ruby / ruby

eileencodes Refactor `rb_class_ivar_set`

Latest commit 23a48d8

Mar 10, 2021

In every caller of `rb_class_ivar_set` it checks for the `RCLASS_IV_TBL`
and then creates it if it doesn't exist. Instead of repeating this in
every caller, this can be done once in `rb_class_ivar_set`.

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	/**********************************************************************

	variable.c -

	$Author$
	created at: Tue Apr 19 23:55:15 JST 1994

	Copyright (C) 1993-2007 Yukihiro Matsumoto
	Copyright (C) 2000 Network Applied Communication Laboratory, Inc.
	Copyright (C) 2000 Information-technology Promotion Agency, Japan

	**********************************************************************/

	#include "ruby/internal/config.h"
	#include <stddef.h>
	#include "ruby/internal/stdbool.h"
	#include "ccan/list/list.h"
	#include "constant.h"
	#include "debug_counter.h"
	#include "id.h"
	#include "id_table.h"
	#include "internal.h"
	#include "internal/class.h"
	#include "internal/compilers.h"
	#include "internal/error.h"
	#include "internal/eval.h"
	#include "internal/hash.h"
	#include "internal/object.h"
	#include "internal/re.h"
	#include "internal/symbol.h"
	#include "internal/thread.h"
	#include "internal/variable.h"
	#include "ruby/encoding.h"
	#include "ruby/st.h"
	#include "ruby/util.h"
	#include "transient_heap.h"
	#include "variable.h"
	#include "vm_core.h"
	#include "ractor_core.h"
	#include "vm_sync.h"

	typedef void rb_gvar_compact_t(void *var);

	static struct rb_id_table *rb_global_tbl;
	static ID autoload, classpath, tmp_classpath;
	static VALUE autoload_featuremap; /* feature => autoload_i */

	static void check_before_mod_set(VALUE, ID, VALUE, const char *);
	static void setup_const_entry(rb_const_entry_t *, VALUE, VALUE, rb_const_flag_t);
	static VALUE rb_const_search(VALUE klass, ID id, int exclude, int recurse, int visibility);
	static st_table *generic_iv_tbl_;

	struct ivar_update {
	union {
	st_table *iv_index_tbl;
	struct gen_ivtbl *ivtbl;
	} u;
	st_data_t index;
	int iv_extended;
	};

	void
	Init_var_tables(void)
	{
	rb_global_tbl = rb_id_table_create(0);
	generic_iv_tbl_ = st_init_numtable();
	autoload = rb_intern_const("__autoload__");
	/* __classpath__: fully qualified class path */
	classpath = rb_intern_const("__classpath__");
	/* __tmp_classpath__: temporary class path which contains anonymous names */
	tmp_classpath = rb_intern_const("__tmp_classpath__");
	}

	static inline bool
	rb_namespace_p(VALUE obj)
	{
	if (RB_SPECIAL_CONST_P(obj)) return false;
	switch (RB_BUILTIN_TYPE(obj)) {
	case T_MODULE: case T_CLASS: return true;
	default: break;
	}
	return false;
	}

	/**
	* Returns +classpath+ of _klass_, if it is named, or +nil+ for
	* anonymous +class+/+module+. A named +classpath+ may contain
	* an anonymous component, but the last component is guaranteed
	* to not be anonymous. <code>*permanent</code> is set to 1
	* if +classpath+ has no anonymous components. There is no builtin
	* Ruby level APIs that can change a permanent +classpath+.
	*/
	static VALUE
	classname(VALUE klass, int *permanent)
	{
	st_table *ivtbl;
	st_data_t n;

	*permanent = 0;
	if (!RCLASS_EXT(klass)) return Qnil;
	if (!(ivtbl = RCLASS_IV_TBL(klass))) return Qnil;
	if (st_lookup(ivtbl, (st_data_t)classpath, &n)) {
	*permanent = 1;
	return (VALUE)n;
	}
	if (st_lookup(ivtbl, (st_data_t)tmp_classpath, &n)) return (VALUE)n;
	return Qnil;
	}

	/*
	* call-seq:
	* mod.name -> string
	*
	* Returns the name of the module <i>mod</i>. Returns nil for anonymous modules.
	*/

	VALUE
	rb_mod_name(VALUE mod)
	{
	int permanent;
	return classname(mod, &permanent);
	}

	static VALUE
	make_temporary_path(VALUE obj, VALUE klass)
	{
	VALUE path;
	switch (klass) {
	case Qnil:
	path = rb_sprintf("#<Class:%p>", (void*)obj);
	break;
	case Qfalse:
	path = rb_sprintf("#<Module:%p>", (void*)obj);
	break;
	default:
	path = rb_sprintf("#<%"PRIsVALUE":%p>", klass, (void*)obj);
	break;
	}
	OBJ_FREEZE(path);
	return path;
	}

	typedef VALUE (*fallback_func)(VALUE obj, VALUE name);

	static VALUE
	rb_tmp_class_path(VALUE klass, int *permanent, fallback_func fallback)
	{
	VALUE path = classname(klass, permanent);

	if (!NIL_P(path)) {
	return path;
	}
	else {
	if (RB_TYPE_P(klass, T_MODULE)) {
	if (rb_obj_class(klass) == rb_cModule) {
	path = Qfalse;
	}
	else {
	int perm;
	path = rb_tmp_class_path(RBASIC(klass)->klass, &perm, fallback);
	}
	}
	*permanent = 0;
	return fallback(klass, path);
	}
	}

	VALUE
	rb_class_path(VALUE klass)
	{
	int permanent;
	VALUE path = rb_tmp_class_path(klass, &permanent, make_temporary_path);
	if (!NIL_P(path)) path = rb_str_dup(path);
	return path;
	}

	VALUE
	rb_class_path_cached(VALUE klass)
	{
	int permanent;
	return classname(klass, &permanent);
	}

	static VALUE
	no_fallback(VALUE obj, VALUE name)
	{
	return name;
	}

	VALUE
	rb_search_class_path(VALUE klass)
	{
	int permanent;
	return rb_tmp_class_path(klass, &permanent, no_fallback);
	}

	static VALUE
	build_const_pathname(VALUE head, VALUE tail)
	{
	VALUE path = rb_str_dup(head);
	rb_str_cat2(path, "::");
	rb_str_append(path, tail);
	OBJ_FREEZE(path);
	return path;
	}

	static VALUE
	build_const_path(VALUE head, ID tail)
	{
	return build_const_pathname(head, rb_id2str(tail));
	}

	void
	rb_set_class_path_string(VALUE klass, VALUE under, VALUE name)
	{
	VALUE str;
	ID pathid = classpath;

	if (under == rb_cObject) {
	str = rb_str_new_frozen(name);
	}
	else {
	int permanent;
	str = rb_tmp_class_path(under, &permanent, make_temporary_path);
	str = build_const_pathname(str, name);
	if (!permanent) {
	pathid = tmp_classpath;
	}
	}
	rb_ivar_set(klass, pathid, str);
	}

	void
	rb_set_class_path(VALUE klass, VALUE under, const char *name)
	{
	VALUE str = rb_str_new2(name);
	OBJ_FREEZE(str);
	rb_set_class_path_string(klass, under, str);
	}

	VALUE
	rb_path_to_class(VALUE pathname)
	{
	rb_encoding *enc = rb_enc_get(pathname);
	const char pbeg, pend, p, path = RSTRING_PTR(pathname);
	ID id;
	VALUE c = rb_cObject;

	if (!rb_enc_asciicompat(enc)) {
	rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
	}
	pbeg = p = path;
	pend = path + RSTRING_LEN(pathname);
	if (path == pend \|\| path[0] == '#') {
	rb_raise(rb_eArgError, "can't retrieve anonymous class %"PRIsVALUE,
	QUOTE(pathname));
	}
	while (p < pend) {
	while (p < pend && *p != ':') p++;
	id = rb_check_id_cstr(pbeg, p-pbeg, enc);
	if (p < pend && p[0] == ':') {
	if ((size_t)(pend - p) < 2 \|\| p[1] != ':') goto undefined_class;
	p += 2;
	pbeg = p;
	}
	if (!id) {
	goto undefined_class;
	}
	c = rb_const_search(c, id, TRUE, FALSE, FALSE);
	if (c == Qundef) goto undefined_class;
	if (!rb_namespace_p(c)) {
	rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
	pathname);
	}
	}
	RB_GC_GUARD(pathname);

	return c;

	undefined_class:
	rb_raise(rb_eArgError, "undefined class/module % "PRIsVALUE,
	rb_str_subseq(pathname, 0, p-path));
	UNREACHABLE_RETURN(Qundef);
	}

	VALUE
	rb_path2class(const char *path)
	{
	return rb_path_to_class(rb_str_new_cstr(path));
	}

	VALUE
	rb_class_name(VALUE klass)
	{
	return rb_class_path(rb_class_real(klass));
	}

	const char *
	rb_class2name(VALUE klass)
	{
	int permanent;
	VALUE path = rb_tmp_class_path(rb_class_real(klass), &permanent, make_temporary_path);
	if (NIL_P(path)) return NULL;
	return RSTRING_PTR(path);
	}

	const char *
	rb_obj_classname(VALUE obj)
	{
	return rb_class2name(CLASS_OF(obj));
	}

	struct trace_var {
	int removed;
	void (*func)(VALUE arg, VALUE val);
	VALUE data;
	struct trace_var *next;
	};

	struct rb_global_variable {
	int counter;
	int block_trace;
	VALUE *data;
	rb_gvar_getter_t *getter;
	rb_gvar_setter_t *setter;
	rb_gvar_marker_t *marker;
	rb_gvar_compact_t *compactor;
	struct trace_var *trace;
	};

	struct rb_global_entry {
	struct rb_global_variable *var;
	ID id;
	bool ractor_local;
	};

	static struct rb_global_entry*
	rb_find_global_entry(ID id)
	{
	struct rb_global_entry *entry;
	VALUE data;

	if (!rb_id_table_lookup(rb_global_tbl, id, &data)) {
	entry = NULL;
	}
	else {
	entry = (struct rb_global_entry *)data;
	RUBY_ASSERT(entry != NULL);
	}

	if (UNLIKELY(!rb_ractor_main_p()) && (!entry \|\| !entry->ractor_local)) {
	rb_raise(rb_eRactorIsolationError, "can not access global variables %s from non-main Ractors", rb_id2name(id));
	}

	return entry;
	}

	void
	rb_gvar_ractor_local(const char *name)
	{
	struct rb_global_entry *entry = rb_find_global_entry(rb_intern(name));
	entry->ractor_local = true;
	}

	static void
	rb_gvar_undef_compactor(void *var)
	{
	}

	static struct rb_global_entry*
	rb_global_entry(ID id)
	{
	struct rb_global_entry *entry = rb_find_global_entry(id);
	if (!entry) {
	struct rb_global_variable *var;
	entry = ALLOC(struct rb_global_entry);
	var = ALLOC(struct rb_global_variable);
	entry->id = id;
	entry->var = var;
	entry->ractor_local = false;
	var->counter = 1;
	var->data = 0;
	var->getter = rb_gvar_undef_getter;
	var->setter = rb_gvar_undef_setter;
	var->marker = rb_gvar_undef_marker;
	var->compactor = rb_gvar_undef_compactor;

	var->block_trace = 0;
	var->trace = 0;
	rb_id_table_insert(rb_global_tbl, id, (VALUE)entry);
	}
	return entry;
	}

	VALUE
	rb_gvar_undef_getter(ID id, VALUE *_)
	{
	rb_warning("global variable `%"PRIsVALUE"' not initialized", QUOTE_ID(id));

	return Qnil;
	}

	static void
	rb_gvar_val_compactor(void *_var)
	{
	struct rb_global_variable var = (struct rb_global_variable )_var;

	VALUE obj = (VALUE)var->data;

	if (obj) {
	VALUE new = rb_gc_location(obj);
	if (new != obj) {
	var->data = (void*)new;
	}
	}
	}

	void
	rb_gvar_undef_setter(VALUE val, ID id, VALUE *_)
	{
	struct rb_global_variable *var = rb_global_entry(id)->var;
	var->getter = rb_gvar_val_getter;
	var->setter = rb_gvar_val_setter;
	var->marker = rb_gvar_val_marker;
	var->compactor = rb_gvar_val_compactor;

	var->data = (void*)val;
	}

	void
	rb_gvar_undef_marker(VALUE *var)
	{
	}

	VALUE
	rb_gvar_val_getter(ID id, VALUE *data)
	{
	return (VALUE)data;
	}

	void
	rb_gvar_val_setter(VALUE val, ID id, VALUE *_)
	{
	struct rb_global_variable *var = rb_global_entry(id)->var;
	var->data = (void*)val;
	}

	void
	rb_gvar_val_marker(VALUE *var)
	{
	VALUE data = (VALUE)var;
	if (data) rb_gc_mark_movable(data);
	}

	VALUE
	rb_gvar_var_getter(ID id, VALUE *var)
	{
	if (!var) return Qnil;
	return *var;
	}

	void
	rb_gvar_var_setter(VALUE val, ID id, VALUE *data)
	{
	*data = val;
	}

	void
	rb_gvar_var_marker(VALUE *var)
	{
	if (var) rb_gc_mark_maybe(*var);
	}

	void
	rb_gvar_readonly_setter(VALUE v, ID id, VALUE *_)
	{
	rb_name_error(id, "%"PRIsVALUE" is a read-only variable", QUOTE_ID(id));
	}

	static enum rb_id_table_iterator_result
	mark_global_entry(VALUE v, void *ignored)
	{
	struct rb_global_entry entry = (struct rb_global_entry )v;
	struct trace_var *trace;
	struct rb_global_variable *var = entry->var;

