array.c

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

 array.c -

 $Author$
 created at: Fri Aug 6 09:46:12 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/ruby.h"
#include "ruby/util.h"
#include "ruby/st.h"
#include "ruby/encoding.h"
#include "internal.h"

#ifndef ARRAY_DEBUG
# define NDEBUG
#endif
#include <assert.h>

#define numberof(array) (int)(sizeof(array) / sizeof((array)[0]))

VALUE rb_cArray;

static ID id_cmp;

#define ARY_DEFAULT_SIZE 16
#define ARY_MAX_SIZE (LONG_MAX / (int)sizeof(VALUE))

void
rb_mem_clear(register VALUE *mem, register long size)
{
 while (size--) {
	*mem++ = Qnil;
 }
}

static inline void
memfill(register VALUE *mem, register long size, register VALUE val)
{
 while (size--) {
	*mem++ = val;
 }
}

# define ARY_SHARED_P(ary) \
 (assert(!FL_TEST((ary), ELTS_SHARED) || !FL_TEST((ary), RARRAY_EMBED_FLAG)), \
 FL_TEST((ary),ELTS_SHARED)!=0)
# define ARY_EMBED_P(ary) \
 (assert(!FL_TEST((ary), ELTS_SHARED) || !FL_TEST((ary), RARRAY_EMBED_FLAG)), \
 FL_TEST((ary), RARRAY_EMBED_FLAG)!=0)

#define ARY_HEAP_PTR(a) (assert(!ARY_EMBED_P(a)), RARRAY(a)->as.heap.ptr)
#define ARY_HEAP_LEN(a) (assert(!ARY_EMBED_P(a)), RARRAY(a)->as.heap.len)
#define ARY_EMBED_PTR(a) (assert(ARY_EMBED_P(a)), RARRAY(a)->as.ary)
#define ARY_EMBED_LEN(a) \
 (assert(ARY_EMBED_P(a)), \
 (long)((RBASIC(a)->flags >> RARRAY_EMBED_LEN_SHIFT) & \
	 (RARRAY_EMBED_LEN_MASK >> RARRAY_EMBED_LEN_SHIFT)))

#define ARY_OWNS_HEAP_P(a) (!FL_TEST((a), ELTS_SHARED|RARRAY_EMBED_FLAG))
#define FL_SET_EMBED(a) do { \
 assert(!ARY_SHARED_P(a)); \
 assert(!OBJ_FROZEN(a)); \
 FL_SET((a), RARRAY_EMBED_FLAG); \
} while (0)
#define FL_UNSET_EMBED(ary) FL_UNSET((ary), RARRAY_EMBED_FLAG|RARRAY_EMBED_LEN_MASK)
#define FL_SET_SHARED(ary) do { \
 assert(!ARY_EMBED_P(ary)); \
 FL_SET((ary), ELTS_SHARED); \
} while (0)
#define FL_UNSET_SHARED(ary) FL_UNSET((ary), ELTS_SHARED)

#define ARY_SET_PTR(ary, p) do { \
 assert(!ARY_EMBED_P(ary)); \
 assert(!OBJ_FROZEN(ary)); \
 RARRAY(ary)->as.heap.ptr = (p); \
} while (0)
#define ARY_SET_EMBED_LEN(ary, n) do { \
 long tmp_n = (n); \
 assert(ARY_EMBED_P(ary)); \
 assert(!OBJ_FROZEN(ary)); \
 RBASIC(ary)->flags &= ~RARRAY_EMBED_LEN_MASK; \
 RBASIC(ary)->flags |= (tmp_n) << RARRAY_EMBED_LEN_SHIFT; \
} while (0)
#define ARY_SET_HEAP_LEN(ary, n) do { \
 assert(!ARY_EMBED_P(ary)); \
 RARRAY(ary)->as.heap.len = (n); \
} while (0)
#define ARY_SET_LEN(ary, n) do { \
 if (ARY_EMBED_P(ary)) { \
 ARY_SET_EMBED_LEN((ary), (n)); \
 } \
 else { \
 ARY_SET_HEAP_LEN((ary), (n)); \
 } \
 assert(RARRAY_LEN(ary) == (n)); \
} while (0)
#define ARY_INCREASE_PTR(ary, n) do { \
 assert(!ARY_EMBED_P(ary)); \
 assert(!OBJ_FROZEN(ary)); \
 RARRAY(ary)->as.heap.ptr += (n); \
} while (0)
#define ARY_INCREASE_LEN(ary, n) do { \
 assert(!OBJ_FROZEN(ary)); \
 if (ARY_EMBED_P(ary)) { \
 ARY_SET_EMBED_LEN((ary), RARRAY_LEN(ary)+(n)); \
 } \
 else { \
 RARRAY(ary)->as.heap.len += (n); \
 } \
} while (0)

#define ARY_CAPA(ary) (ARY_EMBED_P(ary) ? RARRAY_EMBED_LEN_MAX : \
		 ARY_SHARED_ROOT_P(ary) ? RARRAY_LEN(ary) : RARRAY(ary)->as.heap.aux.capa)
#define ARY_SET_CAPA(ary, n) do { \
 assert(!ARY_EMBED_P(ary)); \
 assert(!ARY_SHARED_P(ary)); \
 assert(!OBJ_FROZEN(ary)); \
 RARRAY(ary)->as.heap.aux.capa = (n); \
} while (0)

#define ARY_SHARED(ary) (assert(ARY_SHARED_P(ary)), RARRAY(ary)->as.heap.aux.shared)
#define ARY_SET_SHARED(ary, value) do { \
 assert(!ARY_EMBED_P(ary)); \
 assert(ARY_SHARED_P(ary)); \
 assert(ARY_SHARED_ROOT_P(value)); \
 RARRAY(ary)->as.heap.aux.shared = (value); \
} while (0)
#define RARRAY_SHARED_ROOT_FLAG FL_USER5
#define ARY_SHARED_ROOT_P(ary) (FL_TEST((ary), RARRAY_SHARED_ROOT_FLAG))
#define ARY_SHARED_NUM(ary) \
 (assert(ARY_SHARED_ROOT_P(ary)), RARRAY(ary)->as.heap.aux.capa)
#define ARY_SET_SHARED_NUM(ary, value) do { \
 assert(ARY_SHARED_ROOT_P(ary)); \
 RARRAY(ary)->as.heap.aux.capa = (value); \
} while (0)
#define FL_SET_SHARED_ROOT(ary) do { \
 assert(!ARY_EMBED_P(ary)); \
 FL_SET((ary), RARRAY_SHARED_ROOT_FLAG); \
} while (0)

static void
ary_resize_capa(VALUE ary, long capacity)
{
 assert(RARRAY_LEN(ary) <= capacity);
 assert(!OBJ_FROZEN(ary));
 assert(!ARY_SHARED_P(ary));
 if (capacity > RARRAY_EMBED_LEN_MAX) {
 if (ARY_EMBED_P(ary)) {
 long len = ARY_EMBED_LEN(ary);
 VALUE *ptr = ALLOC_N(VALUE, (capacity));
 MEMCPY(ptr, ARY_EMBED_PTR(ary), VALUE, len);
 FL_UNSET_EMBED(ary);
 ARY_SET_PTR(ary, ptr);
 ARY_SET_HEAP_LEN(ary, len);
 }
 else {
 REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, (capacity));
 }
 ARY_SET_CAPA(ary, (capacity));
 }
 else {
 if (!ARY_EMBED_P(ary)) {
 long len = RARRAY_LEN(ary);
 VALUE *ptr = RARRAY_PTR(ary);
 if (len > capacity) len = capacity;
 MEMCPY(RARRAY(ary)->as.ary, ptr, VALUE, len);
 FL_SET_EMBED(ary);
 ARY_SET_LEN(ary, len);
 xfree(ptr);
 }
 }
}

static void
ary_double_capa(VALUE ary, long min)
{
 long new_capa = ARY_CAPA(ary) / 2;

 if (new_capa < ARY_DEFAULT_SIZE) {
	new_capa = ARY_DEFAULT_SIZE;
 }
 if (new_capa >= ARY_MAX_SIZE - min) {
	new_capa = (ARY_MAX_SIZE - min) / 2;
 }
 new_capa += min;
 ary_resize_capa(ary, new_capa);
}

static void
rb_ary_decrement_share(VALUE shared)
{
 if (shared) {
	long num = ARY_SHARED_NUM(shared) - 1;
	if (num == 0) {
	 rb_ary_free(shared);
	 rb_gc_force_recycle(shared);
	}
	else if (num > 0) {
	 ARY_SET_SHARED_NUM(shared, num);
	}
 }
}

static void
rb_ary_unshare(VALUE ary)
{
 VALUE shared = RARRAY(ary)->as.heap.aux.shared;
 rb_ary_decrement_share(shared);
 FL_UNSET_SHARED(ary);
}

static inline void
rb_ary_unshare_safe(VALUE ary)
{
 if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
	rb_ary_unshare(ary);
 }
}

static VALUE
rb_ary_increment_share(VALUE shared)
{
 long num = ARY_SHARED_NUM(shared);
 if (num >= 0) {
	ARY_SET_SHARED_NUM(shared, num + 1);
 }
 return shared;
}

static void
rb_ary_set_shared(VALUE ary, VALUE shared)
{
 rb_ary_increment_share(shared);
 FL_SET_SHARED(ary);
 ARY_SET_SHARED(ary, shared);
}

static inline void
rb_ary_modify_check(VALUE ary)
{
 rb_check_frozen(ary);
 if (!OBJ_UNTRUSTED(ary) && rb_safe_level() >= 4)
	rb_raise(rb_eSecurityError, "Insecure: can't modify array");
}

void
rb_ary_modify(VALUE ary)
{
 rb_ary_modify_check(ary);
 if (ARY_SHARED_P(ary)) {
 long len = RARRAY_LEN(ary);
 if (len <= RARRAY_EMBED_LEN_MAX) {
 VALUE *ptr = ARY_HEAP_PTR(ary);
 VALUE shared = ARY_SHARED(ary);
 FL_UNSET_SHARED(ary);
 FL_SET_EMBED(ary);
 MEMCPY(ARY_EMBED_PTR(ary), ptr, VALUE, len);
 rb_ary_decrement_share(shared);
 ARY_SET_EMBED_LEN(ary, len);
 }
 else {
 VALUE *ptr = ALLOC_N(VALUE, len);
 MEMCPY(ptr, RARRAY_PTR(ary), VALUE, len);
 rb_ary_unshare(ary);
 ARY_SET_CAPA(ary, len);
 ARY_SET_PTR(ary, ptr);
 }
 }
}

VALUE
rb_ary_freeze(VALUE ary)
{
 return rb_obj_freeze(ary);
}

/*
 * call-seq:
 * ary.frozen? -> true or false
 *
 * Return <code>true</code> if this array is frozen (or temporarily frozen
 * while being sorted).
 */

static VALUE
rb_ary_frozen_p(VALUE ary)
{
 if (OBJ_FROZEN(ary)) return Qtrue;
 return Qfalse;
}

static VALUE
ary_alloc(VALUE klass)
{
 NEWOBJ(ary, struct RArray);
 OBJSETUP(ary, klass, T_ARRAY);
 FL_SET_EMBED((VALUE)ary);
 ARY_SET_EMBED_LEN((VALUE)ary, 0);

 return (VALUE)ary;
}

static VALUE
ary_new(VALUE klass, long capa)
{
 VALUE ary;

 if (capa < 0) {
	rb_raise(rb_eArgError, "negative array size (or size too big)");
 }
 if (capa > ARY_MAX_SIZE) {
	rb_raise(rb_eArgError, "array size too big");
 }
 ary = ary_alloc(klass);
 if (capa > RARRAY_EMBED_LEN_MAX) {
 FL_UNSET_EMBED(ary);
 ARY_SET_PTR(ary, ALLOC_N(VALUE, capa));
 ARY_SET_CAPA(ary, capa);
 ARY_SET_HEAP_LEN(ary, 0);
 }

 return ary;
}

VALUE
rb_ary_new2(long capa)
{
 return ary_new(rb_cArray, capa);
}


VALUE
rb_ary_new(void)
{
 return rb_ary_new2(RARRAY_EMBED_LEN_MAX);
}

#include <stdarg.h>

VALUE
rb_ary_new3(long n, ...)
{
 va_list ar;
 VALUE ary;
 long i;

 ary = rb_ary_new2(n);

 va_start(ar, n);
 for (i=0; i<n; i++) {
	RARRAY_PTR(ary)[i] = va_arg(ar, VALUE);
 }
 va_end(ar);

 ARY_SET_LEN(ary, n);
 return ary;
}

VALUE
rb_ary_new4(long n, const VALUE *elts)
{
 VALUE ary;

 ary = rb_ary_new2(n);
 if (n > 0 && elts) {
	MEMCPY(RARRAY_PTR(ary), elts, VALUE, n);
	ARY_SET_LEN(ary, n);
 }

 return ary;
}

VALUE
rb_ary_tmp_new(long capa)
{
 return ary_new(0, capa);
}

void
rb_ary_free(VALUE ary)
{
 if (ARY_OWNS_HEAP_P(ary)) {
	xfree(ARY_HEAP_PTR(ary));
 }
}

RUBY_FUNC_EXPORTED size_t
rb_ary_memsize(VALUE ary)
{
 if (ARY_OWNS_HEAP_P(ary)) {
	return RARRAY(ary)->as.heap.aux.capa * sizeof(VALUE);
 }
 else {
	return 0;
 }
}

static inline void
ary_discard(VALUE ary)
{
 rb_ary_free(ary);
 RBASIC(ary)->flags |= RARRAY_EMBED_FLAG;
 RBASIC(ary)->flags &= ~RARRAY_EMBED_LEN_MASK;
}

static VALUE
ary_make_shared(VALUE ary)
{
 assert(!ARY_EMBED_P(ary));
 if (ARY_SHARED_P(ary)) {
	return ARY_SHARED(ary);
 }
 else if (ARY_SHARED_ROOT_P(ary)) {
	return ary;
 }
 else if (OBJ_FROZEN(ary)) {
	ary_resize_capa(ary, ARY_HEAP_LEN(ary));
	FL_SET_SHARED_ROOT(ary);
	ARY_SET_SHARED_NUM(ary, 1);
	return ary;
 }
 else {
	NEWOBJ(shared, struct RArray);
	OBJSETUP(shared, 0, T_ARRAY);
 FL_UNSET_EMBED(shared);

