object.c

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

  object.c -

  $Author$
  created at: Thu Jul 15 12:01:24 JST 1993

  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 <ctype.h>
#include <errno.h>
#include <float.h>
#include <math.h>
#include <stdio.h>

#include "constant.h"
#include "id.h"
#include "internal.h"
#include "internal/array.h"
#include "internal/class.h"
#include "internal/error.h"
#include "internal/eval.h"
#include "internal/inits.h"
#include "internal/numeric.h"
#include "internal/object.h"
#include "internal/struct.h"
#include "internal/string.h"
#include "internal/st.h"
#include "internal/symbol.h"
#include "internal/variable.h"
#include "variable.h"
#include "probes.h"
#include "ruby/encoding.h"
#include "ruby/st.h"
#include "ruby/util.h"
#include "ruby/assert.h"
#include "builtin.h"
#include "shape.h"
#include "yjit.h"

/* Flags of RObject
 *
 * 1:    ROBJECT_EMBED
 *           The object has its instance variables embedded (the array of
 *           instance variables directly follow the object, rather than being
 *           on a separately allocated buffer).
 * if !SHAPE_IN_BASIC_FLAGS
 * 4-19: SHAPE_FLAG_MASK
 *           Shape ID for the object.
 * endif
 */

/*!
 * \addtogroup object
 * \{
 */

VALUE rb_cBasicObject;
VALUE rb_mKernel;
VALUE rb_cObject;
VALUE rb_cModule;
VALUE rb_cClass;
VALUE rb_cRefinement;

VALUE rb_cNilClass;
VALUE rb_cTrueClass;
VALUE rb_cFalseClass;

static VALUE rb_cNilClass_to_s;
static VALUE rb_cTrueClass_to_s;
static VALUE rb_cFalseClass_to_s;

/*! \cond INTERNAL_MACRO */

#define id_eq               idEq
#define id_eql              idEqlP
#define id_match            idEqTilde
#define id_inspect          idInspect
#define id_init_copy        idInitialize_copy
#define id_init_clone       idInitialize_clone
#define id_init_dup         idInitialize_dup
#define id_const_missing    idConst_missing
#define id_to_f             idTo_f

#define CLASS_OR_MODULE_P(obj) \
    (!SPECIAL_CONST_P(obj) && \
     (BUILTIN_TYPE(obj) == T_CLASS || BUILTIN_TYPE(obj) == T_MODULE))

/*! \endcond */

size_t
rb_obj_embedded_size(uint32_t numiv)
{
    return offsetof(struct RObject, as.ary) + (sizeof(VALUE) * numiv);
}

VALUE
rb_obj_hide(VALUE obj)
{
    if (!SPECIAL_CONST_P(obj)) {
        RBASIC_CLEAR_CLASS(obj);
    }
    return obj;
}

VALUE
rb_obj_reveal(VALUE obj, VALUE klass)
{
    if (!SPECIAL_CONST_P(obj)) {
        RBASIC_SET_CLASS(obj, klass);
    }
    return obj;
}

VALUE
rb_class_allocate_instance(VALUE klass)
{
    uint32_t index_tbl_num_entries = RCLASS_EXT(klass)->max_iv_count;

    size_t size = rb_obj_embedded_size(index_tbl_num_entries);
    if (!rb_gc_size_allocatable_p(size)) {
        size = sizeof(struct RObject);
    }

    NEWOBJ_OF(o, struct RObject, klass,
              T_OBJECT | ROBJECT_EMBED | (RGENGC_WB_PROTECTED_OBJECT ? FL_WB_PROTECTED : 0), size, 0);
    VALUE obj = (VALUE)o;

    RUBY_ASSERT(rb_shape_get_shape(obj)->type == SHAPE_ROOT);

    // Set the shape to the specific T_OBJECT shape.
    ROBJECT_SET_SHAPE_ID(obj, (shape_id_t)(rb_gc_heap_id_for_size(size) + FIRST_T_OBJECT_SHAPE_ID));

#if RUBY_DEBUG
    RUBY_ASSERT(!rb_shape_obj_too_complex(obj));
    VALUE *ptr = ROBJECT_IVPTR(obj);
    for (size_t i = 0; i < ROBJECT_IV_CAPACITY(obj); i++) {
        ptr[i] = Qundef;
    }
#endif

    return obj;
}

VALUE
rb_obj_setup(VALUE obj, VALUE klass, VALUE type)
{
    VALUE ignored_flags = RUBY_FL_PROMOTED | RUBY_FL_SEEN_OBJ_ID;
    RBASIC(obj)->flags = (type & ~ignored_flags) | (RBASIC(obj)->flags & ignored_flags);
    RBASIC_SET_CLASS(obj, klass);
    return obj;
}

/*
 * call-seq:
 *   true === other -> true or false
 *   false === other -> true or false
 *   nil === other -> true or false
 *
 * Returns +true+ or +false+.
 *
 * Like Object#==, if +object+ is an instance of Object
 * (and not an instance of one of its many subclasses).
 *
 * This method is commonly overridden by those subclasses,
 * to provide meaningful semantics in +case+ statements.
 */
#define case_equal rb_equal
    /* The default implementation of #=== is
     * to call #== with the rb_equal() optimization. */

VALUE
rb_equal(VALUE obj1, VALUE obj2)
{
    VALUE result;

    if (obj1 == obj2) return Qtrue;
    result = rb_equal_opt(obj1, obj2);
    if (UNDEF_P(result)) {
        result = rb_funcall(obj1, id_eq, 1, obj2);
    }
    return RBOOL(RTEST(result));
}

int
rb_eql(VALUE obj1, VALUE obj2)
{
    VALUE result;

    if (obj1 == obj2) return TRUE;
    result = rb_eql_opt(obj1, obj2);
    if (UNDEF_P(result)) {
        result = rb_funcall(obj1, id_eql, 1, obj2);
    }
    return RTEST(result);
}

/**
 *  call-seq:
 *     obj == other        -> true or false
 *     obj.equal?(other)   -> true or false
 *     obj.eql?(other)     -> true or false
 *
 *  Equality --- At the Object level, #== returns <code>true</code>
 *  only if +obj+ and +other+ are the same object.  Typically, this
 *  method is overridden in descendant classes to provide
 *  class-specific meaning.
 *
 *  Unlike #==, the #equal? method should never be overridden by
 *  subclasses as it is used to determine object identity (that is,
 *  <code>a.equal?(b)</code> if and only if <code>a</code> is the same
 *  object as <code>b</code>):
 *
 *    obj = "a"
 *    other = obj.dup
 *
 *    obj == other      #=> true
 *    obj.equal? other  #=> false
 *    obj.equal? obj    #=> true
 *
 *  The #eql? method returns <code>true</code> if +obj+ and +other+
 *  refer to the same hash key.  This is used by Hash to test members
 *  for equality.  For any pair of objects where #eql? returns +true+,
 *  the #hash value of both objects must be equal. So any subclass
 *  that overrides #eql? should also override #hash appropriately.
 *
 *  For objects of class Object, #eql?  is synonymous
 *  with #==.  Subclasses normally continue this tradition by aliasing
 *  #eql? to their overridden #== method, but there are exceptions.
 *  Numeric types, for example, perform type conversion across #==,
 *  but not across #eql?, so:
 *
 *     1 == 1.0     #=> true
 *     1.eql? 1.0   #=> false
 *--
 * \private
 *++
 */
VALUE
rb_obj_equal(VALUE obj1, VALUE obj2)
{
    return RBOOL(obj1 == obj2);
}

VALUE rb_obj_hash(VALUE obj);

/**
 *  call-seq:
 *     !obj    -> true or false
 *
 *  Boolean negate.
 *--
 * \private
 *++
 */

VALUE
rb_obj_not(VALUE obj)
{
    return RBOOL(!RTEST(obj));
}

/**
 *  call-seq:
 *     obj != other        -> true or false
 *
 *  Returns true if two objects are not-equal, otherwise false.
 *--
 * \private
 *++
 */

VALUE
rb_obj_not_equal(VALUE obj1, VALUE obj2)
{
    VALUE result = rb_funcall(obj1, id_eq, 1, obj2);
    return rb_obj_not(result);
}

VALUE
rb_class_real(VALUE cl)
{
    while (cl &&
        (RCLASS_SINGLETON_P(cl) || BUILTIN_TYPE(cl) == T_ICLASS)) {
        cl = RCLASS_SUPER(cl);
    }
    return cl;
}

VALUE
rb_obj_class(VALUE obj)
{
    return rb_class_real(CLASS_OF(obj));
}

/*
 *  call-seq:
 *     obj.singleton_class    -> class
 *
 *  Returns the singleton class of <i>obj</i>.  This method creates
 *  a new singleton class if <i>obj</i> does not have one.
 *
 *  If <i>obj</i> is <code>nil</code>, <code>true</code>, or
 *  <code>false</code>, it returns NilClass, TrueClass, or FalseClass,
 *  respectively.
 *  If <i>obj</i> is an Integer, a Float or a Symbol, it raises a TypeError.
 *
 *     Object.new.singleton_class  #=> #<Class:#<Object:0xb7ce1e24>>
 *     String.singleton_class      #=> #<Class:String>
 *     nil.singleton_class         #=> NilClass
 */

static VALUE
rb_obj_singleton_class(VALUE obj)
{
    return rb_singleton_class(obj);
}

/*! \private */
void
rb_obj_copy_ivar(VALUE dest, VALUE obj)
{
    RUBY_ASSERT(!RB_TYPE_P(obj, T_CLASS) && !RB_TYPE_P(obj, T_MODULE));

    RUBY_ASSERT(BUILTIN_TYPE(dest) == BUILTIN_TYPE(obj));
    rb_shape_t * src_shape = rb_shape_get_shape(obj);

    if (rb_shape_obj_too_complex(obj)) {
        // obj is TOO_COMPLEX so we can copy its iv_hash
        st_table *table = st_copy(ROBJECT_IV_HASH(obj));
        rb_obj_convert_to_too_complex(dest, table);

        return;
    }

    uint32_t src_num_ivs = RBASIC_IV_COUNT(obj);
    rb_shape_t * shape_to_set_on_dest = src_shape;
    VALUE * src_buf;
    VALUE * dest_buf;

    if (!src_num_ivs) {
        return;
    }

    // The copy should be mutable, so we don't want the frozen shape
    if (rb_shape_frozen_shape_p(src_shape)) {
        shape_to_set_on_dest = rb_shape_get_parent(src_shape);
    }

    src_buf = ROBJECT_IVPTR(obj);
    dest_buf = ROBJECT_IVPTR(dest);

    rb_shape_t * initial_shape = rb_shape_get_shape(dest);

    if (initial_shape->heap_index != src_shape->heap_index) {
        RUBY_ASSERT(initial_shape->type == SHAPE_T_OBJECT);

        shape_to_set_on_dest = rb_shape_rebuild_shape(initial_shape, src_shape);
        if (UNLIKELY(rb_shape_id(shape_to_set_on_dest) == OBJ_TOO_COMPLEX_SHAPE_ID)) {
            st_table * table = rb_st_init_numtable_with_size(src_num_ivs);
            rb_obj_copy_ivs_to_hash_table(obj, table);
            rb_obj_convert_to_too_complex(dest, table);

            return;
        }
    }

    RUBY_ASSERT(src_num_ivs <= shape_to_set_on_dest->capacity || rb_shape_id(shape_to_set_on_dest) == OBJ_TOO_COMPLEX_SHAPE_ID);
    if (initial_shape->capacity < shape_to_set_on_dest->capacity) {
        rb_ensure_iv_list_size(dest, initial_shape->capacity, shape_to_set_on_dest->capacity);
        dest_buf = ROBJECT_IVPTR(dest);
    }

    MEMCPY(dest_buf, src_buf, VALUE, src_num_ivs);

    // Fire write barriers
    for (uint32_t i = 0; i < src_num_ivs; i++) {
        RB_OBJ_WRITTEN(dest, Qundef, dest_buf[i]);
    }

    rb_shape_set_shape(dest, shape_to_set_on_dest);
}

static void
init_copy(VALUE dest, VALUE obj)
{
    if (OBJ_FROZEN(dest)) {
        rb_raise(rb_eTypeError, "[bug] frozen object (%s) allocated", rb_obj_classname(dest));
    }
    RBASIC(dest)->flags &= ~(T_MASK|FL_EXIVAR);
    // Copies the shape id from obj to dest
    RBASIC(dest)->flags |= RBASIC(obj)->flags & (T_MASK|FL_EXIVAR);
    rb_gc_copy_attributes(dest, obj);
    rb_copy_generic_ivar(dest, obj);
    if (RB_TYPE_P(obj, T_OBJECT)) {
        rb_obj_copy_ivar(dest, obj);
    }
}

static VALUE immutable_obj_clone(VALUE obj, VALUE kwfreeze);
static VALUE mutable_obj_clone(VALUE obj, VALUE kwfreeze);
PUREFUNC(static inline int special_object_p(VALUE obj)); /*!< \private */
static inline int
special_object_p(VALUE obj)
{
    if (SPECIAL_CONST_P(obj)) return TRUE;
    switch (BUILTIN_TYPE(obj)) {
      case T_BIGNUM:
      case T_FLOAT:
      case T_SYMBOL:
      case T_RATIONAL:
      case T_COMPLEX:
        /* not a comprehensive list */
        return TRUE;
      default:
        return FALSE;
    }
}

static VALUE
obj_freeze_opt(VALUE freeze)
{
    switch (freeze) {
      case Qfalse:
      case Qtrue:
      case Qnil:
        break;
      default:
        rb_raise(rb_eArgError, "unexpected value for freeze: %"PRIsVALUE, rb_obj_class(freeze));
    }

    return freeze;
}

static VALUE
rb_obj_clone2(rb_execution_context_t *ec, VALUE obj, VALUE freeze)
{
    VALUE kwfreeze = obj_freeze_opt(freeze);
    if (!special_object_p(obj))
        return mutable_obj_clone(obj, kwfreeze);
    return immutable_obj_clone(obj, kwfreeze);
}

/*! \private */
VALUE
rb_immutable_obj_clone(int argc, VALUE *argv, VALUE obj)
{
    VALUE kwfreeze = rb_get_freeze_opt(argc, argv);
    return immutable_obj_clone(obj, kwfreeze);
}

VALUE
rb_get_freeze_opt(int argc, VALUE *argv)
{
    static ID keyword_ids[1];
    VALUE opt;
    VALUE kwfreeze = Qnil;

    if (!keyword_ids[0]) {
        CONST_ID(keyword_ids[0], "freeze");
    }
    rb_scan_args(argc, argv, "0:", &opt);
    if (!NIL_P(opt)) {
        rb_get_kwargs(opt, keyword_ids, 0, 1, &kwfreeze);
        if (!UNDEF_P(kwfreeze))
            kwfreeze = obj_freeze_opt(kwfreeze);
    }
    return kwfreeze;
}

static VALUE
immutable_obj_clone(VALUE obj, VALUE kwfreeze)
{
    if (kwfreeze == Qfalse)
        rb_raise(rb_eArgError, "can't unfreeze %"PRIsVALUE,
                 rb_obj_class(obj));
    return obj;
}

VALUE
rb_obj_clone_setup(VALUE obj, VALUE clone, VALUE kwfreeze)
{
    VALUE argv[2];

    VALUE singleton = rb_singleton_class_clone_and_attach(obj, clone);
    RBASIC_SET_CLASS(clone, singleton);
    if (RCLASS_SINGLETON_P(singleton)) {
        rb_singleton_class_attached(singleton, clone);
    }

    init_copy(clone, obj);

    switch (kwfreeze) {
      case Qnil:
        rb_funcall(clone, id_init_clone, 1, obj);
        RBASIC(clone)->flags |= RBASIC(obj)->flags & FL_FREEZE;

        if (RB_TYPE_P(obj, T_STRING)) {
            FL_SET_RAW(clone, FL_TEST_RAW(obj, STR_CHILLED));
        }

        if (RB_OBJ_FROZEN(obj)) {
            rb_shape_t * next_shape = rb_shape_transition_shape_frozen(clone);
            if (!rb_shape_obj_too_complex(clone) && next_shape->type == SHAPE_OBJ_TOO_COMPLEX) {
                rb_evict_ivars_to_hash(clone);
            }
            else {
                rb_shape_set_shape(clone, next_shape);
            }
        }
        break;
      case Qtrue: {
        static VALUE freeze_true_hash;
        if (!freeze_true_hash) {
            freeze_true_hash = rb_hash_new();
            rb_vm_register_global_object(freeze_true_hash);
            rb_hash_aset(freeze_true_hash, ID2SYM(idFreeze), Qtrue);
            rb_obj_freeze(freeze_true_hash);
        }

        argv[0] = obj;
        argv[1] = freeze_true_hash;
        rb_funcallv_kw(clone, id_init_clone, 2, argv, RB_PASS_KEYWORDS);
        RBASIC(clone)->flags |= FL_FREEZE;
        rb_shape_t * next_shape = rb_shape_transition_shape_frozen(clone);
        // If we're out of shapes, but we want to freeze, then we need to
        // evacuate this clone to a hash
        if (!rb_shape_obj_too_complex(clone) && next_shape->type == SHAPE_OBJ_TOO_COMPLEX) {
            rb_evict_ivars_to_hash(clone);
        }
        else {
            rb_shape_set_shape(clone, next_shape);
        }
        break;
      }
      case Qfalse: {
        static VALUE freeze_false_hash;
        if (!freeze_false_hash) {
            freeze_false_hash = rb_hash_new();
            rb_vm_register_global_object(freeze_false_hash);
            rb_hash_aset(freeze_false_hash, ID2SYM(idFreeze), Qfalse);
            rb_obj_freeze(freeze_false_hash);
        }

        argv[0] = obj;
        argv[1] = freeze_false_hash;
        rb_funcallv_kw(clone, id_init_clone, 2, argv, RB_PASS_KEYWORDS);
        break;
      }
      default:
        rb_bug("invalid kwfreeze passed to mutable_obj_clone");
    }

    return clone;
}

static VALUE
mutable_obj_clone(VALUE obj, VALUE kwfreeze)
{
    VALUE clone = rb_obj_alloc(rb_obj_class(obj));
    return rb_obj_clone_setup(obj, clone, kwfreeze);
}

