class.c

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

 class.c -

 $Author$
 created at: Tue Aug 10 15:05:44 JST 1993

 Copyright (C) 1993-2007 Yukihiro Matsumoto

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

/*!
 * \defgroup class Classes and their hierarchy.
 * \par Terminology
 * - class: same as in Ruby.
 * - singleton class: class for a particular object
 * - eigenclass: = singleton class
 * - metaclass: class of a class. metaclass is a kind of singleton class.
 * - metametaclass: class of a metaclass.
 * - meta^(n)-class: class of a meta^(n-1)-class.
 * - attached object: A singleton class knows its unique instance.
 * The instance is called the attached object for the singleton class.
 * \{
 */

#include "ruby/ruby.h"
#include "ruby/st.h"
#include "method.h"
#include "constant.h"
#include "vm_core.h"
#include "internal.h"
#include <ctype.h>

int rb_vm_add_root_module(ID id, VALUE module);


#define id_attached id__attached__

void
rb_class_subclass_add(VALUE super, VALUE klass)
{
 rb_subclass_entry_t *entry, *head;

 if (super && super != Qundef) {
	entry = xmalloc(sizeof(*entry));
	entry->klass = klass;
	entry->next = NULL;

	head = RCLASS_EXT(super)->subclasses;
	if (head) {
	 entry->next = head;
	 RCLASS_EXT(head->klass)->parent_subclasses = &entry->next;
	}

	RCLASS_EXT(super)->subclasses = entry;
	RCLASS_EXT(klass)->parent_subclasses = &RCLASS_EXT(super)->subclasses;
 }
}

static void
rb_module_add_to_subclasses_list(VALUE module, VALUE iclass)
{
 rb_subclass_entry_t *entry, *head;

 entry = xmalloc(sizeof(*entry));
 entry->klass = iclass;
 entry->next = NULL;

 head = RCLASS_EXT(module)->subclasses;
 if (head) {
	entry->next = head;
	RCLASS_EXT(head->klass)->module_subclasses = &entry->next;
 }

 RCLASS_EXT(module)->subclasses = entry;
 RCLASS_EXT(iclass)->module_subclasses = &RCLASS_EXT(module)->subclasses;
}

void
rb_class_remove_from_super_subclasses(VALUE klass)
{
 rb_subclass_entry_t *entry;

 if (RCLASS_EXT(klass)->parent_subclasses) {
	entry = *RCLASS_EXT(klass)->parent_subclasses;

	*RCLASS_EXT(klass)->parent_subclasses = entry->next;
	if (entry->next) {
	 RCLASS_EXT(entry->next->klass)->parent_subclasses = RCLASS_EXT(klass)->parent_subclasses;
	}
	xfree(entry);
 }

 RCLASS_EXT(klass)->parent_subclasses = NULL;
}

void
rb_class_remove_from_module_subclasses(VALUE klass)
{
 rb_subclass_entry_t *entry;

 if (RCLASS_EXT(klass)->module_subclasses) {
	entry = *RCLASS_EXT(klass)->module_subclasses;
	*RCLASS_EXT(klass)->module_subclasses = entry->next;

	if (entry->next) {
	 RCLASS_EXT(entry->next->klass)->module_subclasses = RCLASS_EXT(klass)->module_subclasses;
	}

	xfree(entry);
 }

 RCLASS_EXT(klass)->module_subclasses = NULL;
}

void
rb_class_foreach_subclass(VALUE klass, void(*f)(VALUE))
{
 rb_subclass_entry_t *cur = RCLASS_EXT(klass)->subclasses;

 /* do not be tempted to simplify this loop into a for loop, the order of
 operations is important here if `f` modifies the linked list */
 while (cur) {
	VALUE curklass = cur->klass;
	cur = cur->next;
	f(curklass);
 }
}

void
rb_class_detach_subclasses(VALUE klass)
{
 rb_class_foreach_subclass(klass, rb_class_remove_from_super_subclasses);
}

void
rb_class_detach_module_subclasses(VALUE klass)
{
 rb_class_foreach_subclass(klass, rb_class_remove_from_module_subclasses);
}

/**
 * Allocates a struct RClass for a new class.
 *
 * \param flags initial value for basic.flags of the returned class.
 * \param klass the class of the returned class.
 * \return an uninitialized Class object.
 * \pre \p klass must refer \c Class class or an ancestor of Class.
 * \pre \code (flags | T_CLASS) != 0 \endcode
 * \post the returned class can safely be \c #initialize 'd.
 *
 * \note this function is not Class#allocate.
 */
static VALUE
class_alloc(VALUE flags, VALUE klass)
{
 NEWOBJ_OF(obj, struct RClass, klass, (flags & T_MASK) | (RGENGC_WB_PROTECTED_CLASS ? FL_WB_PROTECTED : 0));
 obj->ptr = ALLOC(rb_classext_t);
 RCLASS_IV_TBL(obj) = 0;
 RCLASS_CONST_TBL(obj) = 0;
 RCLASS_M_TBL_WRAPPER(obj) = 0;
 RCLASS_SET_SUPER((VALUE)obj, 0);
 RCLASS_ORIGIN(obj) = (VALUE)obj;
 RCLASS_IV_INDEX_TBL(obj) = 0;

 RCLASS_EXT(obj)->subclasses = NULL;
 RCLASS_EXT(obj)->parent_subclasses = NULL;
 RCLASS_EXT(obj)->module_subclasses = NULL;
 RCLASS_SERIAL(obj) = rb_next_class_serial();

 RCLASS_REFINED_CLASS(obj) = Qnil;
 RCLASS_EXT(obj)->allocator = 0;
 return (VALUE)obj;
}


/*!
 * A utility function that wraps class_alloc.
 *
 * allocates a class and initializes safely.
 * \param super a class from which the new class derives.
 * \return a class object.
 * \pre \a super must be a class.
 * \post the metaclass of the new class is Class.
 */
VALUE
rb_class_boot(VALUE super)
{
 VALUE klass = class_alloc(T_CLASS, rb_cClass);

 RCLASS_SET_SUPER(klass, super);
 RCLASS_M_TBL_INIT(klass);

 OBJ_INFECT(klass, super);
 return (VALUE)klass;
}


/*!
 * Ensures a class can be derived from super.
 *
 * \param super a reference to an object.
 * \exception TypeError if \a super is not a Class or \a super is a singleton class.
 */
void
rb_check_inheritable(VALUE super)
{
 if (!RB_TYPE_P(super, T_CLASS)) {
	rb_raise(rb_eTypeError, "superclass must be a Class (%s given)",
		 rb_obj_classname(super));
 }
 if (RBASIC(super)->flags & FL_SINGLETON) {
	rb_raise(rb_eTypeError, "can't make subclass of singleton class");
 }
 if (super == rb_cClass) {
	rb_raise(rb_eTypeError, "can't make subclass of Class");
 }
}