	(*var->marker)(var->data);
	trace = var->trace;
	while (trace) {
	if (trace->data) rb_gc_mark_maybe(trace->data);
	trace = trace->next;
	}
	return ID_TABLE_CONTINUE;
	}

	void
	rb_gc_mark_global_tbl(void)
	{
	if (rb_global_tbl) {
	rb_id_table_foreach_values(rb_global_tbl, mark_global_entry, 0);
	}
	}

	static enum rb_id_table_iterator_result
	update_global_entry(VALUE v, void *ignored)
	{
	struct rb_global_entry entry = (struct rb_global_entry )v;
	struct rb_global_variable *var = entry->var;

	(*var->compactor)(var);
	return ID_TABLE_CONTINUE;
	}

	void
	rb_gc_update_global_tbl(void)
	{
	if (rb_global_tbl) {
	rb_id_table_foreach_values(rb_global_tbl, update_global_entry, 0);
	}
	}

	static ID
	global_id(const char *name)
	{
	ID id;

	if (name[0] == '$') id = rb_intern(name);
	else {
	size_t len = strlen(name);
	VALUE vbuf = 0;
	char *buf = ALLOCV_N(char, vbuf, len+1);
	buf[0] = '$';
	memcpy(buf+1, name, len);
	id = rb_intern2(buf, len+1);
	ALLOCV_END(vbuf);
	}
	return id;
	}

	static ID
	find_global_id(const char *name)
	{
	ID id;
	size_t len = strlen(name);

	if (name[0] == '$') {
	id = rb_check_id_cstr(name, len, NULL);
	}
	else {
	VALUE vbuf = 0;
	char *buf = ALLOCV_N(char, vbuf, len+1);
	buf[0] = '$';
	memcpy(buf+1, name, len);
	id = rb_check_id_cstr(buf, len+1, NULL);
	ALLOCV_END(vbuf);
	}

	return id;
	}

	void
	rb_define_hooked_variable(
	const char *name,
	VALUE *var,
	rb_gvar_getter_t *getter,
	rb_gvar_setter_t *setter)
	{
	volatile VALUE tmp = var ? *var : Qnil;
	ID id = global_id(name);
	struct rb_global_variable *gvar = rb_global_entry(id)->var;

	gvar->data = (void*)var;
	gvar->getter = getter ? (rb_gvar_getter_t *)getter : rb_gvar_var_getter;
	gvar->setter = setter ? (rb_gvar_setter_t *)setter : rb_gvar_var_setter;
	gvar->marker = rb_gvar_var_marker;

	RB_GC_GUARD(tmp);
	}

	void
	rb_define_variable(const char name, VALUE var)
	{
	rb_define_hooked_variable(name, var, 0, 0);
	}

	void
	rb_define_readonly_variable(const char name, const VALUE var)
	{
	rb_define_hooked_variable(name, (VALUE *)var, 0, rb_gvar_readonly_setter);
	}

	void
	rb_define_virtual_variable(
	const char *name,
	rb_gvar_getter_t *getter,
	rb_gvar_setter_t *setter)
	{
	if (!getter) getter = rb_gvar_val_getter;
	if (!setter) setter = rb_gvar_readonly_setter;
	rb_define_hooked_variable(name, 0, getter, setter);
	}

	static void
	rb_trace_eval(VALUE cmd, VALUE val)
	{
	rb_eval_cmd_kw(cmd, rb_ary_new3(1, val), RB_NO_KEYWORDS);
	}

	VALUE
	rb_f_trace_var(int argc, const VALUE *argv)
	{
	VALUE var, cmd;
	struct rb_global_entry *entry;
	struct trace_var *trace;

	if (rb_scan_args(argc, argv, "11", &var, &cmd) == 1) {
	cmd = rb_block_proc();
	}
	if (NIL_P(cmd)) {
	return rb_f_untrace_var(argc, argv);
	}
	entry = rb_global_entry(rb_to_id(var));
	trace = ALLOC(struct trace_var);
	trace->next = entry->var->trace;
	trace->func = rb_trace_eval;
	trace->data = cmd;
	trace->removed = 0;
	entry->var->trace = trace;

	return Qnil;
	}

	static void
	remove_trace(struct rb_global_variable *var)
	{
	struct trace_var *trace = var->trace;
	struct trace_var t;
	struct trace_var *next;

	t.next = trace;
	trace = &t;
	while (trace->next) {
	next = trace->next;
	if (next->removed) {
	trace->next = next->next;
	xfree(next);
	}
	else {
	trace = next;
	}
	}
	var->trace = t.next;
	}

	VALUE
	rb_f_untrace_var(int argc, const VALUE *argv)
	{
	VALUE var, cmd;
	ID id;
	struct rb_global_entry *entry;
	struct trace_var *trace;

	rb_scan_args(argc, argv, "11", &var, &cmd);
	id = rb_check_id(&var);
	if (!id) {
	rb_name_error_str(var, "undefined global variable %"PRIsVALUE"", QUOTE(var));
	}
	if ((entry = rb_find_global_entry(id)) == NULL) {
	rb_name_error(id, "undefined global variable %"PRIsVALUE"", QUOTE_ID(id));
	}

	trace = entry->var->trace;
	if (NIL_P(cmd)) {
	VALUE ary = rb_ary_new();

	while (trace) {
	struct trace_var *next = trace->next;
	rb_ary_push(ary, (VALUE)trace->data);
	trace->removed = 1;
	trace = next;
	}

	if (!entry->var->block_trace) remove_trace(entry->var);
	return ary;
	}
	else {
	while (trace) {
	if (trace->data == cmd) {
	trace->removed = 1;
	if (!entry->var->block_trace) remove_trace(entry->var);
	return rb_ary_new3(1, cmd);
	}
	trace = trace->next;
	}
	}
	return Qnil;
	}

	struct trace_data {
	struct trace_var *trace;
	VALUE val;
	};

	static VALUE
	trace_ev(VALUE v)
	{
	struct trace_data data = (void )v;
	struct trace_var *trace = data->trace;

	while (trace) {
	(*trace->func)(trace->data, data->val);
	trace = trace->next;
	}

	return Qnil;
	}

	static VALUE
	trace_en(VALUE v)
	{
	struct rb_global_variable var = (void )v;
	var->block_trace = 0;
	remove_trace(var);
	return Qnil; /* not reached */
	}

	static VALUE
	rb_gvar_set_entry(struct rb_global_entry *entry, VALUE val)
	{
	struct trace_data trace;
	struct rb_global_variable *var = entry->var;

	(*var->setter)(val, entry->id, var->data);

	if (var->trace && !var->block_trace) {
	var->block_trace = 1;
	trace.trace = var->trace;
	trace.val = val;
	rb_ensure(trace_ev, (VALUE)&trace, trace_en, (VALUE)var);
	}
	return val;
	}

	VALUE
	rb_gvar_set(ID id, VALUE val)
	{
	struct rb_global_entry *entry;
	entry = rb_global_entry(id);

	return rb_gvar_set_entry(entry, val);
	}

	VALUE
	rb_gv_set(const char *name, VALUE val)
	{
	return rb_gvar_set(global_id(name), val);
	}

	VALUE
	rb_gvar_get(ID id)
	{
	struct rb_global_entry *entry = rb_global_entry(id);
	struct rb_global_variable *var = entry->var;
	return (*var->getter)(entry->id, var->data);
	}

	VALUE
	rb_gv_get(const char *name)
	{
	ID id = find_global_id(name);

	if (!id) {
	rb_warning("global variable `%s' not initialized", name);
	return Qnil;
	}

	return rb_gvar_get(id);
	}

	MJIT_FUNC_EXPORTED VALUE
	rb_gvar_defined(ID id)
	{
	struct rb_global_entry *entry = rb_global_entry(id);
	if (entry->var->getter == rb_gvar_undef_getter) return Qfalse;
	return Qtrue;
	}

	rb_gvar_getter_t *
	rb_gvar_getter_function_of(ID id)
	{
	const struct rb_global_entry *entry = rb_global_entry(id);
	return entry->var->getter;
	}

	rb_gvar_setter_t *
	rb_gvar_setter_function_of(ID id)
	{
	const struct rb_global_entry *entry = rb_global_entry(id);
	return entry->var->setter;
	}

	static enum rb_id_table_iterator_result
	gvar_i(ID key, VALUE val, void *a)
	{
	VALUE ary = (VALUE)a;
	rb_ary_push(ary, ID2SYM(key));
	return ID_TABLE_CONTINUE;
	}

	VALUE
	rb_f_global_variables(void)
	{
	VALUE ary = rb_ary_new();
	VALUE sym, backref = rb_backref_get();

	if (!rb_ractor_main_p()) {
	rb_raise(rb_eRactorIsolationError, "can not access global variables from non-main Ractors");
	}

	rb_id_table_foreach(rb_global_tbl, gvar_i, (void *)ary);
	if (!NIL_P(backref)) {
	char buf[2];
	int i, nmatch = rb_match_count(backref);
	buf[0] = '$';
	for (i = 1; i <= nmatch; ++i) {
	if (!rb_match_nth_defined(i, backref)) continue;
	if (i < 10) {
	/* probably reused, make static ID */
	buf[1] = (char)(i + '0');
	sym = ID2SYM(rb_intern2(buf, 2));
	}
	else {
	/* dynamic symbol */
	sym = rb_str_intern(rb_sprintf("$%d", i));
	}
	rb_ary_push(ary, sym);
	}
	}
	return ary;
	}

	void
	rb_alias_variable(ID name1, ID name2)
	{
	struct rb_global_entry entry1, entry2;
	VALUE data1;
	struct rb_id_table *gtbl = rb_global_tbl;

	if (!rb_ractor_main_p()) {
	rb_raise(rb_eRactorIsolationError, "can not access global variables from non-main Ractors");
	}

	entry2 = rb_global_entry(name2);
	if (!rb_id_table_lookup(gtbl, name1, &data1)) {
	entry1 = ALLOC(struct rb_global_entry);
	entry1->id = name1;
	rb_id_table_insert(gtbl, name1, (VALUE)entry1);
	}
	else if ((entry1 = (struct rb_global_entry *)data1)->var != entry2->var) {
	struct rb_global_variable *var = entry1->var;
	if (var->block_trace) {
	rb_raise(rb_eRuntimeError, "can't alias in tracer");
	}
	var->counter--;
	if (var->counter == 0) {
	struct trace_var *trace = var->trace;
	while (trace) {
	struct trace_var *next = trace->next;
	xfree(trace);
	trace = next;
	}
	xfree(var);
	}
	}
	else {
	return;
	}
	entry2->var->counter++;
	entry1->var = entry2->var;
	}

	static bool
	iv_index_tbl_lookup(struct st_table tbl, ID id, uint32_t indexp)
	{
	struct rb_iv_index_tbl_entry *ent;
	int r;

	if (tbl == NULL) return false;

	RB_VM_LOCK_ENTER();
	{
	r = st_lookup(tbl, (st_data_t)id, (st_data_t *)&ent);
	}
	RB_VM_LOCK_LEAVE();

	if (r) {
	*indexp = ent->index;
	return true;
	}
	else {
	return false;
	}
	}

	static void
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(ID id)
	{
	if (UNLIKELY(!rb_ractor_main_p())) {
	if (rb_is_instance_id(id)) { // check only normal ivars
	rb_raise(rb_eRactorIsolationError, "can not access instance variables of classes/modules from non-main Ractors");
	}
	}
	}

	#define CVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR() \
	if (UNLIKELY(!rb_ractor_main_p())) { \
	rb_raise(rb_eRactorIsolationError, "can not access class variables from non-main Ractors"); \
	}

	static inline struct st_table *
	generic_ivtbl(VALUE obj, ID id, bool force_check_ractor)
	{
	ASSERT_vm_locking();

	if ((force_check_ractor \|\| LIKELY(rb_is_instance_id(id)) /* not internal ID */ ) &&
	!RB_OBJ_FROZEN_RAW(obj) &&
	UNLIKELY(!rb_ractor_main_p()) &&
	UNLIKELY(rb_ractor_shareable_p(obj))) {

	rb_raise(rb_eRactorIsolationError, "can not access instance variables of shareable objects from non-main Ractors");
	}
	return generic_iv_tbl_;
	}

	static inline struct st_table *
	generic_ivtbl_no_ractor_check(VALUE obj)
	{
	return generic_ivtbl(obj, 0, false);
	}

	static int
	gen_ivtbl_get(VALUE obj, ID id, struct gen_ivtbl **ivtbl)
	{
	st_data_t data;
	int r = 0;

	RB_VM_LOCK_ENTER();
	{
	if (st_lookup(generic_ivtbl(obj, id, false), (st_data_t)obj, &data)) {
	ivtbl = (struct gen_ivtbl )data;
	r = 1;
	}
	}
	RB_VM_LOCK_LEAVE();

	return r;
	}

	MJIT_FUNC_EXPORTED int
	rb_ivar_generic_ivtbl_lookup(VALUE obj, struct gen_ivtbl **ivtbl)
	{
	return gen_ivtbl_get(obj, 0, ivtbl);
	}

