_ORIGIN_SHARED_MTBL(VALUE iclass);
static inline void RICLASS_WRITE_ORIGIN_SHARED_MTBL(VALUE iclass);
static inline bool RICLASS_OWNS_M_TBL_P(VALUE iclass);

static inline void RCLASS_SET_REFINED_CLASS(VALUE klass, VALUE refined);
static inline rb_alloc_func_t RCLASS_ALLOCATOR(VALUE klass);
static inline void RCLASS_SET_ALLOCATOR(VALUE klass, rb_alloc_func_t allocator);
static inline VALUE RCLASS_SET_ATTACHED_OBJECT(VALUE klass, VALUE attached_object);

static inline void RCLASS_SET_INCLUDER(VALUE iclass, VALUE klass);
static inline void RCLASS_SET_MAX_IV_COUNT(VALUE klass, attr_index_t count);
static inline void RCLASS_SET_CLASSPATH(VALUE klass, VALUE classpath, bool permanent);
static inline void RCLASS_WRITE_CLASSPATH(VALUE klass, VALUE classpath, bool permanent);

#define RCLASS_IS_ROOT FL_USER0
// 1 is for RUBY_FL_SINGLETON or RMODULE_IS_REFINEMENT
#define RCLASS_PRIME_CLASSEXT_WRITABLE FL_USER2
#define RCLASS_IS_INITIALIZED FL_USER3
// 3 is RMODULE_IS_REFINEMENT for RMODULE
#define RCLASS_BOXABLE FL_USER4
#define RCLASS_ALLOCATOR_DEFINED FL_USER5
#define RCLASS_HAS_SUBCLASSES FL_USER6

static inline st_table *
RCLASS_CLASSEXT_TBL(VALUE klass)
{
    if (FL_TEST_RAW(klass, RCLASS_BOXABLE)) {
        struct RClass_boxable *box_klass = (struct RClass_boxable *)klass;
        return box_klass->box_classext_tbl;
    }
    return NULL;
}

static inline void
RCLASS_SET_CLASSEXT_TBL(VALUE klass, st_table *tbl)
{
    RUBY_ASSERT(FL_TEST_RAW(klass, RCLASS_BOXABLE));
    struct RClass_boxable *box_klass = (struct RClass_boxable *)klass;
    box_klass->box_classext_tbl = tbl;
}

/* class.c */
rb_classext_t * rb_class_duplicate_classext(rb_classext_t *orig, VALUE obj, const rb_box_t *box);
void rb_class_ensure_writable(VALUE obj);

void rb_class_set_box_classext(VALUE obj, const rb_box_t *box, rb_classext_t *ext);

static inline int
RCLASS_SET_BOX_CLASSEXT(VALUE obj, const rb_box_t *box, rb_classext_t *ext)
{
    int first_set = 0;
    st_table *tbl = RCLASS_CLASSEXT_TBL(obj);
    VM_ASSERT(BOX_MUTABLE_P(box)); // Setting non-prime classext never happens on the master box
    VM_ASSERT(box->box_object);
    VM_ASSERT(RCLASSEXT_BOX(ext) == box);
    if (!tbl) {
        tbl = st_init_numtable_with_size(1);
        RCLASS_SET_CLASSEXT_TBL(obj, tbl);
    }
    if (rb_st_table_size(tbl) == 0) {
        first_set = 1;
    }

    rb_class_set_box_classext(obj, box, ext);

    return first_set;
}

#define VM_ASSERT_BOXABLE_TYPE(klass) \
    VM_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE) || RB_TYPE_P(klass, T_ICLASS), "%s is not boxable type", rb_type_str(BUILTIN_TYPE(klass)))

static inline bool
RCLASS_PRIME_CLASSEXT_READABLE_P(VALUE klass)
{
    VM_ASSERT(klass != 0, "klass should be a valid object");
    VM_ASSERT_BOXABLE_TYPE(klass);
    // if the lookup table exists, then it means the prime classext is NOT directly readable.
    return !FL_TEST_RAW(klass, RCLASS_BOXABLE) || RCLASS_CLASSEXT_TBL(klass) == NULL;
}