VALUE
rb_obj_clone(VALUE obj)
{
    if (special_object_p(obj)) return obj;
    return mutable_obj_clone(obj, Qnil);
}

VALUE
rb_obj_dup_setup(VALUE obj, VALUE dup)
{
    init_copy(dup, obj);
    rb_funcall(dup, id_init_dup, 1, obj);

    return dup;
}

/*
 *  call-seq:
 *     obj.dup -> an_object
 *
 *  Produces a shallow copy of <i>obj</i>---the instance variables of
 *  <i>obj</i> are copied, but not the objects they reference.
 *
 *  This method may have class-specific behavior.  If so, that
 *  behavior will be documented under the #+initialize_copy+ method of
 *  the class.
 *
 *  === on dup vs clone
 *
 *  In general, #clone and #dup may have different semantics in
 *  descendant classes. While #clone is used to duplicate an object,
 *  including its internal state, #dup typically uses the class of the
 *  descendant object to create the new instance.
 *
 *  When using #dup, any modules that the object has been extended with will not
 *  be copied.
 *
 *	class Klass
 *	  attr_accessor :str
 *	end
 *
 *	module Foo
 *	  def foo; 'foo'; end
 *	end
 *
 *	s1 = Klass.new #=> #<Klass:0x401b3a38>
 *	s1.extend(Foo) #=> #<Klass:0x401b3a38>
 *	s1.foo #=> "foo"
 *
 *	s2 = s1.clone #=> #<Klass:0x401be280>
 *	s2.foo #=> "foo"
 *
 *	s3 = s1.dup #=> #<Klass:0x401c1084>
 *	s3.foo #=> NoMethodError: undefined method `foo' for #<Klass:0x401c1084>
 */
VALUE
rb_obj_dup(VALUE obj)
{
    VALUE dup;

    if (special_object_p(obj)) {
        return obj;
    }
    dup = rb_obj_alloc(rb_obj_class(obj));
    return rb_obj_dup_setup(obj, dup);
}

/*
 *  call-seq:
 *     obj.itself    -> obj
 *
 *  Returns the receiver.
 *
 *     string = "my string"
 *     string.itself.object_id == string.object_id   #=> true
 *
 */

static VALUE
rb_obj_itself(VALUE obj)
{
    return obj;
}

VALUE
rb_obj_size(VALUE self, VALUE args, VALUE obj)
{
    return LONG2FIX(1);
}

/**
 * :nodoc:
 *--
 * Default implementation of `#initialize_copy`
 * @param[in,out] obj the receiver being initialized
 * @param[in] orig    the object to be copied from.
 *++
 */
VALUE
rb_obj_init_copy(VALUE obj, VALUE orig)
{
    if (obj == orig) return obj;
    rb_check_frozen(obj);
    if (TYPE(obj) != TYPE(orig) || rb_obj_class(obj) != rb_obj_class(orig)) {
        rb_raise(rb_eTypeError, "initialize_copy should take same class object");
    }
    return obj;
}

/**
 * :nodoc:
 *--
 * Default implementation of `#initialize_dup`
 *
 * @param[in,out] obj the receiver being initialized
 * @param[in] orig    the object to be dup from.
 *++
 **/
VALUE
rb_obj_init_dup_clone(VALUE obj, VALUE orig)
{
    rb_funcall(obj, id_init_copy, 1, orig);
    return obj;
}

/**
 * :nodoc:
 *--
 * Default implementation of `#initialize_clone`
 *
 * @param[in] The number of arguments
 * @param[in] The array of arguments
 * @param[in] obj the receiver being initialized
 *++
 **/
static VALUE
rb_obj_init_clone(int argc, VALUE *argv, VALUE obj)
{
    VALUE orig, opts;
    if (rb_scan_args(argc, argv, "1:", &orig, &opts) < argc) {
        /* Ignore a freeze keyword */
        rb_get_freeze_opt(1, &opts);
    }
    rb_funcall(obj, id_init_copy, 1, orig);
    return obj;
}

/*
 *  call-seq:
 *     obj.to_s    -> string
 *
 *  Returns a string representing <i>obj</i>. The default #to_s prints
 *  the object's class and an encoding of the object id. As a special
 *  case, the top-level object that is the initial execution context
 *  of Ruby programs returns ``main''.
 *
 */
VALUE
rb_any_to_s(VALUE obj)
{
    VALUE str;
    VALUE cname = rb_class_name(CLASS_OF(obj));

    str = rb_sprintf("#<%"PRIsVALUE":%p>", cname, (void*)obj);

    return str;
}

VALUE
rb_inspect(VALUE obj)
{
    VALUE str = rb_obj_as_string(rb_funcallv(obj, id_inspect, 0, 0));

    rb_encoding *enc = rb_default_internal_encoding();
    if (enc == NULL) enc = rb_default_external_encoding();
    if (!rb_enc_asciicompat(enc)) {
        if (!rb_enc_str_asciionly_p(str))
            return rb_str_escape(str);
        return str;
    }
    if (rb_enc_get(str) != enc && !rb_enc_str_asciionly_p(str))
        return rb_str_escape(str);
    return str;
}

static int
inspect_i(ID id, VALUE value, st_data_t a)
{
    VALUE str = (VALUE)a;

    /* need not to show internal data */
    if (CLASS_OF(value) == 0) return ST_CONTINUE;
    if (!rb_is_instance_id(id)) return ST_CONTINUE;
    if (RSTRING_PTR(str)[0] == '-') { /* first element */
        RSTRING_PTR(str)[0] = '#';
        rb_str_cat2(str, " ");
    }
    else {
        rb_str_cat2(str, ", ");
    }
    rb_str_catf(str, "%"PRIsVALUE"=", rb_id2str(id));
    rb_str_buf_append(str, rb_inspect(value));

    return ST_CONTINUE;
}

static VALUE
inspect_obj(VALUE obj, VALUE str, int recur)
{
    if (recur) {
        rb_str_cat2(str, " ...");
    }
    else {
        rb_ivar_foreach(obj, inspect_i, str);
    }
    rb_str_cat2(str, ">");
    RSTRING_PTR(str)[0] = '#';

    return str;
}

/*
 *  call-seq:
 *     obj.inspect   -> string
 *
 * Returns a string containing a human-readable representation of <i>obj</i>.
 * The default #inspect shows the object's class name, an encoding of
 * its memory address, and a list of the instance variables and their
 * values (by calling #inspect on each of them).  User defined classes
 * should override this method to provide a better representation of
 * <i>obj</i>.  When overriding this method, it should return a string
 * whose encoding is compatible with the default external encoding.
 *
 *     [ 1, 2, 3..4, 'five' ].inspect   #=> "[1, 2, 3..4, \"five\"]"
 *     Time.new.inspect                 #=> "2008-03-08 19:43:39 +0900"
 *
 *     class Foo
 *     end
 *     Foo.new.inspect                  #=> "#<Foo:0x0300c868>"
 *
 *     class Bar
 *       def initialize
 *         @bar = 1
 *       end
 *     end
 *     Bar.new.inspect                  #=> "#<Bar:0x0300c868 @bar=1>"
 */

static VALUE
rb_obj_inspect(VALUE obj)
{
    if (rb_ivar_count(obj) > 0) {
        VALUE str;
        VALUE c = rb_class_name(CLASS_OF(obj));

        str = rb_sprintf("-<%"PRIsVALUE":%p", c, (void*)obj);
        return rb_exec_recursive(inspect_obj, obj, str);
    }
    else {
        return rb_any_to_s(obj);
    }
}

static VALUE
class_or_module_required(VALUE c)
{
    switch (OBJ_BUILTIN_TYPE(c)) {
      case T_MODULE:
      case T_CLASS:
      case T_ICLASS:
        break;

      default:
        rb_raise(rb_eTypeError, "class or module required");
    }
    return c;
}

static VALUE class_search_ancestor(VALUE cl, VALUE c);

/*
 *  call-seq:
 *     obj.instance_of?(class)    -> true or false
 *
 *  Returns <code>true</code> if <i>obj</i> is an instance of the given
 *  class. See also Object#kind_of?.
 *
 *     class A;     end
 *     class B < A; end
 *     class C < B; end
 *
 *     b = B.new
 *     b.instance_of? A   #=> false
 *     b.instance_of? B   #=> true
 *     b.instance_of? C   #=> false
 */

VALUE
rb_obj_is_instance_of(VALUE obj, VALUE c)
{
    c = class_or_module_required(c);
    return RBOOL(rb_obj_class(obj) == c);
}

// Returns whether c is a proper (c != cl) superclass of cl
// Both c and cl must be T_CLASS
static VALUE
class_search_class_ancestor(VALUE cl, VALUE c)
{
    RUBY_ASSERT(RB_TYPE_P(c, T_CLASS));
    RUBY_ASSERT(RB_TYPE_P(cl, T_CLASS));

    size_t c_depth = RCLASS_SUPERCLASS_DEPTH(c);
    size_t cl_depth = RCLASS_SUPERCLASS_DEPTH(cl);
    VALUE *classes = RCLASS_SUPERCLASSES(cl);

    // If c's inheritance chain is longer, it cannot be an ancestor
    // We are checking for a proper superclass so don't check if they are equal
    if (cl_depth <= c_depth)
        return Qfalse;

    // Otherwise check that c is in cl's inheritance chain
    return RBOOL(classes[c_depth] == c);
}

/*
 *  call-seq:
 *     obj.is_a?(class)       -> true or false
 *     obj.kind_of?(class)    -> true or false
 *
 *  Returns <code>true</code> if <i>class</i> is the class of
 *  <i>obj</i>, or if <i>class</i> is one of the superclasses of
 *  <i>obj</i> or modules included in <i>obj</i>.
 *
 *     module M;    end
 *     class A
 *       include M
 *     end
 *     class B < A; end
 *     class C < B; end
 *
 *     b = B.new
 *     b.is_a? A          #=> true
 *     b.is_a? B          #=> true
 *     b.is_a? C          #=> false
 *     b.is_a? M          #=> true
 *
 *     b.kind_of? A       #=> true
 *     b.kind_of? B       #=> true
 *     b.kind_of? C       #=> false
 *     b.kind_of? M       #=> true
 */

VALUE
rb_obj_is_kind_of(VALUE obj, VALUE c)
{
    VALUE cl = CLASS_OF(obj);

    RUBY_ASSERT(RB_TYPE_P(cl, T_CLASS));

    // Fastest path: If the object's class is an exact match we know `c` is a
    // class without checking type and can return immediately.
    if (cl == c) return Qtrue;

    // Note: YJIT needs this function to never allocate and never raise when
    // `c` is a class or a module.

    if (LIKELY(RB_TYPE_P(c, T_CLASS))) {
        // Fast path: Both are T_CLASS
        return class_search_class_ancestor(cl, c);
    }
    else if (RB_TYPE_P(c, T_ICLASS)) {
        // First check if we inherit the includer
        // If we do we can return true immediately
        VALUE includer = RCLASS_INCLUDER(c);
        if (cl == includer) return Qtrue;

        // Usually includer is a T_CLASS here, except when including into an
        // already included Module.
        // If it is a class, attempt the fast class-to-class check and return
        // true if there is a match.
        if (RB_TYPE_P(includer, T_CLASS) && class_search_class_ancestor(cl, includer))
            return Qtrue;

        // We don't include the ICLASS directly, so must check if we inherit
        // the module via another include
        return RBOOL(class_search_ancestor(cl, RCLASS_ORIGIN(c)));
    }
    else if (RB_TYPE_P(c, T_MODULE)) {
        // Slow path: check each ancestor in the linked list and its method table
        return RBOOL(class_search_ancestor(cl, RCLASS_ORIGIN(c)));
    }
    else {
        rb_raise(rb_eTypeError, "class or module required");
        UNREACHABLE_RETURN(Qfalse);
    }
}


static VALUE
class_search_ancestor(VALUE cl, VALUE c)
{
    while (cl) {
        if (cl == c || RCLASS_M_TBL(cl) == RCLASS_M_TBL(c))
            return cl;
        cl = RCLASS_SUPER(cl);
    }
    return 0;
}

/*! \private */
VALUE
rb_class_search_ancestor(VALUE cl, VALUE c)
{
    cl = class_or_module_required(cl);
    c = class_or_module_required(c);
    return class_search_ancestor(cl, RCLASS_ORIGIN(c));
}


/*
 * Document-method: inherited
 *
 * call-seq:
 *    inherited(subclass)
 *
 * Callback invoked whenever a subclass of the current class is created.
 *
 * Example:
 *
 *    class Foo
 *      def self.inherited(subclass)
 *        puts "New subclass: #{subclass}"
 *      end
 *    end
 *
 *    class Bar < Foo
 *    end
 *
 *    class Baz < Bar
 *    end
 *
 * <em>produces:</em>
 *
 *    New subclass: Bar
 *    New subclass: Baz
 */
#define rb_obj_class_inherited rb_obj_dummy1

/* Document-method: method_added
 *
 * call-seq:
 *   method_added(method_name)
 *
 * Invoked as a callback whenever an instance method is added to the
 * receiver.
 *
 *   module Chatty
 *     def self.method_added(method_name)
 *       puts "Adding #{method_name.inspect}"
 *     end
 *     def self.some_class_method() end
 *     def some_instance_method() end
 *   end
 *
 * <em>produces:</em>
 *
 *   Adding :some_instance_method
 *
 */
#define rb_obj_mod_method_added rb_obj_dummy1

/* Document-method: method_removed
 *
 * call-seq:
 *   method_removed(method_name)
 *
 * Invoked as a callback whenever an instance method is removed from the
 * receiver.
 *
 *   module Chatty
 *     def self.method_removed(method_name)
 *       puts "Removing #{method_name.inspect}"
 *     end
 *     def self.some_class_method() end
 *     def some_instance_method() end
 *     class << self
 *       remove_method :some_class_method
 *     end
 *     remove_method :some_instance_method
 *   end
 *
 * <em>produces:</em>
 *
 *   Removing :some_instance_method
 *
 */
#define rb_obj_mod_method_removed rb_obj_dummy1

/* Document-method: method_undefined
 *
 * call-seq:
 *   method_undefined(method_name)
 *
 * Invoked as a callback whenever an instance method is undefined from the
 * receiver.
 *
 *   module Chatty
 *     def self.method_undefined(method_name)
 *       puts "Undefining #{method_name.inspect}"
 *     end
 *     def self.some_class_method() end
 *     def some_instance_method() end
 *     class << self
 *       undef_method :some_class_method
 *     end
 *     undef_method :some_instance_method
 *   end
 *
 * <em>produces:</em>
 *
 *   Undefining :some_instance_method
 *
 */
#define rb_obj_mod_method_undefined rb_obj_dummy1

/*
 * Document-method: singleton_method_added
 *
 *  call-seq:
 *     singleton_method_added(symbol)
 *
 *  Invoked as a callback whenever a singleton method is added to the
 *  receiver.
 *
 *     module Chatty
 *       def Chatty.singleton_method_added(id)
 *         puts "Adding #{id.id2name}"
 *       end
 *       def self.one()     end
 *       def two()          end
 *       def Chatty.three() end
 *     end
 *
 *  <em>produces:</em>
 *
 *     Adding singleton_method_added
 *     Adding one
 *     Adding three
 *
 */
#define rb_obj_singleton_method_added rb_obj_dummy1

/*
 * Document-method: singleton_method_removed
 *
 *  call-seq:
 *     singleton_method_removed(symbol)
 *
 *  Invoked as a callback whenever a singleton method is removed from
 *  the receiver.
 *
 *     module Chatty
 *       def Chatty.singleton_method_removed(id)
 *         puts "Removing #{id.id2name}"
 *       end
 *       def self.one()     end
 *       def two()          end
 *       def Chatty.three() end
 *       class << self
 *         remove_method :three
 *         remove_method :one
 *       end
 *     end
 *
 *  <em>produces:</em>
 *
 *     Removing three
 *     Removing one
 */
#define rb_obj_singleton_method_removed rb_obj_dummy1

/*
 * Document-method: singleton_method_undefined
 *
 *  call-seq:
 *     singleton_method_undefined(symbol)
 *
 *  Invoked as a callback whenever a singleton method is undefined in
 *  the receiver.
 *
 *     module Chatty
 *       def Chatty.singleton_method_undefined(id)
 *         puts "Undefining #{id.id2name}"
 *       end
 *       def Chatty.one()   end
 *       class << self
 *          undef_method(:one)
 *       end
 *     end
 *
 *  <em>produces:</em>
 *
 *     Undefining one
 */
#define rb_obj_singleton_method_undefined rb_obj_dummy1

/* Document-method: const_added
 *
 * call-seq:
 *   const_added(const_name)
 *
 * Invoked as a callback whenever a constant is assigned on the receiver
 *
 *   module Chatty
 *     def self.const_added(const_name)
 *       super
 *       puts "Added #{const_name.inspect}"
 *     end
 *     FOO = 1
 *   end
 *
 * <em>produces:</em>
 *
 *   Added :FOO
 *
 */
#define rb_obj_mod_const_added rb_obj_dummy1