	MJIT_FUNC_EXPORTED VALUE
	rb_ivar_generic_lookup_with_index(VALUE obj, ID id, uint32_t index)
	{
	struct gen_ivtbl *ivtbl;

	if (gen_ivtbl_get(obj, id, &ivtbl)) {
	if (LIKELY(index < ivtbl->numiv)) {
	VALUE val = ivtbl->ivptr[index];
	return val;
	}
	}

	return Qundef;
	}

	static VALUE
	generic_ivar_delete(VALUE obj, ID id, VALUE undef)
	{
	struct gen_ivtbl *ivtbl;

	if (gen_ivtbl_get(obj, id, &ivtbl)) {
	st_table *iv_index_tbl = RCLASS_IV_INDEX_TBL(rb_obj_class(obj));
	uint32_t index;

	if (iv_index_tbl && iv_index_tbl_lookup(iv_index_tbl, id, &index)) {
	if (index < ivtbl->numiv) {
	VALUE ret = ivtbl->ivptr[index];

	ivtbl->ivptr[index] = Qundef;
	return ret == Qundef ? undef : ret;
	}
	}
	}
	return undef;
	}

	static VALUE
	generic_ivar_get(VALUE obj, ID id, VALUE undef)
	{
	struct gen_ivtbl *ivtbl;

	if (gen_ivtbl_get(obj, id, &ivtbl)) {
	st_table *iv_index_tbl = RCLASS_IV_INDEX_TBL(rb_obj_class(obj));
	uint32_t index;

	if (iv_index_tbl && iv_index_tbl_lookup(iv_index_tbl, id, &index)) {
	if (index < ivtbl->numiv) {
	VALUE ret = ivtbl->ivptr[index];

	return ret == Qundef ? undef : ret;
	}
	}
	}
	return undef;
	}

	static size_t
	gen_ivtbl_bytes(size_t n)
	{
	return offsetof(struct gen_ivtbl, ivptr) + n * sizeof(VALUE);
	}

	static struct gen_ivtbl *
	gen_ivtbl_resize(struct gen_ivtbl *old, uint32_t n)
	{
	uint32_t len = old ? old->numiv : 0;
	struct gen_ivtbl *ivtbl = xrealloc(old, gen_ivtbl_bytes(n));

	ivtbl->numiv = n;
	for (; len < n; len++) {
	ivtbl->ivptr[len] = Qundef;
	}

	return ivtbl;
	}

	#if 0
	static struct gen_ivtbl *
	gen_ivtbl_dup(const struct gen_ivtbl *orig)
	{
	size_t s = gen_ivtbl_bytes(orig->numiv);
	struct gen_ivtbl *ivtbl = xmalloc(s);

	memcpy(ivtbl, orig, s);

	return ivtbl;
	}
	#endif

	static uint32_t
	iv_index_tbl_newsize(struct ivar_update *ivup)
	{
	if (!ivup->iv_extended) {
	return (uint32_t)ivup->u.iv_index_tbl->num_entries;
	}
	else {
	uint32_t index = (uint32_t)ivup->index; /* should not overflow */
	return (index+1) + (index+1)/4; /* (index+1)1.25 /
	}
	}

	static int
	generic_ivar_update(st_data_t k, st_data_t v, st_data_t u, int existing)
	{
	ASSERT_vm_locking();

	struct ivar_update ivup = (struct ivar_update )u;
	struct gen_ivtbl *ivtbl = 0;

	if (existing) {
	ivtbl = (struct gen_ivtbl )v;
	if (ivup->index < ivtbl->numiv) {
	ivup->u.ivtbl = ivtbl;
	return ST_STOP;
	}
	}
	FL_SET((VALUE)*k, FL_EXIVAR);
	uint32_t newsize = iv_index_tbl_newsize(ivup);
	ivtbl = gen_ivtbl_resize(ivtbl, newsize);
	*v = (st_data_t)ivtbl;
	ivup->u.ivtbl = ivtbl;
	return ST_CONTINUE;
	}

	static VALUE
	generic_ivar_defined(VALUE obj, ID id)
	{
	struct gen_ivtbl *ivtbl;
	st_table *iv_index_tbl = RCLASS_IV_INDEX_TBL(rb_obj_class(obj));
	uint32_t index;

	if (!iv_index_tbl_lookup(iv_index_tbl, id, &index)) return Qfalse;
	if (!gen_ivtbl_get(obj, id, &ivtbl)) return Qfalse;

	if ((index < ivtbl->numiv) && (ivtbl->ivptr[index] != Qundef))
	return Qtrue;

	return Qfalse;
	}

	static int
	generic_ivar_remove(VALUE obj, ID id, VALUE *valp)
	{
	struct gen_ivtbl *ivtbl;
	uint32_t index;
	st_table *iv_index_tbl = RCLASS_IV_INDEX_TBL(rb_obj_class(obj));

	if (!iv_index_tbl) return 0;
	if (!iv_index_tbl_lookup(iv_index_tbl, id, &index)) return 0;
	if (!gen_ivtbl_get(obj, id, &ivtbl)) return 0;

	if (index < ivtbl->numiv) {
	if (ivtbl->ivptr[index] != Qundef) {
	*valp = ivtbl->ivptr[index];
	ivtbl->ivptr[index] = Qundef;
	return 1;
	}
	}
	return 0;
	}

	static void
	gen_ivtbl_mark(const struct gen_ivtbl *ivtbl)
	{
	uint32_t i;

	for (i = 0; i < ivtbl->numiv; i++) {
	rb_gc_mark(ivtbl->ivptr[i]);
	}
	}

	void
	rb_mark_generic_ivar(VALUE obj)
	{
	struct gen_ivtbl *ivtbl;

	if (gen_ivtbl_get(obj, 0, &ivtbl)) {
	gen_ivtbl_mark(ivtbl);
	}
	}

	void
	rb_mv_generic_ivar(VALUE rsrc, VALUE dst)
	{
	st_data_t key = (st_data_t)rsrc;
	struct gen_ivtbl *ivtbl;

	if (st_delete(generic_ivtbl_no_ractor_check(rsrc), &key, (st_data_t *)&ivtbl))
	st_insert(generic_ivtbl_no_ractor_check(dst), (st_data_t)dst, (st_data_t)ivtbl);
	}

	void
	rb_free_generic_ivar(VALUE obj)
	{
	st_data_t key = (st_data_t)obj;
	struct gen_ivtbl *ivtbl;

	if (st_delete(generic_ivtbl_no_ractor_check(obj), &key, (st_data_t *)&ivtbl))
	xfree(ivtbl);
	}

	RUBY_FUNC_EXPORTED size_t
	rb_generic_ivar_memsize(VALUE obj)
	{
	struct gen_ivtbl *ivtbl;

	if (gen_ivtbl_get(obj, 0, &ivtbl))
	return gen_ivtbl_bytes(ivtbl->numiv);
	return 0;
	}

	static size_t
	gen_ivtbl_count(const struct gen_ivtbl *ivtbl)
	{
	uint32_t i;
	size_t n = 0;

	for (i = 0; i < ivtbl->numiv; i++) {
	if (ivtbl->ivptr[i] != Qundef) {
	n++;
	}
	}

	return n;
	}

	VALUE
	rb_ivar_lookup(VALUE obj, ID id, VALUE undef)
	{
	VALUE val;

	if (SPECIAL_CONST_P(obj)) return undef;
	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	{
	uint32_t index;
	uint32_t len = ROBJECT_NUMIV(obj);
	VALUE *ptr = ROBJECT_IVPTR(obj);

	if (iv_index_tbl_lookup(ROBJECT_IV_INDEX_TBL(obj), id, &index) &&
	index < len &&
	(val = ptr[index]) != Qundef) {
	return val;
	}
	else {
	break;
	}
	}
	case T_CLASS:
	case T_MODULE:
	{
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(id);
	if (RCLASS_IV_TBL(obj) &&
	st_lookup(RCLASS_IV_TBL(obj), (st_data_t)id, (st_data_t *)&val)) {
	return val;
	}
	else {
	break;
	}
	}
	default:
	if (FL_TEST(obj, FL_EXIVAR))
	return generic_ivar_get(obj, id, undef);
	break;
	}
	return undef;
	}

	VALUE
	rb_ivar_get(VALUE obj, ID id)
	{
	VALUE iv = rb_ivar_lookup(obj, id, Qnil);
	RB_DEBUG_COUNTER_INC(ivar_get_base);
	return iv;
	}

	VALUE
	rb_attr_get(VALUE obj, ID id)
	{
	return rb_ivar_lookup(obj, id, Qnil);
	}

	static VALUE
	rb_ivar_delete(VALUE obj, ID id, VALUE undef)
	{
	VALUE val, *ptr;
	struct st_table *iv_index_tbl;
	uint32_t len, index;

	rb_check_frozen(obj);
	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	len = ROBJECT_NUMIV(obj);
	ptr = ROBJECT_IVPTR(obj);
	iv_index_tbl = ROBJECT_IV_INDEX_TBL(obj);
	if (iv_index_tbl_lookup(iv_index_tbl, id, &index) &&
	index < len) {
	val = ptr[index];
	ptr[index] = Qundef;

	if (val != Qundef) {
	return val;
	}
	}
	break;
	case T_CLASS:
	case T_MODULE:
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(id);
	if (RCLASS_IV_TBL(obj) &&
	st_delete(RCLASS_IV_TBL(obj), (st_data_t )&id, (st_data_t )&val)) {
	return val;
	}
	break;
	default:
	if (FL_TEST(obj, FL_EXIVAR))
	return generic_ivar_delete(obj, id, undef);
	break;
	}
	return undef;
	}

	VALUE
	rb_attr_delete(VALUE obj, ID id)
	{
	return rb_ivar_delete(obj, id, Qnil);
	}

	static st_table *
	iv_index_tbl_make(VALUE obj, VALUE klass)
	{
	st_table *iv_index_tbl;

	if (UNLIKELY(!klass)) {
	rb_raise(rb_eTypeError, "hidden object cannot have instance variables");
	}

	if ((iv_index_tbl = RCLASS_IV_INDEX_TBL(klass)) == NULL) {
	RB_VM_LOCK_ENTER();
	if ((iv_index_tbl = RCLASS_IV_INDEX_TBL(klass)) == NULL) {
	iv_index_tbl = RCLASS_IV_INDEX_TBL(klass) = st_init_numtable();
	}
	RB_VM_LOCK_LEAVE();
	}

	return iv_index_tbl;
	}

	static void
	iv_index_tbl_extend(struct ivar_update *ivup, ID id, VALUE klass)
	{
	ASSERT_vm_locking();
	struct rb_iv_index_tbl_entry *ent;

	if (st_lookup(ivup->u.iv_index_tbl, (st_data_t)id, (st_data_t *)&ent)) {
	ivup->index = ent->index;
	return;
	}
	if (ivup->u.iv_index_tbl->num_entries >= INT_MAX) {
	rb_raise(rb_eArgError, "too many instance variables");
	}
	ent = ALLOC(struct rb_iv_index_tbl_entry);
	ent->index = ivup->index = (uint32_t)ivup->u.iv_index_tbl->num_entries;
	ent->class_value = klass;
	ent->class_serial = RCLASS_SERIAL(klass);
	st_add_direct(ivup->u.iv_index_tbl, (st_data_t)id, (st_data_t)ent);
	ivup->iv_extended = 1;
	}

	static void
	generic_ivar_set(VALUE obj, ID id, VALUE val)
	{
	VALUE klass = rb_obj_class(obj);
	struct ivar_update ivup;
	ivup.iv_extended = 0;
	ivup.u.iv_index_tbl = iv_index_tbl_make(obj, klass);

	RB_VM_LOCK_ENTER();
	{
	iv_index_tbl_extend(&ivup, id, klass);
	st_update(generic_ivtbl(obj, id, false), (st_data_t)obj, generic_ivar_update,
	(st_data_t)&ivup);
	}
	RB_VM_LOCK_LEAVE();

	ivup.u.ivtbl->ivptr[ivup.index] = val;