 ARY_SET_LEN((VALUE)shared, RARRAY_LEN(ary));
 ARY_SET_PTR((VALUE)shared, RARRAY_PTR(ary));
	FL_SET_SHARED_ROOT(shared);
	ARY_SET_SHARED_NUM((VALUE)shared, 1);
	FL_SET_SHARED(ary);
	ARY_SET_SHARED(ary, (VALUE)shared);
	OBJ_FREEZE(shared);
	return (VALUE)shared;
 }
}


static VALUE
ary_make_substitution(VALUE ary)
{
 if (RARRAY_LEN(ary) <= RARRAY_EMBED_LEN_MAX) {
 VALUE subst = rb_ary_new2(RARRAY_LEN(ary));
 MEMCPY(ARY_EMBED_PTR(subst), RARRAY_PTR(ary), VALUE, RARRAY_LEN(ary));
 ARY_SET_EMBED_LEN(subst, RARRAY_LEN(ary));
 return subst;
 }
 else {
 return rb_ary_increment_share(ary_make_shared(ary));
 }
}

VALUE
rb_assoc_new(VALUE car, VALUE cdr)
{
 return rb_ary_new3(2, car, cdr);
}

static VALUE
to_ary(VALUE ary)
{
 return rb_convert_type(ary, T_ARRAY, "Array", "to_ary");
}

VALUE
rb_check_array_type(VALUE ary)
{
 return rb_check_convert_type(ary, T_ARRAY, "Array", "to_ary");
}

/*
 * call-seq:
 * Array.try_convert(obj) -> array or nil
 *
 * Tries to convert +obj+ into an array, using +to_ary+ method. Returns the
 * converted array or +nil+ if +obj+ cannot be converted for any reason.
 * This method can be used to check if an argument is an array.
 *
 * Array.try_convert([1]) #=> [1]
 * Array.try_convert("1") #=> nil
 *
 * if tmp = Array.try_convert(arg)
 * # the argument is an array
 * elsif tmp = String.try_convert(arg)
 * # the argument is a string
 * end
 *
 */

static VALUE
rb_ary_s_try_convert(VALUE dummy, VALUE ary)
{
 return rb_check_array_type(ary);
}

/*
 * call-seq:
 * Array.new(size=0, obj=nil)
 * Array.new(array)
 * Array.new(size) {|index| block }
 *
 * Returns a new array.
 *
 * In the first form, if no arguments are sent, the new array will be empty.
 * When a +size+ and an optional +obj+ are sent, an array is created with
 * +size+ copies of +obj+. Take notice that all elements will reference the
 * same object +obj+.
 *
 * The second form creates a copy of the array passed as a parameter (the
 * array is generated by calling to_ary on the parameter).
 *
 * first_array = ["Matz", "Guido"]
 *
 * second_array = Array.new(first_array) #=> ["Matz", "Guido"]
 *
 * first_array.equal? second_array #=> false
 *
 * In the last form, an array of the given size is created. Each element in
 * this array is created by passing the element's index to the given block
 * and storing the return value.
 *
 * Array.new(3){ |index| index ** 2 }
 * # => [0, 1, 4]
 *
 * == Common gotchas
 *
 * When sending the second parameter, the same object will be used as the
 * value for all the array elements:
 *
 * a = Array.new(2, Hash.new)
 * # => [{}, {}]
 *
 * a[0]['cat'] = 'feline'
 * a # => [{"cat"=>"feline"}, {"cat"=>"feline"}]
 *
 * a[1]['cat'] = 'Felix'
 * a # => [{"cat"=>"Felix"}, {"cat"=>"Felix"}]
 *
 * Since all the Array elements store the same hash, changes to one of them
 * will affect them all.
 *
 * If multiple copies are what you want, you should use the block
 * version which uses the result of that block each time an element
 * of the array needs to be initialized:
 *
 * a = Array.new(2) { Hash.new }
 * a[0]['cat'] = 'feline'
 * a # => [{"cat"=>"feline"}, {}]
 *
 */

static VALUE
rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
{
 long len;
 VALUE size, val;

 rb_ary_modify(ary);
 if (argc == 0) {
	if (ARY_OWNS_HEAP_P(ary) && RARRAY_PTR(ary)) {
	 xfree(RARRAY_PTR(ary));
	}
 rb_ary_unshare_safe(ary);
 FL_SET_EMBED(ary);
	ARY_SET_EMBED_LEN(ary, 0);
	if (rb_block_given_p()) {
	 rb_warning("given block not used");
	}
	return ary;
 }
 rb_scan_args(argc, argv, "02", &size, &val);
 if (argc == 1 && !FIXNUM_P(size)) {
	val = rb_check_array_type(size);
	if (!NIL_P(val)) {
	 rb_ary_replace(ary, val);
	 return ary;
	}
 }

 len = NUM2LONG(size);
 if (len < 0) {
	rb_raise(rb_eArgError, "negative array size");
 }
 if (len > ARY_MAX_SIZE) {
	rb_raise(rb_eArgError, "array size too big");
 }
 rb_ary_modify(ary);
 ary_resize_capa(ary, len);
 if (rb_block_given_p()) {
	long i;

	if (argc == 2) {
	 rb_warn("block supersedes default value argument");
	}
	for (i=0; i<len; i++) {
	 rb_ary_store(ary, i, rb_yield(LONG2NUM(i)));
	 ARY_SET_LEN(ary, i + 1);
	}
 }
 else {
	memfill(RARRAY_PTR(ary), len, val);
	ARY_SET_LEN(ary, len);
 }
 return ary;
}


/*
* Returns a new array populated with the given objects.
*
* Array.[]( 1, 'a', /^A/ )
* Array[ 1, 'a', /^A/ ]
* [ 1, 'a', /^A/ ]
*/

static VALUE
rb_ary_s_create(int argc, VALUE *argv, VALUE klass)
{
 VALUE ary = ary_new(klass, argc);
 if (argc > 0 && argv) {
 MEMCPY(RARRAY_PTR(ary), argv, VALUE, argc);
 ARY_SET_LEN(ary, argc);
 }

 return ary;
}

void
rb_ary_store(VALUE ary, long idx, VALUE val)
{
 if (idx < 0) {
	idx += RARRAY_LEN(ary);
	if (idx < 0) {
	 rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
		 idx - RARRAY_LEN(ary), -RARRAY_LEN(ary));
	}
 }
 else if (idx >= ARY_MAX_SIZE) {
	rb_raise(rb_eIndexError, "index %ld too big", idx);
 }

 rb_ary_modify(ary);
 if (idx >= ARY_CAPA(ary)) {
	ary_double_capa(ary, idx);
 }
 if (idx > RARRAY_LEN(ary)) {
	rb_mem_clear(RARRAY_PTR(ary) + RARRAY_LEN(ary),
		 idx-RARRAY_LEN(ary) + 1);
 }

 if (idx >= RARRAY_LEN(ary)) {
	ARY_SET_LEN(ary, idx + 1);
 }
 RARRAY_PTR(ary)[idx] = val;
}

static VALUE
ary_make_partial(VALUE ary, VALUE klass, long offset, long len)
{
 assert(offset >= 0);
 assert(len >= 0);
 assert(offset+len <= RARRAY_LEN(ary));

 if (len <= RARRAY_EMBED_LEN_MAX) {
 VALUE result = ary_alloc(klass);
 MEMCPY(ARY_EMBED_PTR(result), RARRAY_PTR(ary) + offset, VALUE, len);
 ARY_SET_EMBED_LEN(result, len);
 return result;
 }
 else {
 VALUE shared, result = ary_alloc(klass);
 FL_UNSET_EMBED(result);

 shared = ary_make_shared(ary);
 ARY_SET_PTR(result, RARRAY_PTR(ary));
 ARY_SET_LEN(result, RARRAY_LEN(ary));
 rb_ary_set_shared(result, shared);

 ARY_INCREASE_PTR(result, offset);
 ARY_SET_LEN(result, len);
 return result;
 }
}

static VALUE
ary_make_shared_copy(VALUE ary)
{
 return ary_make_partial(ary, rb_obj_class(ary), 0, RARRAY_LEN(ary));
}

enum ary_take_pos_flags
{
 ARY_TAKE_FIRST = 0,
 ARY_TAKE_LAST = 1
};

static VALUE
ary_take_first_or_last(int argc, VALUE *argv, VALUE ary, enum ary_take_pos_flags last)
{
 VALUE nv;
 long n;
 long offset = 0;

 rb_scan_args(argc, argv, "1", &nv);
 n = NUM2LONG(nv);
 if (n > RARRAY_LEN(ary)) {
	n = RARRAY_LEN(ary);
 }
 else if (n < 0) {
	rb_raise(rb_eArgError, "negative array size");
 }
 if (last) {
	offset = RARRAY_LEN(ary) - n;
 }
 return ary_make_partial(ary, rb_cArray, offset, n);
}

static VALUE rb_ary_push_1(VALUE ary, VALUE item);

/*
 * call-seq:
 * ary << obj -> ary
 *
 * Append---Pushes the given object on to the end of this array. This
 * expression returns the array itself, so several appends
 * may be chained together.
 *
 * [ 1, 2 ] << "c" << "d" << [ 3, 4 ]
 * #=> [ 1, 2, "c", "d", [ 3, 4 ] ]
 *
 */

VALUE
rb_ary_push(VALUE ary, VALUE item)
{
 rb_ary_modify(ary);
 return rb_ary_push_1(ary, item);
}

static VALUE
rb_ary_push_1(VALUE ary, VALUE item)
{
 long idx = RARRAY_LEN(ary);

 if (idx >= ARY_CAPA(ary)) {
	ary_double_capa(ary, idx);
 }
 RARRAY_PTR(ary)[idx] = item;
 ARY_SET_LEN(ary, idx + 1);
 return ary;
}

/*
 * call-seq:
 * ary.push(obj, ... ) -> ary
 *
 * Append---Pushes the given object(s) on to the end of this array. This
 * expression returns the array itself, so several appends
 * may be chained together.
 *
 * a = [ "a", "b", "c" ]
 * a.push("d", "e", "f")
 * #=> ["a", "b", "c", "d", "e", "f"]
 */

static VALUE
rb_ary_push_m(int argc, VALUE *argv, VALUE ary)
{
 rb_ary_modify(ary);
 while (argc--) {
	rb_ary_push_1(ary, *argv++);
 }
 return ary;
}

VALUE
rb_ary_pop(VALUE ary)
{
 long n;
 rb_ary_modify_check(ary);
 if (RARRAY_LEN(ary) == 0) return Qnil;
 if (ARY_OWNS_HEAP_P(ary) &&
	RARRAY_LEN(ary) * 3 < ARY_CAPA(ary) &&
	ARY_CAPA(ary) > ARY_DEFAULT_SIZE)
 {
	ary_resize_capa(ary, RARRAY_LEN(ary) * 2);
 }
 n = RARRAY_LEN(ary)-1;
 ARY_SET_LEN(ary, n);
 return RARRAY_PTR(ary)[n];
}

/*
 * call-seq:
 * ary.pop -> obj or nil
 * ary.pop(n) -> new_ary
 *
 * Removes the last element from +self+ and returns it, or
 * <code>nil</code> if the array is empty.
 *
 * If a number _n_ is given, returns an array of the last n elements
 * (or less) just like <code>array.slice!(-n, n)</code> does.
 *
 * a = [ "a", "b", "c", "d" ]
 * a.pop #=> "d"
 * a.pop(2) #=> ["b", "c"]
 * a #=> ["a"]
 */

static VALUE
rb_ary_pop_m(int argc, VALUE *argv, VALUE ary)
{
 VALUE result;

 if (argc == 0) {
	return rb_ary_pop(ary);
 }

 rb_ary_modify_check(ary);
 result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
 ARY_INCREASE_LEN(ary, -RARRAY_LEN(result));
 return result;
}

VALUE
rb_ary_shift(VALUE ary)
{
 VALUE top;

 rb_ary_modify_check(ary);
 if (RARRAY_LEN(ary) == 0) return Qnil;
 top = RARRAY_PTR(ary)[0];
 if (!ARY_SHARED_P(ary)) {
	if (RARRAY_LEN(ary) < ARY_DEFAULT_SIZE) {
	 MEMMOVE(RARRAY_PTR(ary), RARRAY_PTR(ary)+1, VALUE, RARRAY_LEN(ary)-1);
 ARY_INCREASE_LEN(ary, -1);
	 return top;
	}
 assert(!ARY_EMBED_P(ary)); /* ARY_EMBED_LEN_MAX < ARY_DEFAULT_SIZE */

	RARRAY_PTR(ary)[0] = Qnil;
	ary_make_shared(ary);
 }
 else if (ARY_SHARED_NUM(ARY_SHARED(ary)) == 1) {
	RARRAY_PTR(ary)[0] = Qnil;
 }
 ARY_INCREASE_PTR(ary, 1);		/* shift ptr */
 ARY_INCREASE_LEN(ary, -1);

 return top;
}

/*
 * call-seq:
 * ary.shift -> obj or nil
 * ary.shift(n) -> new_ary
 *
 * Returns the first element of +self+ and removes it (shifting all
 * other elements down by one). Returns <code>nil</code> if the array
 * is empty.
 *
 * If a number _n_ is given, returns an array of the first n elements
 * (or less) just like <code>array.slice!(0, n)</code> does.
 *
 * args = [ "-m", "-q", "filename" ]
 * args.shift #=> "-m"
 * args #=> ["-q", "filename"]
 *
 * args = [ "-m", "-q", "filename" ]
 * args.shift(2) #=> ["-m", "-q"]
 * args #=> ["filename"]
 */

static VALUE
rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
{
 VALUE result;
 long n;

 if (argc == 0) {
	return rb_ary_shift(ary);
 }

 rb_ary_modify_check(ary);
 result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
 n = RARRAY_LEN(result);
 if (ARY_SHARED_P(ary)) {
	if (ARY_SHARED_NUM(ARY_SHARED(ary)) == 1) {
	 rb_mem_clear(RARRAY_PTR(ary), n);
	}
 ARY_INCREASE_PTR(ary, n);
 }
 else {
	MEMMOVE(RARRAY_PTR(ary), RARRAY_PTR(ary)+n, VALUE, RARRAY_LEN(ary)-n);
 }
 ARY_INCREASE_LEN(ary, -n);

 return result;
}

/*
 * call-seq:
 * ary.unshift(obj, ...) -> ary
 *
 * Prepends objects to the front of +self+,
 * moving other elements upwards.
 *
 * a = [ "b", "c", "d" ]
 * a.unshift("a") #=> ["a", "b", "c", "d"]
 * a.unshift(1, 2) #=> [ 1, 2, "a", "b", "c", "d"]
 */

static VALUE
rb_ary_unshift_m(int argc, VALUE *argv, VALUE ary)
{
 long len;

 rb_ary_modify(ary);
 if (argc == 0) return ary;
 if (ARY_CAPA(ary) <= (len = RARRAY_LEN(ary)) + argc) {
	ary_double_capa(ary, len + argc);
 }