/*
 * Document-method: extended
 *
 * call-seq:
 *    extended(othermod)
 *
 * The equivalent of <tt>included</tt>, but for extended modules.
 *
 *        module A
 *          def self.extended(mod)
 *            puts "#{self} extended in #{mod}"
 *          end
 *        end
 *        module Enumerable
 *          extend A
 *        end
 *         # => prints "A extended in Enumerable"
 */
#define rb_obj_mod_extended rb_obj_dummy1

/*
 * Document-method: included
 *
 * call-seq:
 *    included(othermod)
 *
 * Callback invoked whenever the receiver is included in another
 * module or class. This should be used in preference to
 * <tt>Module.append_features</tt> if your code wants to perform some
 * action when a module is included in another.
 *
 *        module A
 *          def A.included(mod)
 *            puts "#{self} included in #{mod}"
 *          end
 *        end
 *        module Enumerable
 *          include A
 *        end
 *         # => prints "A included in Enumerable"
 */
#define rb_obj_mod_included rb_obj_dummy1

/*
 * Document-method: prepended
 *
 * call-seq:
 *    prepended(othermod)
 *
 * The equivalent of <tt>included</tt>, but for prepended modules.
 *
 *        module A
 *          def self.prepended(mod)
 *            puts "#{self} prepended to #{mod}"
 *          end
 *        end
 *        module Enumerable
 *          prepend A
 *        end
 *         # => prints "A prepended to Enumerable"
 */
#define rb_obj_mod_prepended rb_obj_dummy1

/*
 * Document-method: initialize
 *
 * call-seq:
 *    BasicObject.new
 *
 * Returns a new BasicObject.
 */
#define rb_obj_initialize rb_obj_dummy0

/*
 * Not documented
 */

static VALUE
rb_obj_dummy(void)
{
    return Qnil;
}

static VALUE
rb_obj_dummy0(VALUE _)
{
    return rb_obj_dummy();
}

static VALUE
rb_obj_dummy1(VALUE _x, VALUE _y)
{
    return rb_obj_dummy();
}

/*
 *  call-seq:
 *     obj.freeze    -> obj
 *
 *  Prevents further modifications to <i>obj</i>. A
 *  FrozenError will be raised if modification is attempted.
 *  There is no way to unfreeze a frozen object. See also
 *  Object#frozen?.
 *
 *  This method returns self.
 *
 *     a = [ "a", "b", "c" ]
 *     a.freeze
 *     a << "z"
 *
 *  <em>produces:</em>
 *
 *     prog.rb:3:in `<<': can't modify frozen Array (FrozenError)
 *     	from prog.rb:3
 *
 *  Objects of the following classes are always frozen: Integer,
 *  Float, Symbol.
 */

VALUE
rb_obj_freeze(VALUE obj)
{
    if (!OBJ_FROZEN(obj)) {
        OBJ_FREEZE(obj);
        if (SPECIAL_CONST_P(obj)) {
            rb_bug("special consts should be frozen.");
        }
    }
    return obj;
}

VALUE
rb_obj_frozen_p(VALUE obj)
{
    return RBOOL(OBJ_FROZEN(obj));
}


/*
 * Document-class: NilClass
 *
 * The class of the singleton object +nil+.
 *
 * Several of its methods act as operators:
 *
 * - #&
 * - #|
 * - #===
 * - #=~
 * - #^
 *
 * Others act as converters, carrying the concept of _nullity_
 * to other classes:
 *
 * - #rationalize
 * - #to_a
 * - #to_c
 * - #to_h
 * - #to_r
 * - #to_s
 *
 * While +nil+ doesn't have an explicitly defined #to_hash method,
 * it can be used in <code>**</code> unpacking, not adding any
 * keyword arguments.
 *
 * Another method provides inspection:
 *
 * - #inspect
 *
 * Finally, there is this query method:
 *
 * - #nil?
 *
 */

/*
 * call-seq:
 *   to_s -> ''
 *
 * Returns an empty String:
 *
 *   nil.to_s # => ""
 *
 */

VALUE
rb_nil_to_s(VALUE obj)
{
    return rb_cNilClass_to_s;
}

/*
 * Document-method: to_a
 *
 * call-seq:
 *   to_a -> []
 *
 * Returns an empty Array.
 *
 *   nil.to_a # => []
 *
 */

static VALUE
nil_to_a(VALUE obj)
{
    return rb_ary_new2(0);
}

/*
 * Document-method: to_h
 *
 * call-seq:
 *   to_h -> {}
 *
 * Returns an empty Hash.
 *
 *   nil.to_h   #=> {}
 *
 */

static VALUE
nil_to_h(VALUE obj)
{
    return rb_hash_new();
}

/*
 * call-seq:
 *   inspect -> 'nil'
 *
 * Returns string <tt>'nil'</tt>:
 *
 *   nil.inspect # => "nil"
 *
 */

static VALUE
nil_inspect(VALUE obj)
{
    return rb_usascii_str_new2("nil");
}

/*
 * call-seq:
 *   nil =~ object -> nil
 *
 * Returns +nil+.
 *
 * This method makes it useful to write:
 *
 *   while gets =~ /re/
 *     # ...
 *   end
 *
 */

static VALUE
nil_match(VALUE obj1, VALUE obj2)
{
    return Qnil;
}

/*
 *  Document-class: TrueClass
 *
 * The class of the singleton object +true+.
 *
 * Several of its methods act as operators:
 *
 * - #&
 * - #|
 * - #===
 * - #^
 *
 * One other method:
 *
 * - #to_s and its alias #inspect.
 *
 */


/*
 * call-seq:
 *   true.to_s -> 'true'
 *
 * Returns string <tt>'true'</tt>:
 *
 *   true.to_s # => "true"
 *
 * TrueClass#inspect is an alias for TrueClass#to_s.
 *
 */

VALUE
rb_true_to_s(VALUE obj)
{
    return rb_cTrueClass_to_s;
}


/*
 *  call-seq:
 *    true & object -> true or false
 *
 *  Returns +false+ if +object+ is +false+ or +nil+, +true+ otherwise:
 *
 *  true & Object.new # => true
 *  true & false      # => false
 *  true & nil        # => false
 *
 */

static VALUE
true_and(VALUE obj, VALUE obj2)
{
    return RBOOL(RTEST(obj2));
}

/*
 *  call-seq:
 *    true | object -> true
 *
 *  Returns +true+:
 *
 *    true | Object.new # => true
 *    true | false      # => true
 *    true | nil        # => true
 *
 *  Argument +object+ is evaluated.
 *  This is different from +true+ with the short-circuit operator,
 *  whose operand is evaluated only if necessary:
 *
 *    true | raise # => Raises RuntimeError.
 *    true || raise # => true
 *
 */

static VALUE
true_or(VALUE obj, VALUE obj2)
{
    return Qtrue;
}


/*
 *  call-seq:
 *    true ^ object -> !object
 *
 *  Returns +true+ if +object+ is +false+ or +nil+, +false+ otherwise:
 *
 *    true ^ Object.new # => false
 *    true ^ false      # => true
 *    true ^ nil        # => true
 *
 */

static VALUE
true_xor(VALUE obj, VALUE obj2)
{
    return rb_obj_not(obj2);
}


/*
 *  Document-class: FalseClass
 *
 *  The global value <code>false</code> is the only instance of class
 *  FalseClass and represents a logically false value in
 *  boolean expressions. The class provides operators allowing
 *  <code>false</code> to participate correctly in logical expressions.
 *
 */

/*
 * call-seq:
 *   false.to_s   ->  "false"
 *
 * The string representation of <code>false</code> is "false".
 */

VALUE
rb_false_to_s(VALUE obj)
{
    return rb_cFalseClass_to_s;
}

/*
 * call-seq:
 *   false & object -> false
 *   nil & object   -> false
 *
 * Returns +false+:
 *
 *   false & true       # => false
 *   false & Object.new # => false
 *
 * Argument +object+ is evaluated:
 *
 *   false & raise # Raises RuntimeError.
 *
 */
static VALUE
false_and(VALUE obj, VALUE obj2)
{
    return Qfalse;
}


/*
 * call-seq:
 *   false | object -> true or false
 *   nil   | object -> true or false
 *
 * Returns +false+ if +object+ is +nil+ or +false+, +true+ otherwise:
 *
 *   nil | nil        # => false
 *   nil | false      # => false
 *   nil | Object.new # => true
 *
 */

#define false_or true_and

/*
 * call-seq:
 *   false ^ object -> true or false
 *   nil ^ object   -> true or false
 *
 * Returns +false+ if +object+ is +nil+ or +false+, +true+ otherwise:
 *
 *   nil ^ nil        # => false
 *   nil ^ false      # => false
 *   nil ^ Object.new # => true
 *
 */

#define false_xor true_and

/*
 * call-seq:
 *   nil.nil?  -> true
 *
 * Returns +true+.
 * For all other objects, method <tt>nil?</tt> returns +false+.
 */

static VALUE
rb_true(VALUE obj)
{
    return Qtrue;
}

/*
 * call-seq:
 *   obj.nil?               -> true or false
 *
 * Only the object <i>nil</i> responds <code>true</code> to <code>nil?</code>.
 *
 *    Object.new.nil?   #=> false
 *    nil.nil?          #=> true
 */


VALUE
rb_false(VALUE obj)
{
    return Qfalse;
}

/*
 *  call-seq:
 *     obj !~ other  -> true or false
 *
 *  Returns true if two objects do not match (using the <i>=~</i>
 *  method), otherwise false.
 */

static VALUE
rb_obj_not_match(VALUE obj1, VALUE obj2)
{
    VALUE result = rb_funcall(obj1, id_match, 1, obj2);
    return rb_obj_not(result);
}


/*
 *  call-seq:
 *     obj <=> other -> 0 or nil
 *
 *  Returns 0 if +obj+ and +other+ are the same object
 *  or <code>obj == other</code>, otherwise nil.
 *
 *  The #<=> is used by various methods to compare objects, for example
 *  Enumerable#sort, Enumerable#max etc.
 *
 *  Your implementation of #<=> should return one of the following values: -1, 0,
 *  1 or nil. -1 means self is smaller than other. 0 means self is equal to other.
 *  1 means self is bigger than other. Nil means the two values could not be
 *  compared.
 *
 *  When you define #<=>, you can include Comparable to gain the
 *  methods #<=, #<, #==, #>=, #> and #between?.
 */
static VALUE
rb_obj_cmp(VALUE obj1, VALUE obj2)
{
    if (rb_equal(obj1, obj2))
        return INT2FIX(0);
    return Qnil;
}

/***********************************************************************
 *
 * Document-class: Module
 *
 *  A Module is a collection of methods and constants. The
 *  methods in a module may be instance methods or module methods.
 *  Instance methods appear as methods in a class when the module is
 *  included, module methods do not. Conversely, module methods may be
 *  called without creating an encapsulating object, while instance
 *  methods may not. (See Module#module_function.)
 *
 *  In the descriptions that follow, the parameter <i>sym</i> refers
 *  to a symbol, which is either a quoted string or a
 *  Symbol (such as <code>:name</code>).
 *
 *     module Mod
 *       include Math
 *       CONST = 1
 *       def meth
 *         #  ...
 *       end
 *     end
 *     Mod.class              #=> Module
 *     Mod.constants          #=> [:CONST, :PI, :E]
 *     Mod.instance_methods   #=> [:meth]
 *
 */

/*
 * call-seq:
 *   mod.to_s   -> string
 *
 * Returns a string representing this module or class. For basic
 * classes and modules, this is the name. For singletons, we
 * show information on the thing we're attached to as well.
 */

VALUE
rb_mod_to_s(VALUE klass)
{
    ID id_defined_at;
    VALUE refined_class, defined_at;

    if (RCLASS_SINGLETON_P(klass)) {
        VALUE s = rb_usascii_str_new2("#<Class:");
        VALUE v = RCLASS_ATTACHED_OBJECT(klass);

        if (CLASS_OR_MODULE_P(v)) {
            rb_str_append(s, rb_inspect(v));
        }
        else {
            rb_str_append(s, rb_any_to_s(v));
        }
        rb_str_cat2(s, ">");

        return s;
    }
    refined_class = rb_refinement_module_get_refined_class(klass);
    if (!NIL_P(refined_class)) {
        VALUE s = rb_usascii_str_new2("#<refinement:");

        rb_str_concat(s, rb_inspect(refined_class));
        rb_str_cat2(s, "@");
        CONST_ID(id_defined_at, "__defined_at__");
        defined_at = rb_attr_get(klass, id_defined_at);
        rb_str_concat(s, rb_inspect(defined_at));
        rb_str_cat2(s, ">");
        return s;
    }
    return rb_class_name(klass);
}

/*
 *  call-seq:
 *     mod.freeze       -> mod
 *
 *  Prevents further modifications to <i>mod</i>.
 *
 *  This method returns self.
 */

static VALUE
rb_mod_freeze(VALUE mod)
{
    rb_class_name(mod);
    return rb_obj_freeze(mod);
}

/*
 *  call-seq:
 *     mod === obj    -> true or false
 *
 *  Case Equality---Returns <code>true</code> if <i>obj</i> is an
 *  instance of <i>mod</i> or an instance of one of <i>mod</i>'s descendants.
 *  Of limited use for modules, but can be used in <code>case</code> statements
 *  to classify objects by class.
 */

static VALUE
rb_mod_eqq(VALUE mod, VALUE arg)
{
    return rb_obj_is_kind_of(arg, mod);
}

/*
 * call-seq:
 *   mod <= other   ->  true, false, or nil
 *
 * Returns true if <i>mod</i> is a subclass of <i>other</i> or
 * is the same as <i>other</i>. Returns
 * <code>nil</code> if there's no relationship between the two.
 * (Think of the relationship in terms of the class definition:
 * "class A < B" implies "A < B".)
 */

VALUE
rb_class_inherited_p(VALUE mod, VALUE arg)
{
    if (mod == arg) return Qtrue;

    if (RB_TYPE_P(arg, T_CLASS) && RB_TYPE_P(mod, T_CLASS)) {
        // comparison between classes
        size_t mod_depth = RCLASS_SUPERCLASS_DEPTH(mod);
        size_t arg_depth = RCLASS_SUPERCLASS_DEPTH(arg);
        if (arg_depth < mod_depth) {
            // check if mod < arg
            return RCLASS_SUPERCLASSES(mod)[arg_depth] == arg ?
                Qtrue :
                Qnil;
        }
        else if (arg_depth > mod_depth) {
            // check if mod > arg
            return RCLASS_SUPERCLASSES(arg)[mod_depth] == mod ?
                Qfalse :
                Qnil;
        }
        else {
            // Depths match, and we know they aren't equal: no relation
            return Qnil;
        }
    }
    else {
        if (!CLASS_OR_MODULE_P(arg) && !RB_TYPE_P(arg, T_ICLASS)) {
            rb_raise(rb_eTypeError, "compared with non class/module");
        }
        if (class_search_ancestor(mod, RCLASS_ORIGIN(arg))) {
            return Qtrue;
        }
        /* not mod < arg; check if mod > arg */
        if (class_search_ancestor(arg, mod)) {
            return Qfalse;
        }
        return Qnil;
    }
}

/*
 * call-seq:
 *   mod < other   ->  true, false, or nil
 *
 * Returns true if <i>mod</i> is a subclass of <i>other</i>. Returns
 * <code>false</code> if <i>mod</i> is the same as <i>other</i>
 * or <i>mod</i> is an ancestor of <i>other</i>.
 * Returns <code>nil</code> if there's no relationship between the two.
 * (Think of the relationship in terms of the class definition:
 * "class A < B" implies "A < B".)
 *
 */

static VALUE
rb_mod_lt(VALUE mod, VALUE arg)
{
    if (mod == arg) return Qfalse;
    return rb_class_inherited_p(mod, arg);
}


/*
 * call-seq:
 *   mod >= other   ->  true, false, or nil
 *
 * Returns true if <i>mod</i> is an ancestor of <i>other</i>, or the
 * two modules are the same. Returns
 * <code>nil</code> if there's no relationship between the two.
 * (Think of the relationship in terms of the class definition:
 * "class A < B" implies "B > A".)
 *
 */

static VALUE
rb_mod_ge(VALUE mod, VALUE arg)
{
    if (!CLASS_OR_MODULE_P(arg)) {
        rb_raise(rb_eTypeError, "compared with non class/module");
    }

    return rb_class_inherited_p(arg, mod);
}

/*
 * call-seq:
 *   mod > other   ->  true, false, or nil
 *
 * Returns true if <i>mod</i> is an ancestor of <i>other</i>. Returns
 * <code>false</code> if <i>mod</i> is the same as <i>other</i>
 * or <i>mod</i> is a descendant of <i>other</i>.
 * Returns <code>nil</code> if there's no relationship between the two.
 * (Think of the relationship in terms of the class definition:
 * "class A < B" implies "B > A".)
 *
 */

static VALUE
rb_mod_gt(VALUE mod, VALUE arg)
{
    if (mod == arg) return Qfalse;
    return rb_mod_ge(mod, arg);
}

/*
 *  call-seq:
 *     module <=> other_module   -> -1, 0, +1, or nil
 *
 *  Comparison---Returns -1, 0, +1 or nil depending on whether +module+
 *  includes +other_module+, they are the same, or if +module+ is included by
 *  +other_module+.
 *
 *  Returns +nil+ if +module+ has no relationship with +other_module+, if
 *  +other_module+ is not a module, or if the two values are incomparable.
 */

static VALUE
rb_mod_cmp(VALUE mod, VALUE arg)
{
    VALUE cmp;

    if (mod == arg) return INT2FIX(0);
    if (!CLASS_OR_MODULE_P(arg)) {
        return Qnil;
    }

    cmp = rb_class_inherited_p(mod, arg);
    if (NIL_P(cmp)) return Qnil;
    if (cmp) {
        return INT2FIX(-1);
    }
    return INT2FIX(1);
}

static VALUE rb_mod_initialize_exec(VALUE module);