	RB_OBJ_WRITTEN(obj, Qundef, val);
	}

	static VALUE *
	obj_ivar_heap_alloc(VALUE obj, size_t newsize)
	{
	VALUE newptr = rb_transient_heap_alloc(obj, sizeof(VALUE) newsize);

	if (newptr != NULL) {
	ROBJ_TRANSIENT_SET(obj);
	}
	else {
	ROBJ_TRANSIENT_UNSET(obj);
	newptr = ALLOC_N(VALUE, newsize);
	}
	return newptr;
	}

	static VALUE *
	obj_ivar_heap_realloc(VALUE obj, int32_t len, size_t newsize)
	{
	VALUE *newptr;
	int i;

	if (ROBJ_TRANSIENT_P(obj)) {
	const VALUE *orig_ptr = ROBJECT(obj)->as.heap.ivptr;
	newptr = obj_ivar_heap_alloc(obj, newsize);

	assert(newptr);
	ROBJECT(obj)->as.heap.ivptr = newptr;
	for (i=0; i<(int)len; i++) {
	newptr[i] = orig_ptr[i];
	}
	}
	else {
	REALLOC_N(ROBJECT(obj)->as.heap.ivptr, VALUE, newsize);
	newptr = ROBJECT(obj)->as.heap.ivptr;
	}

	return newptr;
	}

	#if USE_TRANSIENT_HEAP
	void
	rb_obj_transient_heap_evacuate(VALUE obj, int promote)
	{
	if (ROBJ_TRANSIENT_P(obj)) {
	uint32_t len = ROBJECT_NUMIV(obj);
	const VALUE *old_ptr = ROBJECT_IVPTR(obj);
	VALUE *new_ptr;

	if (promote) {
	new_ptr = ALLOC_N(VALUE, len);
	ROBJ_TRANSIENT_UNSET(obj);
	}
	else {
	new_ptr = obj_ivar_heap_alloc(obj, len);
	}
	MEMCPY(new_ptr, old_ptr, VALUE, len);
	ROBJECT(obj)->as.heap.ivptr = new_ptr;
	}
	}
	#endif

	static void
	init_iv_list(VALUE obj, uint32_t len, uint32_t newsize, st_table *index_tbl)
	{
	VALUE *ptr = ROBJECT_IVPTR(obj);
	VALUE *newptr;

	if (RBASIC(obj)->flags & ROBJECT_EMBED) {
	newptr = obj_ivar_heap_alloc(obj, newsize);
	MEMCPY(newptr, ptr, VALUE, len);
	RBASIC(obj)->flags &= ~ROBJECT_EMBED;
	ROBJECT(obj)->as.heap.ivptr = newptr;
	} else {
	newptr = obj_ivar_heap_realloc(obj, len, newsize);
	}

	for (; len < newsize; len++) {
	newptr[len] = Qundef;
	}
	ROBJECT(obj)->as.heap.numiv = newsize;
	ROBJECT(obj)->as.heap.iv_index_tbl = index_tbl;
	}

	void
	rb_init_iv_list(VALUE obj)
	{
	st_table *index_tbl = ROBJECT_IV_INDEX_TBL(obj);
	uint32_t newsize = (uint32_t)index_tbl->num_entries;
	uint32_t len = ROBJECT_NUMIV(obj);
	init_iv_list(obj, len, newsize, index_tbl);
	}

	static VALUE
	obj_ivar_set(VALUE obj, ID id, VALUE val)
	{
	VALUE klass = rb_obj_class(obj);
	struct ivar_update ivup;
	uint32_t len;
	ivup.iv_extended = 0;
	ivup.u.iv_index_tbl = iv_index_tbl_make(obj, klass);

	RB_VM_LOCK_ENTER();
	{
	iv_index_tbl_extend(&ivup, id, klass);
	}
	RB_VM_LOCK_LEAVE();

	len = ROBJECT_NUMIV(obj);
	if (len <= ivup.index) {
	uint32_t newsize = iv_index_tbl_newsize(&ivup);
	init_iv_list(obj, len, newsize, ivup.u.iv_index_tbl);
	}
	RB_OBJ_WRITE(obj, &ROBJECT_IVPTR(obj)[ivup.index], val);

	return val;
	}

	static void
	ivar_set(VALUE obj, ID id, VALUE val)
	{
	RB_DEBUG_COUNTER_INC(ivar_set_base);

	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	obj_ivar_set(obj, id, val);
	break;
	case T_CLASS:
	case T_MODULE:
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(id);
	rb_class_ivar_set(obj, id, val);
	break;
	default:
	generic_ivar_set(obj, id, val);
	break;
	}
	}

	VALUE
	rb_ivar_set(VALUE obj, ID id, VALUE val)
	{
	rb_check_frozen(obj);
	ivar_set(obj, id, val);
	return val;
	}

	void
	rb_ivar_set_internal(VALUE obj, ID id, VALUE val)
	{
	// should be internal instance variable name (no @ prefix)
	VM_ASSERT(!rb_is_instance_id(id));

	ivar_set(obj, id, val);
	}

	VALUE
	rb_ivar_defined(VALUE obj, ID id)
	{
	VALUE val;
	struct st_table *iv_index_tbl;
	uint32_t index;

	if (SPECIAL_CONST_P(obj)) return Qfalse;
	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	iv_index_tbl = ROBJECT_IV_INDEX_TBL(obj);
	if (iv_index_tbl_lookup(iv_index_tbl, id, &index) &&
	index < ROBJECT_NUMIV(obj) &&
	(val = ROBJECT_IVPTR(obj)[index]) != Qundef) {
	return Qtrue;
	}
	break;
	case T_CLASS:
	case T_MODULE:
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(id);
	if (RCLASS_IV_TBL(obj) && st_is_member(RCLASS_IV_TBL(obj), (st_data_t)id))
	return Qtrue;
	break;
	default:
	if (FL_TEST(obj, FL_EXIVAR))
	return generic_ivar_defined(obj, id);
	break;
	}
	return Qfalse;
	}

	typedef int rb_ivar_foreach_callback_func(ID key, VALUE val, st_data_t arg);
	st_data_t rb_st_nth_key(st_table *tab, st_index_t index);

	static ID
	iv_index_tbl_nth_id(st_table *iv_index_tbl, uint32_t index)
	{
	st_data_t key;
	RB_VM_LOCK_ENTER();
	{
	key = rb_st_nth_key(iv_index_tbl, index);
	}
	RB_VM_LOCK_LEAVE();
	return (ID)key;
	}

	static inline bool
	ivar_each_i(st_table iv_index_tbl, VALUE val, uint32_t i, rb_ivar_foreach_callback_func func, st_data_t arg)
	{
	if (val != Qundef) {
	ID id = iv_index_tbl_nth_id(iv_index_tbl, i);
	switch (func(id, val, arg)) {
	case ST_CHECK:
	case ST_CONTINUE:
	break;
	case ST_STOP:
	return true;
	default:
	rb_bug("unreachable");
	}
	}
	return false;
	}

	static void
	obj_ivar_each(VALUE obj, rb_ivar_foreach_callback_func *func, st_data_t arg)
	{
	st_table *iv_index_tbl = ROBJECT_IV_INDEX_TBL(obj);
	if (!iv_index_tbl) return;
	uint32_t i=0;

	for (i=0; i < ROBJECT_NUMIV(obj); i++) {
	VALUE val = ROBJECT_IVPTR(obj)[i];
	if (ivar_each_i(iv_index_tbl, val, i, func, arg)) {
	return;
	}
	}
	}

	static void
	gen_ivar_each(VALUE obj, rb_ivar_foreach_callback_func *func, st_data_t arg)
	{
	struct gen_ivtbl *ivtbl;
	st_table *iv_index_tbl = RCLASS_IV_INDEX_TBL(rb_obj_class(obj));
	if (!iv_index_tbl) return;
	if (!gen_ivtbl_get(obj, 0, &ivtbl)) return;

	for (uint32_t i=0; i<ivtbl->numiv; i++) {
	VALUE val = ivtbl->ivptr[i];
	if (ivar_each_i(iv_index_tbl, val, i, func, arg)) {
	return;
	}
	}
	}

	struct givar_copy {
	VALUE obj;
	VALUE klass;
	st_table *iv_index_tbl;
	struct gen_ivtbl *ivtbl;
	};

	static int
	gen_ivar_copy(ID id, VALUE val, st_data_t arg)
	{
	struct givar_copy c = (struct givar_copy )arg;
	struct ivar_update ivup;

	ivup.iv_extended = 0;
	ivup.u.iv_index_tbl = c->iv_index_tbl;

	RB_VM_LOCK_ENTER();
	{
	iv_index_tbl_extend(&ivup, id, c->klass);
	}
	RB_VM_LOCK_LEAVE();

	if (ivup.index >= c->ivtbl->numiv) {
	uint32_t newsize = iv_index_tbl_newsize(&ivup);
	c->ivtbl = gen_ivtbl_resize(c->ivtbl, newsize);
	}
	c->ivtbl->ivptr[ivup.index] = val;

	RB_OBJ_WRITTEN(c->obj, Qundef, val);

	return ST_CONTINUE;
	}

	void
	rb_copy_generic_ivar(VALUE clone, VALUE obj)
	{
	struct gen_ivtbl *ivtbl;

	rb_check_frozen(clone);

	if (!FL_TEST(obj, FL_EXIVAR)) {
	goto clear;
	}
	if (gen_ivtbl_get(obj, 0, &ivtbl)) {
	struct givar_copy c;
	uint32_t i;

	if (gen_ivtbl_count(ivtbl) == 0)
	goto clear;

	if (gen_ivtbl_get(clone, 0, &c.ivtbl)) {
	for (i = 0; i < c.ivtbl->numiv; i++)
	c.ivtbl->ivptr[i] = Qundef;
	}
	else {
	c.ivtbl = gen_ivtbl_resize(0, ivtbl->numiv);
	FL_SET(clone, FL_EXIVAR);
	}

	VALUE klass = rb_obj_class(clone);
	c.iv_index_tbl = iv_index_tbl_make(clone, klass);
	c.obj = clone;
	c.klass = klass;
	gen_ivar_each(obj, gen_ivar_copy, (st_data_t)&c);
	/*
	* c.ivtbl may change in gen_ivar_copy due to realloc,
	* no need to free
	*/
	RB_VM_LOCK_ENTER();
	{
	generic_ivtbl_no_ractor_check(clone);
	st_insert(generic_ivtbl_no_ractor_check(obj), (st_data_t)clone, (st_data_t)c.ivtbl);
	}
	RB_VM_LOCK_LEAVE();
	}
	return;

	clear:
	if (FL_TEST(clone, FL_EXIVAR)) {
	rb_free_generic_ivar(clone);
	FL_UNSET(clone, FL_EXIVAR);
	}
	}

	void
	rb_replace_generic_ivar(VALUE clone, VALUE obj)
	{
	RUBY_ASSERT(FL_TEST(obj, FL_EXIVAR));

	RB_VM_LOCK_ENTER();
	{
	struct gen_ivtbl **ivtbl;
	if (st_lookup(generic_iv_tbl_, (st_data_t)obj, (st_data_t *)&ivtbl)) {
	st_insert(generic_iv_tbl_, (st_data_t)clone, (st_data_t)ivtbl);
	st_delete(generic_iv_tbl_, (st_data_t *)&obj, NULL);
	}
	else {
	rb_bug("unreachable");
	}
	}
	RB_VM_LOCK_LEAVE();

	FL_SET(clone, FL_EXIVAR);
	}

	void
	rb_ivar_foreach(VALUE obj, rb_ivar_foreach_callback_func *func, st_data_t arg)
	{
	if (SPECIAL_CONST_P(obj)) return;
	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	obj_ivar_each(obj, func, arg);
	break;
	case T_CLASS:
	case T_MODULE:
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(0);
	if (RCLASS_IV_TBL(obj)) {
	st_foreach_safe(RCLASS_IV_TBL(obj), func, arg);
	}
	break;
	default:
	if (FL_TEST(obj, FL_EXIVAR)) {
	gen_ivar_each(obj, func, arg);
	}
	break;
	}
	}

	st_index_t
	rb_ivar_count(VALUE obj)
	{
	st_table *tbl;

	if (SPECIAL_CONST_P(obj)) return 0;

	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	if (ROBJECT_IV_INDEX_TBL(obj) != 0) {
	st_index_t i, count, num = ROBJECT_NUMIV(obj);
	const VALUE *const ivptr = ROBJECT_IVPTR(obj);
	for (i = count = 0; i < num; ++i) {
	if (ivptr[i] != Qundef) {
	count++;
	}
	}
	return count;
	}
	break;
	case T_CLASS:
	case T_MODULE:
	if ((tbl = RCLASS_IV_TBL(obj)) != 0) {
	return tbl->num_entries;
	}
	break;
	default:
	if (FL_TEST(obj, FL_EXIVAR)) {
	struct gen_ivtbl *ivtbl;

	if (gen_ivtbl_get(obj, 0, &ivtbl)) {
	return gen_ivtbl_count(ivtbl);
	}
	}
	break;
	}
	return 0;
	}

	static int
	ivar_i(st_data_t k, st_data_t v, st_data_t a)
	{
	ID key = (ID)k;
	VALUE ary = (VALUE)a;

	if (rb_is_instance_id(key)) {
	rb_ary_push(ary, ID2SYM(key));
	}
	return ST_CONTINUE;
	}

	/*
	* call-seq:
	* obj.instance_variables -> array
	*
	* Returns an array of instance variable names for the receiver. Note
	* that simply defining an accessor does not create the corresponding
	* instance variable.
	*
	* class Fred
	* attr_accessor :a1
	* def initialize
	* @iv = 3
	* end
	* end
	* Fred.new.instance_variables #=> [:@iv]
	*/

	VALUE
	rb_obj_instance_variables(VALUE obj)
	{
	VALUE ary;

	ary = rb_ary_new();
	rb_ivar_foreach(obj, ivar_i, ary);
	return ary;
	}

	#define rb_is_constant_id rb_is_const_id
	#define rb_is_constant_name rb_is_const_name
	#define id_for_var(obj, name, part, type) \
	id_for_var_message(obj, name, type, "`%1$s' is not allowed as "#part" "#type" variable name")
	#define id_for_var_message(obj, name, type, message) \
	check_id_type(obj, &(name), rb_is_##type##_id, rb_is_##type##_name, message, strlen(message))
	static ID
	check_id_type(VALUE obj, VALUE *pname,
	int (valid_id_p)(ID), int (valid_name_p)(VALUE),
	const char *message, size_t message_len)
	{
	ID id = rb_check_id(pname);
	VALUE name = *pname;

	if (id ? !valid_id_p(id) : !valid_name_p(name)) {
	rb_name_err_raise_str(rb_fstring_new(message, message_len),
	obj, name);
	}
	return id;
	}