 /* sliding items */
 MEMMOVE(RARRAY_PTR(ary) + argc, RARRAY_PTR(ary), VALUE, len);
 MEMCPY(RARRAY_PTR(ary), argv, VALUE, argc);
 ARY_INCREASE_LEN(ary, argc);

 return ary;
}

VALUE
rb_ary_unshift(VALUE ary, VALUE item)
{
 return rb_ary_unshift_m(1,&item,ary);
}

/* faster version - use this if you don't need to treat negative offset */
static inline VALUE
rb_ary_elt(VALUE ary, long offset)
{
 if (RARRAY_LEN(ary) == 0) return Qnil;
 if (offset < 0 || RARRAY_LEN(ary) <= offset) {
	return Qnil;
 }
 return RARRAY_PTR(ary)[offset];
}

VALUE
rb_ary_entry(VALUE ary, long offset)
{
 if (offset < 0) {
	offset += RARRAY_LEN(ary);
 }
 return rb_ary_elt(ary, offset);
}

VALUE
rb_ary_subseq(VALUE ary, long beg, long len)
{
 VALUE klass;

 if (beg > RARRAY_LEN(ary)) return Qnil;
 if (beg < 0 || len < 0) return Qnil;

 if (RARRAY_LEN(ary) < len || RARRAY_LEN(ary) < beg + len) {
	len = RARRAY_LEN(ary) - beg;
 }
 klass = rb_obj_class(ary);
 if (len == 0) return ary_new(klass, 0);

 return ary_make_partial(ary, klass, beg, len);
}

/*
 * call-seq:
 * ary[index] -> obj or nil
 * ary[start, length] -> new_ary or nil
 * ary[range] -> new_ary or nil
 * ary.slice(index) -> obj or nil
 * ary.slice(start, length) -> new_ary or nil
 * ary.slice(range) -> new_ary or nil
 *
 * Element Reference---Returns the element at _index_,
 * or returns a subarray starting at _start_ and
 * continuing for _length_ elements, or returns a subarray
 * specified by _range_.
 * Negative indices count backward from the end of the
 * array (-1 is the last element). Returns +nil+ if the index
 * (or starting index) are out of range.
 *
 * a = [ "a", "b", "c", "d", "e" ]
 * a[2] + a[0] + a[1] #=> "cab"
 * a[6] #=> nil
 * a[1, 2] #=> [ "b", "c" ]
 * a[1..3] #=> [ "b", "c", "d" ]
 * a[4..7] #=> [ "e" ]
 * a[6..10] #=> nil
 * a[-3, 3] #=> [ "c", "d", "e" ]
 * # special cases
 * a[5] #=> nil
 * a[5, 1] #=> []
 * a[5..10] #=> []
 *
 */

VALUE
rb_ary_aref(int argc, VALUE *argv, VALUE ary)
{
 VALUE arg;
 long beg, len;

 if (argc == 2) {
	beg = NUM2LONG(argv[0]);
	len = NUM2LONG(argv[1]);
	if (beg < 0) {
	 beg += RARRAY_LEN(ary);
	}
	return rb_ary_subseq(ary, beg, len);
 }
 if (argc != 1) {
	rb_scan_args(argc, argv, "11", 0, 0);
 }
 arg = argv[0];
 /* special case - speeding up */
 if (FIXNUM_P(arg)) {
	return rb_ary_entry(ary, FIX2LONG(arg));
 }
 /* check if idx is Range */
 switch (rb_range_beg_len(arg, &beg, &len, RARRAY_LEN(ary), 0)) {
 case Qfalse:
	break;
 case Qnil:
	return Qnil;
 default:
	return rb_ary_subseq(ary, beg, len);
 }
 return rb_ary_entry(ary, NUM2LONG(arg));
}

/*
 * call-seq:
 * ary.at(index) -> obj or nil
 *
 * Returns the element at _index_. A
 * negative index counts from the end of +self+. Returns +nil+
 * if the index is out of range. See also <code>Array#[]</code>.
 *
 * a = [ "a", "b", "c", "d", "e" ]
 * a.at(0) #=> "a"
 * a.at(-1) #=> "e"
 */

static VALUE
rb_ary_at(VALUE ary, VALUE pos)
{
 return rb_ary_entry(ary, NUM2LONG(pos));
}

/*
 * call-seq:
 * ary.first -> obj or nil
 * ary.first(n) -> new_ary
 *
 * Returns the first element, or the first +n+ elements, of the array.
 * If the array is empty, the first form returns <code>nil</code>, and the
 * second form returns an empty array.
 *
 * a = [ "q", "r", "s", "t" ]
 * a.first #=> "q"
 * a.first(2) #=> ["q", "r"]
 */

static VALUE
rb_ary_first(int argc, VALUE *argv, VALUE ary)
{
 if (argc == 0) {
	if (RARRAY_LEN(ary) == 0) return Qnil;
	return RARRAY_PTR(ary)[0];
 }
 else {
	return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
 }
}

/*
 * call-seq:
 * ary.last -> obj or nil
 * ary.last(n) -> new_ary
 *
 * Returns the last element(s) of +self+. If the array is empty,
 * the first form returns <code>nil</code>.
 *
 * a = [ "w", "x", "y", "z" ]
 * a.last #=> "z"
 * a.last(2) #=> ["y", "z"]
 */

VALUE
rb_ary_last(int argc, VALUE *argv, VALUE ary)
{
 if (argc == 0) {
	if (RARRAY_LEN(ary) == 0) return Qnil;
	return RARRAY_PTR(ary)[RARRAY_LEN(ary)-1];
 }
 else {
	return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
 }
}

/*
 * call-seq:
 * ary.fetch(index) -> obj
 * ary.fetch(index, default ) -> obj
 * ary.fetch(index) {|index| block } -> obj
 *
 * Tries to return the element at position <i>index</i>. If the index
 * lies outside the array, the first form throws an
 * <code>IndexError</code> exception, the second form returns
 * <i>default</i>, and the third form returns the value of invoking
 * the block, passing in the index. Negative values of <i>index</i>
 * count from the end of the array.
 *
 * a = [ 11, 22, 33, 44 ]
 * a.fetch(1) #=> 22
 * a.fetch(-1) #=> 44
 * a.fetch(4, 'cat') #=> "cat"
 * a.fetch(4) { |i| i*i } #=> 16
 */

static VALUE
rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
{
 VALUE pos, ifnone;
 long block_given;
 long idx;

 rb_scan_args(argc, argv, "11", &pos, &ifnone);
 block_given = rb_block_given_p();
 if (block_given && argc == 2) {
	rb_warn("block supersedes default value argument");
 }
 idx = NUM2LONG(pos);

 if (idx < 0) {
	idx += RARRAY_LEN(ary);
 }
 if (idx < 0 || RARRAY_LEN(ary) <= idx) {
	if (block_given) return rb_yield(pos);
	if (argc == 1) {
	 rb_raise(rb_eIndexError, "index %ld outside of array bounds: %ld...%ld",
			idx - (idx < 0 ? RARRAY_LEN(ary) : 0), -RARRAY_LEN(ary), RARRAY_LEN(ary));
	}
	return ifnone;
 }
 return RARRAY_PTR(ary)[idx];
}

/*
 * call-seq:
 * ary.index(obj) -> int or nil
 * ary.index {|item| block} -> int or nil
 * ary.index -> an_enumerator
 *
 * Returns the index of the first object in +self+ such that the object is
 * <code>==</code> to <i>obj</i>. If a block is given instead of an
 * argument, returns index of first object for which <em>block</em> is true.
 * Returns <code>nil</code> if no match is found.
 * See also <code>Array#rindex</code>.
 *
 * If neither block nor argument is given, an enumerator is returned instead.
 *
 * a = [ "a", "b", "c" ]
 * a.index("b") #=> 1
 * a.index("z") #=> nil
 * a.index{|x|x=="b"} #=> 1
 *
 * This is an alias of <code>#find_index</code>.
 */

static VALUE
rb_ary_index(int argc, VALUE *argv, VALUE ary)
{
 VALUE val;
 long i;

 if (argc == 0) {
	RETURN_ENUMERATOR(ary, 0, 0);
	for (i=0; i<RARRAY_LEN(ary); i++) {
	 if (RTEST(rb_yield(RARRAY_PTR(ary)[i]))) {
		return LONG2NUM(i);
	 }
	}
	return Qnil;
 }
 rb_scan_args(argc, argv, "1", &val);
 if (rb_block_given_p())
	rb_warn("given block not used");
 for (i=0; i<RARRAY_LEN(ary); i++) {
	if (rb_equal(RARRAY_PTR(ary)[i], val))
	 return LONG2NUM(i);
 }
 return Qnil;
}

/*
 * call-seq:
 * ary.rindex(obj) -> int or nil
 * ary.rindex {|item| block} -> int or nil
 * ary.rindex -> an_enumerator
 *
 * Returns the index of the last object in +self+
 * <code>==</code> to <i>obj</i>. If a block is given instead of an
 * argument, returns index of first object for which <em>block</em> is
 * true, starting from the last object.
 * Returns <code>nil</code> if no match is found.
 * See also <code>Array#index</code>.
 *
 * If neither block nor argument is given, an enumerator is returned instead.
 *
 * a = [ "a", "b", "b", "b", "c" ]
 * a.rindex("b") #=> 3
 * a.rindex("z") #=> nil
 * a.rindex { |x| x == "b" } #=> 3
 */

static VALUE
rb_ary_rindex(int argc, VALUE *argv, VALUE ary)
{
 VALUE val;
 long i = RARRAY_LEN(ary);

 if (argc == 0) {
	RETURN_ENUMERATOR(ary, 0, 0);
	while (i--) {
	 if (RTEST(rb_yield(RARRAY_PTR(ary)[i])))
		return LONG2NUM(i);
	 if (i > RARRAY_LEN(ary)) {
		i = RARRAY_LEN(ary);
	 }
	}
	return Qnil;
 }
 rb_scan_args(argc, argv, "1", &val);
 if (rb_block_given_p())
	rb_warn("given block not used");
 while (i--) {
	if (rb_equal(RARRAY_PTR(ary)[i], val))
	 return LONG2NUM(i);
	if (i > RARRAY_LEN(ary)) {
	 i = RARRAY_LEN(ary);
	}
 }
 return Qnil;
}

VALUE
rb_ary_to_ary(VALUE obj)
{
 VALUE tmp = rb_check_array_type(obj);

 if (!NIL_P(tmp)) return tmp;
 return rb_ary_new3(1, obj);
}

static void
rb_ary_splice(VALUE ary, long beg, long len, VALUE rpl)
{
 long rlen;

 if (len < 0) rb_raise(rb_eIndexError, "negative length (%ld)", len);
 if (beg < 0) {
	beg += RARRAY_LEN(ary);
	if (beg < 0) {
	 rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
		 beg - RARRAY_LEN(ary), -RARRAY_LEN(ary));
	}
 }
 if (RARRAY_LEN(ary) < len || RARRAY_LEN(ary) < beg + len) {
	len = RARRAY_LEN(ary) - beg;
 }

 if (rpl == Qundef) {
	rlen = 0;
 }
 else {
	rpl = rb_ary_to_ary(rpl);
	rlen = RARRAY_LEN(rpl);
 }
 rb_ary_modify(ary);
 if (beg >= RARRAY_LEN(ary)) {
	if (beg > ARY_MAX_SIZE - rlen) {
	 rb_raise(rb_eIndexError, "index %ld too big", beg);
	}
	len = beg + rlen;
	if (len >= ARY_CAPA(ary)) {
	 ary_double_capa(ary, len);
	}
	rb_mem_clear(RARRAY_PTR(ary) + RARRAY_LEN(ary), beg - RARRAY_LEN(ary));
	if (rlen > 0) {
	 MEMCPY(RARRAY_PTR(ary) + beg, RARRAY_PTR(rpl), VALUE, rlen);
	}
	ARY_SET_LEN(ary, len);
 }
 else {
	long alen;

	alen = RARRAY_LEN(ary) + rlen - len;
	if (alen >= ARY_CAPA(ary)) {
	 ary_double_capa(ary, alen);
	}

	if (len != rlen) {
	 MEMMOVE(RARRAY_PTR(ary) + beg + rlen, RARRAY_PTR(ary) + beg + len,
		 VALUE, RARRAY_LEN(ary) - (beg + len));
	 ARY_SET_LEN(ary, alen);
	}
	if (rlen > 0) {
	 MEMMOVE(RARRAY_PTR(ary) + beg, RARRAY_PTR(rpl), VALUE, rlen);
	}
 }
}