/*
 *  call-seq:
 *    Module.new                  -> mod
 *    Module.new {|mod| block }   -> mod
 *
 *  Creates a new anonymous module. If a block is given, it is passed
 *  the module object, and the block is evaluated in the context of this
 *  module like #module_eval.
 *
 *     fred = Module.new do
 *       def meth1
 *         "hello"
 *       end
 *       def meth2
 *         "bye"
 *       end
 *     end
 *     a = "my string"
 *     a.extend(fred)   #=> "my string"
 *     a.meth1          #=> "hello"
 *     a.meth2          #=> "bye"
 *
 *  Assign the module to a constant (name starting uppercase) if you
 *  want to treat it like a regular module.
 */

static VALUE
rb_mod_initialize(VALUE module)
{
    return rb_mod_initialize_exec(module);
}

static VALUE
rb_mod_initialize_exec(VALUE module)
{
    if (rb_block_given_p()) {
        rb_mod_module_exec(1, &module, module);
    }
    return Qnil;
}

/* :nodoc: */
static VALUE
rb_mod_initialize_clone(int argc, VALUE* argv, VALUE clone)
{
    VALUE ret, orig, opts;
    rb_scan_args(argc, argv, "1:", &orig, &opts);
    ret = rb_obj_init_clone(argc, argv, clone);
    if (OBJ_FROZEN(orig))
        rb_class_name(clone);
    return ret;
}

/*
 *  call-seq:
 *     Class.new(super_class=Object)               -> a_class
 *     Class.new(super_class=Object) { |mod| ... } -> a_class
 *
 *  Creates a new anonymous (unnamed) class with the given superclass
 *  (or Object if no parameter is given). You can give a
 *  class a name by assigning the class object to a constant.
 *
 *  If a block is given, it is passed the class object, and the block
 *  is evaluated in the context of this class like
 *  #class_eval.
 *
 *     fred = Class.new do
 *       def meth1
 *         "hello"
 *       end
 *       def meth2
 *         "bye"
 *       end
 *     end
 *
 *     a = fred.new     #=> #<#<Class:0x100381890>:0x100376b98>
 *     a.meth1          #=> "hello"
 *     a.meth2          #=> "bye"
 *
 *  Assign the class to a constant (name starting uppercase) if you
 *  want to treat it like a regular class.
 */

static VALUE
rb_class_initialize(int argc, VALUE *argv, VALUE klass)
{
    VALUE super;

    if (RCLASS_SUPER(klass) != 0 || klass == rb_cBasicObject) {
        rb_raise(rb_eTypeError, "already initialized class");
    }
    if (rb_check_arity(argc, 0, 1) == 0) {
        super = rb_cObject;
    }
    else {
        super = argv[0];
        rb_check_inheritable(super);
        if (super != rb_cBasicObject && !RCLASS_SUPER(super)) {
            rb_raise(rb_eTypeError, "can't inherit uninitialized class");
        }
    }
    RCLASS_SET_SUPER(klass, super);
    rb_make_metaclass(klass, RBASIC(super)->klass);
    rb_class_inherited(super, klass);
    rb_mod_initialize_exec(klass);

    return klass;
}

/*! \private */
void
rb_undefined_alloc(VALUE klass)
{
    rb_raise(rb_eTypeError, "allocator undefined for %"PRIsVALUE,
             klass);
}

static rb_alloc_func_t class_get_alloc_func(VALUE klass);
static VALUE class_call_alloc_func(rb_alloc_func_t allocator, VALUE klass);

/*
 *  call-seq:
 *     class.allocate()   ->   obj
 *
 *  Allocates space for a new object of <i>class</i>'s class and does not
 *  call initialize on the new instance. The returned object must be an
 *  instance of <i>class</i>.
 *
 *      klass = Class.new do
 *        def initialize(*args)
 *          @initialized = true
 *        end
 *
 *        def initialized?
 *          @initialized || false
 *        end
 *      end
 *
 *      klass.allocate.initialized? #=> false
 *
 */

static VALUE
rb_class_alloc_m(VALUE klass)
{
    rb_alloc_func_t allocator = class_get_alloc_func(klass);
    if (!rb_obj_respond_to(klass, rb_intern("allocate"), 1)) {
        rb_raise(rb_eTypeError, "calling %"PRIsVALUE".allocate is prohibited",
                 klass);
    }
    return class_call_alloc_func(allocator, klass);
}

static VALUE
rb_class_alloc(VALUE klass)
{
    rb_alloc_func_t allocator = class_get_alloc_func(klass);
    return class_call_alloc_func(allocator, klass);
}

static rb_alloc_func_t
class_get_alloc_func(VALUE klass)
{
    rb_alloc_func_t allocator;

    if (RCLASS_SUPER(klass) == 0 && klass != rb_cBasicObject) {
        rb_raise(rb_eTypeError, "can't instantiate uninitialized class");
    }
    if (RCLASS_SINGLETON_P(klass)) {
        rb_raise(rb_eTypeError, "can't create instance of singleton class");
    }
    allocator = rb_get_alloc_func(klass);
    if (!allocator) {
        rb_undefined_alloc(klass);
    }
    return allocator;
}

static VALUE
class_call_alloc_func(rb_alloc_func_t allocator, VALUE klass)
{
    VALUE obj;

    RUBY_DTRACE_CREATE_HOOK(OBJECT, rb_class2name(klass));

    obj = (*allocator)(klass);

    if (rb_obj_class(obj) != rb_class_real(klass)) {
        rb_raise(rb_eTypeError, "wrong instance allocation");
    }
    return obj;
}

VALUE
rb_obj_alloc(VALUE klass)
{
    Check_Type(klass, T_CLASS);
    return rb_class_alloc(klass);
}

/*
 *  call-seq:
 *     class.new(args, ...)    ->  obj
 *
 *  Calls #allocate to create a new object of <i>class</i>'s class,
 *  then invokes that object's #initialize method, passing it
 *  <i>args</i>.  This is the method that ends up getting called
 *  whenever an object is constructed using <code>.new</code>.
 *
 */

VALUE
rb_class_new_instance_pass_kw(int argc, const VALUE *argv, VALUE klass)
{
    VALUE obj;

    obj = rb_class_alloc(klass);
    rb_obj_call_init_kw(obj, argc, argv, RB_PASS_CALLED_KEYWORDS);

    return obj;
}

VALUE
rb_class_new_instance_kw(int argc, const VALUE *argv, VALUE klass, int kw_splat)
{
    VALUE obj;
    Check_Type(klass, T_CLASS);

    obj = rb_class_alloc(klass);
    rb_obj_call_init_kw(obj, argc, argv, kw_splat);

    return obj;
}

VALUE
rb_class_new_instance(int argc, const VALUE *argv, VALUE klass)
{
    return rb_class_new_instance_kw(argc, argv, klass, RB_NO_KEYWORDS);
}

/**
 *  call-seq:
 *     class.superclass -> a_super_class or nil
 *
 *  Returns the superclass of <i>class</i>, or <code>nil</code>.
 *
 *     File.superclass          #=> IO
 *     IO.superclass            #=> Object
 *     Object.superclass        #=> BasicObject
 *     class Foo; end
 *     class Bar < Foo; end
 *     Bar.superclass           #=> Foo
 *
 *  Returns nil when the given class does not have a parent class:
 *
 *     BasicObject.superclass   #=> nil
 *
 *--
 * Returns the superclass of `klass`. Equivalent to `Class#superclass` in Ruby.
 *
 * It skips modules.
 * @param[in] klass a Class object
 * @return the superclass, or `Qnil` if `klass` does not have a parent class.
 * @sa rb_class_get_superclass
 *++
 */

VALUE
rb_class_superclass(VALUE klass)
{
    RUBY_ASSERT(RB_TYPE_P(klass, T_CLASS));

    VALUE super = RCLASS_SUPER(klass);

    if (!super) {
        if (klass == rb_cBasicObject) return Qnil;
        rb_raise(rb_eTypeError, "uninitialized class");
    }

    if (!RCLASS_SUPERCLASS_DEPTH(klass)) {
        return Qnil;
    }
    else {
        super = RCLASS_SUPERCLASSES(klass)[RCLASS_SUPERCLASS_DEPTH(klass) - 1];
        RUBY_ASSERT(RB_TYPE_P(klass, T_CLASS));
        return super;
    }
}

VALUE
rb_class_get_superclass(VALUE klass)
{
    return RCLASS(klass)->super;
}

static const char bad_instance_name[] = "'%1$s' is not allowed as an instance variable name";
static const char bad_class_name[] = "'%1$s' is not allowed as a class variable name";
static const char bad_const_name[] = "wrong constant name %1$s";
static const char bad_attr_name[] = "invalid attribute name '%1$s'";
#define wrong_constant_name bad_const_name

/*! \private */
#define id_for_var(obj, name, type) id_for_setter(obj, name, type, bad_##type##_name)
/*! \private */
#define id_for_setter(obj, name, type, message) \
    check_setter_id(obj, &(name), rb_is_##type##_id, rb_is_##type##_name, message, strlen(message))
static ID
check_setter_id(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;
}

static int
rb_is_attr_name(VALUE name)
{
    return rb_is_local_name(name) || rb_is_const_name(name);
}

static int
rb_is_attr_id(ID id)
{
    return rb_is_local_id(id) || rb_is_const_id(id);
}

static ID
id_for_attr(VALUE obj, VALUE name)
{
    ID id = id_for_var(obj, name, attr);
    if (!id) id = rb_intern_str(name);
    return id;
}

/*
 *  call-seq:
 *     attr_reader(symbol, ...)  -> array
 *     attr(symbol, ...)         -> array
 *     attr_reader(string, ...)  -> array
 *     attr(string, ...)         -> array
 *
 *  Creates instance variables and corresponding methods that return the
 *  value of each instance variable. Equivalent to calling
 *  ``<code>attr</code><i>:name</i>'' on each name in turn.
 *  String arguments are converted to symbols.
 *  Returns an array of defined method names as symbols.
 */

static VALUE
rb_mod_attr_reader(int argc, VALUE *argv, VALUE klass)
{
    int i;
    VALUE names = rb_ary_new2(argc);

    for (i=0; i<argc; i++) {
        ID id = id_for_attr(klass, argv[i]);
        rb_attr(klass, id, TRUE, FALSE, TRUE);
        rb_ary_push(names, ID2SYM(id));
    }
    return names;
}

/**
 *  call-seq:
 *    attr(name, ...) -> array
 *    attr(name, true) -> array
 *    attr(name, false) -> array
 *
 *  The first form is equivalent to #attr_reader.
 *  The second form is equivalent to <code>attr_accessor(name)</code> but deprecated.
 *  The last form is equivalent to <code>attr_reader(name)</code> but deprecated.
 *  Returns an array of defined method names as symbols.
 *--
 * \private
 * \todo can be static?
 *++
 */
VALUE
rb_mod_attr(int argc, VALUE *argv, VALUE klass)
{
    if (argc == 2 && (argv[1] == Qtrue || argv[1] == Qfalse)) {
        ID id = id_for_attr(klass, argv[0]);
        VALUE names = rb_ary_new();

        rb_category_warning(RB_WARN_CATEGORY_DEPRECATED, "optional boolean argument is obsoleted");
        rb_attr(klass, id, 1, RTEST(argv[1]), TRUE);
        rb_ary_push(names, ID2SYM(id));
        if (argv[1] == Qtrue) rb_ary_push(names, ID2SYM(rb_id_attrset(id)));
        return names;
    }
    return rb_mod_attr_reader(argc, argv, klass);
}

/*
 *  call-seq:
 *      attr_writer(symbol, ...)    -> array
 *      attr_writer(string, ...)    -> array
 *
 *  Creates an accessor method to allow assignment to the attribute
 *  <i>symbol</i><code>.id2name</code>.
 *  String arguments are converted to symbols.
 *  Returns an array of defined method names as symbols.
 */

static VALUE
rb_mod_attr_writer(int argc, VALUE *argv, VALUE klass)
{
    int i;
    VALUE names = rb_ary_new2(argc);

    for (i=0; i<argc; i++) {
        ID id = id_for_attr(klass, argv[i]);
        rb_attr(klass, id, FALSE, TRUE, TRUE);
        rb_ary_push(names, ID2SYM(rb_id_attrset(id)));
    }
    return names;
}

/*
 *  call-seq:
 *     attr_accessor(symbol, ...)    -> array
 *     attr_accessor(string, ...)    -> array
 *
 *  Defines a named attribute for this module, where the name is
 *  <i>symbol.</i><code>id2name</code>, creating an instance variable
 *  (<code>@name</code>) and a corresponding access method to read it.
 *  Also creates a method called <code>name=</code> to set the attribute.
 *  String arguments are converted to symbols.
 *  Returns an array of defined method names as symbols.
 *
 *     module Mod
 *       attr_accessor(:one, :two) #=> [:one, :one=, :two, :two=]
 *     end
 *     Mod.instance_methods.sort   #=> [:one, :one=, :two, :two=]
 */

static VALUE
rb_mod_attr_accessor(int argc, VALUE *argv, VALUE klass)
{
    int i;
    VALUE names = rb_ary_new2(argc * 2);

    for (i=0; i<argc; i++) {
        ID id = id_for_attr(klass, argv[i]);

        rb_attr(klass, id, TRUE, TRUE, TRUE);
        rb_ary_push(names, ID2SYM(id));
        rb_ary_push(names, ID2SYM(rb_id_attrset(id)));
    }
    return names;
}

/*
 *  call-seq:
 *     mod.const_get(sym, inherit=true)    -> obj
 *     mod.const_get(str, inherit=true)    -> obj
 *
 *  Checks for a constant with the given name in <i>mod</i>.
 *  If +inherit+ is set, the lookup will also search
 *  the ancestors (and +Object+ if <i>mod</i> is a +Module+).
 *
 *  The value of the constant is returned if a definition is found,
 *  otherwise a +NameError+ is raised.
 *
 *     Math.const_get(:PI)   #=> 3.14159265358979
 *
 *  This method will recursively look up constant names if a namespaced
 *  class name is provided.  For example:
 *
 *     module Foo; class Bar; end end
 *     Object.const_get 'Foo::Bar'
 *
 *  The +inherit+ flag is respected on each lookup.  For example:
 *
 *     module Foo
 *       class Bar
 *         VAL = 10
 *       end
 *
 *       class Baz < Bar; end
 *     end
 *
 *     Object.const_get 'Foo::Baz::VAL'         # => 10
 *     Object.const_get 'Foo::Baz::VAL', false  # => NameError
 *
 *  If the argument is not a valid constant name a +NameError+ will be
 *  raised with a warning "wrong constant name".
 *
 *	Object.const_get 'foobar' #=> NameError: wrong constant name foobar
 *
 */

static VALUE
rb_mod_const_get(int argc, VALUE *argv, VALUE mod)
{
    VALUE name, recur;
    rb_encoding *enc;
    const char *pbeg, *p, *path, *pend;
    ID id;

    rb_check_arity(argc, 1, 2);
    name = argv[0];
    recur = (argc == 1) ? Qtrue : argv[1];

    if (SYMBOL_P(name)) {
        if (!rb_is_const_sym(name)) goto wrong_name;
        id = rb_check_id(&name);
        if (!id) return rb_const_missing(mod, name);
        return RTEST(recur) ? rb_const_get(mod, id) : rb_const_get_at(mod, id);
    }

    path = StringValuePtr(name);
    enc = rb_enc_get(name);

    if (!rb_enc_asciicompat(enc)) {
        rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
    }

    pbeg = p = path;
    pend = path + RSTRING_LEN(name);

    if (p >= pend || !*p) {
        goto wrong_name;
    }

    if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
        mod = rb_cObject;
        p += 2;
        pbeg = p;
    }

    while (p < pend) {
        VALUE part;
        long len, beglen;

        while (p < pend && *p != ':') p++;

        if (pbeg == p) goto wrong_name;

        id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
        beglen = pbeg-path;

        if (p < pend && p[0] == ':') {
            if (p + 2 >= pend || p[1] != ':') goto wrong_name;
            p += 2;
            pbeg = p;
        }

        if (!RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
            rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
                     QUOTE(name));
        }

        if (!id) {
            part = rb_str_subseq(name, beglen, len);
            OBJ_FREEZE(part);
            if (!rb_is_const_name(part)) {
                name = part;
                goto wrong_name;
            }
            else if (!rb_method_basic_definition_p(CLASS_OF(mod), id_const_missing)) {
                part = rb_str_intern(part);
                mod = rb_const_missing(mod, part);
                continue;
            }
            else {
                rb_mod_const_missing(mod, part);
            }
        }
        if (!rb_is_const_id(id)) {
            name = ID2SYM(id);
            goto wrong_name;
        }
#if 0
        mod = rb_const_get_0(mod, id, beglen > 0 || !RTEST(recur), RTEST(recur), FALSE);
#else
        if (!RTEST(recur)) {
            mod = rb_const_get_at(mod, id);
        }
        else if (beglen == 0) {
            mod = rb_const_get(mod, id);
        }
        else {
            mod = rb_const_get_from(mod, id);
        }
#endif
    }

    return mod;

  wrong_name:
    rb_name_err_raise(wrong_constant_name, mod, name);
    UNREACHABLE_RETURN(Qundef);
}