	/*
	* call-seq:
	* obj.remove_instance_variable(symbol) -> obj
	* obj.remove_instance_variable(string) -> obj
	*
	* Removes the named instance variable from <i>obj</i>, returning that
	* variable's value.
	* String arguments are converted to symbols.
	*
	* class Dummy
	* attr_reader :var
	* def initialize
	* @var = 99
	* end
	* def remove
	* remove_instance_variable(:@var)
	* end
	* end
	* d = Dummy.new
	* d.var #=> 99
	* d.remove #=> 99
	* d.var #=> nil
	*/

	VALUE
	rb_obj_remove_instance_variable(VALUE obj, VALUE name)
	{
	VALUE val = Qnil;
	const ID id = id_for_var(obj, name, an, instance);
	st_data_t n, v;
	struct st_table *iv_index_tbl;
	uint32_t index;

	rb_check_frozen(obj);
	if (!id) {
	goto not_defined;
	}

	switch (BUILTIN_TYPE(obj)) {
	case T_OBJECT:
	iv_index_tbl = ROBJECT_IV_INDEX_TBL(obj);
	if (iv_index_tbl_lookup(iv_index_tbl, id, &index) &&
	index < ROBJECT_NUMIV(obj) &&
	(val = ROBJECT_IVPTR(obj)[index]) != Qundef) {
	ROBJECT_IVPTR(obj)[index] = Qundef;
	return val;
	}
	break;
	case T_CLASS:
	case T_MODULE:
	IVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(id);
	n = id;
	if (RCLASS_IV_TBL(obj) && st_delete(RCLASS_IV_TBL(obj), &n, &v)) {
	return (VALUE)v;
	}
	break;
	default:
	if (FL_TEST(obj, FL_EXIVAR)) {
	if (generic_ivar_remove(obj, id, &val)) {
	return val;
	}
	}
	break;
	}

	not_defined:
	rb_name_err_raise("instance variable %1$s not defined",
	obj, name);
	UNREACHABLE_RETURN(Qnil);
	}

	NORETURN(static void uninitialized_constant(VALUE, VALUE));
	static void
	uninitialized_constant(VALUE klass, VALUE name)
	{
	if (klass && rb_class_real(klass) != rb_cObject)
	rb_name_err_raise("uninitialized constant %2$s::%1$s",
	klass, name);
	else
	rb_name_err_raise("uninitialized constant %1$s",
	klass, name);
	}

	VALUE
	rb_const_missing(VALUE klass, VALUE name)
	{
	VALUE value = rb_funcallv(klass, idConst_missing, 1, &name);
	rb_vm_inc_const_missing_count();
	return value;
	}


	/*
	* call-seq:
	* mod.const_missing(sym) -> obj
	*
	* Invoked when a reference is made to an undefined constant in
	* <i>mod</i>. It is passed a symbol for the undefined constant, and
	* returns a value to be used for that constant. The
	* following code is an example of the same:
	*
	* def Foo.const_missing(name)
	* name # return the constant name as Symbol
	* end
	*
	* Foo::UNDEFINED_CONST #=> :UNDEFINED_CONST: symbol returned
	*
	* In the next example when a reference is made to an undefined constant,
	* it attempts to load a file whose name is the lowercase version of the
	* constant (thus class <code>Fred</code> is assumed to be in file
	* <code>fred.rb</code>). If found, it returns the loaded class. It
	* therefore implements an autoload feature similar to Kernel#autoload and
	* Module#autoload.
	*
	* def Object.const_missing(name)
	* @looked_for \|\|= {}
	* str_name = name.to_s
	* raise "Class not found: #{name}" if @looked_for[str_name]
	* @looked_for[str_name] = 1
	* file = str_name.downcase
	* require file
	* klass = const_get(name)
	* return klass if klass
	* raise "Class not found: #{name}"
	* end
	*
	*/

	VALUE
	rb_mod_const_missing(VALUE klass, VALUE name)
	{
	VALUE ref = GET_EC()->private_const_reference;
	rb_vm_pop_cfunc_frame();
	if (ref) {
	rb_name_err_raise("private constant %2$s::%1$s referenced",
	ref, name);
	}
	uninitialized_constant(klass, name);

	UNREACHABLE_RETURN(Qnil);
	}

	static void
	autoload_mark(void *ptr)
	{
	rb_mark_tbl_no_pin((st_table *)ptr);
	}

	static void
	autoload_free(void *ptr)
	{
	st_free_table((st_table *)ptr);
	}

	static size_t
	autoload_memsize(const void *ptr)
	{
	const st_table *tbl = ptr;
	return st_memsize(tbl);
	}

	static void
	autoload_compact(void *ptr)
	{
	rb_gc_update_tbl_refs((st_table *)ptr);
	}

	static const rb_data_type_t autoload_data_type = {
	"autoload",
	{autoload_mark, autoload_free, autoload_memsize, autoload_compact,},
	0, 0, RUBY_TYPED_FREE_IMMEDIATELY
	};

	#define check_autoload_table(av) \
	(struct st_table *)rb_check_typeddata((av), &autoload_data_type)

	static VALUE
	autoload_data(VALUE mod, ID id)
	{
	struct st_table *tbl;
	st_data_t val;

	if (!st_lookup(RCLASS_IV_TBL(mod), autoload, &val) \|\|
	!(tbl = check_autoload_table((VALUE)val)) \|\|
	!st_lookup(tbl, (st_data_t)id, &val)) {
	return 0;
	}
	return (VALUE)val;
	}

	struct autoload_const {
	struct list_node cnode; /* <=> autoload_data_i.constants */
	VALUE mod;
	VALUE ad; /* autoload_data_i */
	VALUE value;
	VALUE file;
	ID id;
	rb_const_flag_t flag;
	int line;
	};

	/* always on stack, no need to mark */
	struct autoload_state {
	struct autoload_const *ac;
	VALUE result;
	VALUE thread;
	struct list_node waitq;
	};

	struct autoload_data_i {
	VALUE feature;
	struct autoload_state state; / points to on-stack struct */
	rb_serial_t fork_gen;
	struct list_head constants; /* <=> autoload_const.cnode */
	};

	static void
	autoload_i_compact(void *ptr)
	{
	struct autoload_data_i *p = ptr;
	p->feature = rb_gc_location(p->feature);
	}

	static void
	autoload_i_mark(void *ptr)
	{
	struct autoload_data_i *p = ptr;

	rb_gc_mark_movable(p->feature);

	/* allow GC to free us if no modules refer to this via autoload_const.ad */
	if (list_empty(&p->constants)) {
	rb_hash_delete(autoload_featuremap, p->feature);
	}
	}

	static void
	autoload_i_free(void *ptr)
	{
	struct autoload_data_i *p = ptr;

	/* we may leak some memory at VM shutdown time, no big deal */
	if (list_empty(&p->constants)) {
	xfree(p);
	}
	}

	static size_t
	autoload_i_memsize(const void *ptr)
	{
	return sizeof(struct autoload_data_i);
	}

	static const rb_data_type_t autoload_data_i_type = {
	"autoload_i",
	{autoload_i_mark, autoload_i_free, autoload_i_memsize, autoload_i_compact},
	0, 0, RUBY_TYPED_FREE_IMMEDIATELY
	};

	static void
	autoload_c_compact(void *ptr)
	{
	struct autoload_const *ac = ptr;

	ac->mod = rb_gc_location(ac->mod);
	ac->ad = rb_gc_location(ac->ad);
	ac->value = rb_gc_location(ac->value);
	ac->file = rb_gc_location(ac->file);
	}

	static void
	autoload_c_mark(void *ptr)
	{
	struct autoload_const *ac = ptr;

	rb_gc_mark_movable(ac->mod);
	rb_gc_mark_movable(ac->ad);
	rb_gc_mark_movable(ac->value);
	rb_gc_mark_movable(ac->file);
	}

	static void
	autoload_c_free(void *ptr)
	{
	struct autoload_const *ac = ptr;
	list_del(&ac->cnode);
	xfree(ac);
	}

	static size_t
	autoload_c_memsize(const void *ptr)
	{
	return sizeof(struct autoload_const);
	}

	static const rb_data_type_t autoload_const_type = {
	"autoload_const",
	{autoload_c_mark, autoload_c_free, autoload_c_memsize, autoload_c_compact,},
	0, 0, RUBY_TYPED_FREE_IMMEDIATELY
	};

	static struct autoload_data_i *
	get_autoload_data(VALUE acv, struct autoload_const **acp)
	{
	struct autoload_const *ac = rb_check_typeddata(acv, &autoload_const_type);
	struct autoload_data_i *ele;

	ele = rb_check_typeddata(ac->ad, &autoload_data_i_type);
	/* do not reach across stack for ->state after forking: */
	if (ele && ele->state && ele->fork_gen != GET_VM()->fork_gen) {
	ele->state = 0;
	ele->fork_gen = 0;
	}
	if (acp) *acp = ac;
	return ele;
	}

	RUBY_FUNC_EXPORTED void
	rb_autoload(VALUE mod, ID id, const char *file)
	{
	if (!file \|\| !*file) {
	rb_raise(rb_eArgError, "empty file name");
	}
	rb_autoload_str(mod, id, rb_fstring_cstr(file));
	}

	void
	rb_autoload_str(VALUE mod, ID id, VALUE file)
	{
	st_data_t av;
	VALUE ad;
	struct st_table *tbl;
	struct autoload_data_i *ele;
	rb_const_entry_t *ce;

	if (!rb_is_const_id(id)) {
	rb_raise(rb_eNameError, "autoload must be constant name: %"PRIsVALUE"",
	QUOTE_ID(id));
	}

	Check_Type(file, T_STRING);
	if (!RSTRING_LEN(file)) {
	rb_raise(rb_eArgError, "empty file name");
	}

	ce = rb_const_lookup(mod, id);
	if (ce && ce->value != Qundef) {
	return;
	}

	rb_const_set(mod, id, Qundef);
	tbl = RCLASS_IV_TBL(mod);
	if (tbl && st_lookup(tbl, (st_data_t)autoload, &av)) {
	tbl = check_autoload_table((VALUE)av);
	}
	else {
	if (!tbl) tbl = RCLASS_IV_TBL(mod) = st_init_numtable();
	av = (st_data_t)TypedData_Wrap_Struct(0, &autoload_data_type, 0);
	st_add_direct(tbl, (st_data_t)autoload, av);
	RB_OBJ_WRITTEN(mod, Qnil, av);
	DATA_PTR(av) = tbl = st_init_numtable();
	}

	file = rb_fstring(file);
	if (!autoload_featuremap) {
	autoload_featuremap = rb_ident_hash_new();
	rb_obj_hide(autoload_featuremap);
	rb_gc_register_mark_object(autoload_featuremap);
	}
	ad = rb_hash_aref(autoload_featuremap, file);
	if (NIL_P(ad)) {
	ad = TypedData_Make_Struct(0, struct autoload_data_i,
	&autoload_data_i_type, ele);
	ele->feature = file;
	ele->state = 0;
	list_head_init(&ele->constants);
	rb_hash_aset(autoload_featuremap, file, ad);
	}
	else {
	ele = rb_check_typeddata(ad, &autoload_data_i_type);
	}
	{
	VALUE acv;
	struct autoload_const *ac;
	acv = TypedData_Make_Struct(0, struct autoload_const,
	&autoload_const_type, ac);
	ac->mod = mod;
	ac->id = id;
	ac->value = Qundef;
	ac->flag = CONST_PUBLIC;
	ac->ad = ad;
	list_add_tail(&ele->constants, &ac->cnode);
	st_insert(tbl, (st_data_t)id, (st_data_t)acv);
	}
	}

	static void
	autoload_delete(VALUE mod, ID id)
	{
	st_data_t val, load = 0, n = id;

	if (st_lookup(RCLASS_IV_TBL(mod), (st_data_t)autoload, &val)) {
	struct st_table *tbl = check_autoload_table((VALUE)val);
	struct autoload_data_i *ele;
	struct autoload_const *ac;

	st_delete(tbl, &n, &load);
	ele = get_autoload_data((VALUE)load, &ac);
	VM_ASSERT(ele);
	if (ele) {
	VM_ASSERT(!list_empty(&ele->constants));
	}

	/*
	* we must delete here to avoid "already initialized" warnings
	* with parallel autoload. Using list_del_init here so list_del
	* works in autoload_c_free
	*/
	list_del_init(&ac->cnode);

	if (tbl->num_entries == 0) {
	n = autoload;
	st_delete(RCLASS_IV_TBL(mod), &n, &val);
	}
	}
	}

	static VALUE
	check_autoload_required(VALUE mod, ID id, const char **loadingpath)
	{
	VALUE file;
	VALUE load = autoload_data(mod, id);
	struct autoload_data_i *ele;
	const char *loading;

	if (!load \|\| !(ele = get_autoload_data(load, 0))) {
	return 0;
	}
	file = ele->feature;
	Check_Type(file, T_STRING);
	if (!RSTRING_LEN(file) \|\| !*RSTRING_PTR(file)) {
	rb_raise(rb_eArgError, "empty file name");
	}