static inline bool
RCLASS_PRIME_CLASSEXT_WRITABLE_P(VALUE klass)
{
    VM_ASSERT(klass != 0, "klass should be a valid object");
    VM_ASSERT_BOXABLE_TYPE(klass);
    RBIMPL_ASSUME(klass != 0);
    return FL_TEST_RAW(klass, RCLASS_PRIME_CLASSEXT_WRITABLE);
}

static inline void
RCLASS_SET_PRIME_CLASSEXT_WRITABLE(VALUE klass, bool writable)
{
    VM_ASSERT(klass != 0, "klass should be a valid object");
    VM_ASSERT_BOXABLE_TYPE(klass);
    if (writable) {
        FL_SET_RAW(klass, RCLASS_PRIME_CLASSEXT_WRITABLE);
    }
    else {
        FL_UNSET_RAW(klass, RCLASS_PRIME_CLASSEXT_WRITABLE);
    }
}

static inline rb_classext_t *
RCLASS_EXT_TABLE_LOOKUP_INTERNAL(VALUE obj, const rb_box_t *box)
{
    st_data_t classext_ptr;
    st_table *classext_tbl = RCLASS_CLASSEXT_TBL(obj);
    if (classext_tbl) {
        if (rb_st_lookup(classext_tbl, (st_data_t)box->box_object, &classext_ptr)) {
            return (rb_classext_t *)classext_ptr;
        }
    }
    return NULL;
}

static inline rb_classext_t *
RCLASS_EXT_READABLE_LOOKUP(VALUE obj, const rb_box_t *box)
{
    rb_classext_t *ext = RCLASS_EXT_TABLE_LOOKUP_INTERNAL(obj, box);
    if (ext)
        return ext;
    // Classext for the ns not found. Refer the prime one instead.
    return RCLASS_EXT_PRIME(obj);
}

static inline rb_classext_t *
RCLASS_EXT_READABLE_IN_BOX(VALUE obj, const rb_box_t *box)
{
    if (BOX_MASTER_P(box)
        || RCLASS_PRIME_CLASSEXT_READABLE_P(obj)) {
        return RCLASS_EXT_PRIME(obj);
    }
    return RCLASS_EXT_READABLE_LOOKUP(obj, box);
}

static inline rb_classext_t *
RCLASS_EXT_READABLE(VALUE obj)
{
    const rb_box_t *box;
    if (RCLASS_PRIME_CLASSEXT_READABLE_P(obj)) {
        return RCLASS_EXT_PRIME(obj);
    }
    // delay determining the current box to optimize for unmodified classes
    box = rb_current_box();
    if (BOX_MASTER_P(box)) {
        return RCLASS_EXT_PRIME(obj);
    }
    return RCLASS_EXT_READABLE_LOOKUP(obj, box);
}

static inline rb_classext_t *
RCLASS_EXT_WRITABLE_LOOKUP(VALUE obj, const rb_box_t *box)
{
    rb_classext_t *ext;
    int first_set = 0;

    ext = RCLASS_EXT_TABLE_LOOKUP_INTERNAL(obj, box);
    if (ext)
        return ext;

    RB_VM_LOCKING() {
        // re-check the classext is not created to avoid the multi-thread race
        ext = RCLASS_EXT_TABLE_LOOKUP_INTERNAL(obj, box);
        if (!ext) {
            ext = rb_class_duplicate_classext(RCLASS_EXT_PRIME(obj), obj, box);
            first_set = RCLASS_SET_BOX_CLASSEXT(obj, box, ext);
            if (first_set) {
                // TODO: are there any case that a class/module become non-writable after its birthtime?
                RCLASS_SET_PRIME_CLASSEXT_WRITABLE(obj, false);
            }
        }
    }
    return ext;
}