/*!
 * Creates a new class.
 * \param super a class from which the new class derives.
 * \exception TypeError \a super is not inheritable.
 * \exception TypeError \a super is the Class class.
 */
VALUE
rb_class_new(VALUE super)
{
 Check_Type(super, T_CLASS);
 rb_check_inheritable(super);
 return rb_class_boot(super);
}

static void
rewrite_cref_stack(NODE *node, VALUE old_klass, VALUE new_klass, NODE **new_cref_ptr)
{
 NODE *new_node;
 while (node) {
	if (node->nd_clss == old_klass) {
	 new_node = NEW_CREF(new_klass);
	 RB_OBJ_WRITE(new_node, &new_node->nd_next, node->nd_next);
	 *new_cref_ptr = new_node;
	 return;
	}
	new_node = NEW_CREF(node->nd_clss);
	node = node->nd_next;
	*new_cref_ptr = new_node;
	new_cref_ptr = &new_node->nd_next;
 }
 *new_cref_ptr = NULL;
}

static void
clone_method(VALUE klass, ID mid, const rb_method_entry_t *me)
{
 VALUE newiseqval;
 if (me->def && me->def->type == VM_METHOD_TYPE_ISEQ) {
	rb_iseq_t *iseq;
	NODE *new_cref;
	newiseqval = rb_iseq_clone(me->def->body.iseq->self, klass);
	GetISeqPtr(newiseqval, iseq);
	rewrite_cref_stack(me->def->body.iseq->cref_stack, me->klass, klass, &new_cref);
	RB_OBJ_WRITE(iseq->self, &iseq->cref_stack, new_cref);
	rb_add_method(klass, mid, VM_METHOD_TYPE_ISEQ, iseq, me->flag);
	RB_GC_GUARD(newiseqval);
 }
 else {
	rb_method_entry_set(klass, mid, me, me->flag);
 }
}

static int
clone_method_i(st_data_t key, st_data_t value, st_data_t data)
{
 clone_method((VALUE)data, (ID)key, (const rb_method_entry_t *)value);
 return ST_CONTINUE;
}

struct clone_const_arg {
 VALUE klass;
 st_table *tbl;
};

static int
clone_const(ID key, const rb_const_entry_t *ce, struct clone_const_arg *arg)
{
 rb_const_entry_t *nce = ALLOC(rb_const_entry_t);
 MEMCPY(nce, ce, rb_const_entry_t, 1);
 RB_OBJ_WRITTEN(arg->klass, Qundef, ce->value);
 RB_OBJ_WRITTEN(arg->klass, Qundef, ce->file);

 st_insert(arg->tbl, key, (st_data_t)nce);
 return ST_CONTINUE;
}

static int
clone_const_i(st_data_t key, st_data_t value, st_data_t data)
{
 return clone_const((ID)key, (const rb_const_entry_t *)value, (struct clone_const_arg *)data);
}

static void
class_init_copy_check(VALUE clone, VALUE orig)
{
 if (orig == rb_cBasicObject) {
	rb_raise(rb_eTypeError, "can't copy the root class");
 }
 if (RCLASS_SUPER(clone) != 0 || clone == rb_cBasicObject) {
	rb_raise(rb_eTypeError, "already initialized class");
 }
 if (FL_TEST(orig, FL_SINGLETON)) {
	rb_raise(rb_eTypeError, "can't copy singleton class");
 }
}

/* :nodoc: */
VALUE
rb_mod_init_copy(VALUE clone, VALUE orig)
{
 if (RB_TYPE_P(clone, T_CLASS)) {
	class_init_copy_check(clone, orig);
 }
 if (!OBJ_INIT_COPY(clone, orig)) return clone;
 if (!FL_TEST(CLASS_OF(clone), FL_SINGLETON)) {
	RBASIC_SET_CLASS(clone, rb_singleton_class_clone(orig));
	rb_singleton_class_attached(RBASIC(clone)->klass, (VALUE)clone);
 }
 RCLASS_SET_SUPER(clone, RCLASS_SUPER(orig));
 RCLASS_EXT(clone)->allocator = RCLASS_EXT(orig)->allocator;
 if (RCLASS_IV_TBL(clone)) {
	st_free_table(RCLASS_IV_TBL(clone));
	RCLASS_IV_TBL(clone) = 0;
 }
 if (RCLASS_CONST_TBL(clone)) {
	rb_free_const_table(RCLASS_CONST_TBL(clone));
	RCLASS_CONST_TBL(clone) = 0;
 }
 if (RCLASS_M_TBL_WRAPPER(clone)) {
	rb_free_m_tbl_wrapper(RCLASS_M_TBL_WRAPPER(clone));
	RCLASS_M_TBL_WRAPPER(clone) = 0;
 }
 if (RCLASS_IV_TBL(orig)) {
	st_data_t id;

	RCLASS_IV_TBL(clone) = rb_st_copy(clone, RCLASS_IV_TBL(orig));
	CONST_ID(id, "__tmp_classpath__");
	st_delete(RCLASS_IV_TBL(clone), &id, 0);
	CONST_ID(id, "__classpath__");
	st_delete(RCLASS_IV_TBL(clone), &id, 0);
	CONST_ID(id, "__classid__");
	st_delete(RCLASS_IV_TBL(clone), &id, 0);
 }
 if (RCLASS_CONST_TBL(orig)) {
	struct clone_const_arg arg;

	RCLASS_CONST_TBL(clone) = st_init_numtable();
	arg.klass = clone;
	arg.tbl = RCLASS_CONST_TBL(clone);
	st_foreach(RCLASS_CONST_TBL(orig), clone_const_i, (st_data_t)&arg);
 }
 if (RCLASS_M_TBL(orig)) {
	RCLASS_M_TBL_INIT(clone);
	st_foreach(RCLASS_M_TBL(orig), clone_method_i, (st_data_t)clone);
 }

 return clone;
}

VALUE
rb_singleton_class_clone(VALUE obj)
{
 return rb_singleton_class_clone_and_attach(obj, Qundef);
}

VALUE
rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach)
{
 VALUE klass = RBASIC(obj)->klass;

 if (!FL_TEST(klass, FL_SINGLETON))
	return klass;
 else {
	/* copy singleton(unnamed) class */
	VALUE clone = class_alloc(RBASIC(klass)->flags, 0);

	if (BUILTIN_TYPE(obj) == T_CLASS) {
	 RBASIC_SET_CLASS(clone, clone);
	}
	else {
	 RBASIC_SET_CLASS(clone, rb_singleton_class_clone(klass));
	}

	RCLASS_SET_SUPER(clone, RCLASS_SUPER(klass));
	RCLASS_EXT(clone)->allocator = RCLASS_EXT(klass)->allocator;
	if (RCLASS_IV_TBL(klass)) {
	 RCLASS_IV_TBL(clone) = rb_st_copy(clone, RCLASS_IV_TBL(klass));
	}
	if (RCLASS_CONST_TBL(klass)) {
	 struct clone_const_arg arg;
	 RCLASS_CONST_TBL(clone) = st_init_numtable();
	 arg.klass = clone;
	 arg.tbl = RCLASS_CONST_TBL(clone);
	 st_foreach(RCLASS_CONST_TBL(klass), clone_const_i, (st_data_t)&arg);
	}
	if (attach != Qundef) {
	 rb_singleton_class_attached(clone, attach);
	}
	RCLASS_M_TBL_INIT(clone);
	st_foreach(RCLASS_M_TBL(klass), clone_method_i, (st_data_t)clone);
	rb_singleton_class_attached(RBASIC(clone)->klass, clone);
	FL_SET(clone, FL_SINGLETON);

	return clone;
 }
}

/*!
 * Attach a object to a singleton class.
 * @pre \a klass is the singleton class of \a obj.
 */
void
rb_singleton_class_attached(VALUE klass, VALUE obj)
{
 if (FL_TEST(klass, FL_SINGLETON)) {
	if (!RCLASS_IV_TBL(klass)) {
	 RCLASS_IV_TBL(klass) = st_init_numtable();
	}
	rb_st_insert_id_and_value(klass, RCLASS_IV_TBL(klass), id_attached, obj);
 }
}



#define METACLASS_OF(k) RBASIC(k)->klass
#define SET_METACLASS_OF(k, cls) RBASIC_SET_CLASS(k, cls)