	/*
	* if somebody else is autoloading, we MUST wait for them, since
	* rb_provide_feature can provide a feature before autoload_const_set
	* completes. We must wait until autoload_const_set finishes in
	* the other thread.
	*/
	if (ele->state && ele->state->thread != rb_thread_current()) {
	return load;
	}

	loading = RSTRING_PTR(file);
	if (!rb_feature_provided(loading, &loading)) {
	return load;
	}
	if (loadingpath && loading) {
	*loadingpath = loading;
	return load;
	}
	return 0;
	}

	static struct autoload_const *autoloading_const_entry(VALUE mod, ID id);

	MJIT_FUNC_EXPORTED int
	rb_autoloading_value(VALUE mod, ID id, VALUE* value, rb_const_flag_t *flag)
	{
	struct autoload_const *ac = autoloading_const_entry(mod, id);
	if (!ac) return FALSE;

	if (value) {
	*value = ac->value;
	}
	if (flag) {
	*flag = ac->flag;
	}
	return TRUE;
	}

	struct autoload_const *
	autoloading_const_entry(VALUE mod, ID id)
	{
	VALUE load = autoload_data(mod, id);
	struct autoload_data_i *ele;
	struct autoload_const *ac;

	if (!load \|\| !(ele = get_autoload_data(load, &ac))) {
	return 0;
	}

	if (ele->state && ele->state->thread == rb_thread_current()) {
	if (ac->value != Qundef) {
	return ac;
	}
	}
	return 0;
	}

	static int
	autoload_defined_p(VALUE mod, ID id)
	{
	rb_const_entry_t *ce = rb_const_lookup(mod, id);

	if (!ce \|\| ce->value != Qundef) {
	return 0;
	}
	return !rb_autoloading_value(mod, id, NULL, NULL);
	}

	static void const_tbl_update(struct autoload_const *);

	static VALUE
	autoload_const_set(struct autoload_const *ac)
	{
	VALUE klass = ac->mod;
	ID id = ac->id;
	check_before_mod_set(klass, id, ac->value, "constant");

	RB_VM_LOCK_ENTER();
	{
	const_tbl_update(ac);
	}
	RB_VM_LOCK_LEAVE();

	return 0; /* ignored */
	}

	static VALUE
	autoload_require(VALUE arg)
	{
	struct autoload_state state = (struct autoload_state )arg;
	struct autoload_const *ac = state->ac;
	struct autoload_data_i *ele;

	ele = rb_check_typeddata(ac->ad, &autoload_data_i_type);
	/* this may release GVL and switch threads: */
	state->result = rb_funcall(rb_vm_top_self(), rb_intern("require"), 1,
	ele->feature);

	return state->result;
	}

	static VALUE
	autoload_reset(VALUE arg)
	{
	struct autoload_state state = (struct autoload_state )arg;
	int need_wakeups = 0;
	struct autoload_const *ac = state->ac;
	struct autoload_data_i *ele;

	ele = rb_check_typeddata(ac->ad, &autoload_data_i_type);
	if (ele->state == state) {
	need_wakeups = 1;
	ele->state = 0;
	ele->fork_gen = 0;
	}

	/* At the last, move a value defined in autoload to constant table */
	if (RTEST(state->result)) {
	struct autoload_const *next;

	list_for_each_safe(&ele->constants, ac, next, cnode) {
	if (ac->value != Qundef) {
	autoload_const_set(ac);
	}
	}
	}

	/* wakeup any waiters we had */
	if (need_wakeups) {
	struct autoload_state cur = 0, nxt;

	list_for_each_safe((struct list_head *)&state->waitq, cur, nxt, waitq) {
	VALUE th = cur->thread;

	cur->thread = Qfalse;
	list_del_init(&cur->waitq); /* idempotent */

	/*
	* cur is stored on the stack of cur->waiting_th,
	* do not touch cur after waking up waiting_th
	*/
	rb_thread_wakeup_alive(th);
	}
	}

	return 0; /* ignored */
	}

	static VALUE
	autoload_sleep(VALUE arg)
	{
	struct autoload_state state = (struct autoload_state )arg;

	/*
	* autoload_reset in other thread will resume us and remove us
	* from the waitq list
	*/
	do {
	rb_thread_sleep_deadly();
	} while (state->thread != Qfalse);

	return Qfalse;
	}

	static VALUE
	autoload_sleep_done(VALUE arg)
	{
	struct autoload_state state = (struct autoload_state )arg;

	if (state->thread != Qfalse && rb_thread_to_be_killed(state->thread)) {
	list_del(&state->waitq); /* idempotent after list_del_init */
	}

	return Qfalse;
	}

	VALUE
	rb_autoload_load(VALUE mod, ID id)
	{
	VALUE load, result;
	const char loading = 0, src;
	struct autoload_data_i *ele;
	struct autoload_const *ac;
	struct autoload_state state;
	int flag = -1;
	rb_const_entry_t *ce;

	if (!autoload_defined_p(mod, id)) return Qfalse;
	load = check_autoload_required(mod, id, &loading);
	if (!load) return Qfalse;
	src = rb_sourcefile();
	if (src && loading && strcmp(src, loading) == 0) return Qfalse;

	if ((ce = rb_const_lookup(mod, id))) {
	flag = ce->flag & (CONST_DEPRECATED \| CONST_VISIBILITY_MASK);
	}

	/* set ele->state for a marker of autoloading thread */
	if (!(ele = get_autoload_data(load, &ac))) {
	return Qfalse;
	}
	state.ac = ac;
	state.thread = rb_thread_current();
	if (!ele->state) {
	ele->state = &state;
	ele->fork_gen = GET_VM()->fork_gen;

	/*
	* autoload_reset will wake up any threads added to this
	* if and only if the GVL is released during autoload_require
	*/
	list_head_init((struct list_head *)&state.waitq);
	}
	else if (state.thread == ele->state->thread) {
	return Qfalse;
	}
	else {
	list_add_tail((struct list_head *)&ele->state->waitq, &state.waitq);

	rb_ensure(autoload_sleep, (VALUE)&state,
	autoload_sleep_done, (VALUE)&state);
	}

	/* autoload_data_i can be deleted by another thread while require */
	state.result = Qfalse;
	result = rb_ensure(autoload_require, (VALUE)&state,
	autoload_reset, (VALUE)&state);

	if (flag > 0 && (ce = rb_const_lookup(mod, id))) {
	ce->flag \|= flag;
	}
	RB_GC_GUARD(load);
	return result;
	}

	VALUE
	rb_autoload_p(VALUE mod, ID id)
	{
	return rb_autoload_at_p(mod, id, TRUE);
	}

	VALUE
	rb_autoload_at_p(VALUE mod, ID id, int recur)
	{
	VALUE load;
	struct autoload_data_i *ele;

	while (!autoload_defined_p(mod, id)) {
	if (!recur) return Qnil;
	mod = RCLASS_SUPER(mod);
	if (!mod) return Qnil;
	}
	load = check_autoload_required(mod, id, 0);
	if (!load) return Qnil;
	return (ele = get_autoload_data(load, 0)) ? ele->feature : Qnil;
	}

	MJIT_FUNC_EXPORTED void
	rb_const_warn_if_deprecated(const rb_const_entry_t *ce, VALUE klass, ID id)
	{
	if (RB_CONST_DEPRECATED_P(ce) &&
	rb_warning_category_enabled_p(RB_WARN_CATEGORY_DEPRECATED)) {
	if (klass == rb_cObject) {
	rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "constant ::%"PRIsVALUE" is deprecated", QUOTE_ID(id));
	}
	else {
	rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "constant %"PRIsVALUE"::%"PRIsVALUE" is deprecated",
	rb_class_name(klass), QUOTE_ID(id));
	}
	}
	}

	static VALUE
	rb_const_get_0(VALUE klass, ID id, int exclude, int recurse, int visibility)
	{
	VALUE c = rb_const_search(klass, id, exclude, recurse, visibility);
	if (c != Qundef) {
	if (UNLIKELY(!rb_ractor_main_p())) {
	if (!rb_ractor_shareable_p(c)) {
	rb_raise(rb_eRactorIsolationError, "can not access non-shareable objects in constant %"PRIsVALUE"::%s by non-main Ractor.", rb_class_path(klass), rb_id2name(id));
	}
	}
	return c;
	}
	return rb_const_missing(klass, ID2SYM(id));
	}

	static VALUE
	rb_const_search_from(VALUE klass, ID id, int exclude, int recurse, int visibility)
	{
	VALUE value, tmp;

	tmp = klass;
	while (RTEST(tmp)) {
	VALUE am = 0;
	rb_const_entry_t *ce;

	while ((ce = rb_const_lookup(tmp, id))) {
	if (visibility && RB_CONST_PRIVATE_P(ce)) {
	if (BUILTIN_TYPE(tmp) == T_ICLASS) tmp = RBASIC(tmp)->klass;
	GET_EC()->private_const_reference = tmp;
	return Qundef;
	}
	rb_const_warn_if_deprecated(ce, tmp, id);
	value = ce->value;
	if (value == Qundef) {
	struct autoload_const *ac;
	if (am == tmp) break;
	am = tmp;
	ac = autoloading_const_entry(tmp, id);
	if (ac) return ac->value;
	rb_autoload_load(tmp, id);
	continue;
	}
	if (exclude && tmp == rb_cObject) {
	goto not_found;
	}
	return value;
	}
	if (!recurse) break;
	tmp = RCLASS_SUPER(tmp);
	}

	not_found:
	GET_EC()->private_const_reference = 0;
	return Qundef;
	}

	static VALUE
	rb_const_search(VALUE klass, ID id, int exclude, int recurse, int visibility)
	{
	VALUE value;

	if (klass == rb_cObject) exclude = FALSE;
	value = rb_const_search_from(klass, id, exclude, recurse, visibility);
	if (value != Qundef) return value;
	if (exclude) return value;
	if (BUILTIN_TYPE(klass) != T_MODULE) return value;
	/* search global const too, if klass is a module */
	return rb_const_search_from(rb_cObject, id, FALSE, recurse, visibility);
	}

	VALUE
	rb_const_get_from(VALUE klass, ID id)
	{
	return rb_const_get_0(klass, id, TRUE, TRUE, FALSE);
	}

	VALUE
	rb_const_get(VALUE klass, ID id)
	{
	return rb_const_get_0(klass, id, FALSE, TRUE, FALSE);
	}

	VALUE
	rb_const_get_at(VALUE klass, ID id)
	{
	return rb_const_get_0(klass, id, TRUE, FALSE, FALSE);
	}

	MJIT_FUNC_EXPORTED VALUE
	rb_public_const_get_from(VALUE klass, ID id)
	{
	return rb_const_get_0(klass, id, TRUE, TRUE, TRUE);
	}

	MJIT_FUNC_EXPORTED VALUE
	rb_public_const_get_at(VALUE klass, ID id)
	{
	return rb_const_get_0(klass, id, TRUE, FALSE, TRUE);
	}

	NORETURN(static void undefined_constant(VALUE mod, VALUE name));
	static void
	undefined_constant(VALUE mod, VALUE name)
	{
	rb_name_err_raise("constant %2$s::%1$s not defined",
	mod, name);
	}

	static VALUE
	rb_const_location_from(VALUE klass, ID id, int exclude, int recurse, int visibility)
	{
	while (RTEST(klass)) {
	rb_const_entry_t *ce;

	while ((ce = rb_const_lookup(klass, id))) {
	if (visibility && RB_CONST_PRIVATE_P(ce)) {
	return Qnil;
	}
	if (exclude && klass == rb_cObject) {
	goto not_found;
	}
	if (NIL_P(ce->file)) return rb_ary_new();
	return rb_assoc_new(ce->file, INT2NUM(ce->line));
	}
	if (!recurse) break;
	klass = RCLASS_SUPER(klass);
	}

	not_found:
	return Qnil;
	}

	static VALUE
	rb_const_location(VALUE klass, ID id, int exclude, int recurse, int visibility)
	{
	VALUE loc;

	if (klass == rb_cObject) exclude = FALSE;
	loc = rb_const_location_from(klass, id, exclude, recurse, visibility);
	if (!NIL_P(loc)) return loc;
	if (exclude) return loc;
	if (BUILTIN_TYPE(klass) != T_MODULE) return loc;
	/* search global const too, if klass is a module */
	return rb_const_location_from(rb_cObject, id, FALSE, recurse, visibility);
	}

	VALUE
	rb_const_source_location(VALUE klass, ID id)
	{
	return rb_const_location(klass, id, FALSE, TRUE, FALSE);
	}

	MJIT_FUNC_EXPORTED VALUE
	rb_const_source_location_at(VALUE klass, ID id)
	{
	return rb_const_location(klass, id, TRUE, FALSE, FALSE);
	}

	/*
	* call-seq:
	* remove_const(sym) -> obj
	*
	* Removes the definition of the given constant, returning that
	* constant's previous value. If that constant referred to
	* a module, this will not change that module's name and can lead
	* to confusion.
	*/

	VALUE
	rb_mod_remove_const(VALUE mod, VALUE name)
	{
	const ID id = id_for_var(mod, name, a, constant);

	if (!id) {
	undefined_constant(mod, name);
	}
	return rb_const_remove(mod, id);
	}