/*
 *  call-seq:
 *     mod.const_set(sym, obj)    -> obj
 *     mod.const_set(str, obj)    -> obj
 *
 *  Sets the named constant to the given object, returning that object.
 *  Creates a new constant if no constant with the given name previously
 *  existed.
 *
 *     Math.const_set("HIGH_SCHOOL_PI", 22.0/7.0)   #=> 3.14285714285714
 *     Math::HIGH_SCHOOL_PI - Math::PI              #=> 0.00126448926734968
 *
 *  If +sym+ or +str+ is not a valid constant name a +NameError+ will be
 *  raised with a warning "wrong constant name".
 *
 *	Object.const_set('foobar', 42) #=> NameError: wrong constant name foobar
 *
 */

static VALUE
rb_mod_const_set(VALUE mod, VALUE name, VALUE value)
{
    ID id = id_for_var(mod, name, const);
    if (!id) id = rb_intern_str(name);
    rb_const_set(mod, id, value);

    return value;
}

/*
 *  call-seq:
 *     mod.const_defined?(sym, inherit=true)   -> true or false
 *     mod.const_defined?(str, inherit=true)   -> true or false
 *
 *  Says whether _mod_ or its ancestors have a constant with the given name:
 *
 *    Float.const_defined?(:EPSILON)      #=> true, found in Float itself
 *    Float.const_defined?("String")      #=> true, found in Object (ancestor)
 *    BasicObject.const_defined?(:Hash)   #=> false
 *
 *  If _mod_ is a +Module+, additionally +Object+ and its ancestors are checked:
 *
 *    Math.const_defined?(:String)   #=> true, found in Object
 *
 *  In each of the checked classes or modules, if the constant is not present
 *  but there is an autoload for it, +true+ is returned directly without
 *  autoloading:
 *
 *    module Admin
 *      autoload :User, 'admin/user'
 *    end
 *    Admin.const_defined?(:User)   #=> true
 *
 *  If the constant is not found the callback +const_missing+ is *not* called
 *  and the method returns +false+.
 *
 *  If +inherit+ is false, the lookup only checks the constants in the receiver:
 *
 *    IO.const_defined?(:SYNC)          #=> true, found in File::Constants (ancestor)
 *    IO.const_defined?(:SYNC, false)   #=> false, not found in IO itself
 *
 *  In this case, the same logic for autoloading applies.
 *
 *  If the argument is not a valid constant name a +NameError+ is raised with the
 *  message "wrong constant name _name_":
 *
 *    Hash.const_defined? 'foobar'   #=> NameError: wrong constant name foobar
 *
 */

static VALUE
rb_mod_const_defined(int argc, VALUE *argv, VALUE mod)
{
    VALUE name, recur;
    rb_encoding *enc;
    const char *pbeg, *p, *path, *pend;
    ID id;

    rb_check_arity(argc, 1, 2);
    name = argv[0];
    recur = (argc == 1) ? Qtrue : argv[1];

    if (SYMBOL_P(name)) {
        if (!rb_is_const_sym(name)) goto wrong_name;
        id = rb_check_id(&name);
        if (!id) return Qfalse;
        return RTEST(recur) ? rb_const_defined(mod, id) : rb_const_defined_at(mod, id);
    }

    path = StringValuePtr(name);
    enc = rb_enc_get(name);

    if (!rb_enc_asciicompat(enc)) {
        rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
    }

    pbeg = p = path;
    pend = path + RSTRING_LEN(name);

    if (p >= pend || !*p) {
        goto wrong_name;
    }

    if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
        mod = rb_cObject;
        p += 2;
        pbeg = p;
    }

    while (p < pend) {
        VALUE part;
        long len, beglen;

        while (p < pend && *p != ':') p++;

        if (pbeg == p) goto wrong_name;

        id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
        beglen = pbeg-path;

        if (p < pend && p[0] == ':') {
            if (p + 2 >= pend || p[1] != ':') goto wrong_name;
            p += 2;
            pbeg = p;
        }

        if (!id) {
            part = rb_str_subseq(name, beglen, len);
            OBJ_FREEZE(part);
            if (!rb_is_const_name(part)) {
                name = part;
                goto wrong_name;
            }
            else {
                return Qfalse;
            }
        }
        if (!rb_is_const_id(id)) {
            name = ID2SYM(id);
            goto wrong_name;
        }

#if 0
        mod = rb_const_search(mod, id, beglen > 0 || !RTEST(recur), RTEST(recur), FALSE);
        if (UNDEF_P(mod)) return Qfalse;
#else
        if (!RTEST(recur)) {
            if (!rb_const_defined_at(mod, id))
                return Qfalse;
            if (p == pend) return Qtrue;
            mod = rb_const_get_at(mod, id);
        }
        else if (beglen == 0) {
            if (!rb_const_defined(mod, id))
                return Qfalse;
            if (p == pend) return Qtrue;
            mod = rb_const_get(mod, id);
        }
        else {
            if (!rb_const_defined_from(mod, id))
                return Qfalse;
            if (p == pend) return Qtrue;
            mod = rb_const_get_from(mod, id);
        }
#endif

        if (p < pend && !RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
            rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
                     QUOTE(name));
        }
    }

    return Qtrue;

  wrong_name:
    rb_name_err_raise(wrong_constant_name, mod, name);
    UNREACHABLE_RETURN(Qundef);
}

/*
 *  call-seq:
 *     mod.const_source_location(sym, inherit=true)   -> [String, Integer]
 *     mod.const_source_location(str, inherit=true)   -> [String, Integer]
 *
 *  Returns the Ruby source filename and line number containing the definition
 *  of the constant specified. If the named constant is not found, +nil+ is returned.
 *  If the constant is found, but its source location can not be extracted
 *  (constant is defined in C code), empty array is returned.
 *
 *  _inherit_ specifies whether to lookup in <code>mod.ancestors</code> (+true+
 *  by default).
 *
 *      # test.rb:
 *      class A         # line 1
 *        C1 = 1
 *        C2 = 2
 *      end
 *
 *      module M        # line 6
 *        C3 = 3
 *      end
 *
 *      class B < A     # line 10
 *        include M
 *        C4 = 4
 *      end
 *
 *      class A # continuation of A definition
 *        C2 = 8 # constant redefinition; warned yet allowed
 *      end
 *
 *      p B.const_source_location('C4')           # => ["test.rb", 12]
 *      p B.const_source_location('C3')           # => ["test.rb", 7]
 *      p B.const_source_location('C1')           # => ["test.rb", 2]
 *
 *      p B.const_source_location('C3', false)    # => nil  -- don't lookup in ancestors
 *
 *      p A.const_source_location('C2')           # => ["test.rb", 16] -- actual (last) definition place
 *
 *      p Object.const_source_location('B')       # => ["test.rb", 10] -- top-level constant could be looked through Object
 *      p Object.const_source_location('A')       # => ["test.rb", 1] -- class reopening is NOT considered new definition
 *
 *      p B.const_source_location('A')            # => ["test.rb", 1]  -- because Object is in ancestors
 *      p M.const_source_location('A')            # => ["test.rb", 1]  -- Object is not ancestor, but additionally checked for modules
 *
 *      p Object.const_source_location('A::C1')   # => ["test.rb", 2]  -- nesting is supported
 *      p Object.const_source_location('String')  # => []  -- constant is defined in C code
 *
 *
 */
static VALUE
rb_mod_const_source_location(int argc, VALUE *argv, VALUE mod)
{
    VALUE name, recur, loc = Qnil;
    rb_encoding *enc;
    const char *pbeg, *p, *path, *pend;
    ID id;

    rb_check_arity(argc, 1, 2);
    name = argv[0];
    recur = (argc == 1) ? Qtrue : argv[1];

    if (SYMBOL_P(name)) {
        if (!rb_is_const_sym(name)) goto wrong_name;
        id = rb_check_id(&name);
        if (!id) return Qnil;
        return RTEST(recur) ? rb_const_source_location(mod, id) : rb_const_source_location_at(mod, id);
    }

    path = StringValuePtr(name);
    enc = rb_enc_get(name);

    if (!rb_enc_asciicompat(enc)) {
        rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
    }

    pbeg = p = path;
    pend = path + RSTRING_LEN(name);

    if (p >= pend || !*p) {
        goto wrong_name;
    }

    if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
        mod = rb_cObject;
        p += 2;
        pbeg = p;
    }

    while (p < pend) {
        VALUE part;
        long len, beglen;

        while (p < pend && *p != ':') p++;

        if (pbeg == p) goto wrong_name;

        id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
        beglen = pbeg-path;

        if (p < pend && p[0] == ':') {
            if (p + 2 >= pend || p[1] != ':') goto wrong_name;
            p += 2;
            pbeg = p;
        }

        if (!id) {
            part = rb_str_subseq(name, beglen, len);
            OBJ_FREEZE(part);
            if (!rb_is_const_name(part)) {
                name = part;
                goto wrong_name;
            }
            else {
                return Qnil;
            }
        }
        if (!rb_is_const_id(id)) {
            name = ID2SYM(id);
            goto wrong_name;
        }
        if (p < pend) {
            if (RTEST(recur)) {
                mod = rb_const_get(mod, id);
            }
            else {
                mod = rb_const_get_at(mod, id);
            }
            if (!RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
                rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
                         QUOTE(name));
            }
        }
        else {
            if (RTEST(recur)) {
                loc = rb_const_source_location(mod, id);
            }
            else {
                loc = rb_const_source_location_at(mod, id);
            }
            break;
        }
        recur = Qfalse;
    }

    return loc;

  wrong_name:
    rb_name_err_raise(wrong_constant_name, mod, name);
    UNREACHABLE_RETURN(Qundef);
}

/*
 *  call-seq:
 *     obj.instance_variable_get(symbol)    -> obj
 *     obj.instance_variable_get(string)    -> obj
 *
 *  Returns the value of the given instance variable, or nil if the
 *  instance variable is not set. The <code>@</code> part of the
 *  variable name should be included for regular instance
 *  variables. Throws a NameError exception if the
 *  supplied symbol is not valid as an instance variable name.
 *  String arguments are converted to symbols.
 *
 *     class Fred
 *       def initialize(p1, p2)
 *         @a, @b = p1, p2
 *       end
 *     end
 *     fred = Fred.new('cat', 99)
 *     fred.instance_variable_get(:@a)    #=> "cat"
 *     fred.instance_variable_get("@b")   #=> 99
 */

static VALUE
rb_obj_ivar_get(VALUE obj, VALUE iv)
{
    ID id = id_for_var(obj, iv, instance);

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

/*
 *  call-seq:
 *     obj.instance_variable_set(symbol, obj)    -> obj
 *     obj.instance_variable_set(string, obj)    -> obj
 *
 *  Sets the instance variable named by <i>symbol</i> to the given
 *  object. This may circumvent the encapsulation intended by
 *  the author of the class, so it should be used with care.
 *  The variable does not have to exist prior to this call.
 *  If the instance variable name is passed as a string, that string
 *  is converted to a symbol.
 *
 *     class Fred
 *       def initialize(p1, p2)
 *         @a, @b = p1, p2
 *       end
 *     end
 *     fred = Fred.new('cat', 99)
 *     fred.instance_variable_set(:@a, 'dog')   #=> "dog"
 *     fred.instance_variable_set(:@c, 'cat')   #=> "cat"
 *     fred.inspect                             #=> "#<Fred:0x401b3da8 @a=\"dog\", @b=99, @c=\"cat\">"
 */

static VALUE
rb_obj_ivar_set_m(VALUE obj, VALUE iv, VALUE val)
{
    ID id = id_for_var(obj, iv, instance);
    if (!id) id = rb_intern_str(iv);
    return rb_ivar_set(obj, id, val);
}

/*
 *  call-seq:
 *     obj.instance_variable_defined?(symbol)    -> true or false
 *     obj.instance_variable_defined?(string)    -> true or false
 *
 *  Returns <code>true</code> if the given instance variable is
 *  defined in <i>obj</i>.
 *  String arguments are converted to symbols.
 *
 *     class Fred
 *       def initialize(p1, p2)
 *         @a, @b = p1, p2
 *       end
 *     end
 *     fred = Fred.new('cat', 99)
 *     fred.instance_variable_defined?(:@a)    #=> true
 *     fred.instance_variable_defined?("@b")   #=> true
 *     fred.instance_variable_defined?("@c")   #=> false
 */

static VALUE
rb_obj_ivar_defined(VALUE obj, VALUE iv)
{
    ID id = id_for_var(obj, iv, instance);

    if (!id) {
        return Qfalse;
    }
    return rb_ivar_defined(obj, id);
}

/*
 *  call-seq:
 *     mod.class_variable_get(symbol)    -> obj
 *     mod.class_variable_get(string)    -> obj
 *
 *  Returns the value of the given class variable (or throws a
 *  NameError exception). The <code>@@</code> part of the
 *  variable name should be included for regular class variables.
 *  String arguments are converted to symbols.
 *
 *     class Fred
 *       @@foo = 99
 *     end
 *     Fred.class_variable_get(:@@foo)     #=> 99
 */

static VALUE
rb_mod_cvar_get(VALUE obj, VALUE iv)
{
    ID id = id_for_var(obj, iv, class);

    if (!id) {
        rb_name_err_raise("uninitialized class variable %1$s in %2$s",
                          obj, iv);
    }
    return rb_cvar_get(obj, id);
}

/*
 *  call-seq:
 *     obj.class_variable_set(symbol, obj)    -> obj
 *     obj.class_variable_set(string, obj)    -> obj
 *
 *  Sets the class variable named by <i>symbol</i> to the given
 *  object.
 *  If the class variable name is passed as a string, that string
 *  is converted to a symbol.
 *
 *     class Fred
 *       @@foo = 99
 *       def foo
 *         @@foo
 *       end
 *     end
 *     Fred.class_variable_set(:@@foo, 101)     #=> 101
 *     Fred.new.foo                             #=> 101
 */

static VALUE
rb_mod_cvar_set(VALUE obj, VALUE iv, VALUE val)
{
    ID id = id_for_var(obj, iv, class);
    if (!id) id = rb_intern_str(iv);
    rb_cvar_set(obj, id, val);
    return val;
}

/*
 *  call-seq:
 *     obj.class_variable_defined?(symbol)    -> true or false
 *     obj.class_variable_defined?(string)    -> true or false
 *
 *  Returns <code>true</code> if the given class variable is defined
 *  in <i>obj</i>.
 *  String arguments are converted to symbols.
 *
 *     class Fred
 *       @@foo = 99
 *     end
 *     Fred.class_variable_defined?(:@@foo)    #=> true
 *     Fred.class_variable_defined?(:@@bar)    #=> false
 */

static VALUE
rb_mod_cvar_defined(VALUE obj, VALUE iv)
{
    ID id = id_for_var(obj, iv, class);

    if (!id) {
        return Qfalse;
    }
    return rb_cvar_defined(obj, id);
}

/*
 *  call-seq:
 *     mod.singleton_class?    -> true or false
 *
 *  Returns <code>true</code> if <i>mod</i> is a singleton class or
 *  <code>false</code> if it is an ordinary class or module.
 *
 *     class C
 *     end
 *     C.singleton_class?                  #=> false
 *     C.singleton_class.singleton_class?  #=> true
 */

static VALUE
rb_mod_singleton_p(VALUE klass)
{
    return RBOOL(RCLASS_SINGLETON_P(klass));
}

/*! \private */
static const struct conv_method_tbl {
    const char method[6];
    unsigned short id;
} conv_method_names[] = {
#define M(n) {#n, (unsigned short)idTo_##n}
    M(int),
    M(ary),
    M(str),
    M(sym),
    M(hash),
    M(proc),
    M(io),
    M(a),
    M(s),
    M(i),
    M(f),
    M(r),
#undef M
};
#define IMPLICIT_CONVERSIONS 7

static int
conv_method_index(const char *method)
{
    static const char prefix[] = "to_";

    if (strncmp(prefix, method, sizeof(prefix)-1) == 0) {
        const char *const meth = &method[sizeof(prefix)-1];
        int i;
        for (i=0; i < numberof(conv_method_names); i++) {
            if (conv_method_names[i].method[0] == meth[0] &&
                strcmp(conv_method_names[i].method, meth) == 0) {
                return i;
            }
        }
    }
    return numberof(conv_method_names);
}

static VALUE
convert_type_with_id(VALUE val, const char *tname, ID method, int raise, int index)
{
    VALUE r = rb_check_funcall(val, method, 0, 0);
    if (UNDEF_P(r)) {
        if (raise) {
            const char *msg =
                ((index < 0 ? conv_method_index(rb_id2name(method)) : index)
                 < IMPLICIT_CONVERSIONS) ?
                "no implicit conversion of" : "can't convert";
            const char *cname = NIL_P(val) ? "nil" :
                val == Qtrue ? "true" :
                val == Qfalse ? "false" :
                NULL;
            if (cname)
                rb_raise(rb_eTypeError, "%s %s into %s", msg, cname, tname);
            rb_raise(rb_eTypeError, "%s %"PRIsVALUE" into %s", msg,
                     rb_obj_class(val),
                     tname);
        }
        return Qnil;
    }
    return r;
}

static VALUE
convert_type(VALUE val, const char *tname, const char *method, int raise)
{
    int i = conv_method_index(method);
    ID m = i < numberof(conv_method_names) ?
        conv_method_names[i].id : rb_intern(method);
    return convert_type_with_id(val, tname, m, raise, i);
}

/*! \private */
NORETURN(static void conversion_mismatch(VALUE, const char *, const char *, VALUE));
static void
conversion_mismatch(VALUE val, const char *tname, const char *method, VALUE result)
{
    VALUE cname = rb_obj_class(val);
    rb_raise(rb_eTypeError,
             "can't convert %"PRIsVALUE" to %s (%"PRIsVALUE"#%s gives %"PRIsVALUE")",
             cname, tname, cname, method, rb_obj_class(result));
}