/*!
 * whether k is a meta^(n)-class of Class class
 * @retval 1 if \a k is a meta^(n)-class of Class class (n >= 0)
 * @retval 0 otherwise
 */
#define META_CLASS_OF_CLASS_CLASS_P(k) (METACLASS_OF(k) == (k))

/*!
 * whether k has a metaclass
 * @retval 1 if \a k has a metaclass
 * @retval 0 otherwise
 */
#define HAVE_METACLASS_P(k) \
 (FL_TEST(METACLASS_OF(k), FL_SINGLETON) && \
 rb_ivar_get(METACLASS_OF(k), id_attached) == (k))

/*!
 * ensures \a klass belongs to its own eigenclass.
 * @return the eigenclass of \a klass
 * @post \a klass belongs to the returned eigenclass.
 * i.e. the attached object of the eigenclass is \a klass.
 * @note this macro creates a new eigenclass if necessary.
 */
#define ENSURE_EIGENCLASS(klass) \
 (HAVE_METACLASS_P(klass) ? METACLASS_OF(klass) : make_metaclass(klass))


/*!
 * Creates a metaclass of \a klass
 * \param klass a class
 * \return created metaclass for the class
 * \pre \a klass is a Class object
 * \pre \a klass has no singleton class.
 * \post the class of \a klass is the returned class.
 * \post the returned class is meta^(n+1)-class when \a klass is a meta^(n)-klass for n >= 0
 */
static inline VALUE
make_metaclass(VALUE klass)
{
 VALUE super;
 VALUE metaclass = rb_class_boot(Qundef);

 FL_SET(metaclass, FL_SINGLETON);
 rb_singleton_class_attached(metaclass, klass);

 if (META_CLASS_OF_CLASS_CLASS_P(klass)) {
	SET_METACLASS_OF(klass, metaclass);
	SET_METACLASS_OF(metaclass, metaclass);
 }
 else {
	VALUE tmp = METACLASS_OF(klass); /* for a meta^(n)-class klass, tmp is meta^(n)-class of Class class */
	SET_METACLASS_OF(klass, metaclass);
	SET_METACLASS_OF(metaclass, ENSURE_EIGENCLASS(tmp));
 }

 super = RCLASS_SUPER(klass);
 while (RB_TYPE_P(super, T_ICLASS)) super = RCLASS_SUPER(super);
 RCLASS_SET_SUPER(metaclass, super ? ENSURE_EIGENCLASS(super) : rb_cClass);

 OBJ_INFECT(metaclass, RCLASS_SUPER(metaclass));

 return metaclass;
}

/*!
 * Creates a singleton class for \a obj.
 * \pre \a obj must not a immediate nor a special const.
 * \pre \a obj must not a Class object.
 * \pre \a obj has no singleton class.
 */
static inline VALUE
make_singleton_class(VALUE obj)
{
 VALUE orig_class = RBASIC(obj)->klass;
 VALUE klass = rb_class_boot(orig_class);

 FL_SET(klass, FL_SINGLETON);
 RBASIC_SET_CLASS(obj, klass);
 rb_singleton_class_attached(klass, obj);

 SET_METACLASS_OF(klass, METACLASS_OF(rb_class_real(orig_class)));
 return klass;
}


static VALUE
boot_defclass(const char *name, VALUE super)
{
 VALUE obj = rb_class_boot(super);
 ID id = rb_intern(name);

 rb_name_class(obj, id);
 rb_const_set((rb_cObject ? rb_cObject : obj), id, obj);
 return obj;
}

void
Init_class_hierarchy(void)
{
 rb_cBasicObject = boot_defclass("BasicObject", 0);
 rb_cObject = boot_defclass("Object", rb_cBasicObject);
 rb_cModule = boot_defclass("Module", rb_cObject);
 rb_cClass = boot_defclass("Class", rb_cModule);

 rb_const_set(rb_cObject, rb_intern_const("BasicObject"), rb_cBasicObject);
 RBASIC_SET_CLASS(rb_cClass, rb_cClass);
 RBASIC_SET_CLASS(rb_cModule, rb_cClass);
 RBASIC_SET_CLASS(rb_cObject, rb_cClass);
 RBASIC_SET_CLASS(rb_cBasicObject, rb_cClass);
}


/*!
 * \internal
 * Creates a new *singleton class* for an object.
 *
 * \pre \a obj has no singleton class.
 * \note DO NOT USE the function in an extension libraries. Use \ref rb_singleton_class.
 * \param obj An object.
 * \param unused ignored.
 * \return The singleton class of the object.
 */
VALUE
rb_make_metaclass(VALUE obj, VALUE unused)
{
 if (BUILTIN_TYPE(obj) == T_CLASS) {
	return make_metaclass(obj);
 }
 else {
	return make_singleton_class(obj);
 }
}


/*!
 * Defines a new class.
 * \param id ignored
 * \param super A class from which the new class will derive. NULL means \c Object class.
 * \return the created class
 * \throw TypeError if super is not a \c Class object.
 *
 * \note the returned class will not be associated with \a id.
 * You must explicitly set a class name if necessary.
 */
VALUE
rb_define_class_id(ID id, VALUE super)
{
 VALUE klass;

 if (!super) super = rb_cObject;
 klass = rb_class_new(super);
 rb_make_metaclass(klass, RBASIC(super)->klass);

 return klass;
}


/*!
 * Calls Class#inherited.
 * \param super A class which will be called #inherited.
 * NULL means Object class.
 * \param klass A Class object which derived from \a super
 * \return the value \c Class#inherited's returns
 * \pre Each of \a super and \a klass must be a \c Class object.
 */
VALUE
rb_class_inherited(VALUE super, VALUE klass)
{
 ID inherited;
 if (!super) super = rb_cObject;
 CONST_ID(inherited, "inherited");
 return rb_funcall(super, inherited, 1, klass);
}



/*!
 * Defines a top-level class.
 * \param name name of the class
 * \param super a class from which the new class will derive.
 * NULL means \c Object class.
 * \return the created class
 * \throw TypeError if the constant name \a name is already taken but
 * the constant is not a \c Class.
 * \throw NameError if the class is already defined but the class can not
 * be reopened because its superclass is not \a super.
 * \post top-level constant named \a name refers the returned class.
 *
 * \note if a class named \a name is already defined and its superclass is
 * \a super, the function just returns the defined class.
 */
VALUE
rb_define_class(const char *name, VALUE super)
{
 VALUE klass;
 ID id;

 id = rb_intern(name);
 if (rb_const_defined(rb_cObject, id)) {
	klass = rb_const_get(rb_cObject, id);
	if (!RB_TYPE_P(klass, T_CLASS)) {
	 rb_raise(rb_eTypeError, "%s is not a class", name);
	}
	if (rb_class_real(RCLASS_SUPER(klass)) != super) {
	 rb_raise(rb_eTypeError, "superclass mismatch for class %s", name);
	}
	return klass;
 }
 if (!super) {
	rb_warn("no super class for `%s', Object assumed", name);
 }
 klass = rb_define_class_id(id, super);
 rb_vm_add_root_module(id, klass);
 rb_name_class(klass, id);
 rb_const_set(rb_cObject, id, klass);
 rb_class_inherited(super, klass);

 return klass;
}


/*!
 * Defines a class under the namespace of \a outer.
 * \param outer a class which contains the new class.
 * \param name name of the new class
 * \param super a class from which the new class will derive.
 * NULL means \c Object class.
 * \return the created class
 * \throw TypeError if the constant name \a name is already taken but
 * the constant is not a \c Class.
 * \throw NameError if the class is already defined but the class can not
 * be reopened because its superclass is not \a super.
 * \post top-level constant named \a name refers the returned class.
 *
 * \note if a class named \a name is already defined and its superclass is
 * \a super, the function just returns the defined class.
 */
VALUE
rb_define_class_under(VALUE outer, const char *name, VALUE super)
{
 return rb_define_class_id_under(outer, rb_intern(name), super);
}