	VALUE
	rb_const_remove(VALUE mod, ID id)
	{
	VALUE val;
	rb_const_entry_t *ce;

	rb_check_frozen(mod);
	ce = rb_const_lookup(mod, id);
	if (!ce \|\| !rb_id_table_delete(RCLASS_CONST_TBL(mod), id)) {
	if (rb_const_defined_at(mod, id)) {
	rb_name_err_raise("cannot remove %2$s::%1$s",
	mod, ID2SYM(id));
	}
	undefined_constant(mod, ID2SYM(id));
	}

	rb_clear_constant_cache();

	val = ce->value;
	if (val == Qundef) {
	autoload_delete(mod, id);
	val = Qnil;
	}
	xfree(ce);
	return val;
	}

	static int
	cv_i_update(st_data_t k, st_data_t v, st_data_t a, int existing)
	{
	if (existing) return ST_STOP;
	*v = a;
	return ST_CONTINUE;
	}

	static enum rb_id_table_iterator_result
	sv_i(ID key, VALUE v, void *a)
	{
	rb_const_entry_t ce = (rb_const_entry_t )v;
	st_table *tbl = a;

	if (rb_is_const_id(key)) {
	st_update(tbl, (st_data_t)key, cv_i_update, (st_data_t)ce);
	}
	return ID_TABLE_CONTINUE;
	}

	static enum rb_id_table_iterator_result
	rb_local_constants_i(ID const_name, VALUE const_value, void *ary)
	{
	if (rb_is_const_id(const_name) && !RB_CONST_PRIVATE_P((rb_const_entry_t *)const_value)) {
	rb_ary_push((VALUE)ary, ID2SYM(const_name));
	}
	return ID_TABLE_CONTINUE;
	}

	static VALUE
	rb_local_constants(VALUE mod)
	{
	struct rb_id_table *tbl = RCLASS_CONST_TBL(mod);
	VALUE ary;

	if (!tbl) return rb_ary_new2(0);

	RB_VM_LOCK_ENTER();
	{
	ary = rb_ary_new2(rb_id_table_size(tbl));
	rb_id_table_foreach(tbl, rb_local_constants_i, (void *)ary);
	}
	RB_VM_LOCK_LEAVE();

	return ary;
	}

	void*
	rb_mod_const_at(VALUE mod, void *data)
	{
	st_table *tbl = data;
	if (!tbl) {
	tbl = st_init_numtable();
	}
	if (RCLASS_CONST_TBL(mod)) {
	RB_VM_LOCK_ENTER();
	{
	rb_id_table_foreach(RCLASS_CONST_TBL(mod), sv_i, tbl);
	}
	RB_VM_LOCK_LEAVE();
	}
	return tbl;
	}

	void*
	rb_mod_const_of(VALUE mod, void *data)
	{
	VALUE tmp = mod;
	for (;;) {
	data = rb_mod_const_at(tmp, data);
	tmp = RCLASS_SUPER(tmp);
	if (!tmp) break;
	if (tmp == rb_cObject && mod != rb_cObject) break;
	}
	return data;
	}

	static int
	list_i(st_data_t key, st_data_t value, VALUE ary)
	{
	ID sym = (ID)key;
	rb_const_entry_t ce = (rb_const_entry_t )value;
	if (RB_CONST_PUBLIC_P(ce)) rb_ary_push(ary, ID2SYM(sym));
	return ST_CONTINUE;
	}

	VALUE
	rb_const_list(void *data)
	{
	st_table *tbl = data;
	VALUE ary;

	if (!tbl) return rb_ary_new2(0);
	ary = rb_ary_new2(tbl->num_entries);
	st_foreach_safe(tbl, list_i, ary);
	st_free_table(tbl);

	return ary;
	}

	/*
	* call-seq:
	* mod.constants(inherit=true) -> array
	*
	* Returns an array of the names of the constants accessible in
	* <i>mod</i>. This includes the names of constants in any included
	* modules (example at start of section), unless the <i>inherit</i>
	* parameter is set to <code>false</code>.
	*
	* The implementation makes no guarantees about the order in which the
	* constants are yielded.
	*
	* IO.constants.include?(:SYNC) #=> true
	* IO.constants(false).include?(:SYNC) #=> false
	*
	* Also see Module#const_defined?.
	*/

	VALUE
	rb_mod_constants(int argc, const VALUE *argv, VALUE mod)
	{
	bool inherit = true;

	if (rb_check_arity(argc, 0, 1)) inherit = RTEST(argv[0]);

	if (inherit) {
	return rb_const_list(rb_mod_const_of(mod, 0));
	}
	else {
	return rb_local_constants(mod);
	}
	}

	static int
	rb_const_defined_0(VALUE klass, ID id, int exclude, int recurse, int visibility)
	{
	VALUE tmp;
	int mod_retry = 0;
	rb_const_entry_t *ce;

	tmp = klass;
	retry:
	while (tmp) {
	if ((ce = rb_const_lookup(tmp, id))) {
	if (visibility && RB_CONST_PRIVATE_P(ce)) {
	return (int)Qfalse;
	}
	if (ce->value == Qundef && !check_autoload_required(tmp, id, 0) &&
	!rb_autoloading_value(tmp, id, NULL, NULL))
	return (int)Qfalse;

	if (exclude && tmp == rb_cObject && klass != rb_cObject) {
	return (int)Qfalse;
	}

	return (int)Qtrue;
	}
	if (!recurse) break;
	tmp = RCLASS_SUPER(tmp);
	}
	if (!exclude && !mod_retry && BUILTIN_TYPE(klass) == T_MODULE) {
	mod_retry = 1;
	tmp = rb_cObject;
	goto retry;
	}
	return (int)Qfalse;
	}

	int
	rb_const_defined_from(VALUE klass, ID id)
	{
	return rb_const_defined_0(klass, id, TRUE, TRUE, FALSE);
	}

	int
	rb_const_defined(VALUE klass, ID id)
	{
	return rb_const_defined_0(klass, id, FALSE, TRUE, FALSE);
	}

	int
	rb_const_defined_at(VALUE klass, ID id)
	{
	return rb_const_defined_0(klass, id, TRUE, FALSE, FALSE);
	}

	MJIT_FUNC_EXPORTED int
	rb_public_const_defined_from(VALUE klass, ID id)
	{
	return rb_const_defined_0(klass, id, TRUE, TRUE, TRUE);
	}

	static void
	check_before_mod_set(VALUE klass, ID id, VALUE val, const char *dest)
	{
	rb_check_frozen(klass);
	}

	static void set_namespace_path(VALUE named_namespace, VALUE name);

	static enum rb_id_table_iterator_result
	set_namespace_path_i(ID id, VALUE v, void *payload)
	{
	rb_const_entry_t ce = (rb_const_entry_t )v;
	VALUE value = ce->value;
	int has_permanent_classpath;
	VALUE parental_path = ((VALUE ) payload);
	if (!rb_is_const_id(id)) {
	return ID_TABLE_CONTINUE;
	}
	if (!rb_namespace_p(value)) {
	return ID_TABLE_CONTINUE;
	}
	classname(value, &has_permanent_classpath);
	if (has_permanent_classpath) {
	return ID_TABLE_CONTINUE;
	}
	set_namespace_path(value, build_const_path(parental_path, id));
	if (RCLASS_IV_TBL(value)) {
	st_data_t tmp = tmp_classpath;
	st_delete(RCLASS_IV_TBL(value), &tmp, 0);
	}

	return ID_TABLE_CONTINUE;
	}

	/*
	* Assign permanent classpaths to all namespaces that are directly or indirectly
	* nested under +named_namespace+. +named_namespace+ must have a permanent
	* classpath.
	*/
	static void
	set_namespace_path(VALUE named_namespace, VALUE namespace_path)
	{
	struct rb_id_table *const_table = RCLASS_CONST_TBL(named_namespace);

	RB_VM_LOCK_ENTER();
	{
	rb_class_ivar_set(named_namespace, classpath, namespace_path);
	if (const_table) {
	rb_id_table_foreach(const_table, set_namespace_path_i, &namespace_path);
	}
	}
	RB_VM_LOCK_LEAVE();
	}

	void
	rb_const_set(VALUE klass, ID id, VALUE val)
	{
	rb_const_entry_t *ce;

	if (NIL_P(klass)) {
	rb_raise(rb_eTypeError, "no class/module to define constant %"PRIsVALUE"",
	QUOTE_ID(id));
	}

	if (!rb_ractor_main_p() && !rb_ractor_shareable_p(val)) {
	rb_raise(rb_eRactorIsolationError, "can not set constants with non-shareable objects by non-main Ractors");
	}

	check_before_mod_set(klass, id, val, "constant");

	RB_VM_LOCK_ENTER();
	{
	struct rb_id_table *tbl = RCLASS_CONST_TBL(klass);
	if (!tbl) {
	RCLASS_CONST_TBL(klass) = tbl = rb_id_table_create(0);
	rb_clear_constant_cache();
	ce = ZALLOC(rb_const_entry_t);
	rb_id_table_insert(tbl, id, (VALUE)ce);
	setup_const_entry(ce, klass, val, CONST_PUBLIC);
	}
	else {
	struct autoload_const ac = {
	.mod = klass, .id = id,
	.value = val, .flag = CONST_PUBLIC,
	/* fill the rest with 0 */
	};
	const_tbl_update(&ac);
	}
	}
	RB_VM_LOCK_LEAVE();

	/*
	* Resolve and cache class name immediately to resolve ambiguity
	* and avoid order-dependency on const_tbl
	*/
	if (rb_cObject && rb_namespace_p(val)) {
	int val_path_permanent;
	VALUE val_path = classname(val, &val_path_permanent);
	if (NIL_P(val_path) \|\| !val_path_permanent) {
	if (klass == rb_cObject) {
	set_namespace_path(val, rb_id2str(id));
	}
	else {
	int parental_path_permanent;
	VALUE parental_path = classname(klass, &parental_path_permanent);
	if (NIL_P(parental_path)) {
	int throwaway;
	parental_path = rb_tmp_class_path(klass, &throwaway, make_temporary_path);
	}
	if (parental_path_permanent && !val_path_permanent) {
	set_namespace_path(val, build_const_path(parental_path, id));
	}
	else if (!parental_path_permanent && NIL_P(val_path)) {
	ivar_set(val, tmp_classpath, build_const_path(parental_path, id));
	}
	}
	}
	}
	}

	static struct autoload_data_i *
	current_autoload_data(VALUE mod, ID id, struct autoload_const **acp)
	{
	struct autoload_data_i *ele;
	VALUE load = autoload_data(mod, id);
	if (!load) return 0;
	ele = get_autoload_data(load, acp);
	if (!ele) return 0;
	/* for autoloading thread, keep the defined value to autoloading storage */
	if (ele->state && (ele->state->thread == rb_thread_current())) {
	return ele;
	}
	return 0;
	}

	static void
	const_tbl_update(struct autoload_const *ac)
	{
	VALUE value;
	VALUE klass = ac->mod;
	VALUE val = ac->value;
	ID id = ac->id;
	struct rb_id_table *tbl = RCLASS_CONST_TBL(klass);
	rb_const_flag_t visibility = ac->flag;
	rb_const_entry_t *ce;

	if (rb_id_table_lookup(tbl, id, &value)) {
	ce = (rb_const_entry_t *)value;
	if (ce->value == Qundef) {
	struct autoload_data_i *ele = current_autoload_data(klass, id, &ac);

	if (ele) {
	rb_clear_constant_cache();

	ac->value = val; /* autoload_i is non-WB-protected */
	ac->file = rb_source_location(&ac->line);
	}
	else {
	/* otherwise autoloaded constant, allow to override */
	autoload_delete(klass, id);
	ce->flag = visibility;
	RB_OBJ_WRITE(klass, &ce->value, val);
	RB_OBJ_WRITE(klass, &ce->file, ac->file);
	ce->line = ac->line;
	}
	return;
	}
	else {
	VALUE name = QUOTE_ID(id);
	visibility = ce->flag;
	if (klass == rb_cObject)
	rb_warn("already initialized constant %"PRIsVALUE"", name);
	else
	rb_warn("already initialized constant %"PRIsVALUE"::%"PRIsVALUE"",
	rb_class_name(klass), name);
	if (!NIL_P(ce->file) && ce->line) {
	rb_compile_warn(RSTRING_PTR(ce->file), ce->line,
	"previous definition of %"PRIsVALUE" was here", name);
	}
	}
	rb_clear_constant_cache();
	setup_const_entry(ce, klass, val, visibility);
	}
	else {
	rb_clear_constant_cache();

	ce = ZALLOC(rb_const_entry_t);
	rb_id_table_insert(tbl, id, (VALUE)ce);
	setup_const_entry(ce, klass, val, visibility);
	}
	}

	static void
	setup_const_entry(rb_const_entry_t *ce, VALUE klass, VALUE val,
	rb_const_flag_t visibility)
	{
	ce->flag = visibility;
	RB_OBJ_WRITE(klass, &ce->value, val);
	RB_OBJ_WRITE(klass, &ce->file, rb_source_location(&ce->line));
	}

	void
	rb_define_const(VALUE klass, const char *name, VALUE val)
	{
	ID id = rb_intern(name);

	if (!rb_is_const_id(id)) {
	rb_warn("rb_define_const: invalid name `%s' for constant", name);
	}
	rb_gc_register_mark_object(val);
	rb_const_set(klass, id, val);
	}

	void
	rb_define_global_const(const char *name, VALUE val)
	{
	rb_define_const(rb_cObject, name, val);
	}

	static void
	set_const_visibility(VALUE mod, int argc, const VALUE *argv,
	rb_const_flag_t flag, rb_const_flag_t mask)
	{
	int i;
	rb_const_entry_t *ce;
	ID id;

	rb_class_modify_check(mod);
	if (argc == 0) {
	rb_warning("%"PRIsVALUE" with no argument is just ignored",
	QUOTE_ID(rb_frame_callee()));
	return;
	}

	for (i = 0; i < argc; i++) {
	struct autoload_const *ac;
	VALUE val = argv[i];
	id = rb_check_id(&val);
	if (!id) {
	if (i > 0) {
	rb_clear_constant_cache();
	}

	undefined_constant(mod, val);
	}
	if ((ce = rb_const_lookup(mod, id))) {
	ce->flag &= ~mask;
	ce->flag \|= flag;
	if (ce->value == Qundef) {
	struct autoload_data_i *ele;

	ele = current_autoload_data(mod, id, &ac);
	if (ele) {
	ac->flag &= ~mask;
	ac->flag \|= flag;
	}
	}
	}
	else {
	if (i > 0) {
	rb_clear_constant_cache();
	}
	undefined_constant(mod, ID2SYM(id));
	}
	}
	rb_clear_constant_cache();
	}

	void
	rb_deprecate_constant(VALUE mod, const char *name)
	{
	rb_const_entry_t *ce;
	ID id;
	long len = strlen(name);

	rb_class_modify_check(mod);
	if (!(id = rb_check_id_cstr(name, len, NULL))) {
	undefined_constant(mod, rb_fstring_new(name, len));
	}
	if (!(ce = rb_const_lookup(mod, id))) {
	undefined_constant(mod, ID2SYM(id));
	}
	ce->flag \|= CONST_DEPRECATED;
	}