VALUE
rb_convert_type(VALUE val, int type, const char *tname, const char *method)
{
    VALUE v;

    if (TYPE(val) == type) return val;
    v = convert_type(val, tname, method, TRUE);
    if (TYPE(v) != type) {
        conversion_mismatch(val, tname, method, v);
    }
    return v;
}

/*! \private */
VALUE
rb_convert_type_with_id(VALUE val, int type, const char *tname, ID method)
{
    VALUE v;

    if (TYPE(val) == type) return val;
    v = convert_type_with_id(val, tname, method, TRUE, -1);
    if (TYPE(v) != type) {
        conversion_mismatch(val, tname, RSTRING_PTR(rb_id2str(method)), v);
    }
    return v;
}

VALUE
rb_check_convert_type(VALUE val, int type, const char *tname, const char *method)
{
    VALUE v;

    /* always convert T_DATA */
    if (TYPE(val) == type && type != T_DATA) return val;
    v = convert_type(val, tname, method, FALSE);
    if (NIL_P(v)) return Qnil;
    if (TYPE(v) != type) {
        conversion_mismatch(val, tname, method, v);
    }
    return v;
}

/*! \private */
VALUE
rb_check_convert_type_with_id(VALUE val, int type, const char *tname, ID method)
{
    VALUE v;

    /* always convert T_DATA */
    if (TYPE(val) == type && type != T_DATA) return val;
    v = convert_type_with_id(val, tname, method, FALSE, -1);
    if (NIL_P(v)) return Qnil;
    if (TYPE(v) != type) {
        conversion_mismatch(val, tname, RSTRING_PTR(rb_id2str(method)), v);
    }
    return v;
}

#define try_to_int(val, mid, raise) \
    convert_type_with_id(val, "Integer", mid, raise, -1)

ALWAYS_INLINE(static VALUE rb_to_integer_with_id_exception(VALUE val, const char *method, ID mid, int raise));
/* Integer specific rb_check_convert_type_with_id */
static inline VALUE
rb_to_integer_with_id_exception(VALUE val, const char *method, ID mid, int raise)
{
    // We need to pop the lazily pushed frame when not raising an exception.
    rb_control_frame_t *current_cfp;
    VALUE v;

    if (RB_INTEGER_TYPE_P(val)) return val;
    current_cfp = GET_EC()->cfp;
    rb_yjit_lazy_push_frame(GET_EC()->cfp->pc);
    v = try_to_int(val, mid, raise);
    if (!raise && NIL_P(v)) {
        GET_EC()->cfp = current_cfp;
        return Qnil;
    }
    if (!RB_INTEGER_TYPE_P(v)) {
        conversion_mismatch(val, "Integer", method, v);
    }
    GET_EC()->cfp = current_cfp;
    return v;
}
#define rb_to_integer(val, method, mid) \
    rb_to_integer_with_id_exception(val, method, mid, TRUE)

VALUE
rb_check_to_integer(VALUE val, const char *method)
{
    VALUE v;

    if (RB_INTEGER_TYPE_P(val)) return val;
    v = convert_type(val, "Integer", method, FALSE);
    if (!RB_INTEGER_TYPE_P(v)) {
        return Qnil;
    }
    return v;
}

VALUE
rb_to_int(VALUE val)
{
    return rb_to_integer(val, "to_int", idTo_int);
}

VALUE
rb_check_to_int(VALUE val)
{
    if (RB_INTEGER_TYPE_P(val)) return val;
    val = try_to_int(val, idTo_int, FALSE);
    if (RB_INTEGER_TYPE_P(val)) return val;
    return Qnil;
}

static VALUE
rb_check_to_i(VALUE val)
{
    if (RB_INTEGER_TYPE_P(val)) return val;
    val = try_to_int(val, idTo_i, FALSE);
    if (RB_INTEGER_TYPE_P(val)) return val;
    return Qnil;
}

static VALUE
rb_convert_to_integer(VALUE val, int base, int raise_exception)
{
    VALUE tmp;

    if (base) {
        tmp = rb_check_string_type(val);

        if (! NIL_P(tmp)) {
            val =  tmp;
        }
        else if (! raise_exception) {
            return Qnil;
        }
        else {
            rb_raise(rb_eArgError, "base specified for non string value");
        }
    }
    if (RB_FLOAT_TYPE_P(val)) {
        double f = RFLOAT_VALUE(val);
        if (!raise_exception && !isfinite(f)) return Qnil;
        if (FIXABLE(f)) return LONG2FIX((long)f);
        return rb_dbl2big(f);
    }
    else if (RB_INTEGER_TYPE_P(val)) {
        return val;
    }
    else if (RB_TYPE_P(val, T_STRING)) {
        return rb_str_convert_to_inum(val, base, TRUE, raise_exception);
    }
    else if (NIL_P(val)) {
        if (!raise_exception) return Qnil;
        rb_raise(rb_eTypeError, "can't convert nil into Integer");
    }

    tmp = rb_protect(rb_check_to_int, val, NULL);
    if (RB_INTEGER_TYPE_P(tmp)) return tmp;
    rb_set_errinfo(Qnil);
    if (!NIL_P(tmp = rb_check_string_type(val))) {
        return rb_str_convert_to_inum(tmp, base, TRUE, raise_exception);
    }

    if (!raise_exception) {
        VALUE result = rb_protect(rb_check_to_i, val, NULL);
        rb_set_errinfo(Qnil);
        return result;
    }

    return rb_to_integer(val, "to_i", idTo_i);
}

VALUE
rb_Integer(VALUE val)
{
    return rb_convert_to_integer(val, 0, TRUE);
}

VALUE
rb_check_integer_type(VALUE val)
{
    return rb_to_integer_with_id_exception(val, "to_int", idTo_int, FALSE);
}

int
rb_bool_expected(VALUE obj, const char *flagname, int raise)
{
    switch (obj) {
      case Qtrue:
        return TRUE;
      case Qfalse:
        return FALSE;
      default: {
        static const char message[] = "expected true or false as %s: %+"PRIsVALUE;
        if (raise) {
            rb_raise(rb_eArgError, message, flagname, obj);
        }
        rb_warning(message, flagname, obj);
        return !NIL_P(obj);
      }
    }
}

int
rb_opts_exception_p(VALUE opts, int default_value)
{
    static const ID kwds[1] = {idException};
    VALUE exception;
    if (rb_get_kwargs(opts, kwds, 0, 1, &exception))
        return rb_bool_expected(exception, "exception", TRUE);
    return default_value;
}

static VALUE
rb_f_integer1(rb_execution_context_t *ec, VALUE obj, VALUE arg)
{
    return rb_convert_to_integer(arg, 0, TRUE);
}

static VALUE
rb_f_integer(rb_execution_context_t *ec, VALUE obj, VALUE arg, VALUE base, VALUE exception)
{
    int exc = rb_bool_expected(exception, "exception", TRUE);
    return rb_convert_to_integer(arg, NUM2INT(base), exc);
}

static double
rb_cstr_to_dbl_raise(const char *p, rb_encoding *enc, int badcheck, int raise, int *error)
{
    const char *q;
    char *end;
    double d;
    const char *ellipsis = "";
    int w;
    enum {max_width = 20};
#define OutOfRange() ((end - p > max_width) ? \
                      (w = max_width, ellipsis = "...") : \
                      (w = (int)(end - p), ellipsis = ""))
    /* p...end has been parsed with strtod, should be ASCII-only */

    if (!p) return 0.0;
    q = p;
    while (ISSPACE(*p)) p++;

    if (!badcheck && p[0] == '0' && (p[1] == 'x' || p[1] == 'X')) {
        return 0.0;
    }

    d = strtod(p, &end);
    if (errno == ERANGE) {
        OutOfRange();
        rb_warning("Float %.*s%s out of range", w, p, ellipsis);
        errno = 0;
    }
    if (p == end) {
        if (badcheck) {
            goto bad;
        }
        return d;
    }
    if (*end) {
        char buf[DBL_DIG * 4 + 10];
        char *n = buf;
        char *const init_e = buf + DBL_DIG * 4;
        char *e = init_e;
        char prev = 0;
        int dot_seen = FALSE;

        switch (*p) {case '+': case '-': prev = *n++ = *p++;}
        if (*p == '0') {
            prev = *n++ = '0';
            while (*++p == '0');
        }
        while (p < end && n < e) prev = *n++ = *p++;
        while (*p) {
            if (*p == '_') {
                /* remove an underscore between digits */
                if (n == buf || !ISDIGIT(prev) || (++p, !ISDIGIT(*p))) {
                    if (badcheck) goto bad;
                    break;
                }
            }
            prev = *p++;
            if (e == init_e && (prev == 'e' || prev == 'E' || prev == 'p' || prev == 'P')) {
                e = buf + sizeof(buf) - 1;
                *n++ = prev;
                switch (*p) {case '+': case '-': prev = *n++ = *p++;}
                if (*p == '0') {
                    prev = *n++ = '0';
                    while (*++p == '0');
                }
                continue;
            }
            else if (ISSPACE(prev)) {
                while (ISSPACE(*p)) ++p;
                if (*p) {
                    if (badcheck) goto bad;
                    break;
                }
            }
            else if (prev == '.' ? dot_seen++ : !ISDIGIT(prev)) {
                if (badcheck) goto bad;
                break;
            }
            if (n < e) *n++ = prev;
        }
        *n = '\0';
        p = buf;

        if (!badcheck && p[0] == '0' && (p[1] == 'x' || p[1] == 'X')) {
            return 0.0;
        }

        d = strtod(p, &end);
        if (errno == ERANGE) {
            OutOfRange();
            rb_warning("Float %.*s%s out of range", w, p, ellipsis);
            errno = 0;
        }
        if (badcheck) {
            if (!end || p == end) goto bad;
            while (*end && ISSPACE(*end)) end++;
            if (*end) goto bad;
        }
    }
    if (errno == ERANGE) {
        errno = 0;
        OutOfRange();
        rb_raise(rb_eArgError, "Float %.*s%s out of range", w, q, ellipsis);
    }
    return d;

  bad:
    if (raise) {
        VALUE s = rb_enc_str_new_cstr(q, enc);
        rb_raise(rb_eArgError, "invalid value for Float(): %+"PRIsVALUE, s);
        UNREACHABLE_RETURN(nan(""));
    }
    else {
        if (error) *error = 1;
        return 0.0;
    }
}

double
rb_cstr_to_dbl(const char *p, int badcheck)
{
    return rb_cstr_to_dbl_raise(p, NULL, badcheck, TRUE, NULL);
}

static double
rb_str_to_dbl_raise(VALUE str, int badcheck, int raise, int *error)
{
    char *s;
    long len;
    double ret;
    VALUE v = 0;

    StringValue(str);
    rb_must_asciicompat(str);
    s = RSTRING_PTR(str);
    len = RSTRING_LEN(str);
    if (s) {
        if (badcheck && memchr(s, '\0', len)) {
            if (raise)
                rb_raise(rb_eArgError, "string for Float contains null byte");
            else {
                if (error) *error = 1;
                return 0.0;
            }
        }
        if (s[len]) {		/* no sentinel somehow */
            char *p = ALLOCV(v, (size_t)len + 1);
            MEMCPY(p, s, char, len);
            p[len] = '\0';
            s = p;
        }
    }
    ret = rb_cstr_to_dbl_raise(s, rb_enc_get(str), badcheck, raise, error);
    if (v)
        ALLOCV_END(v);
    else
        RB_GC_GUARD(str);
    return ret;
}

FUNC_MINIMIZED(double rb_str_to_dbl(VALUE str, int badcheck));

double
rb_str_to_dbl(VALUE str, int badcheck)
{
    return rb_str_to_dbl_raise(str, badcheck, TRUE, NULL);
}

/*! \cond INTERNAL_MACRO */
#define fix2dbl_without_to_f(x) (double)FIX2LONG(x)
#define big2dbl_without_to_f(x) rb_big2dbl(x)
#define int2dbl_without_to_f(x) \
    (FIXNUM_P(x) ? fix2dbl_without_to_f(x) : big2dbl_without_to_f(x))
#define num2dbl_without_to_f(x) \
    (FIXNUM_P(x) ? fix2dbl_without_to_f(x) : \
     RB_BIGNUM_TYPE_P(x) ? big2dbl_without_to_f(x) : \
     (Check_Type(x, T_FLOAT), RFLOAT_VALUE(x)))
static inline double
rat2dbl_without_to_f(VALUE x)
{
    VALUE num = rb_rational_num(x);
    VALUE den = rb_rational_den(x);
    return num2dbl_without_to_f(num) / num2dbl_without_to_f(den);
}

#define special_const_to_float(val, pre, post) \
    switch (val) { \
      case Qnil: \
        rb_raise_static(rb_eTypeError, pre "nil" post); \
      case Qtrue: \
        rb_raise_static(rb_eTypeError, pre "true" post); \
      case Qfalse: \
        rb_raise_static(rb_eTypeError, pre "false" post); \
    }
/*! \endcond */

static inline void
conversion_to_float(VALUE val)
{
    special_const_to_float(val, "can't convert ", " into Float");
}

static inline void
implicit_conversion_to_float(VALUE val)
{
    special_const_to_float(val, "no implicit conversion to float from ", "");
}

static int
to_float(VALUE *valp, int raise_exception)
{
    VALUE val = *valp;
    if (SPECIAL_CONST_P(val)) {
        if (FIXNUM_P(val)) {
            *valp = DBL2NUM(fix2dbl_without_to_f(val));
            return T_FLOAT;
        }
        else if (FLONUM_P(val)) {
            return T_FLOAT;
        }
        else if (raise_exception) {
            conversion_to_float(val);
        }
    }
    else {
        int type = BUILTIN_TYPE(val);
        switch (type) {
          case T_FLOAT:
            return T_FLOAT;
          case T_BIGNUM:
            *valp = DBL2NUM(big2dbl_without_to_f(val));
            return T_FLOAT;
          case T_RATIONAL:
            *valp = DBL2NUM(rat2dbl_without_to_f(val));
            return T_FLOAT;
          case T_STRING:
            return T_STRING;
        }
    }
    return T_NONE;
}

static VALUE
convert_type_to_float_protected(VALUE val)
{
    return rb_convert_type_with_id(val, T_FLOAT, "Float", id_to_f);
}

static VALUE
rb_convert_to_float(VALUE val, int raise_exception)
{
    switch (to_float(&val, raise_exception)) {
      case T_FLOAT:
        return val;
      case T_STRING:
        if (!raise_exception) {
            int e = 0;
            double x = rb_str_to_dbl_raise(val, TRUE, raise_exception, &e);
            return e ? Qnil : DBL2NUM(x);
        }
        return DBL2NUM(rb_str_to_dbl(val, TRUE));
      case T_NONE:
        if (SPECIAL_CONST_P(val) && !raise_exception)
            return Qnil;
    }

    if (!raise_exception) {
        int state;
        VALUE result = rb_protect(convert_type_to_float_protected, val, &state);
        if (state) rb_set_errinfo(Qnil);
        return result;
    }

    return rb_convert_type_with_id(val, T_FLOAT, "Float", id_to_f);
}

FUNC_MINIMIZED(VALUE rb_Float(VALUE val));

VALUE
rb_Float(VALUE val)
{
    return rb_convert_to_float(val, TRUE);
}

static VALUE
rb_f_float1(rb_execution_context_t *ec, VALUE obj, VALUE arg)
{
    return rb_convert_to_float(arg, TRUE);
}

static VALUE
rb_f_float(rb_execution_context_t *ec, VALUE obj, VALUE arg, VALUE opts)
{
    int exception = rb_bool_expected(opts, "exception", TRUE);
    return rb_convert_to_float(arg, exception);
}

static VALUE
numeric_to_float(VALUE val)
{
    if (!rb_obj_is_kind_of(val, rb_cNumeric)) {
        rb_raise(rb_eTypeError, "can't convert %"PRIsVALUE" into Float",
                 rb_obj_class(val));
    }
    return rb_convert_type_with_id(val, T_FLOAT, "Float", id_to_f);
}

VALUE
rb_to_float(VALUE val)
{
    switch (to_float(&val, TRUE)) {
      case T_FLOAT:
        return val;
    }
    return numeric_to_float(val);
}

VALUE
rb_check_to_float(VALUE val)
{
    if (RB_FLOAT_TYPE_P(val)) return val;
    if (!rb_obj_is_kind_of(val, rb_cNumeric)) {
        return Qnil;
    }
    return rb_check_convert_type_with_id(val, T_FLOAT, "Float", id_to_f);
}

static inline int
basic_to_f_p(VALUE klass)
{
    return rb_method_basic_definition_p(klass, id_to_f);
}