/*!
 * expands or shrinks \a ary to \a len elements.
 * expanded region will be filled with Qnil.
 * \param ary an array
 * \param len new size
 * \return \a ary
 * \post the size of \a ary is \a len.
 */
VALUE
rb_ary_resize(VALUE ary, long len)
{
 long olen;

 rb_ary_modify(ary);
 olen = RARRAY_LEN(ary);
 if (len == olen) return ary;
 if (len > ARY_MAX_SIZE) {
	rb_raise(rb_eIndexError, "index %ld too big", len);
 }
 if (len > olen) {
	if (len >= ARY_CAPA(ary)) {
	 ary_double_capa(ary, len);
	}
	rb_mem_clear(RARRAY_PTR(ary) + olen, len - olen);
 ARY_SET_LEN(ary, len);
 }
 else if (ARY_EMBED_P(ary)) {
 ARY_SET_EMBED_LEN(ary, len);
 }
 else if (len <= RARRAY_EMBED_LEN_MAX) {
	VALUE tmp[RARRAY_EMBED_LEN_MAX];
	MEMCPY(tmp, ARY_HEAP_PTR(ary), VALUE, len);
	ary_discard(ary);
	MEMCPY(ARY_EMBED_PTR(ary), tmp, VALUE, len);
 ARY_SET_EMBED_LEN(ary, len);
 }
 else {
	if (olen > len + ARY_DEFAULT_SIZE) {
	 REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, len);
	 ARY_SET_CAPA(ary, len);
	}
	ARY_SET_HEAP_LEN(ary, len);
 }
 return ary;
}

/*
 * call-seq:
 * ary[index] = obj -> obj
 * ary[start, length] = obj or other_ary or nil -> obj or other_ary or nil
 * ary[range] = obj or other_ary or nil -> obj or other_ary or nil
 *
 * Element Assignment---Sets the element at _index_,
 * or replaces a subarray starting at _start_ and
 * continuing for _length_ elements, or replaces a subarray
 * specified by _range_. If indices are greater than
 * the current capacity of the array, the array grows
 * automatically. A negative indices will count backward
 * from the end of the array. Inserts elements if _length_ is
 * zero. An +IndexError+ is raised if a negative index points
 * past the beginning of the array. See also
 * <code>Array#push</code>, and <code>Array#unshift</code>.
 *
 * a = Array.new
 * a[4] = "4"; #=> [nil, nil, nil, nil, "4"]
 * a[0, 3] = [ 'a', 'b', 'c' ] #=> ["a", "b", "c", nil, "4"]
 * a[1..2] = [ 1, 2 ] #=> ["a", 1, 2, nil, "4"]
 * a[0, 2] = "?" #=> ["?", 2, nil, "4"]
 * a[0..2] = "A" #=> ["A", "4"]
 * a[-1] = "Z" #=> ["A", "Z"]
 * a[1..-1] = nil #=> ["A", nil]
 * a[1..-1] = [] #=> ["A"]
 */

static VALUE
rb_ary_aset(int argc, VALUE *argv, VALUE ary)
{
 long offset, beg, len;

 if (argc == 3) {
	rb_ary_modify_check(ary);
	beg = NUM2LONG(argv[0]);
	len = NUM2LONG(argv[1]);
	rb_ary_splice(ary, beg, len, argv[2]);
	return argv[2];
 }
 if (argc != 2) {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 2)", argc);
 }
 rb_ary_modify_check(ary);
 if (FIXNUM_P(argv[0])) {
	offset = FIX2LONG(argv[0]);
	goto fixnum;
 }
 if (rb_range_beg_len(argv[0], &beg, &len, RARRAY_LEN(ary), 1)) {
	/* check if idx is Range */
	rb_ary_splice(ary, beg, len, argv[1]);
	return argv[1];
 }

 offset = NUM2LONG(argv[0]);
fixnum:
 rb_ary_store(ary, offset, argv[1]);
 return argv[1];
}

/*
 * call-seq:
 * ary.insert(index, obj...) -> ary
 *
 * Inserts the given values before the element with the given index
 * (which may be negative).
 *
 * a = %w{ a b c d }
 * a.insert(2, 99) #=> ["a", "b", 99, "c", "d"]
 * a.insert(-2, 1, 2, 3) #=> ["a", "b", 99, "c", 1, 2, 3, "d"]
 */

static VALUE
rb_ary_insert(int argc, VALUE *argv, VALUE ary)
{
 long pos;

 if (argc < 1) {
	rb_raise(rb_eArgError, "wrong number of arguments (at least 1)");
 }
 rb_ary_modify_check(ary);
 if (argc == 1) return ary;
 pos = NUM2LONG(argv[0]);
 if (pos == -1) {
	pos = RARRAY_LEN(ary);
 }
 if (pos < 0) {
	pos++;
 }
 rb_ary_splice(ary, pos, 0, rb_ary_new4(argc - 1, argv + 1));
 return ary;
}

/*
 * call-seq:
 * ary.each {|item| block } -> ary
 * ary.each -> an_enumerator
 *
 * Calls <i>block</i> once for each element in +self+, passing that
 * element as a parameter.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = [ "a", "b", "c" ]
 * a.each {|x| print x, " -- " }
 *
 * produces:
 *
 * a -- b -- c --
 */

VALUE
rb_ary_each(VALUE array)
{
 long i;
 volatile VALUE ary = array;

 RETURN_ENUMERATOR(ary, 0, 0);
 for (i=0; i<RARRAY_LEN(ary); i++) {
	rb_yield(RARRAY_PTR(ary)[i]);
 }
 return ary;
}

/*
 * call-seq:
 * ary.each_index {|index| block } -> ary
 * ary.each_index -> an_enumerator
 *
 * Same as <code>Array#each</code>, but passes the index of the element
 * instead of the element itself.
 *
 * If no block is given, an enumerator is returned instead.
 *
 *
 * a = [ "a", "b", "c" ]
 * a.each_index {|x| print x, " -- " }
 *
 * produces:
 *
 * 0 -- 1 -- 2 --
 */

static VALUE
rb_ary_each_index(VALUE ary)
{
 long i;
 RETURN_ENUMERATOR(ary, 0, 0);

 for (i=0; i<RARRAY_LEN(ary); i++) {
	rb_yield(LONG2NUM(i));
 }
 return ary;
}

/*
 * call-seq:
 * ary.reverse_each {|item| block } -> ary
 * ary.reverse_each -> an_enumerator
 *
 * Same as <code>Array#each</code>, but traverses +self+ in reverse
 * order.
 *
 * a = [ "a", "b", "c" ]
 * a.reverse_each {|x| print x, " " }
 *
 * produces:
 *
 * c b a
 */

static VALUE
rb_ary_reverse_each(VALUE ary)
{
 long len;

 RETURN_ENUMERATOR(ary, 0, 0);
 len = RARRAY_LEN(ary);
 while (len--) {
	rb_yield(RARRAY_PTR(ary)[len]);
	if (RARRAY_LEN(ary) < len) {
	 len = RARRAY_LEN(ary);
	}
 }
 return ary;
}

/*
 * call-seq:
 * ary.length -> int
 *
 * Returns the number of elements in +self+. May be zero.
 *
 * [ 1, 2, 3, 4, 5 ].length #=> 5
 */

static VALUE
rb_ary_length(VALUE ary)
{
 long len = RARRAY_LEN(ary);
 return LONG2NUM(len);
}

/*
 * call-seq:
 * ary.empty? -> true or false
 *
 * Returns <code>true</code> if +self+ contains no elements.
 *
 * [].empty? #=> true
 */

static VALUE
rb_ary_empty_p(VALUE ary)
{
 if (RARRAY_LEN(ary) == 0)
	return Qtrue;
 return Qfalse;
}

VALUE
rb_ary_dup(VALUE ary)
{
 VALUE dup = rb_ary_new2(RARRAY_LEN(ary));
 MEMCPY(RARRAY_PTR(dup), RARRAY_PTR(ary), VALUE, RARRAY_LEN(ary));
 ARY_SET_LEN(dup, RARRAY_LEN(ary));
 return dup;
}

VALUE
rb_ary_resurrect(VALUE ary)
{
 return rb_ary_new4(RARRAY_LEN(ary), RARRAY_PTR(ary));
}

extern VALUE rb_output_fs;

static void ary_join_1(VALUE obj, VALUE ary, VALUE sep, long i, VALUE result, int *first);

static VALUE
recursive_join(VALUE obj, VALUE argp, int recur)
{
 VALUE *arg = (VALUE *)argp;
 VALUE ary = arg[0];
 VALUE sep = arg[1];
 VALUE result = arg[2];
 int *first = (int *)arg[3];

 if (recur) {
	rb_raise(rb_eArgError, "recursive array join");
 }
 else {
	ary_join_1(obj, ary, sep, 0, result, first);
 }
 return Qnil;
}

static void
ary_join_0(VALUE ary, VALUE sep, long max, VALUE result)
{
 long i;
 VALUE val;

 if (max > 0) rb_enc_copy(result, RARRAY_PTR(ary)[0]);
 for (i=0; i<max; i++) {
	val = RARRAY_PTR(ary)[i];
	if (i > 0 && !NIL_P(sep))
	 rb_str_buf_append(result, sep);
	rb_str_buf_append(result, val);
	if (OBJ_TAINTED(val)) OBJ_TAINT(result);
	if (OBJ_UNTRUSTED(val)) OBJ_TAINT(result);
 }
}

static void
ary_join_1(VALUE obj, VALUE ary, VALUE sep, long i, VALUE result, int *first)
{
 VALUE val, tmp;

 for (; i<RARRAY_LEN(ary); i++) {
	if (i > 0 && !NIL_P(sep))
	 rb_str_buf_append(result, sep);

	val = RARRAY_PTR(ary)[i];
	switch (TYPE(val)) {
	 case T_STRING:
	 str_join:
	 rb_str_buf_append(result, val);
	 *first = FALSE;
	 break;
	 case T_ARRAY:
	 obj = val;
	 ary_join:
	 if (val == ary) {
		rb_raise(rb_eArgError, "recursive array join");
	 }
	 else {
		VALUE args[4];

		args[0] = val;
		args[1] = sep;
		args[2] = result;
		args[3] = (VALUE)first;
		rb_exec_recursive(recursive_join, obj, (VALUE)args);
	 }
	 break;
	 default:
	 tmp = rb_check_string_type(val);
	 if (!NIL_P(tmp)) {
		val = tmp;
		goto str_join;
	 }
	 tmp = rb_check_convert_type(val, T_ARRAY, "Array", "to_ary");
	 if (!NIL_P(tmp)) {
		obj = val;
		val = tmp;
		goto ary_join;
	 }
	 val = rb_obj_as_string(val);
	 if (*first) {
		rb_enc_copy(result, val);
		*first = FALSE;
	 }
	 goto str_join;
	}
 }
}

VALUE
rb_ary_join(VALUE ary, VALUE sep)
{
 long len = 1, i;
 int taint = FALSE;
 int untrust = FALSE;
 VALUE val, tmp, result;

 if (RARRAY_LEN(ary) == 0) return rb_usascii_str_new(0, 0);
 if (OBJ_TAINTED(ary) || OBJ_TAINTED(sep)) taint = TRUE;
 if (OBJ_UNTRUSTED(ary) || OBJ_UNTRUSTED(sep)) untrust = TRUE;

 if (!NIL_P(sep)) {
	StringValue(sep);
	len += RSTRING_LEN(sep) * (RARRAY_LEN(ary) - 1);
 }
 for (i=0; i<RARRAY_LEN(ary); i++) {
	val = RARRAY_PTR(ary)[i];
	tmp = rb_check_string_type(val);

	if (NIL_P(tmp) || tmp != val) {
	 int first;
	 result = rb_str_buf_new(len + (RARRAY_LEN(ary)-i)*10);
	 rb_enc_associate(result, rb_usascii_encoding());
	 if (taint) OBJ_TAINT(result);
	 if (untrust) OBJ_UNTRUST(result);
	 ary_join_0(ary, sep, i, result);
	 first = i == 0;
	 ary_join_1(ary, ary, sep, i, result, &first);
	 return result;
	}

	len += RSTRING_LEN(tmp);
 }

 result = rb_str_buf_new(len);
 if (taint) OBJ_TAINT(result);
 if (untrust) OBJ_UNTRUST(result);
 ary_join_0(ary, sep, RARRAY_LEN(ary), result);

 return result;
}

/*
 * call-seq:
 * ary.join(sep=$,) -> str
 *
 * Returns a string created by converting each element of the array to
 * a string, separated by <i>sep</i>.
 *
 * [ "a", "b", "c" ].join #=> "abc"
 * [ "a", "b", "c" ].join("-") #=> "a-b-c"
 */

static VALUE
rb_ary_join_m(int argc, VALUE *argv, VALUE ary)
{
 VALUE sep;

 rb_scan_args(argc, argv, "01", &sep);
 if (NIL_P(sep)) sep = rb_output_fs;

 return rb_ary_join(ary, sep);
}

static VALUE
inspect_ary(VALUE ary, VALUE dummy, int recur)
{
 int tainted = OBJ_TAINTED(ary);
 int untrust = OBJ_UNTRUSTED(ary);
 long i;
 VALUE s, str;

 if (recur) return rb_usascii_str_new_cstr("[...]");
 str = rb_str_buf_new2("[");
 for (i=0; i<RARRAY_LEN(ary); i++) {
	s = rb_inspect(RARRAY_PTR(ary)[i]);
	if (OBJ_TAINTED(s)) tainted = TRUE;
	if (OBJ_UNTRUSTED(s)) untrust = TRUE;
	if (i > 0) rb_str_buf_cat2(str, ", ");
	else rb_enc_copy(str, s);
	rb_str_buf_append(str, s);
 }
 rb_str_buf_cat2(str, "]");
 if (tainted) OBJ_TAINT(str);
 if (untrust) OBJ_UNTRUST(str);
 return str;
}

/*
 * call-seq:
 * ary.to_s -> string
 * ary.inspect -> string
 *
 * Creates a string representation of +self+.
 */

static VALUE
rb_ary_inspect(VALUE ary)
{
 if (RARRAY_LEN(ary) == 0) return rb_usascii_str_new2("[]");
 return rb_exec_recursive(inspect_ary, ary, 0);
}

VALUE
rb_ary_to_s(VALUE ary)
{
 return rb_ary_inspect(ary);
}

/*
 * call-seq:
 * ary.to_a -> ary
 *
 * Returns +self+. If called on a subclass of Array, converts
 * the receiver to an Array object.
 */

static VALUE
rb_ary_to_a(VALUE ary)
{
 if (rb_obj_class(ary) != rb_cArray) {
	VALUE dup = rb_ary_new2(RARRAY_LEN(ary));
	rb_ary_replace(dup, ary);
	return dup;
 }
 return ary;
}