	/*
	* call-seq:
	* mod.private_constant(symbol, ...) => mod
	*
	* Makes a list of existing constants private.
	*/

	VALUE
	rb_mod_private_constant(int argc, const VALUE *argv, VALUE obj)
	{
	set_const_visibility(obj, argc, argv, CONST_PRIVATE, CONST_VISIBILITY_MASK);
	return obj;
	}

	/*
	* call-seq:
	* mod.public_constant(symbol, ...) => mod
	*
	* Makes a list of existing constants public.
	*/

	VALUE
	rb_mod_public_constant(int argc, const VALUE *argv, VALUE obj)
	{
	set_const_visibility(obj, argc, argv, CONST_PUBLIC, CONST_VISIBILITY_MASK);
	return obj;
	}

	/*
	* call-seq:
	* mod.deprecate_constant(symbol, ...) => mod
	*
	* Makes a list of existing constants deprecated. Attempt
	* to refer to them will produce a warning.
	*
	* module HTTP
	* NotFound = Exception.new
	* NOT_FOUND = NotFound # previous version of the library used this name
	*
	* deprecate_constant :NOT_FOUND
	* end
	*
	* HTTP::NOT_FOUND
	* # warning: constant HTTP::NOT_FOUND is deprecated
	*
	*/

	VALUE
	rb_mod_deprecate_constant(int argc, const VALUE *argv, VALUE obj)
	{
	set_const_visibility(obj, argc, argv, CONST_DEPRECATED, CONST_DEPRECATED);
	return obj;
	}

	static VALUE
	original_module(VALUE c)
	{
	if (RB_TYPE_P(c, T_ICLASS))
	return RBASIC(c)->klass;
	return c;
	}

	static int
	cvar_lookup_at(VALUE klass, ID id, st_data_t *v)
	{
	if (!RCLASS_IV_TBL(klass)) return 0;
	return st_lookup(RCLASS_IV_TBL(klass), (st_data_t)id, v);
	}

	static VALUE
	cvar_front_klass(VALUE klass)
	{
	if (FL_TEST(klass, FL_SINGLETON)) {
	VALUE obj = rb_ivar_get(klass, id__attached__);
	if (rb_namespace_p(obj)) {
	return obj;
	}
	}
	return RCLASS_SUPER(klass);
	}

	static void
	cvar_overtaken(VALUE front, VALUE target, ID id)
	{
	if (front && target != front) {
	st_data_t did = (st_data_t)id;

	if (original_module(front) != original_module(target)) {
	rb_raise(rb_eRuntimeError,
	"class variable % "PRIsVALUE" of %"PRIsVALUE" is overtaken by %"PRIsVALUE"",
	ID2SYM(id), rb_class_name(original_module(front)),
	rb_class_name(original_module(target)));
	}
	if (BUILTIN_TYPE(front) == T_CLASS) {
	st_delete(RCLASS_IV_TBL(front), &did, 0);
	}
	}
	}

	#define CVAR_FOREACH_ANCESTORS(klass, v, r) \
	for (klass = cvar_front_klass(klass); klass; klass = RCLASS_SUPER(klass)) { \
	if (cvar_lookup_at(klass, id, (v))) { \
	r; \
	} \
	}

	#define CVAR_LOOKUP(v,r) do {\
	CVAR_ACCESSOR_SHOULD_BE_MAIN_RACTOR(); \
	if (cvar_lookup_at(klass, id, (v))) {r;}\
	CVAR_FOREACH_ANCESTORS(klass, v, r);\
	} while(0)

	void
	rb_cvar_set(VALUE klass, ID id, VALUE val)
	{
	VALUE tmp, front = 0, target = 0;

	tmp = klass;
	CVAR_LOOKUP(0, {if (!front) front = klass; target = klass;});
	if (target) {
	cvar_overtaken(front, target, id);
	}
	else {
	target = tmp;
	}

	if (RB_TYPE_P(target, T_ICLASS)) {
	target = RBASIC(target)->klass;
	}
	check_before_mod_set(target, id, val, "class variable");

	rb_class_ivar_set(target, id, val);
	}

	VALUE
	rb_cvar_get(VALUE klass, ID id)
	{
	VALUE tmp, front = 0, target = 0;
	st_data_t value;

	tmp = klass;
	CVAR_LOOKUP(&value, {if (!front) front = klass; target = klass;});
	if (!target) {
	rb_name_err_raise("uninitialized class variable %1$s in %2$s",
	tmp, ID2SYM(id));
	}
	cvar_overtaken(front, target, id);
	return (VALUE)value;
	}

	VALUE
	rb_cvar_defined(VALUE klass, ID id)
	{
	if (!klass) return Qfalse;
	CVAR_LOOKUP(0,return Qtrue);
	return Qfalse;
	}

	static ID
	cv_intern(VALUE klass, const char *name)
	{
	ID id = rb_intern(name);
	if (!rb_is_class_id(id)) {
	rb_name_err_raise("wrong class variable name %1$s",
	klass, rb_str_new_cstr(name));
	}
	return id;
	}

	void
	rb_cv_set(VALUE klass, const char *name, VALUE val)
	{
	ID id = cv_intern(klass, name);
	rb_cvar_set(klass, id, val);
	}

	VALUE
	rb_cv_get(VALUE klass, const char *name)
	{
	ID id = cv_intern(klass, name);
	return rb_cvar_get(klass, id);
	}

	void
	rb_define_class_variable(VALUE klass, const char *name, VALUE val)
	{
	ID id = cv_intern(klass, name);
	rb_cvar_set(klass, id, val);
	}

	static int
	cv_i(st_data_t k, st_data_t v, st_data_t a)
	{
	ID key = (ID)k;
	st_table tbl = (st_table )a;

	if (rb_is_class_id(key)) {
	st_update(tbl, (st_data_t)key, cv_i_update, 0);
	}
	return ST_CONTINUE;
	}

	static void*
	mod_cvar_at(VALUE mod, void *data)
	{
	st_table *tbl = data;
	if (!tbl) {
	tbl = st_init_numtable();
	}
	if (RCLASS_IV_TBL(mod)) {
	st_foreach_safe(RCLASS_IV_TBL(mod), cv_i, (st_data_t)tbl);
	}
	return tbl;
	}

	static void*
	mod_cvar_of(VALUE mod, void *data)
	{
	VALUE tmp = mod;
	if (FL_TEST(mod, FL_SINGLETON)) {
	if (rb_namespace_p(rb_ivar_get(mod, id__attached__))) {
	data = mod_cvar_at(tmp, data);
	tmp = cvar_front_klass(tmp);
	}
	}
	for (;;) {
	data = mod_cvar_at(tmp, data);
	tmp = RCLASS_SUPER(tmp);
	if (!tmp) break;
	}
	return data;
	}

	static int
	cv_list_i(st_data_t key, st_data_t value, VALUE ary)
	{
	ID sym = (ID)key;
	rb_ary_push(ary, ID2SYM(sym));
	return ST_CONTINUE;
	}

	static VALUE
	cvar_list(void *data)
	{
	st_table *tbl = data;
	VALUE ary;

	if (!tbl) return rb_ary_new2(0);
	ary = rb_ary_new2(tbl->num_entries);
	st_foreach_safe(tbl, cv_list_i, ary);
	st_free_table(tbl);

	return ary;
	}

	/*
	* call-seq:
	* mod.class_variables(inherit=true) -> array
	*
	* Returns an array of the names of class variables in <i>mod</i>.
	* This includes the names of class variables in any included
	* modules, unless the <i>inherit</i> parameter is set to
	* <code>false</code>.
	*
	* class One
	* @@var1 = 1
	* end
	* class Two < One
	* @@var2 = 2
	* end
	* One.class_variables #=> [:@@var1]
	* Two.class_variables #=> [:@@var2, :@@var1]
	* Two.class_variables(false) #=> [:@@var2]
	*/

	VALUE
	rb_mod_class_variables(int argc, const VALUE *argv, VALUE mod)
	{
	bool inherit = true;
	st_table *tbl;

	if (rb_check_arity(argc, 0, 1)) inherit = RTEST(argv[0]);
	if (inherit) {
	tbl = mod_cvar_of(mod, 0);
	}
	else {
	tbl = mod_cvar_at(mod, 0);
	}
	return cvar_list(tbl);
	}

	/*
	* call-seq:
	* remove_class_variable(sym) -> obj
	*
	* Removes the named class variable from the receiver, returning that
	* variable's value.
	*
	* class Example
	* @@var = 99
	* puts remove_class_variable(:@@var)
	* p(defined? @@var)
	* end
	*
	* <em>produces:</em>
	*
	* 99
	* nil
	*/

	VALUE
	rb_mod_remove_cvar(VALUE mod, VALUE name)
	{
	const ID id = id_for_var_message(mod, name, class, "wrong class variable name %1$s");
	st_data_t val, n = id;

	if (!id) {
	goto not_defined;
	}
	rb_check_frozen(mod);
	if (RCLASS_IV_TBL(mod) && st_delete(RCLASS_IV_TBL(mod), &n, &val)) {
	return (VALUE)val;
	}
	if (rb_cvar_defined(mod, id)) {
	rb_name_err_raise("cannot remove %1$s for %2$s", mod, ID2SYM(id));
	}
	not_defined:
	rb_name_err_raise("class variable %1$s not defined for %2$s",
	mod, name);
	UNREACHABLE_RETURN(Qundef);
	}

	VALUE
	rb_iv_get(VALUE obj, const char *name)
	{
	ID id = rb_check_id_cstr(name, strlen(name), rb_usascii_encoding());

	if (!id) {
	return Qnil;
	}
	return rb_ivar_get(obj, id);
	}

	VALUE
	rb_iv_set(VALUE obj, const char *name, VALUE val)
	{
	ID id = rb_intern(name);

	return rb_ivar_set(obj, id, val);
	}

	/* tbl = xx(obj); tbl[key] = value; */
	int
	rb_class_ivar_set(VALUE obj, ID key, VALUE value)
	{
	if (!RCLASS_IV_TBL(obj)) {
	RCLASS_IV_TBL(obj) = st_init_numtable();
	}

	st_table *tbl = RCLASS_IV_TBL(obj);
	int result = st_insert(tbl, (st_data_t)key, (st_data_t)value);
	RB_OBJ_WRITTEN(obj, Qundef, value);
	return result;
	}

	static int
	tbl_copy_i(st_data_t key, st_data_t value, st_data_t data)
	{
	RB_OBJ_WRITTEN((VALUE)data, Qundef, (VALUE)value);
	return ST_CONTINUE;
	}

	void
	rb_iv_tbl_copy(VALUE dst, VALUE src)
	{
	st_table *orig_tbl = RCLASS_IV_TBL(src);
	st_table *new_tbl = st_copy(orig_tbl);
	st_foreach(new_tbl, tbl_copy_i, (st_data_t)dst);
	RCLASS_IV_TBL(dst) = new_tbl;
	}

	MJIT_FUNC_EXPORTED rb_const_entry_t *
	rb_const_lookup(VALUE klass, ID id)
	{
	struct rb_id_table *tbl = RCLASS_CONST_TBL(klass);

	if (tbl) {
	VALUE val;
	bool r;
	RB_VM_LOCK_ENTER();
	{
	r = rb_id_table_lookup(tbl, id, &val);
	}
	RB_VM_LOCK_LEAVE();

	if (r) return (rb_const_entry_t *)val;
	}
	return NULL;
	}

ruby / ruby

ruby/variable.c

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