/*! \private */
double
rb_num_to_dbl(VALUE val)
{
    if (SPECIAL_CONST_P(val)) {
        if (FIXNUM_P(val)) {
            if (basic_to_f_p(rb_cInteger))
                return fix2dbl_without_to_f(val);
        }
        else if (FLONUM_P(val)) {
            return rb_float_flonum_value(val);
        }
        else {
            conversion_to_float(val);
        }
    }
    else {
        switch (BUILTIN_TYPE(val)) {
          case T_FLOAT:
            return rb_float_noflonum_value(val);
          case T_BIGNUM:
            if (basic_to_f_p(rb_cInteger))
                return big2dbl_without_to_f(val);
            break;
          case T_RATIONAL:
            if (basic_to_f_p(rb_cRational))
                return rat2dbl_without_to_f(val);
            break;
          default:
            break;
        }
    }
    val = numeric_to_float(val);
    return RFLOAT_VALUE(val);
}

double
rb_num2dbl(VALUE val)
{
    if (SPECIAL_CONST_P(val)) {
        if (FIXNUM_P(val)) {
            return fix2dbl_without_to_f(val);
        }
        else if (FLONUM_P(val)) {
            return rb_float_flonum_value(val);
        }
        else {
            implicit_conversion_to_float(val);
        }
    }
    else {
        switch (BUILTIN_TYPE(val)) {
          case T_FLOAT:
            return rb_float_noflonum_value(val);
          case T_BIGNUM:
            return big2dbl_without_to_f(val);
          case T_RATIONAL:
            return rat2dbl_without_to_f(val);
          case T_STRING:
            rb_raise(rb_eTypeError, "no implicit conversion to float from string");
          default:
            break;
        }
    }
    val = rb_convert_type_with_id(val, T_FLOAT, "Float", id_to_f);
    return RFLOAT_VALUE(val);
}

VALUE
rb_String(VALUE val)
{
    VALUE tmp = rb_check_string_type(val);
    if (NIL_P(tmp))
        tmp = rb_convert_type_with_id(val, T_STRING, "String", idTo_s);
    return tmp;
}


/*
 *  call-seq:
 *    String(object) -> object or new_string
 *
 *  Returns a string converted from +object+.
 *
 *  Tries to convert +object+ to a string
 *  using +to_str+ first and +to_s+ second:
 *
 *    String([0, 1, 2])        # => "[0, 1, 2]"
 *    String(0..5)             # => "0..5"
 *    String({foo: 0, bar: 1}) # => "{foo: 0, bar: 1}"
 *
 *  Raises +TypeError+ if +object+ cannot be converted to a string.
 */

static VALUE
rb_f_string(VALUE obj, VALUE arg)
{
    return rb_String(arg);
}

VALUE
rb_Array(VALUE val)
{
    VALUE tmp = rb_check_array_type(val);

    if (NIL_P(tmp)) {
        tmp = rb_check_to_array(val);
        if (NIL_P(tmp)) {
            return rb_ary_new3(1, val);
        }
    }
    return tmp;
}

/*
 *  call-seq:
 *    Array(object) -> object or new_array
 *
 *  Returns an array converted from +object+.
 *
 *  Tries to convert +object+ to an array
 *  using +to_ary+ first and +to_a+ second:
 *
 *    Array([0, 1, 2])        # => [0, 1, 2]
 *    Array({foo: 0, bar: 1}) # => [[:foo, 0], [:bar, 1]]
 *    Array(0..4)             # => [0, 1, 2, 3, 4]
 *
 *  Returns +object+ in an array, <tt>[object]</tt>,
 *  if +object+ cannot be converted:
 *
 *    Array(:foo)             # => [:foo]
 *
 */

static VALUE
rb_f_array(VALUE obj, VALUE arg)
{
    return rb_Array(arg);
}

/**
 * Equivalent to \c Kernel\#Hash in Ruby
 */
VALUE
rb_Hash(VALUE val)
{
    VALUE tmp;

    if (NIL_P(val)) return rb_hash_new();
    tmp = rb_check_hash_type(val);
    if (NIL_P(tmp)) {
        if (RB_TYPE_P(val, T_ARRAY) && RARRAY_LEN(val) == 0)
            return rb_hash_new();
        rb_raise(rb_eTypeError, "can't convert %s into Hash", rb_obj_classname(val));
    }
    return tmp;
}

/*
 *  call-seq:
 *    Hash(object) -> object or new_hash
 *
 *  Returns a hash converted from +object+.
 *
 *  - If +object+ is:
 *
 *    - A hash, returns +object+.
 *    - An empty array or +nil+, returns an empty hash.
 *
 *  - Otherwise, if <tt>object.to_hash</tt> returns a hash, returns that hash.
 *  - Otherwise, returns TypeError.
 *
 *  Examples:
 *
 *    Hash({foo: 0, bar: 1}) # => {:foo=>0, :bar=>1}
 *    Hash(nil)              # => {}
 *    Hash([])               # => {}
 *
 */

static VALUE
rb_f_hash(VALUE obj, VALUE arg)
{
    return rb_Hash(arg);
}

/*! \private */
struct dig_method {
    VALUE klass;
    int basic;
};

static ID id_dig;

static int
dig_basic_p(VALUE obj, struct dig_method *cache)
{
    VALUE klass = RBASIC_CLASS(obj);
    if (klass != cache->klass) {
        cache->klass = klass;
        cache->basic = rb_method_basic_definition_p(klass, id_dig);
    }
    return cache->basic;
}

static void
no_dig_method(int found, VALUE recv, ID mid, int argc, const VALUE *argv, VALUE data)
{
    if (!found) {
        rb_raise(rb_eTypeError, "%"PRIsVALUE" does not have #dig method",
                 CLASS_OF(data));
    }
}

/*! \private */
VALUE
rb_obj_dig(int argc, VALUE *argv, VALUE obj, VALUE notfound)
{
    struct dig_method hash = {Qnil}, ary = {Qnil}, strt = {Qnil};

    for (; argc > 0; ++argv, --argc) {
        if (NIL_P(obj)) return notfound;
        if (!SPECIAL_CONST_P(obj)) {
            switch (BUILTIN_TYPE(obj)) {
              case T_HASH:
                if (dig_basic_p(obj, &hash)) {
                    obj = rb_hash_aref(obj, *argv);
                    continue;
                }
                break;
              case T_ARRAY:
                if (dig_basic_p(obj, &ary)) {
                    obj = rb_ary_at(obj, *argv);
                    continue;
                }
                break;
              case T_STRUCT:
                if (dig_basic_p(obj, &strt)) {
                    obj = rb_struct_lookup(obj, *argv);
                    continue;
                }
                break;
              default:
                break;
            }
        }
        return rb_check_funcall_with_hook_kw(obj, id_dig, argc, argv,
                                          no_dig_method, obj,
                                          RB_NO_KEYWORDS);
    }
    return obj;
}

/*
 *  call-seq:
 *     sprintf(format_string *objects)  -> string
 *
 *  Returns the string resulting from formatting +objects+
 *  into +format_string+.
 *
 *  For details on +format_string+, see
 *  {Format Specifications}[rdoc-ref:format_specifications.rdoc].
 */

static VALUE
f_sprintf(int c, const VALUE *v, VALUE _)
{
    return rb_f_sprintf(c, v);
}

static VALUE
rb_f_loop_size(VALUE self, VALUE args, VALUE eobj)
{
    return DBL2NUM(HUGE_VAL);
}

/*
 *  Document-class: Class
 *
 *  Classes in Ruby are first-class objects---each is an instance of
 *  class Class.
 *
 *  Typically, you create a new class by using:
 *
 *    class Name
 *     # some code describing the class behavior
 *    end
 *
 *  When a new class is created, an object of type Class is initialized and
 *  assigned to a global constant (Name in this case).
 *
 *  When <code>Name.new</code> is called to create a new object, the
 *  #new method in Class is run by default.
 *  This can be demonstrated by overriding #new in Class:
 *
 *     class Class
 *       alias old_new new
 *       def new(*args)
 *         print "Creating a new ", self.name, "\n"
 *         old_new(*args)
 *       end
 *     end
 *
 *     class Name
 *     end
 *
 *     n = Name.new
 *
 *  <em>produces:</em>
 *
 *     Creating a new Name
 *
 *  Classes, modules, and objects are interrelated. In the diagram
 *  that follows, the vertical arrows represent inheritance, and the
 *  parentheses metaclasses. All metaclasses are instances
 *  of the class `Class'.
 *                             +---------+             +-...
 *                             |         |             |
 *             BasicObject-----|-->(BasicObject)-------|-...
 *                 ^           |         ^             |
 *                 |           |         |             |
 *              Object---------|----->(Object)---------|-...
 *                 ^           |         ^             |
 *                 |           |         |             |
 *                 +-------+   |         +--------+    |
 *                 |       |   |         |        |    |
 *                 |    Module-|---------|--->(Module)-|-...
 *                 |       ^   |         |        ^    |
 *                 |       |   |         |        |    |
 *                 |     Class-|---------|---->(Class)-|-...
 *                 |       ^   |         |        ^    |
 *                 |       +---+         |        +----+
 *                 |                     |
 *    obj--->OtherClass---------->(OtherClass)-----------...
 *
 */


/*
 *  Document-class: BasicObject
 *
 *  +BasicObject+ is the parent class of all classes in Ruby.
 *  In particular, +BasicObject+ is the parent class of class Object,
 *  which is itself the default parent class of every Ruby class:
 *
 *    class Foo; end
 *    Foo.superclass    # => Object
 *    Object.superclass # => BasicObject
 *
 *  +BasicObject+ is the only class that has no parent:
 *
 *    BasicObject.superclass # => nil
 *
 *  Class +BasicObject+ can be used to create an object hierarchy
 *  (e.g., class Delegator) that is independent of Ruby's object hierarchy.
 *  Such objects:
 *
 *  - Do not have namespace "pollution" from the many methods
 *    provided in class Object and its included module Kernel.
 *  - Do not have definitions of common classes,
 *    and so references to such common classes must be fully qualified
 *    (+::String+, not +String+).
 *
 *  A variety of strategies can be used to provide useful portions
 *  of the Standard Library in subclasses of +BasicObject+:
 *
 *  - The immediate subclass could <tt>include Kernel</tt>,
 *    which would define methods such as +puts+, +exit+, etc.
 *  - A custom Kernel-like module could be created and included.
 *  - Delegation can be used via #method_missing:
 *
 *      class MyObjectSystem < BasicObject
 *        DELEGATE = [:puts, :p]
 *
 *        def method_missing(name, *args, &block)
 *          return super unless DELEGATE.include? name
 *          ::Kernel.send(name, *args, &block)
 *        end
 *
 *        def respond_to_missing?(name, include_private = false)
 *          DELEGATE.include?(name)
 *        end
 *      end
 *
 *  === What's Here
 *
 *  These are the methods defined for \BasicObject:
 *
 *  - ::new: Returns a new \BasicObject instance.
 *  - #!: Returns the boolean negation of +self+: +true+ or +false+.
 *  - #!=: Returns whether +self+ and the given object are _not_ equal.
 *  - #==: Returns whether +self+ and the given object are equivalent.
 *  - #__id__: Returns the integer object identifier for +self+.
 *  - #__send__: Calls the method identified by the given symbol.
 *  - #equal?: Returns whether +self+ and the given object are the same object.
 *  - #instance_eval: Evaluates the given string or block in the context of +self+.
 *  - #instance_exec: Executes the given block in the context of +self+, passing the given arguments.
 *  - #method_missing: Called when +self+ is called with a method it does not define.
 *  - #singleton_method_added: Called when a singleton method is added to +self+.
 *  - #singleton_method_removed: Called when a singleton method is removed from +self+.
 *  - #singleton_method_undefined: Called when a singleton method is undefined in +self+.
 *
 */

/*  Document-class: Object
 *
 *  Object is the default root of all Ruby objects.  Object inherits from
 *  BasicObject which allows creating alternate object hierarchies.  Methods
 *  on Object are available to all classes unless explicitly overridden.
 *
 *  Object mixes in the Kernel module, making the built-in kernel functions
 *  globally accessible.  Although the instance methods of Object are defined
 *  by the Kernel module, we have chosen to document them here for clarity.
 *
 *  When referencing constants in classes inheriting from Object you do not
 *  need to use the full namespace.  For example, referencing +File+ inside
 *  +YourClass+ will find the top-level File class.
 *
 *  In the descriptions of Object's methods, the parameter <i>symbol</i> refers
 *  to a symbol, which is either a quoted string or a Symbol (such as
 *  <code>:name</code>).
 *
 *  == What's Here
 *
 *  First, what's elsewhere. Class \Object:
 *
 *  - Inherits from {class BasicObject}[rdoc-ref:BasicObject@What-27s+Here].
 *  - Includes {module Kernel}[rdoc-ref:Kernel@What-27s+Here].
 *
 *  Here, class \Object provides methods for:
 *
 *  - {Querying}[rdoc-ref:Object@Querying]
 *  - {Instance Variables}[rdoc-ref:Object@Instance+Variables]
 *  - {Other}[rdoc-ref:Object@Other]
 *
 *  === Querying
 *
 *  - #!~: Returns +true+ if +self+ does not match the given object,
 *    otherwise +false+.
 *  - #<=>: Returns 0 if +self+ and the given object +object+ are the same
 *    object, or if <tt>self == object</tt>; otherwise returns +nil+.
 *  - #===: Implements case equality, effectively the same as calling #==.
 *  - #eql?: Implements hash equality, effectively the same as calling #==.
 *  - #kind_of? (aliased as #is_a?): Returns whether given argument is an ancestor
 *    of the singleton class of +self+.
 *  - #instance_of?: Returns whether +self+ is an instance of the given class.
 *  - #instance_variable_defined?: Returns whether the given instance variable
 *    is defined in +self+.
 *  - #method: Returns the +Method+ object for the given method in +self+.
 *  - #methods: Returns an array of symbol names of public and protected methods
 *    in +self+.
 *  - #nil?: Returns +false+. (Only +nil+ responds +true+ to method <tt>nil?</tt>.)
 *  - #object_id: Returns an integer corresponding to +self+ that is unique
 *    for the current process
 *  - #private_methods: Returns an array of the symbol names
 *    of the private methods in +self+.
 *  - #protected_methods: Returns an array of the symbol names
 *    of the protected methods in +self+.
 *  - #public_method: Returns the +Method+ object for the given public method in +self+.
 *  - #public_methods: Returns an array of the symbol names
 *    of the public methods in +self+.
 *  - #respond_to?: Returns whether +self+ responds to the given method.
 *  - #singleton_class: Returns the singleton class of +self+.
 *  - #singleton_method: Returns the +Method+ object for the given singleton method
 *    in +self+.
 *  - #singleton_methods: Returns an array of the symbol names
 *    of the singleton methods in +self+.
 *
 *  - #define_singleton_method: Defines a singleton method in +self+
 *    for the given symbol method-name and block or proc.
 *  - #extend: Includes the given modules in the singleton class of +self+.
 *  - #public_send: Calls the given public method in +self+ with the given argument.
 *  - #send: Calls the given method in +self+ with the given argument.
 *
 *  === Instance Variables
 *
 *  - #instance_variable_get: Returns the value of the given instance variable
 *    in +self+, or +nil+ if the instance variable is not set.
 *  - #instance_variable_set: Sets the value of the given instance variable in +self+
 *    to the given object.
 *  - #instance_variables: Returns an array of the symbol names
 *    of the instance variables in +self+.
 *  - #remove_instance_variable: Removes the named instance variable from +self+.
 *
 *  === Other
 *
 *  - #clone:  Returns a shallow copy of +self+, including singleton class
 *    and frozen state.
 *  - #define_singleton_method: Defines a singleton method in +self+
 *    for the given symbol method-name and block or proc.
 *  - #display: Prints +self+ to the given IO stream or <tt>$stdout</tt>.
 *  - #dup: Returns a shallow unfrozen copy of +self+.
 *  - #enum_for (aliased as #to_enum): Returns an Enumerator for +self+
 *    using the using the given method, arguments, and block.
 *  - #extend: Includes the given modules in the singleton class of +self+.
 *  - #freeze: Prevents further modifications to +self+.
 *  - #hash: Returns the integer hash value for +self+.
 *  - #inspect: Returns a human-readable  string representation of +self+.
 *  - #itself: Returns +self+.
 *  - #method_missing: Method called when an undefined method is called on +self+.
 *  - #public_send: Calls the given public method in +self+ with the given argument.
 *  - #send: Calls the given method in +self+ with the given argument.
 *  - #to_s: Returns a string representation of +self+.
 *
 */

void
InitVM_Object(void)
{
    Init_class_hierarchy();

#if 0
    // teach RDoc about these classes
    rb_cBasicObject = rb_define_class("BasicObject", Qnil);
    rb_cObject = rb_define_class("Object", rb_cBasicObject);
    rb_cModule = rb_define_class("Module", rb_cObject);
    rb_cClass =  rb_define_class("Class",  rb_cModule);
    rb_cRefinement = rb_define_class("Refinement", rb_cModule);
#endif

    rb_define_private_method(rb_cBasicObject, "initialize", rb_obj_initialize, 0);
    rb_define_alloc_func(rb_cBasicObject, rb_class_allocate_instance);
    rb_define_method(rb_cBasicObject, "==", rb_obj_equal, 1);
    rb_define_method(rb_cBasicObject, "equal?", rb_obj_equal, 1);
    rb_define_method(rb_cBasicObject, "!", rb_obj_not, 0);
    rb_define_method(rb_cBasicObject, "!=", rb_obj_not_equal, 1);

    rb_define_private_method(rb_cBasicObject, "singleton_method_added", rb_obj_singleton_method_added, 1);
    rb_define_private_method(rb_cBasicObject, "singleton_method_removed", rb_obj_singleton_method_removed, 1);
    rb_define_private_method(rb_cBasicObject, "singleton_method_undefined", rb_obj_singleton_method_undefined, 1);