/*!
 * Defines a class under the namespace of \a outer.
 * \param outer a class which contains the new class.
 * \param id name of the new class
 * \param super a class from which the new class will derive.
 * NULL means \c Object class.
 * \return the created class
 * \throw TypeError if the constant name \a name is already taken but
 * the constant is not a \c Class.
 * \throw NameError if the class is already defined but the class can not
 * be reopened because its superclass is not \a super.
 * \post top-level constant named \a name refers the returned class.
 *
 * \note if a class named \a name is already defined and its superclass is
 * \a super, the function just returns the defined class.
 */
VALUE
rb_define_class_id_under(VALUE outer, ID id, VALUE super)
{
 VALUE klass;

 if (rb_const_defined_at(outer, id)) {
	klass = rb_const_get_at(outer, id);
	if (!RB_TYPE_P(klass, T_CLASS)) {
	 rb_raise(rb_eTypeError, "%s is not a class", rb_id2name(id));
	}
	if (rb_class_real(RCLASS_SUPER(klass)) != super) {
	 rb_name_error(id, "%s is already defined", rb_id2name(id));
	}
	return klass;
 }
 if (!super) {
	rb_warn("no super class for `%s::%s', Object assumed",
		rb_class2name(outer), rb_id2name(id));
 }
 klass = rb_define_class_id(id, super);
 rb_set_class_path_string(klass, outer, rb_id2str(id));
 rb_const_set(outer, id, klass);
 rb_class_inherited(super, klass);
 rb_gc_register_mark_object(klass);

 return klass;
}

VALUE
rb_module_new(void)
{
 VALUE mdl = class_alloc(T_MODULE, rb_cModule);
 RCLASS_M_TBL_INIT(mdl);
 return (VALUE)mdl;
}

VALUE
rb_define_module_id(ID id)
{
 VALUE mdl;

 mdl = rb_module_new();
 rb_name_class(mdl, id);

 return mdl;
}

VALUE
rb_define_module(const char *name)
{
 VALUE module;
 ID id;

 id = rb_intern(name);
 if (rb_const_defined(rb_cObject, id)) {
	module = rb_const_get(rb_cObject, id);
	if (RB_TYPE_P(module, T_MODULE))
	 return module;
	rb_raise(rb_eTypeError, "%s is not a module", rb_obj_classname(module));
 }
 module = rb_define_module_id(id);
 rb_vm_add_root_module(id, module);
 rb_const_set(rb_cObject, id, module);

 return module;
}

VALUE
rb_define_module_under(VALUE outer, const char *name)
{
 return rb_define_module_id_under(outer, rb_intern(name));
}

VALUE
rb_define_module_id_under(VALUE outer, ID id)
{
 VALUE module;

 if (rb_const_defined_at(outer, id)) {
	module = rb_const_get_at(outer, id);
	if (RB_TYPE_P(module, T_MODULE))
	 return module;
	rb_raise(rb_eTypeError, "%s::%s is not a module",
		 rb_class2name(outer), rb_obj_classname(module));
 }
 module = rb_define_module_id(id);
 rb_const_set(outer, id, module);
 rb_set_class_path_string(module, outer, rb_id2str(id));
 rb_gc_register_mark_object(module);

 return module;
}

VALUE
rb_include_class_new(VALUE module, VALUE super)
{
 VALUE klass = class_alloc(T_ICLASS, rb_cClass);

 if (BUILTIN_TYPE(module) == T_ICLASS) {
	module = RBASIC(module)->klass;
 }
 if (!RCLASS_IV_TBL(module)) {
	RCLASS_IV_TBL(module) = st_init_numtable();
 }
 if (!RCLASS_CONST_TBL(module)) {
	RCLASS_CONST_TBL(module) = st_init_numtable();
 }
 RCLASS_IV_TBL(klass) = RCLASS_IV_TBL(module);
 RCLASS_CONST_TBL(klass) = RCLASS_CONST_TBL(module);

 RCLASS_M_TBL_WRAPPER(OBJ_WB_UNPROTECT(klass)) =
	RCLASS_M_TBL_WRAPPER(OBJ_WB_UNPROTECT(RCLASS_ORIGIN(module)));

 RCLASS_SET_SUPER(klass, super);
 if (RB_TYPE_P(module, T_ICLASS)) {
	RBASIC_SET_CLASS(klass, RBASIC(module)->klass);
 }
 else {
	RBASIC_SET_CLASS(klass, module);
 }
 OBJ_INFECT(klass, module);
 OBJ_INFECT(klass, super);

 return (VALUE)klass;
}

static int include_modules_at(const VALUE klass, VALUE c, VALUE module);

void
rb_include_module(VALUE klass, VALUE module)
{
 int changed = 0;

 rb_frozen_class_p(klass);

 if (!RB_TYPE_P(module, T_MODULE)) {
	Check_Type(module, T_MODULE);
 }

 OBJ_INFECT(klass, module);

 changed = include_modules_at(klass, RCLASS_ORIGIN(klass), module);
 if (changed < 0)
	rb_raise(rb_eArgError, "cyclic include detected");
}

static int
add_refined_method_entry_i(st_data_t key, st_data_t value, st_data_t data)
{
 rb_add_refined_method_entry((VALUE) data, (ID) key);
 return ST_CONTINUE;
}

static int
include_modules_at(const VALUE klass, VALUE c, VALUE module)
{
 VALUE p, iclass;
 int method_changed = 0, constant_changed = 0;
 const st_table *const klass_m_tbl = RCLASS_M_TBL(RCLASS_ORIGIN(klass));

 while (module) {
	int superclass_seen = FALSE;

	if (RCLASS_ORIGIN(module) != module)
	 goto skip;
	if (klass_m_tbl && klass_m_tbl == RCLASS_M_TBL(module))
	 return -1;
	/* ignore if the module included already in superclasses */
	for (p = RCLASS_SUPER(klass); p; p = RCLASS_SUPER(p)) {
	 switch (BUILTIN_TYPE(p)) {
	 case T_ICLASS:
		if (RCLASS_M_TBL_WRAPPER(p) == RCLASS_M_TBL_WRAPPER(module)) {
		 if (!superclass_seen) {
			c = p; /* move insertion point */
		 }
		 goto skip;
		}
		break;
	 case T_CLASS:
		superclass_seen = TRUE;
		break;
	 }
	}
	iclass = rb_include_class_new(module, RCLASS_SUPER(c));
	c = RCLASS_SET_SUPER(c, iclass);

	if (BUILTIN_TYPE(module) == T_ICLASS) {
	 rb_module_add_to_subclasses_list(RBASIC(module)->klass, iclass);
	}
	else {
	 rb_module_add_to_subclasses_list(module, iclass);
	}

	if (FL_TEST(klass, RMODULE_IS_REFINEMENT)) {
	 VALUE refined_class =
		rb_refinement_module_get_refined_class(klass);

	 st_foreach(RMODULE_M_TBL(module), add_refined_method_entry_i,
		 (st_data_t) refined_class);
	 FL_SET(c, RMODULE_INCLUDED_INTO_REFINEMENT);
	}
	if (RMODULE_M_TBL(module) && RMODULE_M_TBL(module)->num_entries)
	 method_changed = 1;
	if (RMODULE_CONST_TBL(module) && RMODULE_CONST_TBL(module)->num_entries)
	 constant_changed = 1;
 skip:
	module = RCLASS_SUPER(module);
 }