/*
 * call-seq:
 * ary.to_ary -> ary
 *
 * Returns +self+.
 */

static VALUE
rb_ary_to_ary_m(VALUE ary)
{
 return ary;
}

static void
ary_reverse(p1, p2)
 VALUE *p1, *p2;
{
 while (p1 < p2) {
	VALUE tmp = *p1;
	*p1++ = *p2;
	*p2-- = tmp;
 }
}

VALUE
rb_ary_reverse(VALUE ary)
{
 VALUE *p1, *p2;

 rb_ary_modify(ary);
 if (RARRAY_LEN(ary) > 1) {
	p1 = RARRAY_PTR(ary);
	p2 = p1 + RARRAY_LEN(ary) - 1;	/* points last item */
	ary_reverse(p1, p2);
 }
 return ary;
}

/*
 * call-seq:
 * ary.reverse! -> ary
 *
 * Reverses +self+ in place.
 *
 * a = [ "a", "b", "c" ]
 * a.reverse! #=> ["c", "b", "a"]
 * a #=> ["c", "b", "a"]
 */

static VALUE
rb_ary_reverse_bang(VALUE ary)
{
 return rb_ary_reverse(ary);
}

/*
 * call-seq:
 * ary.reverse -> new_ary
 *
 * Returns a new array containing +self+'s elements in reverse order.
 *
 * [ "a", "b", "c" ].reverse #=> ["c", "b", "a"]
 * [ 1 ].reverse #=> [1]
 */

static VALUE
rb_ary_reverse_m(VALUE ary)
{
 long len = RARRAY_LEN(ary);
 VALUE dup = rb_ary_new2(len);

 if (len > 0) {
	VALUE *p1 = RARRAY_PTR(ary);
	VALUE *p2 = RARRAY_PTR(dup) + len - 1;
	do *p2-- = *p1++; while (--len > 0);
 }
 ARY_SET_LEN(dup, RARRAY_LEN(ary));
 return dup;
}

static inline long
rotate_count(long cnt, long len)
{
 return (cnt < 0) ? (len - (~cnt % len) - 1) : (cnt % len);
}

VALUE
rb_ary_rotate(VALUE ary, long cnt)
{
 rb_ary_modify(ary);

 if (cnt != 0) {
	VALUE *ptr = RARRAY_PTR(ary);
	long len = RARRAY_LEN(ary);

	if (len > 0 && (cnt = rotate_count(cnt, len)) > 0) {
	 --len;
	 if (cnt < len) ary_reverse(ptr + cnt, ptr + len);
	 if (--cnt > 0) ary_reverse(ptr, ptr + cnt);
	 if (len > 0) ary_reverse(ptr, ptr + len);
	 return ary;
	}
 }

 return Qnil;
}

/*
 * call-seq:
 * ary.rotate!(cnt=1) -> ary
 *
 * Rotates +self+ in place so that the element at +cnt+ comes first,
 * and returns +self+. If +cnt+ is negative then it rotates in
 * the opposite direction.
 *
 * a = [ "a", "b", "c", "d" ]
 * a.rotate! #=> ["b", "c", "d", "a"]
 * a #=> ["b", "c", "d", "a"]
 * a.rotate!(2) #=> ["d", "a", "b", "c"]
 * a.rotate!(-3) #=> ["a", "b", "c", "d"]
 */

static VALUE
rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary)
{
 long n = 1;

 switch (argc) {
 case 1: n = NUM2LONG(argv[0]);
 case 0: break;
 default: rb_scan_args(argc, argv, "01", NULL);
 }
 rb_ary_rotate(ary, n);
 return ary;
}

/*
 * call-seq:
 * ary.rotate(cnt=1) -> new_ary
 *
 * Returns new array by rotating +self+ so that the element at
 * +cnt+ in +self+ is the first element of the new array. If +cnt+
 * is negative then it rotates in the opposite direction.
 *
 * a = [ "a", "b", "c", "d" ]
 * a.rotate #=> ["b", "c", "d", "a"]
 * a #=> ["a", "b", "c", "d"]
 * a.rotate(2) #=> ["c", "d", "a", "b"]
 * a.rotate(-3) #=> ["b", "c", "d", "a"]
 */

static VALUE
rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
{
 VALUE rotated, *ptr, *ptr2;
 long len, cnt = 1;

 switch (argc) {
 case 1: cnt = NUM2LONG(argv[0]);
 case 0: break;
 default: rb_scan_args(argc, argv, "01", NULL);
 }

 len = RARRAY_LEN(ary);
 rotated = rb_ary_new2(len);
 if (len > 0) {
	cnt = rotate_count(cnt, len);
	ptr = RARRAY_PTR(ary);
	ptr2 = RARRAY_PTR(rotated);
	len -= cnt;
	MEMCPY(ptr2, ptr + cnt, VALUE, len);
	MEMCPY(ptr2 + len, ptr, VALUE, cnt);
 }
 ARY_SET_LEN(rotated, RARRAY_LEN(ary));
 return rotated;
}

struct ary_sort_data {
 VALUE ary;
 int opt_methods;
 int opt_inited;
};

enum {
 sort_opt_Fixnum,
 sort_opt_String,
 sort_optimizable_count
};

#define STRING_P(s) (TYPE(s) == T_STRING && CLASS_OF(s) == rb_cString)

#define SORT_OPTIMIZABLE_BIT(type) (1U << TOKEN_PASTE(sort_opt_,type))
#define SORT_OPTIMIZABLE(data, type) \
 (((data)->opt_inited & SORT_OPTIMIZABLE_BIT(type)) ? \
 ((data)->opt_methods & SORT_OPTIMIZABLE_BIT(type)) : \
 (((data)->opt_inited |= SORT_OPTIMIZABLE_BIT(type)), \
 rb_method_basic_definition_p(TOKEN_PASTE(rb_c,type), id_cmp) && \
 ((data)->opt_methods |= SORT_OPTIMIZABLE_BIT(type))))

static VALUE
sort_reentered(VALUE ary)
{
 if (RBASIC(ary)->klass) {
	rb_raise(rb_eRuntimeError, "sort reentered");
 }
 return Qnil;
}

static int
sort_1(const void *ap, const void *bp, void *dummy)
{
 struct ary_sort_data *data = dummy;
 VALUE retval = sort_reentered(data->ary);
 VALUE a = *(const VALUE *)ap, b = *(const VALUE *)bp;
 int n;

 retval = rb_yield_values(2, a, b);
 n = rb_cmpint(retval, a, b);
 sort_reentered(data->ary);
 return n;
}

static int
sort_2(const void *ap, const void *bp, void *dummy)
{
 struct ary_sort_data *data = dummy;
 VALUE retval = sort_reentered(data->ary);
 VALUE a = *(const VALUE *)ap, b = *(const VALUE *)bp;
 int n;

 if (FIXNUM_P(a) && FIXNUM_P(b) && SORT_OPTIMIZABLE(data, Fixnum)) {
	if ((long)a > (long)b) return 1;
	if ((long)a < (long)b) return -1;
	return 0;
 }
 if (STRING_P(a) && STRING_P(b) && SORT_OPTIMIZABLE(data, String)) {
	return rb_str_cmp(a, b);
 }

 retval = rb_funcall(a, id_cmp, 1, b);
 n = rb_cmpint(retval, a, b);
 sort_reentered(data->ary);

 return n;
}

/*
 * call-seq:
 * ary.sort! -> ary
 * ary.sort! {| a,b | block } -> ary
 *
 * Sorts +self+. Comparisons for
 * the sort will be done using the <code><=></code> operator or using
 * an optional code block. The block implements a comparison between
 * <i>a</i> and <i>b</i>, returning -1, 0, or +1. See also
 * <code>Enumerable#sort_by</code>.
 *
 * a = [ "d", "a", "e", "c", "b" ]
 * a.sort! #=> ["a", "b", "c", "d", "e"]
 * a.sort! {|x,y| y <=> x } #=> ["e", "d", "c", "b", "a"]
 */

VALUE
rb_ary_sort_bang(VALUE ary)
{
 rb_ary_modify(ary);
 assert(!ARY_SHARED_P(ary));
 if (RARRAY_LEN(ary) > 1) {
	VALUE tmp = ary_make_substitution(ary); /* only ary refers tmp */
	struct ary_sort_data data;

	RBASIC(tmp)->klass = 0;
	data.ary = tmp;
	data.opt_methods = 0;
	data.opt_inited = 0;
	ruby_qsort(RARRAY_PTR(tmp), RARRAY_LEN(tmp), sizeof(VALUE),
		 rb_block_given_p()?sort_1:sort_2, &data);

 if (ARY_EMBED_P(tmp)) {
 assert(ARY_EMBED_P(tmp));
 if (ARY_SHARED_P(ary)) { /* ary might be destructively operated in the given block */
 rb_ary_unshare(ary);
 }
 FL_SET_EMBED(ary);
 MEMCPY(RARRAY_PTR(ary), ARY_EMBED_PTR(tmp), VALUE, ARY_EMBED_LEN(tmp));
 ARY_SET_LEN(ary, ARY_EMBED_LEN(tmp));
 }
 else {
 assert(!ARY_EMBED_P(tmp));
 if (ARY_HEAP_PTR(ary) == ARY_HEAP_PTR(tmp)) {
 assert(!ARY_EMBED_P(ary));
 FL_UNSET_SHARED(ary);
 ARY_SET_CAPA(ary, ARY_CAPA(tmp));
 }
 else {
 assert(!ARY_SHARED_P(tmp));
 if (ARY_EMBED_P(ary)) {
 FL_UNSET_EMBED(ary);
 }
 else if (ARY_SHARED_P(ary)) {
 /* ary might be destructively operated in the given block */
 rb_ary_unshare(ary);
 }
 else {
 xfree(ARY_HEAP_PTR(ary));
 }
 ARY_SET_PTR(ary, RARRAY_PTR(tmp));
 ARY_SET_HEAP_LEN(ary, RARRAY_LEN(tmp));
 ARY_SET_CAPA(ary, ARY_CAPA(tmp));
 }
 /* tmp was lost ownership for the ptr */
 FL_UNSET(tmp, FL_FREEZE);
 FL_SET_EMBED(tmp);
 ARY_SET_EMBED_LEN(tmp, 0);
 FL_SET(tmp, FL_FREEZE);
	}
 /* tmp will be GC'ed. */
 RBASIC(tmp)->klass = rb_cArray;
 }
 return ary;
}

/*
 * call-seq:
 * ary.sort -> new_ary
 * ary.sort {| a,b | block } -> new_ary
 *
 * Returns a new array created by sorting +self+. Comparisons for
 * the sort will be done using the <code><=></code> operator or using
 * an optional code block. The block implements a comparison between
 * <i>a</i> and <i>b</i>, returning -1, 0, or +1. See also
 * <code>Enumerable#sort_by</code>.
 *
 * a = [ "d", "a", "e", "c", "b" ]
 * a.sort #=> ["a", "b", "c", "d", "e"]
 * a.sort {|x,y| y <=> x } #=> ["e", "d", "c", "b", "a"]
 */

VALUE
rb_ary_sort(VALUE ary)
{
 ary = rb_ary_dup(ary);
 rb_ary_sort_bang(ary);
 return ary;
}


static VALUE
sort_by_i(VALUE i)
{
 return rb_yield(i);
}

/*
 * call-seq:
 * ary.sort_by! {| obj | block } -> ary
 * ary.sort_by! -> an_enumerator
 *
 * Sorts +self+ in place using a set of keys generated by mapping the
 * values in +self+ through the given block.
 *
 * If no block is given, an enumerator is returned instead.
 *
 */

static VALUE
rb_ary_sort_by_bang(VALUE ary)
{
 VALUE sorted;

 RETURN_ENUMERATOR(ary, 0, 0);
 rb_ary_modify(ary);
 sorted = rb_block_call(ary, rb_intern("sort_by"), 0, 0, sort_by_i, 0);
 rb_ary_replace(ary, sorted);
 return ary;
}


/*
 * call-seq:
 * ary.collect {|item| block } -> new_ary
 * ary.map {|item| block } -> new_ary
 * ary.collect -> an_enumerator
 * ary.map -> an_enumerator
 *
 * Invokes <i>block</i> once for each element of +self+. Creates a
 * new array containing the values returned by the block.
 * See also <code>Enumerable#collect</code>.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = [ "a", "b", "c", "d" ]
 * a.collect {|x| x + "!" } #=> ["a!", "b!", "c!", "d!"]
 * a #=> ["a", "b", "c", "d"]
 */

static VALUE
rb_ary_collect(VALUE ary)
{
 long i;
 VALUE collect;

 RETURN_ENUMERATOR(ary, 0, 0);
 collect = rb_ary_new2(RARRAY_LEN(ary));
 for (i = 0; i < RARRAY_LEN(ary); i++) {
	rb_ary_push(collect, rb_yield(RARRAY_PTR(ary)[i]));
 }
 return collect;
}


/*
 * call-seq:
 * ary.collect! {|item| block } -> ary
 * ary.map! {|item| block } -> ary
 * ary.collect -> an_enumerator
 * ary.map -> an_enumerator
 *
 * Invokes the block once for each element of +self+, replacing the
 * element with the value returned by _block_.
 * See also <code>Enumerable#collect</code>.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = [ "a", "b", "c", "d" ]
 * a.collect! {|x| x + "!" }
 * a #=> [ "a!", "b!", "c!", "d!" ]
 */

static VALUE
rb_ary_collect_bang(VALUE ary)
{
 long i;

 RETURN_ENUMERATOR(ary, 0, 0);
 rb_ary_modify(ary);
 for (i = 0; i < RARRAY_LEN(ary); i++) {
	rb_ary_store(ary, i, rb_yield(RARRAY_PTR(ary)[i]));
 }
 return ary;
}