static inline rb_classext_t *
RCLASS_EXT_WRITABLE_IN_BOX(VALUE obj, const rb_box_t *box)
{
    if (BOX_MASTER_P(box)
        || RCLASS_PRIME_CLASSEXT_WRITABLE_P(obj)) {
        return RCLASS_EXT_PRIME(obj);
    }
    return RCLASS_EXT_WRITABLE_LOOKUP(obj, box);
}

static inline rb_classext_t *
RCLASS_EXT_WRITABLE(VALUE obj)
{
    const rb_box_t *box;
    if (LIKELY(RCLASS_PRIME_CLASSEXT_WRITABLE_P(obj))) {
        return RCLASS_EXT_PRIME(obj);
    }
    // delay determining the current box to optimize for unmodified classes
    box = rb_current_box();
    if (BOX_MASTER_P(box)) {
        return RCLASS_EXT_PRIME(obj);
    }
    return RCLASS_EXT_WRITABLE_LOOKUP(obj, box);
}

static inline void
RCLASSEXT_SET_ORIGIN(rb_classext_t *ext, VALUE klass, VALUE origin)
{
    RB_OBJ_WRITE(klass, &(RCLASSEXT_ORIGIN(ext)), origin);
}

static inline void
RCLASSEXT_SET_INCLUDER(rb_classext_t *ext, VALUE klass, VALUE includer)
{
    RUBY_ASSERT(RB_TYPE_P(klass, T_ICLASS));
    RB_OBJ_WRITE(klass, &(RCLASSEXT_INCLUDER(ext)), includer);
}

/* class.c */
typedef void rb_class_classext_foreach_callback_func(rb_classext_t *classext, bool is_prime, VALUE box_value, void *arg);
void rb_class_classext_foreach(VALUE klass, rb_class_classext_foreach_callback_func *func, void *arg);
void rb_class_subclass_add(VALUE super, VALUE klass);
void rb_class_foreach_subclass(VALUE klass, void (*f)(VALUE, VALUE), VALUE);
void rb_class_update_superclasses(VALUE);
int rb_singleton_class_internal_p(VALUE sklass);
VALUE rb_class_set_super(VALUE klass, VALUE super);
VALUE rb_class_boot(VALUE);
VALUE rb_class_s_alloc(VALUE klass);
VALUE rb_module_s_alloc(VALUE klass);
void rb_class_set_initialized(VALUE klass);
void rb_module_check_initializable(VALUE module);
VALUE rb_make_metaclass(VALUE, VALUE);
VALUE rb_include_class_new(VALUE, VALUE);
VALUE rb_define_class_id_under_no_pin(VALUE outer, ID id, VALUE super);
VALUE rb_obj_methods(int argc, const VALUE *argv, VALUE obj);
VALUE rb_obj_protected_methods(int argc, const VALUE *argv, VALUE obj);
VALUE rb_obj_private_methods(int argc, const VALUE *argv, VALUE obj);
VALUE rb_obj_public_methods(int argc, const VALUE *argv, VALUE obj);
VALUE rb_class_undefined_instance_methods(VALUE mod);
VALUE rb_special_singleton_class(VALUE);
VALUE rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach);
VALUE rb_singleton_class_get(VALUE obj);
void rb_undef_methods_from(VALUE klass, VALUE super);
VALUE rb_class_inherited(VALUE, VALUE);
VALUE rb_keyword_error_new(const char *, VALUE);

rb_classext_t *rb_class_unlink_classext(VALUE klass, const rb_box_t *box);
void rb_class_classext_free(VALUE klass, rb_classext_t *ext, bool is_prime);
void rb_iclass_classext_free(VALUE klass, rb_classext_t *ext, bool is_prime);

RUBY_SYMBOL_EXPORT_BEGIN

/* for objspace */
VALUE rb_class_super_of(VALUE klass);
VALUE rb_class_singleton_p(VALUE klass);
unsigned char rb_class_variation_count(VALUE klass);