 if (method_changed) rb_clear_method_cache_by_class(klass);
 if (constant_changed) rb_clear_constant_cache();

 return method_changed;
}

static int
move_refined_method(st_data_t key, st_data_t value, st_data_t data)
{
 rb_method_entry_t *me = (rb_method_entry_t *) value;
 st_table *tbl = (st_table *) data;

 if (me->def->type == VM_METHOD_TYPE_REFINED) {
	if (me->def->body.orig_me) {
	 rb_method_entry_t *orig_me = me->def->body.orig_me, *new_me;
	 me->def->body.orig_me = NULL;
	 new_me = ALLOC(rb_method_entry_t);
	 *new_me = *me;
	 st_add_direct(tbl, key, (st_data_t) new_me);
	 *me = *orig_me;
	 xfree(orig_me);
	 return ST_CONTINUE;
	}
	else {
	 st_add_direct(tbl, key, (st_data_t) me);
	 return ST_DELETE;
	}
 }
 else {
	return ST_CONTINUE;
 }
}

void
rb_prepend_module(VALUE klass, VALUE module)
{
 void rb_vm_check_redefinition_by_prepend(VALUE klass);
 VALUE origin;
 int changed = 0;

 rb_frozen_class_p(klass);

 Check_Type(module, T_MODULE);

 OBJ_INFECT(klass, module);

 origin = RCLASS_ORIGIN(klass);
 if (origin == klass) {
	origin = class_alloc(T_ICLASS, klass);
	OBJ_WB_UNPROTECT(origin); /* TODO: conservertive shading. Need more survery. */
	RCLASS_SET_SUPER(origin, RCLASS_SUPER(klass));
	RCLASS_SET_SUPER(klass, origin);
	RCLASS_ORIGIN(klass) = origin;
	RCLASS_M_TBL_WRAPPER(origin) = RCLASS_M_TBL_WRAPPER(klass);
	RCLASS_M_TBL_INIT(klass);
	st_foreach(RCLASS_M_TBL(origin), move_refined_method,
		 (st_data_t) RCLASS_M_TBL(klass));
 }
 changed = include_modules_at(klass, klass, module);
 if (changed < 0)
	rb_raise(rb_eArgError, "cyclic prepend detected");
 if (changed) {
	rb_vm_check_redefinition_by_prepend(klass);
 }
}

/*
 * call-seq:
 * mod.included_modules -> array
 *
 * Returns the list of modules included in <i>mod</i>.
 *
 * module Mixin
 * end
 *
 * module Outer
 * include Mixin
 * end
 *
 * Mixin.included_modules #=> []
 * Outer.included_modules #=> [Mixin]
 */

VALUE
rb_mod_included_modules(VALUE mod)
{
 VALUE ary = rb_ary_new();
 VALUE p;
 VALUE origin = RCLASS_ORIGIN(mod);

 for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
	if (p != origin && BUILTIN_TYPE(p) == T_ICLASS) {
	 VALUE m = RBASIC(p)->klass;
	 if (RB_TYPE_P(m, T_MODULE))
		rb_ary_push(ary, m);
	}
 }
 return ary;
}

/*
 * call-seq:
 * mod.include?(module) -> true or false
 *
 * Returns <code>true</code> if <i>module</i> is included in
 * <i>mod</i> or one of <i>mod</i>'s ancestors.
 *
 * module A
 * end
 * class B
 * include A
 * end
 * class C < B
 * end
 * B.include?(A) #=> true
 * C.include?(A) #=> true
 * A.include?(A) #=> false
 */

VALUE
rb_mod_include_p(VALUE mod, VALUE mod2)
{
 VALUE p;

 Check_Type(mod2, T_MODULE);
 for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
	if (BUILTIN_TYPE(p) == T_ICLASS) {
	 if (RBASIC(p)->klass == mod2) return Qtrue;
	}
 }
 return Qfalse;
}

/*
 * call-seq:
 * mod.ancestors -> array
 *
 * Returns a list of modules included/prepended in <i>mod</i>
 * (including <i>mod</i> itself).
 *
 * module Mod
 * include Math
 * include Comparable
 * prepend Enumerable
 * end
 *
 * Mod.ancestors #=> [Enumerable, Mod, Comparable, Math]
 * Math.ancestors #=> [Math]
 * Enumerable.ancestors #=> [Enumerable]
 */

VALUE
rb_mod_ancestors(VALUE mod)
{
 VALUE p, ary = rb_ary_new();

 for (p = mod; p; p = RCLASS_SUPER(p)) {
	if (BUILTIN_TYPE(p) == T_ICLASS) {
	 rb_ary_push(ary, RBASIC(p)->klass);
	}
	else if (p == RCLASS_ORIGIN(p)) {
	 rb_ary_push(ary, p);
	}
 }
 return ary;
}

#define VISI(x) ((x)&NOEX_MASK)
#define VISI_CHECK(x,f) (VISI(x) == (f))

static int
ins_methods_push(ID name, long type, VALUE ary, long visi)
{
 if (type == -1) return ST_CONTINUE;

 switch (visi) {
 case NOEX_PRIVATE:
 case NOEX_PROTECTED:
 case NOEX_PUBLIC:
	visi = (type == visi);
	break;
 default:
	visi = (type != NOEX_PRIVATE);
	break;
 }
 if (visi) {
	rb_ary_push(ary, ID2SYM(name));
 }
 return ST_CONTINUE;
}

static int
ins_methods_i(st_data_t name, st_data_t type, st_data_t ary)
{
 return ins_methods_push((ID)name, (long)type, (VALUE)ary, -1); /* everything but private */
}

static int
ins_methods_prot_i(st_data_t name, st_data_t type, st_data_t ary)
{
 return ins_methods_push((ID)name, (long)type, (VALUE)ary, NOEX_PROTECTED);
}

static int
ins_methods_priv_i(st_data_t name, st_data_t type, st_data_t ary)
{
 return ins_methods_push((ID)name, (long)type, (VALUE)ary, NOEX_PRIVATE);
}

static int
ins_methods_pub_i(st_data_t name, st_data_t type, st_data_t ary)
{
 return ins_methods_push((ID)name, (long)type, (VALUE)ary, NOEX_PUBLIC);
}

static int
method_entry_i(st_data_t key, st_data_t value, st_data_t data)
{
 const rb_method_entry_t *me = (const rb_method_entry_t *)value;
 st_table *list = (st_table *)data;
 long type;

 if (me && me->def->type == VM_METHOD_TYPE_REFINED) {
	me = rb_resolve_refined_method(Qnil, me, NULL);
	if (!me) return ST_CONTINUE;
 }
 if (!st_lookup(list, key, 0)) {
	if (UNDEFINED_METHOD_ENTRY_P(me)) {
	 type = -1; /* none */
	}
	else {
	 type = VISI(me->flag);
	}
	st_add_direct(list, key, type);
 }
 return ST_CONTINUE;
}

static VALUE
class_instance_method_list(int argc, const VALUE *argv, VALUE mod, int obj, int (*func) (st_data_t, st_data_t, st_data_t))
{
 VALUE ary;
 int recur, prepended = 0;
 st_table *list;

 if (argc == 0) {
	recur = TRUE;
 }
 else {
	VALUE r;
	rb_scan_args(argc, argv, "01", &r);
	recur = RTEST(r);
 }

 if (!recur && RCLASS_ORIGIN(mod) != mod) {
	mod = RCLASS_ORIGIN(mod);
	prepended = 1;
 }