VALUE
rb_get_values_at(VALUE obj, long olen, int argc, VALUE *argv, VALUE (*func) (VALUE, long))
{
 VALUE result = rb_ary_new2(argc);
 long beg, len, i, j;

 for (i=0; i<argc; i++) {
	if (FIXNUM_P(argv[i])) {
	 rb_ary_push(result, (*func)(obj, FIX2LONG(argv[i])));
	 continue;
	}
	/* check if idx is Range */
	switch (rb_range_beg_len(argv[i], &beg, &len, olen, 0)) {
	 case Qfalse:
	 break;
	 case Qnil:
	 continue;
	 default:
	 for (j=0; j<len; j++) {
		rb_ary_push(result, (*func)(obj, j+beg));
	 }
	 continue;
	}
	rb_ary_push(result, (*func)(obj, NUM2LONG(argv[i])));
 }
 return result;
}

/*
 * call-seq:
 * ary.values_at(selector,... ) -> new_ary
 *
 * Returns an array containing the elements in
 * +self+ corresponding to the given selector(s). The selectors
 * may be either integer indices or ranges.
 * See also <code>Array#select</code>.
 *
 * a = %w{ a b c d e f }
 * a.values_at(1, 3, 5)
 * a.values_at(1, 3, 5, 7)
 * a.values_at(-1, -3, -5, -7)
 * a.values_at(1..3, 2...5)
 */

static VALUE
rb_ary_values_at(int argc, VALUE *argv, VALUE ary)
{
 return rb_get_values_at(ary, RARRAY_LEN(ary), argc, argv, rb_ary_entry);
}


/*
 * call-seq:
 * ary.select {|item| block } -> new_ary
 * ary.select -> an_enumerator
 *
 * Invokes the block passing in successive elements from +self+,
 * returning an array containing those elements for which the block
 * returns a true value (equivalent to <code>Enumerable#select</code>).
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = %w{ a b c d e f }
 * a.select {|v| v =~ /[aeiou]/} #=> ["a", "e"]
 */

static VALUE
rb_ary_select(VALUE ary)
{
 VALUE result;
 long i;

 RETURN_ENUMERATOR(ary, 0, 0);
 result = rb_ary_new2(RARRAY_LEN(ary));
 for (i = 0; i < RARRAY_LEN(ary); i++) {
	if (RTEST(rb_yield(RARRAY_PTR(ary)[i]))) {
	 rb_ary_push(result, rb_ary_elt(ary, i));
	}
 }
 return result;
}

/*
 * call-seq:
 * ary.select! {|item| block } -> ary or nil
 * ary.select! -> an_enumerator
 *
 * Invokes the block passing in successive elements from
 * +self+, deleting elements for which the block returns a
 * false value. It returns +self+ if changes were made,
 * otherwise it returns <code>nil</code>.
 * See also <code>Array#keep_if</code>
 *
 * If no block is given, an enumerator is returned instead.
 *
 */

static VALUE
rb_ary_select_bang(VALUE ary)
{
 long i1, i2;

 RETURN_ENUMERATOR(ary, 0, 0);
 rb_ary_modify(ary);
 for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) {
	VALUE v = RARRAY_PTR(ary)[i1];
	if (!RTEST(rb_yield(v))) continue;
	if (i1 != i2) {
	 rb_ary_store(ary, i2, v);
	}
	i2++;
 }

 if (RARRAY_LEN(ary) == i2) return Qnil;
 if (i2 < RARRAY_LEN(ary))
	ARY_SET_LEN(ary, i2);
 return ary;
}

/*
 * call-seq:
 * ary.keep_if {|item| block } -> ary
 * ary.keep_if -> an_enumerator
 *
 * Deletes every element of +self+ for which <i>block</i> evaluates
 * to false.
 * See also <code>Array#select!</code>
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = %w{ a b c d e f }
 * a.keep_if {|v| v =~ /[aeiou]/} #=> ["a", "e"]
 */

static VALUE
rb_ary_keep_if(VALUE ary)
{
 RETURN_ENUMERATOR(ary, 0, 0);
 rb_ary_select_bang(ary);
 return ary;
}

/*
 * call-seq:
 * ary.delete(obj) -> obj or nil
 * ary.delete(obj) { block } -> obj or nil
 *
 * Deletes items from +self+ that are equal to <i>obj</i>.
 * If any items are found, returns <i>obj</i>. If
 * the item is not found, returns <code>nil</code>. If the optional
 * code block is given, returns the result of <i>block</i> if the item
 * is not found. (To remove <code>nil</code> elements and
 * get an informative return value, use #compact!)
 *
 * a = [ "a", "b", "b", "b", "c" ]
 * a.delete("b") #=> "b"
 * a #=> ["a", "c"]
 * a.delete("z") #=> nil
 * a.delete("z") { "not found" } #=> "not found"
 */

VALUE
rb_ary_delete(VALUE ary, VALUE item)
{
 VALUE v = item;
 long i1, i2;

 for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) {
	VALUE e = RARRAY_PTR(ary)[i1];

	if (rb_equal(e, item)) {
	 v = e;
	 continue;
	}
	if (i1 != i2) {
	 rb_ary_store(ary, i2, e);
	}
	i2++;
 }
 if (RARRAY_LEN(ary) == i2) {
	if (rb_block_given_p()) {
	 return rb_yield(item);
	}
	return Qnil;
 }

 rb_ary_modify(ary);
 if (RARRAY_LEN(ary) > i2) {
	ARY_SET_LEN(ary, i2);
	if (i2 * 2 < ARY_CAPA(ary) &&
	 ARY_CAPA(ary) > ARY_DEFAULT_SIZE) {
	 ary_resize_capa(ary, i2*2);
	}
 }

 return v;
}

VALUE
rb_ary_delete_at(VALUE ary, long pos)
{
 long len = RARRAY_LEN(ary);
 VALUE del;

 if (pos >= len) return Qnil;
 if (pos < 0) {
	pos += len;
	if (pos < 0) return Qnil;
 }

 rb_ary_modify(ary);
 del = RARRAY_PTR(ary)[pos];
 MEMMOVE(RARRAY_PTR(ary)+pos, RARRAY_PTR(ary)+pos+1, VALUE,
	 RARRAY_LEN(ary)-pos-1);
 ARY_INCREASE_LEN(ary, -1);

 return del;
}

/*
 * call-seq:
 * ary.delete_at(index) -> obj or nil
 *
 * Deletes the element at the specified index, returning that element,
 * or <code>nil</code> if the index is out of range. See also
 * <code>Array#slice!</code>.
 *
 * a = %w( ant bat cat dog )
 * a.delete_at(2) #=> "cat"
 * a #=> ["ant", "bat", "dog"]
 * a.delete_at(99) #=> nil
 */

static VALUE
rb_ary_delete_at_m(VALUE ary, VALUE pos)
{
 return rb_ary_delete_at(ary, NUM2LONG(pos));
}

/*
 * call-seq:
 * ary.slice!(index) -> obj or nil
 * ary.slice!(start, length) -> new_ary or nil
 * ary.slice!(range) -> new_ary or nil
 *
 * Deletes the element(s) given by an index (optionally with a length)
 * or by a range. Returns the deleted object (or objects), or
 * <code>nil</code> if the index is out of range.
 *
 * a = [ "a", "b", "c" ]
 * a.slice!(1) #=> "b"
 * a #=> ["a", "c"]
 * a.slice!(-1) #=> "c"
 * a #=> ["a"]
 * a.slice!(100) #=> nil
 * a #=> ["a"]
 */

static VALUE
rb_ary_slice_bang(int argc, VALUE *argv, VALUE ary)
{
 VALUE arg1, arg2;
 long pos, len, orig_len;

 rb_ary_modify_check(ary);
 if (argc == 2) {
	pos = NUM2LONG(argv[0]);
	len = NUM2LONG(argv[1]);
 delete_pos_len:
	if (len < 0) return Qnil;
	orig_len = RARRAY_LEN(ary);
	if (pos < 0) {
	 pos += orig_len;
	 if (pos < 0) return Qnil;
	}
	else if (orig_len < pos) return Qnil;
	if (orig_len < pos + len) {
	 len = orig_len - pos;
	}
	if (len == 0) return rb_ary_new2(0);
	arg2 = rb_ary_new4(len, RARRAY_PTR(ary)+pos);
	RBASIC(arg2)->klass = rb_obj_class(ary);
	rb_ary_splice(ary, pos, len, Qundef);
	return arg2;
 }

 if (argc != 1) {
	/* error report */
	rb_scan_args(argc, argv, "11", NULL, NULL);
 }
 arg1 = argv[0];

 if (!FIXNUM_P(arg1)) {
	switch (rb_range_beg_len(arg1, &pos, &len, RARRAY_LEN(ary), 0)) {
	 case Qtrue:
	 /* valid range */
	 goto delete_pos_len;
	 case Qnil:
	 /* invalid range */
	 return Qnil;
	 default:
	 /* not a range */
	 break;
	}
 }

 return rb_ary_delete_at(ary, NUM2LONG(arg1));
}

static VALUE
ary_reject(VALUE orig, VALUE result)
{
 long i;

 for (i = 0; i < RARRAY_LEN(orig); i++) {
	VALUE v = RARRAY_PTR(orig)[i];
	if (!RTEST(rb_yield(v))) {
	 rb_ary_push_1(result, v);
	}
 }
 return result;
}

static VALUE
ary_reject_bang(VALUE ary)
{
 long i;
 VALUE result = Qnil;

 rb_ary_modify_check(ary);
 for (i = 0; i < RARRAY_LEN(ary); ) {
	VALUE v = RARRAY_PTR(ary)[i];
	if (RTEST(rb_yield(v))) {
	 rb_ary_delete_at(ary, i);
	 result = ary;
	}
	else {
	 i++;
	}
 }
 return result;
}

/*
 * call-seq:
 * ary.reject! {|item| block } -> ary or nil
 * ary.reject! -> an_enumerator
 *
 * Equivalent to <code>Array#delete_if</code>, deleting elements from
 * +self+ for which the block evaluates to true, but returns
 * <code>nil</code> if no changes were made.
 * The array is changed instantly every time the block is called and
 * not after the iteration is over.
 * See also <code>Enumerable#reject</code> and <code>Array#delete_if</code>.
 *
 * If no block is given, an enumerator is returned instead.
 *
 */

static VALUE
rb_ary_reject_bang(VALUE ary)
{
 RETURN_ENUMERATOR(ary, 0, 0);
 return ary_reject_bang(ary);
}

/*
 * call-seq:
 * ary.reject {|item| block } -> new_ary
 * ary.reject -> an_enumerator
 *
 * Returns a new array containing the items in +self+
 * for which the block is not true.
 * See also <code>Array#delete_if</code>
 *
 * If no block is given, an enumerator is returned instead.
 *
 */

static VALUE
rb_ary_reject(VALUE ary)
{
 VALUE rejected_ary;

 RETURN_ENUMERATOR(ary, 0, 0);
 rejected_ary = rb_ary_new();
 ary_reject(ary, rejected_ary);
 return rejected_ary;
}

/*
 * call-seq:
 * ary.delete_if {|item| block } -> ary
 * ary.delete_if -> an_enumerator
 *
 * Deletes every element of +self+ for which <i>block</i> evaluates
 * to true.
 * The array is changed instantly every time the block is called and
 * not after the iteration is over.
 * See also <code>Array#reject!</code>
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = [ "a", "b", "c" ]
 * a.delete_if {|x| x >= "b" } #=> ["a"]
 */

static VALUE
rb_ary_delete_if(VALUE ary)
{
 RETURN_ENUMERATOR(ary, 0, 0);
 ary_reject_bang(ary);
 return ary;
}

static VALUE
take_i(VALUE val, VALUE *args, int argc, VALUE *argv)
{
 if (args[1]-- == 0) rb_iter_break();
 if (argc > 1) val = rb_ary_new4(argc, argv);
 rb_ary_push(args[0], val);
 return Qnil;
}

static VALUE
take_items(VALUE obj, long n)
{
 VALUE result = rb_check_array_type(obj);
 VALUE args[2];

 if (!NIL_P(result)) return rb_ary_subseq(result, 0, n);
 result = rb_ary_new2(n);
 args[0] = result; args[1] = (VALUE)n;
 rb_block_call(obj, rb_intern("each"), 0, 0, take_i, (VALUE)args);
 return result;
}


/*
 * call-seq:
 * ary.zip(arg, ...) -> new_ary
 * ary.zip(arg, ...) {| arr | block } -> nil
 *
 * Converts any arguments to arrays, then merges elements of
 * +self+ with corresponding elements from each argument. This
 * generates a sequence of <code>self.size</code> <em>n</em>-element
 * arrays, where <em>n</em> is one more that the count of arguments. If
 * the size of any argument is less than <code>enumObj.size</code>,
 * <code>nil</code> values are supplied. If a block is given, it is
 * invoked for each output array, otherwise an array of arrays is
 * returned.
 *
 * a = [ 4, 5, 6 ]
 * b = [ 7, 8, 9 ]
 * [1,2,3].zip(a, b) #=> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
 * [1,2].zip(a,b) #=> [[1, 4, 7], [2, 5, 8]]
 * a.zip([1,2],[8]) #=> [[4,1,8], [5,2,nil], [6,nil,nil]]
 */

static VALUE
rb_ary_zip(int argc, VALUE *argv, VALUE ary)
{
 int i, j;
 long len;
 VALUE result = Qnil;

 len = RARRAY_LEN(ary);
 for (i=0; i<argc; i++) {
	argv[i] = take_items(argv[i], len);
 }
 if (!rb_block_given_p()) {
	result = rb_ary_new2(len);
 }

 for (i=0; i<RARRAY_LEN(ary); i++) {
	VALUE tmp = rb_ary_new2(argc+1);

	rb_ary_push(tmp, rb_ary_elt(ary, i));
	for (j=0; j<argc; j++) {
	 rb_ary_push(tmp, rb_ary_elt(argv[j], i));
	}
	if (NIL_P(result)) {
	 rb_yield(tmp);
	}
	else {
	 rb_ary_push(result, tmp);
	}
 }
 return result;
}