RUBY_SYMBOL_EXPORT_END

static inline bool
RCLASS_SINGLETON_P(VALUE klass)
{
    RUBY_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE) || RB_TYPE_P(klass, T_ICLASS));
    return RB_BUILTIN_TYPE(klass) == T_CLASS && FL_TEST_RAW(klass, FL_SINGLETON);
}

static inline void
RCLASS_SET_SUPER(VALUE klass, VALUE super)
{
    RB_OBJ_WRITE(klass, &RCLASSEXT_SUPER(RCLASS_EXT_PRIME(klass)), super);
}

static inline void
RCLASS_WRITE_SUPER(VALUE klass, VALUE super)
{
    RB_OBJ_WRITE(klass, &RCLASSEXT_SUPER(RCLASS_EXT_WRITABLE(klass)), super);
}

static inline VALUE
RCLASS_WRITABLE_ENSURE_FIELDS_OBJ(VALUE obj)
{
    RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));
    rb_classext_t *ext = RCLASS_EXT_WRITABLE(obj);
    if (!ext->fields_obj) {
        RB_OBJ_WRITE(obj, &ext->fields_obj, rb_imemo_fields_new(obj, ROOT_SHAPE_ID, true));
    }
    return ext->fields_obj;
}

static inline VALUE
RCLASS_WRITABLE_FIELDS_OBJ(VALUE obj)
{
    RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));
    return RCLASSEXT_FIELDS_OBJ(RCLASS_EXT_WRITABLE(obj));
}

static inline void
RCLASSEXT_SET_FIELDS_OBJ(VALUE obj, rb_classext_t *ext, VALUE fields_obj)
{
    RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));

    RB_OBJ_ATOMIC_WRITE(obj, &ext->fields_obj, fields_obj);
}

static inline void
RCLASS_WRITABLE_SET_FIELDS_OBJ(VALUE obj, VALUE fields_obj)
{
    RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));

    RCLASSEXT_SET_FIELDS_OBJ(obj, RCLASS_EXT_WRITABLE(obj), fields_obj);
}

static inline uint32_t
RCLASS_FIELDS_COUNT(VALUE obj)
{
    RUBY_ASSERT(RB_TYPE_P(obj, RUBY_T_CLASS) || RB_TYPE_P(obj, RUBY_T_MODULE));

    VALUE fields_obj = RCLASS_WRITABLE_FIELDS_OBJ(obj);
    if (fields_obj) {
        if (rb_obj_shape_complex_p(fields_obj)) {
            return (uint32_t)rb_st_table_size(rb_imemo_fields_complex_tbl(fields_obj));
        }
        else {
            return RSHAPE_LEN(RBASIC_SHAPE_ID(fields_obj));
        }
    }
    return 0;
}

static inline void
RCLASS_SET_M_TBL(VALUE klass, struct rb_id_table *table)
{
    RCLASSEXT_M_TBL(RCLASS_EXT_PRIME(klass)) = table;
}

static inline void
RCLASS_WRITE_M_TBL(VALUE klass, struct rb_id_table *table)
{
    RCLASSEXT_M_TBL(RCLASS_EXT_WRITABLE(klass)) = table;
}

static inline void
RCLASS_SET_CONST_TBL(VALUE klass, struct rb_id_table *table, bool shared)
{
    rb_classext_t *ext = RCLASS_EXT_PRIME(klass);
    RCLASSEXT_CONST_TBL(ext) = table;
    if (shared)
        RCLASSEXT_SHARED_CONST_TBL(ext) = true;
}

static inline void
RCLASS_WRITE_CONST_TBL(VALUE klass, struct rb_id_table *table, bool shared)
{
    rb_classext_t *ext = RCLASS_EXT_WRITABLE(klass);
    RCLASSEXT_CONST_TBL(ext) = table;
    if (shared)
        RCLASSEXT_SHARED_CONST_TBL(ext) = true;
}