    /* Document-module: Kernel
     *
     * The Kernel module is included by class Object, so its methods are
     * available in every Ruby object.
     *
     * The Kernel instance methods are documented in class Object while the
     * module methods are documented here.  These methods are called without a
     * receiver and thus can be called in functional form:
     *
     *   sprintf "%.1f", 1.234 #=> "1.2"
     *
     * == What's Here
     *
     * Module \Kernel provides methods that are useful for:
     *
     * - {Converting}[rdoc-ref:Kernel@Converting]
     * - {Querying}[rdoc-ref:Kernel@Querying]
     * - {Exiting}[rdoc-ref:Kernel@Exiting]
     * - {Exceptions}[rdoc-ref:Kernel@Exceptions]
     * - {IO}[rdoc-ref:Kernel@IO]
     * - {Procs}[rdoc-ref:Kernel@Procs]
     * - {Tracing}[rdoc-ref:Kernel@Tracing]
     * - {Subprocesses}[rdoc-ref:Kernel@Subprocesses]
     * - {Loading}[rdoc-ref:Kernel@Loading]
     * - {Yielding}[rdoc-ref:Kernel@Yielding]
     * - {Random Values}[rdoc-ref:Kernel@Random+Values]
     * - {Other}[rdoc-ref:Kernel@Other]
     *
     * === Converting
     *
     * - #Array: Returns an Array based on the given argument.
     * - #Complex: Returns a Complex based on the given arguments.
     * - #Float: Returns a Float based on the given arguments.
     * - #Hash: Returns a Hash based on the given argument.
     * - #Integer: Returns an Integer based on the given arguments.
     * - #Rational: Returns a Rational based on the given arguments.
     * - #String: Returns a String based on the given argument.
     *
     * === Querying
     *
     * - #__callee__: Returns the called name of the current method as a symbol.
     * - #__dir__: Returns the path to the directory from which the current
     *   method is called.
     * - #__method__: Returns the name of the current method as a symbol.
     * - #autoload?: Returns the file to be loaded when the given module is referenced.
     * - #binding: Returns a Binding for the context at the point of call.
     * - #block_given?: Returns +true+ if a block was passed to the calling method.
     * - #caller: Returns the current execution stack as an array of strings.
     * - #caller_locations: Returns the current execution stack as an array
     *   of Thread::Backtrace::Location objects.
     * - #class: Returns the class of +self+.
     * - #frozen?: Returns whether +self+ is frozen.
     * - #global_variables: Returns an array of global variables as symbols.
     * - #local_variables: Returns an array of local variables as symbols.
     * - #test: Performs specified tests on the given single file or pair of files.
     *
     * === Exiting
     *
     * - #abort: Exits the current process after printing the given arguments.
     * - #at_exit: Executes the given block when the process exits.
     * - #exit: Exits the current process after calling any registered
     *   +at_exit+ handlers.
     * - #exit!: Exits the current process without calling any registered
     *   +at_exit+ handlers.
     *
     * === Exceptions
     *
     * - #catch: Executes the given block, possibly catching a thrown object.
     * - #raise (aliased as #fail): Raises an exception based on the given arguments.
     * - #throw: Returns from the active catch block waiting for the given tag.
     *
     *
     * === \IO
     *
     * - ::pp: Prints the given objects in pretty form.
     * - #gets: Returns and assigns to <tt>$_</tt> the next line from the current input.
     * - #open: Creates an IO object connected to the given stream, file, or subprocess.
     * - #p:  Prints the given objects' inspect output to the standard output.
     * - #print: Prints the given objects to standard output without a newline.
     * - #printf: Prints the string resulting from applying the given format string
     *   to any additional arguments.
     * - #putc: Equivalent to <tt>$stdout.putc(object)</tt> for the given object.
     * - #puts: Equivalent to <tt>$stdout.puts(*objects)</tt> for the given objects.
     * - #readline: Similar to #gets, but raises an exception at the end of file.
     * - #readlines: Returns an array of the remaining lines from the current input.
     * - #select: Same as IO.select.
     *
     * === Procs
     *
     * - #lambda: Returns a lambda proc for the given block.
     * - #proc: Returns a new Proc; equivalent to Proc.new.
     *
     * === Tracing
     *
     * - #set_trace_func: Sets the given proc as the handler for tracing,
     *   or disables tracing if given +nil+.
     * - #trace_var: Starts tracing assignments to the given global variable.
     * - #untrace_var: Disables tracing of assignments to the given global variable.
     *
     * === Subprocesses
     *
     * - {\`command`}[rdoc-ref:Kernel#`]: Returns the standard output of running
     *   +command+ in a subshell.
     * - #exec: Replaces current process with a new process.
     * - #fork: Forks the current process into two processes.
     * - #spawn: Executes the given command and returns its pid without waiting
     *   for completion.
     * - #system: Executes the given command in a subshell.
     *
     * === Loading
     *
     * - #autoload: Registers the given file to be loaded when the given constant
     *   is first referenced.
     * - #load: Loads the given Ruby file.
     * - #require: Loads the given Ruby file unless it has already been loaded.
     * - #require_relative: Loads the Ruby file path relative to the calling file,
     *   unless it has already been loaded.
     *
     * === Yielding
     *
     * - #tap: Yields +self+ to the given block; returns +self+.
     * - #then (aliased as #yield_self): Yields +self+ to the block
     *   and returns the result of the block.
     *
     * === \Random Values
     *
     * - #rand: Returns a pseudo-random floating point number
     *   strictly between 0.0 and 1.0.
     * - #srand: Seeds the pseudo-random number generator with the given number.
     *
     * === Other
     *
     * - #eval: Evaluates the given string as Ruby code.
     * - #loop: Repeatedly executes the given block.
     * - #sleep: Suspends the current thread for the given number of seconds.
     * - #sprintf (aliased as #format): Returns the string resulting from applying
     *   the given format string to any additional arguments.
     * - #syscall: Runs an operating system call.
     * - #trap: Specifies the handling of system signals.
     * - #warn: Issue a warning based on the given messages and options.
     *
     */
    rb_mKernel = rb_define_module("Kernel");
    rb_include_module(rb_cObject, rb_mKernel);
    rb_define_private_method(rb_cClass, "inherited", rb_obj_class_inherited, 1);
    rb_define_private_method(rb_cModule, "included", rb_obj_mod_included, 1);
    rb_define_private_method(rb_cModule, "extended", rb_obj_mod_extended, 1);
    rb_define_private_method(rb_cModule, "prepended", rb_obj_mod_prepended, 1);
    rb_define_private_method(rb_cModule, "method_added", rb_obj_mod_method_added, 1);
    rb_define_private_method(rb_cModule, "const_added", rb_obj_mod_const_added, 1);
    rb_define_private_method(rb_cModule, "method_removed", rb_obj_mod_method_removed, 1);
    rb_define_private_method(rb_cModule, "method_undefined", rb_obj_mod_method_undefined, 1);

    rb_define_method(rb_mKernel, "nil?", rb_false, 0);
    rb_define_method(rb_mKernel, "===", case_equal, 1);
    rb_define_method(rb_mKernel, "!~", rb_obj_not_match, 1);
    rb_define_method(rb_mKernel, "eql?", rb_obj_equal, 1);
    rb_define_method(rb_mKernel, "hash", rb_obj_hash, 0); /* in hash.c */
    rb_define_method(rb_mKernel, "<=>", rb_obj_cmp, 1);

    rb_define_method(rb_mKernel, "singleton_class", rb_obj_singleton_class, 0);
    rb_define_method(rb_mKernel, "dup", rb_obj_dup, 0);
    rb_define_method(rb_mKernel, "itself", rb_obj_itself, 0);
    rb_define_method(rb_mKernel, "initialize_copy", rb_obj_init_copy, 1);
    rb_define_method(rb_mKernel, "initialize_dup", rb_obj_init_dup_clone, 1);
    rb_define_method(rb_mKernel, "initialize_clone", rb_obj_init_clone, -1);

    rb_define_method(rb_mKernel, "freeze", rb_obj_freeze, 0);

    rb_define_method(rb_mKernel, "to_s", rb_any_to_s, 0);
    rb_define_method(rb_mKernel, "inspect", rb_obj_inspect, 0);
    rb_define_method(rb_mKernel, "methods", rb_obj_methods, -1); /* in class.c */
    rb_define_method(rb_mKernel, "singleton_methods", rb_obj_singleton_methods, -1); /* in class.c */
    rb_define_method(rb_mKernel, "protected_methods", rb_obj_protected_methods, -1); /* in class.c */
    rb_define_method(rb_mKernel, "private_methods", rb_obj_private_methods, -1); /* in class.c */
    rb_define_method(rb_mKernel, "public_methods", rb_obj_public_methods, -1); /* in class.c */
    rb_define_method(rb_mKernel, "instance_variables", rb_obj_instance_variables, 0); /* in variable.c */
    rb_define_method(rb_mKernel, "instance_variable_get", rb_obj_ivar_get, 1);
    rb_define_method(rb_mKernel, "instance_variable_set", rb_obj_ivar_set_m, 2);
    rb_define_method(rb_mKernel, "instance_variable_defined?", rb_obj_ivar_defined, 1);
    rb_define_method(rb_mKernel, "remove_instance_variable",
                     rb_obj_remove_instance_variable, 1); /* in variable.c */

    rb_define_method(rb_mKernel, "instance_of?", rb_obj_is_instance_of, 1);
    rb_define_method(rb_mKernel, "kind_of?", rb_obj_is_kind_of, 1);
    rb_define_method(rb_mKernel, "is_a?", rb_obj_is_kind_of, 1);

    rb_define_global_function("sprintf", f_sprintf, -1);
    rb_define_global_function("format", f_sprintf, -1);

    rb_define_global_function("String", rb_f_string, 1);
    rb_define_global_function("Array", rb_f_array, 1);
    rb_define_global_function("Hash", rb_f_hash, 1);

    rb_cNilClass = rb_define_class("NilClass", rb_cObject);
    rb_cNilClass_to_s = rb_fstring_enc_lit("", rb_usascii_encoding());
    rb_vm_register_global_object(rb_cNilClass_to_s);
    rb_define_method(rb_cNilClass, "to_s", rb_nil_to_s, 0);
    rb_define_method(rb_cNilClass, "to_a", nil_to_a, 0);
    rb_define_method(rb_cNilClass, "to_h", nil_to_h, 0);
    rb_define_method(rb_cNilClass, "inspect", nil_inspect, 0);
    rb_define_method(rb_cNilClass, "=~", nil_match, 1);
    rb_define_method(rb_cNilClass, "&", false_and, 1);
    rb_define_method(rb_cNilClass, "|", false_or, 1);
    rb_define_method(rb_cNilClass, "^", false_xor, 1);
    rb_define_method(rb_cNilClass, "===", case_equal, 1);

    rb_define_method(rb_cNilClass, "nil?", rb_true, 0);
    rb_undef_alloc_func(rb_cNilClass);
    rb_undef_method(CLASS_OF(rb_cNilClass), "new");

    rb_define_method(rb_cModule, "freeze", rb_mod_freeze, 0);
    rb_define_method(rb_cModule, "===", rb_mod_eqq, 1);
    rb_define_method(rb_cModule, "==", rb_obj_equal, 1);
    rb_define_method(rb_cModule, "<=>",  rb_mod_cmp, 1);
    rb_define_method(rb_cModule, "<",  rb_mod_lt, 1);
    rb_define_method(rb_cModule, "<=", rb_class_inherited_p, 1);
    rb_define_method(rb_cModule, ">",  rb_mod_gt, 1);
    rb_define_method(rb_cModule, ">=", rb_mod_ge, 1);
    rb_define_method(rb_cModule, "initialize_copy", rb_mod_init_copy, 1); /* in class.c */
    rb_define_method(rb_cModule, "to_s", rb_mod_to_s, 0);
    rb_define_alias(rb_cModule, "inspect", "to_s");
    rb_define_method(rb_cModule, "included_modules", rb_mod_included_modules, 0); /* in class.c */
    rb_define_method(rb_cModule, "include?", rb_mod_include_p, 1); /* in class.c */
    rb_define_method(rb_cModule, "name", rb_mod_name, 0);  /* in variable.c */
    rb_define_method(rb_cModule, "set_temporary_name", rb_mod_set_temporary_name, 1);  /* in variable.c */
    rb_define_method(rb_cModule, "ancestors", rb_mod_ancestors, 0); /* in class.c */

    rb_define_method(rb_cModule, "attr", rb_mod_attr, -1);
    rb_define_method(rb_cModule, "attr_reader", rb_mod_attr_reader, -1);
    rb_define_method(rb_cModule, "attr_writer", rb_mod_attr_writer, -1);
    rb_define_method(rb_cModule, "attr_accessor", rb_mod_attr_accessor, -1);

    rb_define_alloc_func(rb_cModule, rb_module_s_alloc);
    rb_undef_method(rb_singleton_class(rb_cModule), "allocate");
    rb_define_method(rb_cModule, "initialize", rb_mod_initialize, 0);
    rb_define_method(rb_cModule, "initialize_clone", rb_mod_initialize_clone, -1);
    rb_define_method(rb_cModule, "instance_methods", rb_class_instance_methods, -1); /* in class.c */
    rb_define_method(rb_cModule, "public_instance_methods",
                     rb_class_public_instance_methods, -1);    /* in class.c */
    rb_define_method(rb_cModule, "protected_instance_methods",
                     rb_class_protected_instance_methods, -1); /* in class.c */
    rb_define_method(rb_cModule, "private_instance_methods",
                     rb_class_private_instance_methods, -1);   /* in class.c */
    rb_define_method(rb_cModule, "undefined_instance_methods",
                     rb_class_undefined_instance_methods, 0); /* in class.c */

    rb_define_method(rb_cModule, "constants", rb_mod_constants, -1); /* in variable.c */
    rb_define_method(rb_cModule, "const_get", rb_mod_const_get, -1);
    rb_define_method(rb_cModule, "const_set", rb_mod_const_set, 2);
    rb_define_method(rb_cModule, "const_defined?", rb_mod_const_defined, -1);
    rb_define_method(rb_cModule, "const_source_location", rb_mod_const_source_location, -1);
    rb_define_private_method(rb_cModule, "remove_const",
                             rb_mod_remove_const, 1); /* in variable.c */
    rb_define_method(rb_cModule, "const_missing",
                     rb_mod_const_missing, 1); /* in variable.c */
    rb_define_method(rb_cModule, "class_variables",
                     rb_mod_class_variables, -1); /* in variable.c */
    rb_define_method(rb_cModule, "remove_class_variable",
                     rb_mod_remove_cvar, 1); /* in variable.c */
    rb_define_method(rb_cModule, "class_variable_get", rb_mod_cvar_get, 1);
    rb_define_method(rb_cModule, "class_variable_set", rb_mod_cvar_set, 2);
    rb_define_method(rb_cModule, "class_variable_defined?", rb_mod_cvar_defined, 1);
    rb_define_method(rb_cModule, "public_constant", rb_mod_public_constant, -1); /* in variable.c */
    rb_define_method(rb_cModule, "private_constant", rb_mod_private_constant, -1); /* in variable.c */
    rb_define_method(rb_cModule, "deprecate_constant", rb_mod_deprecate_constant, -1); /* in variable.c */
    rb_define_method(rb_cModule, "singleton_class?", rb_mod_singleton_p, 0);

    rb_define_method(rb_singleton_class(rb_cClass), "allocate", rb_class_alloc_m, 0);
    rb_define_method(rb_cClass, "allocate", rb_class_alloc_m, 0);
    rb_define_method(rb_cClass, "new", rb_class_new_instance_pass_kw, -1);
    rb_define_method(rb_cClass, "initialize", rb_class_initialize, -1);
    rb_define_method(rb_cClass, "superclass", rb_class_superclass, 0);
    rb_define_method(rb_cClass, "subclasses", rb_class_subclasses, 0); /* in class.c */
    rb_define_method(rb_cClass, "attached_object", rb_class_attached_object, 0); /* in class.c */
    rb_define_alloc_func(rb_cClass, rb_class_s_alloc);
    rb_undef_method(rb_cClass, "extend_object");
    rb_undef_method(rb_cClass, "append_features");
    rb_undef_method(rb_cClass, "prepend_features");

    rb_cTrueClass = rb_define_class("TrueClass", rb_cObject);
    rb_cTrueClass_to_s = rb_fstring_enc_lit("true", rb_usascii_encoding());
    rb_vm_register_global_object(rb_cTrueClass_to_s);
    rb_define_method(rb_cTrueClass, "to_s", rb_true_to_s, 0);
    rb_define_alias(rb_cTrueClass, "inspect", "to_s");
    rb_define_method(rb_cTrueClass, "&", true_and, 1);
    rb_define_method(rb_cTrueClass, "|", true_or, 1);
    rb_define_method(rb_cTrueClass, "^", true_xor, 1);
    rb_define_method(rb_cTrueClass, "===", case_equal, 1);
    rb_undef_alloc_func(rb_cTrueClass);
    rb_undef_method(CLASS_OF(rb_cTrueClass), "new");

    rb_cFalseClass = rb_define_class("FalseClass", rb_cObject);
    rb_cFalseClass_to_s = rb_fstring_enc_lit("false", rb_usascii_encoding());
    rb_vm_register_global_object(rb_cFalseClass_to_s);
    rb_define_method(rb_cFalseClass, "to_s", rb_false_to_s, 0);
    rb_define_alias(rb_cFalseClass, "inspect", "to_s");
    rb_define_method(rb_cFalseClass, "&", false_and, 1);
    rb_define_method(rb_cFalseClass, "|", false_or, 1);
    rb_define_method(rb_cFalseClass, "^", false_xor, 1);
    rb_define_method(rb_cFalseClass, "===", case_equal, 1);
    rb_undef_alloc_func(rb_cFalseClass);
    rb_undef_method(CLASS_OF(rb_cFalseClass), "new");
}

#include "kernel.rbinc"
#include "nilclass.rbinc"

void
Init_Object(void)
{
    id_dig = rb_intern_const("dig");
    InitVM(Object);
}

/*!
 * \}
 */