/*
 * call-seq:
 * ary.transpose -> new_ary
 *
 * Assumes that +self+ is an array of arrays and transposes the
 * rows and columns.
 *
 * a = [[1,2], [3,4], [5,6]]
 * a.transpose #=> [[1, 3, 5], [2, 4, 6]]
 */

static VALUE
rb_ary_transpose(VALUE ary)
{
 long elen = -1, alen, i, j;
 VALUE tmp, result = 0;

 alen = RARRAY_LEN(ary);
 if (alen == 0) return rb_ary_dup(ary);
 for (i=0; i<alen; i++) {
	tmp = to_ary(rb_ary_elt(ary, i));
	if (elen < 0) {		/* first element */
	 elen = RARRAY_LEN(tmp);
	 result = rb_ary_new2(elen);
	 for (j=0; j<elen; j++) {
		rb_ary_store(result, j, rb_ary_new2(alen));
	 }
	}
	else if (elen != RARRAY_LEN(tmp)) {
	 rb_raise(rb_eIndexError, "element size differs (%ld should be %ld)",
		 RARRAY_LEN(tmp), elen);
	}
	for (j=0; j<elen; j++) {
	 rb_ary_store(rb_ary_elt(result, j), i, rb_ary_elt(tmp, j));
	}
 }
 return result;
}

/*
 * call-seq:
 * ary.replace(other_ary) -> ary
 *
 * Replaces the contents of +self+ with the contents of
 * <i>other_ary</i>, truncating or expanding if necessary.
 *
 * a = [ "a", "b", "c", "d", "e" ]
 * a.replace([ "x", "y", "z" ]) #=> ["x", "y", "z"]
 * a #=> ["x", "y", "z"]
 */

VALUE
rb_ary_replace(VALUE copy, VALUE orig)
{
 rb_ary_modify_check(copy);
 orig = to_ary(orig);
 if (copy == orig) return copy;

 if (RARRAY_LEN(orig) <= RARRAY_EMBED_LEN_MAX) {
 VALUE *ptr;
 VALUE shared = 0;

 if (ARY_OWNS_HEAP_P(copy)) {
 xfree(RARRAY_PTR(copy));
 }
 else if (ARY_SHARED_P(copy)) {
 shared = ARY_SHARED(copy);
 FL_UNSET_SHARED(copy);
 }
 FL_SET_EMBED(copy);
 ptr = RARRAY_PTR(orig);
 MEMCPY(RARRAY_PTR(copy), ptr, VALUE, RARRAY_LEN(orig));
 if (shared) {
 rb_ary_decrement_share(shared);
 }
 ARY_SET_LEN(copy, RARRAY_LEN(orig));
 }
 else {
 VALUE shared = ary_make_shared(orig);
 if (ARY_OWNS_HEAP_P(copy)) {
 xfree(RARRAY_PTR(copy));
 }
 else {
 rb_ary_unshare_safe(copy);
 }
 FL_UNSET_EMBED(copy);
 ARY_SET_PTR(copy, RARRAY_PTR(orig));
 ARY_SET_LEN(copy, RARRAY_LEN(orig));
 rb_ary_set_shared(copy, shared);
 }
 return copy;
}

/*
 * call-seq:
 * ary.clear -> ary
 *
 * Removes all elements from +self+.
 *
 * a = [ "a", "b", "c", "d", "e" ]
 * a.clear #=> [ ]
 */

VALUE
rb_ary_clear(VALUE ary)
{
 rb_ary_modify_check(ary);
 ARY_SET_LEN(ary, 0);
 if (ARY_SHARED_P(ary)) {
	if (!ARY_EMBED_P(ary)) {
	 rb_ary_unshare(ary);
	 FL_SET_EMBED(ary);
	}
 }
 else if (ARY_DEFAULT_SIZE * 2 < ARY_CAPA(ary)) {
	ary_resize_capa(ary, ARY_DEFAULT_SIZE * 2);
 }
 return ary;
}

/*
 * call-seq:
 * ary.fill(obj) -> ary
 * ary.fill(obj, start [, length]) -> ary
 * ary.fill(obj, range ) -> ary
 * ary.fill {|index| block } -> ary
 * ary.fill(start [, length] ) {|index| block } -> ary
 * ary.fill(range) {|index| block } -> ary
 *
 * The first three forms set the selected elements of +self+ (which
 * may be the entire array) to <i>obj</i>. A <i>start</i> of
 * <code>nil</code> is equivalent to zero. A <i>length</i> of
 * <code>nil</code> is equivalent to <i>self.length</i>. The last three
 * forms fill the array with the value of the block. The block is
 * passed the absolute index of each element to be filled.
 * Negative values of <i>start</i> count from the end of the array.
 *
 * a = [ "a", "b", "c", "d" ]
 * a.fill("x") #=> ["x", "x", "x", "x"]
 * a.fill("z", 2, 2) #=> ["x", "x", "z", "z"]
 * a.fill("y", 0..1) #=> ["y", "y", "z", "z"]
 * a.fill {|i| i*i} #=> [0, 1, 4, 9]
 * a.fill(-2) {|i| i*i*i} #=> [0, 1, 8, 27]
 */

static VALUE
rb_ary_fill(int argc, VALUE *argv, VALUE ary)
{
 VALUE item, arg1, arg2;
 long beg = 0, end = 0, len = 0;
 VALUE *p, *pend;
 int block_p = FALSE;

 if (rb_block_given_p()) {
	block_p = TRUE;
	rb_scan_args(argc, argv, "02", &arg1, &arg2);
	argc += 1;		/* hackish */
 }
 else {
	rb_scan_args(argc, argv, "12", &item, &arg1, &arg2);
 }
 switch (argc) {
 case 1:
	beg = 0;
	len = RARRAY_LEN(ary);
	break;
 case 2:
	if (rb_range_beg_len(arg1, &beg, &len, RARRAY_LEN(ary), 1)) {
	 break;
	}
	/* fall through */
 case 3:
	beg = NIL_P(arg1) ? 0 : NUM2LONG(arg1);
	if (beg < 0) {
	 beg = RARRAY_LEN(ary) + beg;
	 if (beg < 0) beg = 0;
	}
	len = NIL_P(arg2) ? RARRAY_LEN(ary) - beg : NUM2LONG(arg2);
	break;
 }
 rb_ary_modify(ary);
 if (len < 0) {
 return ary;
 }
 if (beg >= ARY_MAX_SIZE || len > ARY_MAX_SIZE - beg) {
	rb_raise(rb_eArgError, "argument too big");
 }
 end = beg + len;
 if (RARRAY_LEN(ary) < end) {
	if (end >= ARY_CAPA(ary)) {
	 ary_resize_capa(ary, end);
	}
	rb_mem_clear(RARRAY_PTR(ary) + RARRAY_LEN(ary), end - RARRAY_LEN(ary));
	ARY_SET_LEN(ary, end);
 }

 if (block_p) {
	VALUE v;
	long i;

	for (i=beg; i<end; i++) {
	 v = rb_yield(LONG2NUM(i));
	 if (i>=RARRAY_LEN(ary)) break;
	 RARRAY_PTR(ary)[i] = v;
	}
 }
 else {
	p = RARRAY_PTR(ary) + beg;
	pend = p + len;
	while (p < pend) {
	 *p++ = item;
	}
 }
 return ary;
}

/*
 * call-seq:
 * ary + other_ary -> new_ary
 *
 * Concatenation---Returns a new array built by concatenating the
 * two arrays together to produce a third array.
 *
 * [ 1, 2, 3 ] + [ 4, 5 ] #=> [ 1, 2, 3, 4, 5 ]
 */

VALUE
rb_ary_plus(VALUE x, VALUE y)
{
 VALUE z;
 long len;

 y = to_ary(y);
 len = RARRAY_LEN(x) + RARRAY_LEN(y);
 z = rb_ary_new2(len);
 MEMCPY(RARRAY_PTR(z), RARRAY_PTR(x), VALUE, RARRAY_LEN(x));
 MEMCPY(RARRAY_PTR(z) + RARRAY_LEN(x), RARRAY_PTR(y), VALUE, RARRAY_LEN(y));
 ARY_SET_LEN(z, len);
 return z;
}

/*
 * call-seq:
 * ary.concat(other_ary) -> ary
 *
 * Appends the elements of <i>other_ary</i> to +self+.
 *
 * [ "a", "b" ].concat( ["c", "d"] ) #=> [ "a", "b", "c", "d" ]
 */


VALUE
rb_ary_concat(VALUE x, VALUE y)
{
 rb_ary_modify_check(x);
 y = to_ary(y);
 if (RARRAY_LEN(y) > 0) {
	rb_ary_splice(x, RARRAY_LEN(x), 0, y);
 }
 return x;
}


/*
 * call-seq:
 * ary * int -> new_ary
 * ary * str -> new_string
 *
 * Repetition---With a String argument, equivalent to
 * self.join(str). Otherwise, returns a new array
 * built by concatenating the _int_ copies of +self+.
 *
 *
 * [ 1, 2, 3 ] * 3 #=> [ 1, 2, 3, 1, 2, 3, 1, 2, 3 ]
 * [ 1, 2, 3 ] * "," #=> "1,2,3"
 *
 */

static VALUE
rb_ary_times(VALUE ary, VALUE times)
{
 VALUE ary2, tmp, *ptr, *ptr2;
 long t, len;

 tmp = rb_check_string_type(times);
 if (!NIL_P(tmp)) {
	return rb_ary_join(ary, tmp);
 }

 len = NUM2LONG(times);
 if (len == 0) {
	ary2 = ary_new(rb_obj_class(ary), 0);
	goto out;
 }
 if (len < 0) {
	rb_raise(rb_eArgError, "negative argument");
 }
 if (ARY_MAX_SIZE/len < RARRAY_LEN(ary)) {
	rb_raise(rb_eArgError, "argument too big");
 }
 len *= RARRAY_LEN(ary);

 ary2 = ary_new(rb_obj_class(ary), len);
 ARY_SET_LEN(ary2, len);

 ptr = RARRAY_PTR(ary);
 ptr2 = RARRAY_PTR(ary2);
 t = RARRAY_LEN(ary);
 if (0 < t) {
 MEMCPY(ptr2, ptr, VALUE, t);
 while (t <= len/2) {
 MEMCPY(ptr2+t, ptr2, VALUE, t);
 t *= 2;
 }
 if (t < len) {
 MEMCPY(ptr2+t, ptr2, VALUE, len-t);
 }
 }
 out:
 OBJ_INFECT(ary2, ary);

 return ary2;
}

/*
 * call-seq:
 * ary.assoc(obj) -> new_ary or nil
 *
 * Searches through an array whose elements are also arrays
 * comparing _obj_ with the first element of each contained array
 * using obj.==.
 * Returns the first contained array that matches (that
 * is, the first associated array),
 * or +nil+ if no match is found.
 * See also <code>Array#rassoc</code>.
 *
 * s1 = [ "colors", "red", "blue", "green" ]
 * s2 = [ "letters", "a", "b", "c" ]
 * s3 = "foo"
 * a = [ s1, s2, s3 ]
 * a.assoc("letters") #=> [ "letters", "a", "b", "c" ]
 * a.assoc("foo") #=> nil
 */

VALUE
rb_ary_assoc(VALUE ary, VALUE key)
{
 long i;
 VALUE v;

 for (i = 0; i < RARRAY_LEN(ary); ++i) {
	v = rb_check_array_type(RARRAY_PTR(ary)[i]);
	if (!NIL_P(v) && RARRAY_LEN(v) > 0 &&
	 rb_equal(RARRAY_PTR(v)[0], key))
	 return v;
 }
 return Qnil;
}

/*
 * call-seq:
 * ary.rassoc(obj) -> new_ary or nil
 *
 * Searches through the array whose elements are also arrays. Compares
 * _obj_ with the second element of each contained array using
 * <code>==</code>. Returns the first contained array that matches. See
 * also <code>Array#assoc</code>.
 *
 * a = [ [ 1, "one"], [2, "two"], [3, "three"], ["ii", "two"] ]
 * a.rassoc("two") #=> [2, "two"]
 * a.rassoc("four") #=> nil
 */

VALUE
rb_ary_rassoc(VALUE ary, VALUE value)
{
 long i;
 VALUE v;

 for (i = 0; i < RARRAY_LEN(ary); ++i) {
	v = RARRAY_PTR(ary)[i];
	if (TYPE(v) == T_ARRAY &&
	 RARRAY_LEN(v) > 1 &&
	 rb_equal(RARRAY_PTR(v)[1], value))
	 return v;
 }
 return Qnil;
}

static VALUE
recursive_equal(VALUE ary1, VALUE ary2, int recur)
{
 long i;

 if (recur) return Qtrue; /* Subtle! */
 for (i=0; i<RARRAY_LEN(ary1); i++) {
	if (!rb_equal(rb_ary_elt(ary1, i), rb_ary_elt(ary2, i)))
	 return Qfalse;
 }
 return Qtrue;
}

/*
 * call-seq:
 * ary == other_ary -> bool
 *
 * Equality---Two arrays are equal if they contain the same number
 * of elements and if each element is equal to (according to
 * Object.==) the corresponding element in the other array.
 *
 * [ "a", "c" ] == [ "a", "c", 7 ] #=> false
 * [ "a", "c", 7 ] == [ "a", "c", 7 ] #=> true
 * [ "a", "c", 7 ] == [ "a", "d", "f" ] #=> false
 *
 */

static VALUE
rb_ary_equal(VALUE ary1, VALUE ary2)
{
 if (ary1 == ary2) return Qtrue;
 if (TYPE(ary2) != T_ARRAY) {
	if (!rb_respond_to(ary2, rb_intern("to_ary"))) {
	 return Qfalse;
	}
	return rb_equal(ary2, ary1);
 }
 if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse;
 return rb_exec_recursive_paired(recursive_equal, ary1, ary2, ary2);
}

static VALUE
recursive_eql(VALUE ary1, VALUE ary2, int recur)
{
 long i;

 if (recur) return Qtrue; /* Subtle! */
 for (i=0; i<RARRAY_LEN(ary1); i++) {
	if (!rb_eql(rb_ary_elt(ary1, i), rb_ary_elt(ary2, i)))
	 return Qfalse;
 }
 return Qtrue;
}