static inline void
RCLASS_WRITE_CALLABLE_M_TBL(VALUE klass, struct rb_id_table *table)
{
    RCLASSEXT_CALLABLE_M_TBL(RCLASS_EXT_WRITABLE(klass)) = table;
}

static inline void
RCLASS_WRITE_CC_TBL(VALUE klass, VALUE table)
{
    RB_OBJ_ATOMIC_WRITE(klass, &RCLASSEXT_CC_TBL(RCLASS_EXT_WRITABLE(klass)), table);
}

static inline void
RCLASS_SET_CVC_TBL(VALUE klass, VALUE table)
{
    RB_OBJ_ATOMIC_WRITE(klass, &RCLASSEXT_CVC_TBL(RCLASS_EXT_PRIME(klass)), table);
}

static inline void
RCLASS_WRITE_CVC_TBL(VALUE klass, VALUE table)
{
    RB_OBJ_ATOMIC_WRITE(klass, &RCLASSEXT_CVC_TBL(RCLASS_EXT_WRITABLE(klass)), table);
}

static inline void
RCLASS_SET_REFINED_CLASS(VALUE klass, VALUE refined)
{
    RB_OBJ_WRITE(klass, &RCLASSEXT_REFINED_CLASS(RCLASS_EXT_PRIME(klass)), refined);
}

static inline rb_alloc_func_t
RCLASS_ALLOCATOR(VALUE klass)
{
    RBIMPL_ASSERT_TYPE(klass, T_CLASS);
    RUBY_ASSERT(!RCLASS_SINGLETON_P(klass));
    return RCLASS_EXT_PRIME(klass)->as.class.allocator;
}

static inline void
RCLASS_SET_ALLOCATOR(VALUE klass, rb_alloc_func_t allocator)
{
    RUBY_ASSERT(RB_TYPE_P(klass, T_CLASS));
    RUBY_ASSERT(!RCLASS_SINGLETON_P(klass));
    RCLASS_EXT_PRIME(klass)->as.class.allocator = allocator; // Allocator is set only on the initial definition
}

static inline void
RCLASS_SET_ORIGIN(VALUE klass, VALUE origin)
{
    rb_classext_t *ext = RCLASS_EXT_PRIME(klass);
    RB_OBJ_WRITE(klass, &RCLASSEXT_ORIGIN(ext), origin);
    if (klass != origin) RCLASSEXT_ICLASS_IS_ORIGIN(RCLASS_EXT_WRITABLE(origin)) = true;
}

static inline void
RCLASS_WRITE_ORIGIN(VALUE klass, VALUE origin)
{
    rb_classext_t *ext = RCLASS_EXT_WRITABLE(klass);
    RB_OBJ_WRITE(klass, &RCLASSEXT_ORIGIN(ext), origin);
    if (klass != origin) RCLASSEXT_ICLASS_IS_ORIGIN(RCLASS_EXT_WRITABLE(origin)) = true;
}

static inline void
RICLASS_SET_ORIGIN_SHARED_MTBL(VALUE iclass)
{
    RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(RCLASS_EXT_PRIME(iclass)) = true;
}

static inline void
RICLASS_WRITE_ORIGIN_SHARED_MTBL(VALUE iclass)
{
    RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(RCLASS_EXT_WRITABLE(iclass)) = true;
}

static inline bool
RICLASS_OWNS_M_TBL_P(VALUE iclass)
{
    rb_classext_t *ext = RCLASS_EXT_READABLE(iclass);
    return RCLASSEXT_ICLASS_IS_ORIGIN(ext) && !RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(ext);
}

static inline bool
RICLASS_FOR_REFINEMENT_P(VALUE iclass)
{
    return BUILTIN_TYPE(iclass) == T_ICLASS &&
            RB_TYPE_P(RBASIC(iclass)->klass, T_MODULE) &&
            FL_TEST_RAW(RBASIC(iclass)->klass, RMODULE_IS_REFINEMENT);
}