 list = st_init_numtable();
 for (; mod; mod = RCLASS_SUPER(mod)) {
	if (RCLASS_M_TBL(mod)) st_foreach(RCLASS_M_TBL(mod), method_entry_i, (st_data_t)list);
	if (BUILTIN_TYPE(mod) == T_ICLASS && !prepended) continue;
	if (obj && FL_TEST(mod, FL_SINGLETON)) continue;
	if (!recur) break;
 }
 ary = rb_ary_new();
 st_foreach(list, func, ary);
 st_free_table(list);

 return ary;
}

/*
 * call-seq:
 * mod.instance_methods(include_super=true) -> array
 *
 * Returns an array containing the names of the public and protected instance
 * methods in the receiver. For a module, these are the public and protected methods;
 * for a class, they are the instance (not singleton) methods. If the optional
 * parameter is <code>false</code>, the methods of any ancestors are not included.
 *
 * module A
 * def method1() end
 * end
 * class B
 * include A
 * def method2() end
 * end
 * class C < B
 * def method3() end
 * end
 *
 * A.instance_methods(false) #=> [:method1]
 * B.instance_methods(false) #=> [:method2]
 * B.instance_methods(true).include?(:method1) #=> true
 * C.instance_methods(false) #=> [:method3]
 * C.instance_methods.include?(:method2) #=> true
 */

VALUE
rb_class_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
 return class_instance_method_list(argc, argv, mod, 0, ins_methods_i);
}

/*
 * call-seq:
 * mod.protected_instance_methods(include_super=true) -> array
 *
 * Returns a list of the protected instance methods defined in
 * <i>mod</i>. If the optional parameter is <code>false</code>, the
 * methods of any ancestors are not included.
 */

VALUE
rb_class_protected_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
 return class_instance_method_list(argc, argv, mod, 0, ins_methods_prot_i);
}

/*
 * call-seq:
 * mod.private_instance_methods(include_super=true) -> array
 *
 * Returns a list of the private instance methods defined in
 * <i>mod</i>. If the optional parameter is <code>false</code>, the
 * methods of any ancestors are not included.
 *
 * module Mod
 * def method1() end
 * private :method1
 * def method2() end
 * end
 * Mod.instance_methods #=> [:method2]
 * Mod.private_instance_methods #=> [:method1]
 */

VALUE
rb_class_private_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
 return class_instance_method_list(argc, argv, mod, 0, ins_methods_priv_i);
}

/*
 * call-seq:
 * mod.public_instance_methods(include_super=true) -> array
 *
 * Returns a list of the public instance methods defined in <i>mod</i>.
 * If the optional parameter is <code>false</code>, the methods of
 * any ancestors are not included.
 */

VALUE
rb_class_public_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
 return class_instance_method_list(argc, argv, mod, 0, ins_methods_pub_i);
}

/*
 * call-seq:
 * obj.methods(regular=true) -> array
 *
 * Returns a list of the names of public and protected methods of
 * <i>obj</i>. This will include all the methods accessible in
 * <i>obj</i>'s ancestors.
 * If the optional parameter is <code>false</code>, it
 * returns an array of <i>obj<i>'s public and protected singleton methods,
 * the array will not include methods in modules included in <i>obj</i>.
 *
 * class Klass
 * def klass_method()
 * end
 * end
 * k = Klass.new
 * k.methods[0..9] #=> [:klass_method, :nil?, :===,
 * # :==~, :!, :eql?
 * # :hash, :<=>, :class, :singleton_class]
 * k.methods.length #=> 56
 *
 * k.methods(false) #=> []
 * def k.singleton_method; end
 * k.methods(false) #=> [:singleton_method]
 *
 * module M123; def m123; end end
 * k.extend M123
 * k.methods(false) #=> [:singleton_method]
 */

VALUE
rb_obj_methods(int argc, const VALUE *argv, VALUE obj)
{
 rb_check_arity(argc, 0, 1);
 if (argc > 0 && !RTEST(argv[0])) {
	return rb_obj_singleton_methods(argc, argv, obj);
 }
 return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_i);
}

/*
 * call-seq:
 * obj.protected_methods(all=true) -> array
 *
 * Returns the list of protected methods accessible to <i>obj</i>. If
 * the <i>all</i> parameter is set to <code>false</code>, only those methods
 * in the receiver will be listed.
 */

VALUE
rb_obj_protected_methods(int argc, const VALUE *argv, VALUE obj)
{
 return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_prot_i);
}

/*
 * call-seq:
 * obj.private_methods(all=true) -> array
 *
 * Returns the list of private methods accessible to <i>obj</i>. If
 * the <i>all</i> parameter is set to <code>false</code>, only those methods
 * in the receiver will be listed.
 */

VALUE
rb_obj_private_methods(int argc, const VALUE *argv, VALUE obj)
{
 return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_priv_i);
}

/*
 * call-seq:
 * obj.public_methods(all=true) -> array
 *
 * Returns the list of public methods accessible to <i>obj</i>. If
 * the <i>all</i> parameter is set to <code>false</code>, only those methods
 * in the receiver will be listed.
 */

VALUE
rb_obj_public_methods(int argc, const VALUE *argv, VALUE obj)
{
 return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_pub_i);
}

/*
 * call-seq:
 * obj.singleton_methods(all=true) -> array
 *
 * Returns an array of the names of singleton methods for <i>obj</i>.
 * If the optional <i>all</i> parameter is true, the list will include
 * methods in modules included in <i>obj</i>.
 * Only public and protected singleton methods are returned.
 *
 * module Other
 * def three() end
 * end
 *
 * class Single
 * def Single.four() end
 * end
 *
 * a = Single.new
 *
 * def a.one()
 * end
 *
 * class << a
 * include Other
 * def two()
 * end
 * end
 *
 * Single.singleton_methods #=> [:four]
 * a.singleton_methods(false) #=> [:two, :one]
 * a.singleton_methods #=> [:two, :one, :three]
 */

VALUE
rb_obj_singleton_methods(int argc, const VALUE *argv, VALUE obj)
{
 VALUE recur, ary, klass, origin;
 st_table *list, *mtbl;

 if (argc == 0) {
	recur = Qtrue;
 }
 else {
	rb_scan_args(argc, argv, "01", &recur);
 }
 klass = CLASS_OF(obj);
 origin = RCLASS_ORIGIN(klass);
 list = st_init_numtable();
 if (klass && FL_TEST(klass, FL_SINGLETON)) {
	if ((mtbl = RCLASS_M_TBL(origin)) != 0)
	 st_foreach(mtbl, method_entry_i, (st_data_t)list);
	klass = RCLASS_SUPER(klass);
 }
 if (RTEST(recur)) {
	while (klass && (FL_TEST(klass, FL_SINGLETON) || RB_TYPE_P(klass, T_ICLASS))) {
	 if (klass != origin && (mtbl = RCLASS_M_TBL(klass)) != 0)
		st_foreach(mtbl, method_entry_i, (st_data_t)list);
	 klass = RCLASS_SUPER(klass);
	}
 }
 ary = rb_ary_new();
 st_foreach(list, ins_methods_i, ary);
 st_free_table(list);

 return ary;
}

/*!
 * \}
 */
/*!
 * \defgroup defmethod Defining methods
 * There are some APIs to define a method from C.
 * These API takes a C function as a method body.
 *
 * \par Method body functions
 * Method body functions must return a VALUE and
 * can be one of the following form:
 * <dl>
 * <dt>Fixed number of parameters</dt>
 * <dd>
 * This form is a normal C function, excepting it takes
 * a receiver object as the first argument.
 *
 * \code
 * static VALUE my_method(VALUE self, VALUE x, VALUE y);
 * \endcode
 * </dd>
 * <dt>argc and argv style</dt>
 * <dd>
 * This form takes three parameters: \a argc, \a argv and \a self.
 * \a self is the receiver. \a argc is the number of arguments.
 * \a argv is a pointer to an array of the arguments.
 *
 * \code
 * static VALUE my_method(int argc, VALUE *argv, VALUE self);
 * \endcode
 * </dd>
 * <dt>Ruby array style</dt>
 * <dd>
 * This form takes two parameters: self and args.
 * \a self is the receiver. \a args is an Array object which
 * contains the arguments.
 *
 * \code
 * static VALUE my_method(VALUE self, VALUE args);
 * \endcode
 * </dd>
 *
 * \par Number of parameters
 * Method defining APIs takes the number of parameters which the
 * method will takes. This number is called \a argc.
 * \a argc can be:
 * <dl>
 * <dt>zero or positive number</dt>
 * <dd>This means the method body function takes a fixed number of parameters</dd>
 * <dt>-1</dt>
 * <dd>This means the method body function is "argc and argv" style.</dd>
 * <dt>-2</dt>
 * <dd>This means the method body function is "self and args" style.</dd>
 * </dl>
 * \{
 */

void
rb_define_method_id(VALUE klass, ID mid, VALUE (*func)(ANYARGS), int argc)
{
 rb_add_method_cfunc(klass, mid, func, argc, NOEX_PUBLIC);
}

void
rb_define_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
{
 rb_add_method_cfunc(klass, rb_intern(name), func, argc, NOEX_PUBLIC);
}

void
rb_define_protected_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
{
 rb_add_method_cfunc(klass, rb_intern(name), func, argc, NOEX_PROTECTED);
}

void
rb_define_private_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
{
 rb_add_method_cfunc(klass, rb_intern(name), func, argc, NOEX_PRIVATE);
}

void
rb_undef_method(VALUE klass, const char *name)
{
 rb_add_method(klass, rb_intern(name), VM_METHOD_TYPE_UNDEF, 0, NOEX_UNDEF);
}

/*!
 * \}
 */
/*!
 * \addtogroup class
 * \{
 */

#define SPECIAL_SINGLETON(x,c) do {\
 if (obj == (x)) {\
	return (c);\
 }\
} while (0)

static inline VALUE
special_singleton_class_of(VALUE obj)
{
 SPECIAL_SINGLETON(Qnil, rb_cNilClass);
 SPECIAL_SINGLETON(Qfalse, rb_cFalseClass);
 SPECIAL_SINGLETON(Qtrue, rb_cTrueClass);
 return Qnil;
}

VALUE
rb_special_singleton_class(VALUE obj)
{
 return special_singleton_class_of(obj);
}

/*!
 * \internal
 * Returns the singleton class of \a obj. Creates it if necessary.
 *
 * \note DO NOT expose the returned singleton class to
 * outside of class.c.
 * Use \ref rb_singleton_class instead for
 * consistency of the metaclass hierarchy.
 */
static VALUE
singleton_class_of(VALUE obj)
{
 VALUE klass;

 if (FIXNUM_P(obj) || FLONUM_P(obj) || SYMBOL_P(obj)) {
	rb_raise(rb_eTypeError, "can't define singleton");
 }
 if (SPECIAL_CONST_P(obj)) {
	klass = special_singleton_class_of(obj);
	if (NIL_P(klass))
	 rb_bug("unknown immediate %p", (void *)obj);
	return klass;
 }
 else {
	enum ruby_value_type type = BUILTIN_TYPE(obj);
	if (type == T_FLOAT || type == T_BIGNUM) {
	 rb_raise(rb_eTypeError, "can't define singleton");
	}
 }

 if (FL_TEST(RBASIC(obj)->klass, FL_SINGLETON) &&
	rb_ivar_get(RBASIC(obj)->klass, id_attached) == obj) {
	klass = RBASIC(obj)->klass;
 }
 else {
	klass = rb_make_metaclass(obj, RBASIC(obj)->klass);
 }

 if (OBJ_TAINTED(obj)) {
	OBJ_TAINT(klass);
 }
 else {
	FL_UNSET(klass, FL_TAINT);
 }
 if (OBJ_FROZEN(obj)) OBJ_FREEZE(klass);

 return klass;
}

/*!
 * Returns the singleton class of \a obj, or nil if obj is not a
 * singleton object.
 *
 * \param obj an arbitrary object.
 * \return the singleton class or nil.
 */
VALUE
rb_singleton_class_get(VALUE obj)
{
 VALUE klass;

 if (SPECIAL_CONST_P(obj)) {
	return rb_special_singleton_class(obj);
 }
 klass = RBASIC(obj)->klass;
 if (!FL_TEST(klass, FL_SINGLETON)) return Qnil;
 if (rb_ivar_get(klass, id_attached) != obj) return Qnil;
 return klass;
}

/*!
 * Returns the singleton class of \a obj. Creates it if necessary.
 *
 * \param obj an arbitrary object.
 * \throw TypeError if \a obj is a Fixnum or a Symbol.
 * \return the singleton class.
 *
 * \post \a obj has its own singleton class.
 * \post if \a obj is a class,
 * the returned singleton class also has its own
 * singleton class in order to keep consistency of the
 * inheritance structure of metaclasses.
 * \note a new singleton class will be created
 * if \a obj does not have it.
 * \note the singleton classes for nil, true and false are:
 * NilClass, TrueClass and FalseClass.
 */
VALUE
rb_singleton_class(VALUE obj)
{
 VALUE klass = singleton_class_of(obj);

 /* ensures an exposed class belongs to its own eigenclass */
 if (RB_TYPE_P(obj, T_CLASS)) (void)ENSURE_EIGENCLASS(klass);

 return klass;
}

/*!
 * \}
 */

/*!
 * \addtogroup defmethod
 * \{
 */

/*!
 * Defines a singleton method for \a obj.
 * \param obj an arbitrary object
 * \param name name of the singleton method
 * \param func the method body
 * \param argc the number of parameters, or -1 or -2. see \ref defmethod.
 */
void
rb_define_singleton_method(VALUE obj, const char *name, VALUE (*func)(ANYARGS), int argc)
{
 rb_define_method(singleton_class_of(obj), name, func, argc);
}



/*!
 * Defines a module function for \a module.
 * \param module an module or a class.
 * \param name name of the function
 * \param func the method body
 * \param argc the number of parameters, or -1 or -2. see \ref defmethod.
 */
void
rb_define_module_function(VALUE module, const char *name, VALUE (*func)(ANYARGS), int argc)
{
 rb_define_private_method(module, name, func, argc);
 rb_define_singleton_method(module, name, func, argc);
}


/*!
 * Defines a global function
 * \param name name of the function
 * \param func the method body
 * \param argc the number of parameters, or -1 or -2. see \ref defmethod.
 */
void
rb_define_global_function(const char *name, VALUE (*func)(ANYARGS), int argc)
{
 rb_define_module_function(rb_mKernel, name, func, argc);
}


/*!
 * Defines an alias of a method.
 * \param klass the class which the original method belongs to
 * \param name1 a new name for the method
 * \param name2 the original name of the method
 */
void
rb_define_alias(VALUE klass, const char *name1, const char *name2)
{
 rb_alias(klass, rb_intern(name1), rb_intern(name2));
}

/*!
 * Defines (a) public accessor method(s) for an attribute.
 * \param klass the class which the attribute will belongs to
 * \param name name of the attribute
 * \param read a getter method for the attribute will be defined if \a read is non-zero.
 * \param write a setter method for the attribute will be defined if \a write is non-zero.
 */
void
rb_define_attr(VALUE klass, const char *name, int read, int write)
{
 rb_attr(klass, rb_intern(name), read, write, FALSE);
}

int
rb_obj_basic_to_s_p(VALUE obj)
{
 const rb_method_entry_t *me = rb_method_entry(CLASS_OF(obj), rb_intern("to_s"), 0);
 if (me && me->def && me->def->type == VM_METHOD_TYPE_CFUNC &&
	me->def->body.cfunc.func == rb_any_to_s)
	return 1;
 return 0;
}