static inline void
RCLASS_SET_INCLUDER(VALUE iclass, VALUE klass)
{
    RUBY_ASSERT(RB_TYPE_P(iclass, T_ICLASS));
    RB_OBJ_WRITE(iclass, &RCLASS_INCLUDER(iclass), klass);
}

static inline void
RCLASS_WRITE_SUPERCLASSES(VALUE klass, size_t depth, VALUE *superclasses, bool with_self)
{
    RUBY_ASSERT(depth <= RCLASS_MAX_SUPERCLASS_DEPTH);

    rb_classext_t *ext = RCLASS_EXT_PRIME(klass);
    RCLASSEXT_SUPERCLASS_DEPTH(ext) = depth;
    RCLASSEXT_SUPERCLASSES(ext) = superclasses;
    RCLASSEXT_SUPERCLASSES_WITH_SELF(ext) = with_self;
}

static inline void
RCLASS_SET_SUBCLASSES(VALUE klass, VALUE subclasses)
{
    rb_classext_t *ext = RCLASS_EXT_PRIME(klass);
    RB_OBJ_WRITE(klass, &RCLASSEXT_SUBCLASSES(ext), subclasses);
}

static inline void
RCLASS_SET_CLASSPATH(VALUE klass, VALUE classpath, bool permanent)
{
    rb_classext_t *ext = RCLASS_EXT_READABLE(klass);
    assert(BUILTIN_TYPE(klass) == T_CLASS || BUILTIN_TYPE(klass) == T_MODULE);
    assert(classpath == 0 || BUILTIN_TYPE(classpath) == T_STRING);
    assert(FL_TEST_RAW(classpath, RUBY_FL_SHAREABLE));

    RB_OBJ_WRITE(klass, &(RCLASSEXT_CLASSPATH(ext)), classpath);
    RCLASSEXT_PERMANENT_CLASSPATH(ext) = permanent;
}

static inline void
RCLASS_WRITE_CLASSPATH(VALUE klass, VALUE classpath, bool permanent)
{
    rb_classext_t *ext = RCLASS_EXT_WRITABLE(klass);
    assert(BUILTIN_TYPE(klass) == T_CLASS || BUILTIN_TYPE(klass) == T_MODULE);
    assert(classpath == 0 || BUILTIN_TYPE(classpath) == T_STRING);
    assert(!RB_FL_ABLE(classpath) || FL_TEST_RAW(classpath, RUBY_FL_SHAREABLE));

    RB_OBJ_WRITE(klass, &(RCLASSEXT_CLASSPATH(ext)), classpath);
    RCLASSEXT_PERMANENT_CLASSPATH(ext) = permanent;
}

static inline VALUE
RCLASS_SET_ATTACHED_OBJECT(VALUE klass, VALUE attached_object)
{
    assert(RCLASS_SINGLETON_P(klass));

    RB_OBJ_WRITE(klass, &RCLASS_EXT_PRIME(klass)->as.singleton_class.attached_object, attached_object);
    return attached_object;
}

static inline void
RCLASS_SET_MAX_IV_COUNT(VALUE klass, attr_index_t count)
{
    RUBY_ASSERT(klass != rb_cObject);
    RUBY_ASSERT(klass != rb_cBasicObject);

    RCLASS_MAX_IV_COUNT(klass) = count;
}

static inline void
RCLASS_SET_EXPECT_NO_IVAR(VALUE klass)
{
    RCLASS_EXT_PRIME(klass)->expect_no_ivar = true;
}

static inline bool
RCLASS_EXPECT_NO_IVAR(VALUE klass)
{
    return RCLASS_EXT_PRIME(klass)->expect_no_ivar;
}

static inline bool
RCLASS_INITIALIZED_P(VALUE klass)
{
    VM_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE));
    return FL_TEST_RAW(klass, RCLASS_IS_INITIALIZED);
}

#endif /* INTERNAL_CLASS_H */