#include <stdarg.h>

int
rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
{
 int i;
 const char *p = fmt;
 VALUE *var;
 va_list vargs;
 int f_var = 0, f_hash = 0, f_block = 0;
 int n_lead = 0, n_opt = 0, n_trail = 0, n_mand;
 int argi = 0;
 VALUE hash = Qnil;

 if (ISDIGIT(*p)) {
	n_lead = *p - '0';
	p++;
	if (ISDIGIT(*p)) {
	 n_opt = *p - '0';
	 p++;
	 if (ISDIGIT(*p)) {
		n_trail = *p - '0';
		p++;
		goto block_arg;
	 }
	}
 }
 if (*p == '*') {
	f_var = 1;
	p++;
	if (ISDIGIT(*p)) {
	 n_trail = *p - '0';
	 p++;
	}
 }
 block_arg:
 if (*p == ':') {
	f_hash = 1;
	p++;
 }
 if (*p == '&') {
	f_block = 1;
	p++;
 }
 if (*p != '\0') {
	rb_fatal("bad scan arg format: %s", fmt);
 }
 n_mand = n_lead + n_trail;

 if (argc < n_mand)
	goto argc_error;

 va_start(vargs, fmt);

 /* capture an option hash - phase 1: pop */
 if (f_hash && n_mand < argc) {
	VALUE last = argv[argc - 1];

	if (NIL_P(last)) {
	 /* nil is taken as an empty option hash only if it is not
	 ambiguous; i.e. '*' is not specified and arguments are
	 given more than sufficient */
	 if (!f_var && n_mand + n_opt < argc)
		argc--;
	}
	else {
	 hash = rb_check_hash_type(last);
	 if (!NIL_P(hash)) {
		VALUE opts = rb_extract_keywords(&hash);
		if (!hash) argc--;
		hash = opts ? opts : Qnil;
	 }
	}
 }
 /* capture leading mandatory arguments */
 for (i = n_lead; i-- > 0; ) {
	var = va_arg(vargs, VALUE *);
	if (var) *var = argv[argi];
	argi++;
 }
 /* capture optional arguments */
 for (i = n_opt; i-- > 0; ) {
	var = va_arg(vargs, VALUE *);
	if (argi < argc - n_trail) {
	 if (var) *var = argv[argi];
	 argi++;
	}
	else {
	 if (var) *var = Qnil;
	}
 }
 /* capture variable length arguments */
 if (f_var) {
	int n_var = argc - argi - n_trail;

	var = va_arg(vargs, VALUE *);
	if (0 < n_var) {
	 if (var) *var = rb_ary_new4(n_var, &argv[argi]);
	 argi += n_var;
	}
	else {
	 if (var) *var = rb_ary_new();
	}
 }
 /* capture trailing mandatory arguments */
 for (i = n_trail; i-- > 0; ) {
	var = va_arg(vargs, VALUE *);
	if (var) *var = argv[argi];
	argi++;
 }
 /* capture an option hash - phase 2: assignment */
 if (f_hash) {
	var = va_arg(vargs, VALUE *);
	if (var) *var = hash;
 }
 /* capture iterator block */
 if (f_block) {
	var = va_arg(vargs, VALUE *);
	if (rb_block_given_p()) {
	 *var = rb_block_proc();
	}
	else {
	 *var = Qnil;
	}
 }
 va_end(vargs);

 if (argi < argc) {
 argc_error:
	rb_error_arity(argc, n_mand, f_var ? UNLIMITED_ARGUMENTS : n_mand + n_opt);
 }

 return argc;
}

NORETURN(static void keyword_error(const char *error, VALUE keys));
static void
keyword_error(const char *error, VALUE keys)
{
 const char *msg = "";
 if (RARRAY_LEN(keys) == 1) {
	keys = RARRAY_AREF(keys, 0);
 }
 else {
	keys = rb_ary_join(keys, rb_usascii_str_new2(", "));
	msg = "s";
 }
 rb_raise(rb_eArgError, "%s keyword%s: %"PRIsVALUE, error, msg, keys);
}

NORETURN(static void unknown_keyword_error(VALUE hash, const ID *table, int keywords));
static void
unknown_keyword_error(VALUE hash, const ID *table, int keywords)
{
 VALUE keys;
 int i;
 for (i = 0; i < keywords; i++) {
	rb_hash_delete(hash, ID2SYM(table[i]));
 }
 keys = rb_funcall(hash, rb_intern("keys"), 0, 0);
 if (!RB_TYPE_P(keys, T_ARRAY)) rb_raise(rb_eArgError, "unknown keyword");
 keyword_error("unknown", keys);
}

static int
separate_symbol(st_data_t key, st_data_t value, st_data_t arg)
{
 VALUE *kwdhash = (VALUE *)arg;

 if (!SYMBOL_P(key)) kwdhash++;
 if (!*kwdhash) *kwdhash = rb_hash_new();
 rb_hash_aset(*kwdhash, (VALUE)key, (VALUE)value);
 return ST_CONTINUE;
}

VALUE
rb_extract_keywords(VALUE *orighash)
{
 VALUE parthash[2] = {0, 0};
 VALUE hash = *orighash;

 if (RHASH_EMPTY_P(hash)) {
	*orighash = 0;
	return hash;
 }
 st_foreach(rb_hash_tbl_raw(hash), separate_symbol, (st_data_t)&parthash);
 *orighash = parthash[1];
 return parthash[0];
}

int
rb_get_kwargs(VALUE keyword_hash, const ID *table, int required, int optional, VALUE *values)
{
 int i = 0, j;
 int rest = 0;
 VALUE missing = Qnil;
 st_data_t key;

#define extract_kwarg(keyword, val) \
 (key = (st_data_t)(keyword), values ? \
 st_delete(rb_hash_tbl_raw(keyword_hash), &key, (val)) : \
 st_lookup(rb_hash_tbl_raw(keyword_hash), key, (val)))

 if (NIL_P(keyword_hash)) keyword_hash = 0;

 if (optional < 0) {
	rest = 1;
	optional = -1-optional;
 }
 if (values) {
	for (j = 0; j < required + optional; j++) {
	 values[j] = Qundef;
	}
 }
 if (required) {
	for (; i < required; i++) {
	 VALUE keyword = ID2SYM(table[i]);
	 if (keyword_hash) {
		st_data_t val;
		if (extract_kwarg(keyword, &val)) {
		 if (values) values[i] = (VALUE)val;
		 continue;
		}
	 }
	 if (NIL_P(missing)) missing = rb_ary_tmp_new(1);
	 rb_ary_push(missing, keyword);
	}
	if (!NIL_P(missing)) {
	 keyword_error("missing", missing);
	}
 }
 j = i;
 if (optional && keyword_hash) {
	for (i = 0; i < optional; i++) {
	 st_data_t val;
	 if (extract_kwarg(ID2SYM(table[required+i]), &val)) {
		if (values) values[required+i] = (VALUE)val;
		j++;
	 }
	}
 }
 if (!rest && keyword_hash) {
	if (RHASH_SIZE(keyword_hash) > (unsigned int)j) {
	 unknown_keyword_error(keyword_hash, table, required+optional);
	}
 }
 return j;
#undef extract_kwarg
}

/*!
 * \}
 */