/*
 * call-seq:
 * ary.eql?(other) -> true or false
 *
 * Returns <code>true</code> if +self+ and _other_ are the same object,
 * or are both arrays with the same content.
 */

static VALUE
rb_ary_eql(VALUE ary1, VALUE ary2)
{
 if (ary1 == ary2) return Qtrue;
 if (TYPE(ary2) != T_ARRAY) return Qfalse;
 if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse;
 return rb_exec_recursive_paired(recursive_eql, ary1, ary2, ary2);
}

static VALUE
recursive_hash(VALUE ary, VALUE dummy, int recur)
{
 long i;
 st_index_t h;
 VALUE n;

 h = rb_hash_start(RARRAY_LEN(ary));
 if (recur) {
	h = rb_hash_uint(h, NUM2LONG(rb_hash(rb_cArray)));
 }
 else {
	for (i=0; i<RARRAY_LEN(ary); i++) {
	 n = rb_hash(RARRAY_PTR(ary)[i]);
	 h = rb_hash_uint(h, NUM2LONG(n));
	}
 }
 h = rb_hash_end(h);
 return LONG2FIX(h);
}

/*
 * call-seq:
 * ary.hash -> fixnum
 *
 * Compute a hash-code for this array. Two arrays with the same content
 * will have the same hash code (and will compare using <code>eql?</code>).
 */

static VALUE
rb_ary_hash(VALUE ary)
{
 return rb_exec_recursive_outer(recursive_hash, ary, 0);
}

/*
 * call-seq:
 * ary.include?(obj) -> true or false
 *
 * Returns <code>true</code> if the given object is present in
 * +self+ (that is, if any object <code>==</code> <i>anObject</i>),
 * <code>false</code> otherwise.
 *
 * a = [ "a", "b", "c" ]
 * a.include?("b") #=> true
 * a.include?("z") #=> false
 */

VALUE
rb_ary_includes(VALUE ary, VALUE item)
{
 long i;

 for (i=0; i<RARRAY_LEN(ary); i++) {
	if (rb_equal(RARRAY_PTR(ary)[i], item)) {
	 return Qtrue;
	}
 }
 return Qfalse;
}


static VALUE
recursive_cmp(VALUE ary1, VALUE ary2, int recur)
{
 long i, len;

 if (recur) return Qundef;	/* Subtle! */
 len = RARRAY_LEN(ary1);
 if (len > RARRAY_LEN(ary2)) {
	len = RARRAY_LEN(ary2);
 }
 for (i=0; i<len; i++) {
	VALUE v = rb_funcall(rb_ary_elt(ary1, i), id_cmp, 1, rb_ary_elt(ary2, i));
	if (v != INT2FIX(0)) {
	 return v;
	}
 }
 return Qundef;
}

/*
 * call-seq:
 * ary <=> other_ary -> -1, 0, +1 or nil
 *
 * Comparison---Returns an integer (-1, 0,
 * or +1) if this array is less than, equal to, or greater than
 * <i>other_ary</i>. Each object in each array is compared
 * (using <=>). If any value isn't
 * equal, then that inequality is the return value. If all the
 * values found are equal, then the return is based on a
 * comparison of the array lengths. Thus, two arrays are
 * ``equal'' according to <code>Array#<=></code> if and only if they have
 * the same length and the value of each element is equal to the
 * value of the corresponding element in the other array.
 *
 * [ "a", "a", "c" ] <=> [ "a", "b", "c" ] #=> -1
 * [ 1, 2, 3, 4, 5, 6 ] <=> [ 1, 2 ] #=> +1
 *
 */

VALUE
rb_ary_cmp(VALUE ary1, VALUE ary2)
{
 long len;
 VALUE v;

 ary2 = rb_check_array_type(ary2);
 if (NIL_P(ary2)) return Qnil;
 if (ary1 == ary2) return INT2FIX(0);
 v = rb_exec_recursive_paired(recursive_cmp, ary1, ary2, ary2);
 if (v != Qundef) return v;
 len = RARRAY_LEN(ary1) - RARRAY_LEN(ary2);
 if (len == 0) return INT2FIX(0);
 if (len > 0) return INT2FIX(1);
 return INT2FIX(-1);
}

static VALUE
ary_add_hash(VALUE hash, VALUE ary)
{
 long i;

 for (i=0; i<RARRAY_LEN(ary); i++) {
	rb_hash_aset(hash, RARRAY_PTR(ary)[i], Qtrue);
 }
 return hash;
}

static inline VALUE
ary_tmp_hash_new(void)
{
 VALUE hash = rb_hash_new();

 RBASIC(hash)->klass = 0;
 return hash;
}

static VALUE
ary_make_hash(VALUE ary)
{
 VALUE hash = ary_tmp_hash_new();
 return ary_add_hash(hash, ary);
}

static VALUE
ary_add_hash_by(VALUE hash, VALUE ary)
{
 long i;

 for (i = 0; i < RARRAY_LEN(ary); ++i) {
	VALUE v = rb_ary_elt(ary, i), k = rb_yield(v);
	if (rb_hash_lookup2(hash, k, Qundef) == Qundef) {
	 rb_hash_aset(hash, k, v);
	}
 }
 return hash;
}

static VALUE
ary_make_hash_by(VALUE ary)
{
 VALUE hash = ary_tmp_hash_new();
 return ary_add_hash_by(hash, ary);
}

static inline void
ary_recycle_hash(VALUE hash)
{
 if (RHASH(hash)->ntbl) {
	st_table *tbl = RHASH(hash)->ntbl;
	RHASH(hash)->ntbl = 0;
	st_free_table(tbl);
 }
}

/*
 * call-seq:
 * ary - other_ary -> new_ary
 *
 * Array Difference---Returns a new array that is a copy of
 * the original array, removing any items that also appear in
 * <i>other_ary</i>. (If you need set-like behavior, see the
 * library class Set.)
 *
 * [ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ] #=> [ 3, 3, 5 ]
 */

static VALUE
rb_ary_diff(VALUE ary1, VALUE ary2)
{
 VALUE ary3;
 volatile VALUE hash;
 long i;

 hash = ary_make_hash(to_ary(ary2));
 ary3 = rb_ary_new();

 for (i=0; i<RARRAY_LEN(ary1); i++) {
	if (st_lookup(RHASH_TBL(hash), RARRAY_PTR(ary1)[i], 0)) continue;
	rb_ary_push(ary3, rb_ary_elt(ary1, i));
 }
 ary_recycle_hash(hash);
 return ary3;
}

/*
 * call-seq:
 * ary & other_ary -> new_ary
 *
 * Set Intersection---Returns a new array
 * containing elements common to the two arrays, with no duplicates.
 *
 * [ 1, 1, 3, 5 ] & [ 1, 2, 3 ] #=> [ 1, 3 ]
 */


static VALUE
rb_ary_and(VALUE ary1, VALUE ary2)
{
 VALUE hash, ary3, v;
 st_data_t vv;
 long i;

 ary2 = to_ary(ary2);
 ary3 = rb_ary_new2(RARRAY_LEN(ary1) < RARRAY_LEN(ary2) ?
	 RARRAY_LEN(ary1) : RARRAY_LEN(ary2));
 hash = ary_make_hash(ary2);

 if (RHASH_EMPTY_P(hash))
 return ary3;

 for (i=0; i<RARRAY_LEN(ary1); i++) {
	vv = (st_data_t)(v = rb_ary_elt(ary1, i));
	if (st_delete(RHASH_TBL(hash), &vv, 0)) {
	 rb_ary_push(ary3, v);
	}
 }
 ary_recycle_hash(hash);

 return ary3;
}

/*
 * call-seq:
 * ary | other_ary -> new_ary
 *
 * Set Union---Returns a new array by joining this array with
 * <i>other_ary</i>, removing duplicates.
 *
 * [ "a", "b", "c" ] | [ "c", "d", "a" ]
 * #=> [ "a", "b", "c", "d" ]
 */

static VALUE
rb_ary_or(VALUE ary1, VALUE ary2)
{
 VALUE hash, ary3, v;
 st_data_t vv;
 long i;

 ary2 = to_ary(ary2);
 ary3 = rb_ary_new2(RARRAY_LEN(ary1)+RARRAY_LEN(ary2));
 hash = ary_add_hash(ary_make_hash(ary1), ary2);

 for (i=0; i<RARRAY_LEN(ary1); i++) {
	vv = (st_data_t)(v = rb_ary_elt(ary1, i));
	if (st_delete(RHASH_TBL(hash), &vv, 0)) {
	 rb_ary_push(ary3, v);
	}
 }
 for (i=0; i<RARRAY_LEN(ary2); i++) {
	vv = (st_data_t)(v = rb_ary_elt(ary2, i));
	if (st_delete(RHASH_TBL(hash), &vv, 0)) {
	 rb_ary_push(ary3, v);
	}
 }
 ary_recycle_hash(hash);
 return ary3;
}

static int
push_value(st_data_t key, st_data_t val, st_data_t ary)
{
 rb_ary_push((VALUE)ary, (VALUE)val);
 return ST_CONTINUE;
}

/*
 * call-seq:
 * ary.uniq! -> ary or nil
 * ary.uniq! { |item| ... } -> ary or nil
 *
 * Removes duplicate elements from +self+. If a block is given,
 * it will use the return value of the block for comparison.
 * Returns <code>nil</code> if no changes are made (that is, no
 * duplicates are found).
 *
 * a = [ "a", "a", "b", "b", "c" ]
 * a.uniq! # => ["a", "b", "c"]
 *
 * b = [ "a", "b", "c" ]
 * b.uniq! # => nil
 *
 * c = [["student","sam"], ["student","george"], ["teacher","matz"]]
 * c.uniq! { |s| s.first } # => [["student", "sam"], ["teacher", "matz"]]
 *
 */

static VALUE
rb_ary_uniq_bang(VALUE ary)
{
 VALUE hash, v;
 long i, j;

 rb_ary_modify_check(ary);
 if (RARRAY_LEN(ary) <= 1)
 return Qnil;
 if (rb_block_given_p()) {
	hash = ary_make_hash_by(ary);
	if (RARRAY_LEN(ary) == (i = RHASH_SIZE(hash))) {
	 return Qnil;
	}
	ARY_SET_LEN(ary, 0);
	if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
	 rb_ary_unshare(ary);
	 FL_SET_EMBED(ary);
	}
	ary_resize_capa(ary, i);
	st_foreach(RHASH_TBL(hash), push_value, ary);
 }
 else {
	hash = ary_make_hash(ary);
	if (RARRAY_LEN(ary) == (long)RHASH_SIZE(hash)) {
	 return Qnil;
	}
	for (i=j=0; i<RARRAY_LEN(ary); i++) {
	 st_data_t vv = (st_data_t)(v = rb_ary_elt(ary, i));
	 if (st_delete(RHASH_TBL(hash), &vv, 0)) {
		rb_ary_store(ary, j++, v);
	 }
	}
	ARY_SET_LEN(ary, j);
 }
 ary_recycle_hash(hash);

 return ary;
}

/*
 * call-seq:
 * ary.uniq -> new_ary
 * ary.uniq { |item| ... } -> new_ary
 *
 * Returns a new array by removing duplicate values in +self+. If a block
 * is given, it will use the return value of the block for comparison.
 *
 * a = [ "a", "a", "b", "b", "c" ]
 * a.uniq # => ["a", "b", "c"]
 *
 * b = [["student","sam"], ["student","george"], ["teacher","matz"]]
 * b.uniq { |s| s.first } # => [["student", "sam"], ["teacher", "matz"]]
 *
 */

static VALUE
rb_ary_uniq(VALUE ary)
{
 VALUE hash, uniq, v;
 long i;

 if (RARRAY_LEN(ary) <= 1)
 return rb_ary_dup(ary);
 if (rb_block_given_p()) {
	hash = ary_make_hash_by(ary);
	uniq = ary_new(rb_obj_class(ary), RHASH_SIZE(hash));
	st_foreach(RHASH_TBL(hash), push_value, uniq);
 }
 else {
	hash = ary_make_hash(ary);
	uniq = ary_new(rb_obj_class(ary), RHASH_SIZE(hash));
	for (i=0; i<RARRAY_LEN(ary); i++) {
	 st_data_t vv = (st_data_t)(v = rb_ary_elt(ary, i));
	 if (st_delete(RHASH_TBL(hash), &vv, 0)) {
		rb_ary_push(uniq, v);
	 }
	}
 }
 ary_recycle_hash(hash);

 return uniq;
}

/*
 * call-seq:
 * ary.compact! -> ary or nil
 *
 * Removes +nil+ elements from the array.
 * Returns +nil+ if no changes were made, otherwise returns
 * <i>ary</i>.
 *
 * [ "a", nil, "b", nil, "c" ].compact! #=> [ "a", "b", "c" ]
 * [ "a", "b", "c" ].compact! #=> nil
 */

static VALUE
rb_ary_compact_bang(VALUE ary)
{
 VALUE *p, *t, *end;
 long n;

 rb_ary_modify(ary);
 p = t = RARRAY_PTR(ary);
 end = p + RARRAY_LEN(ary);

 while (t < end) {
	if (NIL_P(*t)) t++;
	else *p++ = *t++;
 }
 n = p - RARRAY_PTR(ary);
 if (RARRAY_LEN(ary) == n) {
	return Qnil;
 }
 ARY_SET_LEN(ary, n);
 if (n * 2 < ARY_CAPA(ary) && ARY_DEFAULT_SIZE * 2 < ARY_CAPA(ary)) {
	ary_resize_capa(ary, n * 2);
 }

 return ary;
}

/*
 * call-seq:
 * ary.compact -> new_ary
 *
 * Returns a copy of +self+ with all +nil+ elements removed.
 *
 * [ "a", nil, "b", nil, "c", nil ].compact
 * #=> [ "a", "b", "c" ]
 */

static VALUE
rb_ary_compact(VALUE ary)
{
 ary = rb_ary_dup(ary);
 rb_ary_compact_bang(ary);
 return ary;
}

/*
 * call-seq:
 * ary.count -> int
 * ary.count(obj) -> int
 * ary.count { |item| block } -> int
 *
 * Returns the number of elements. If an argument is given, counts
 * the number of elements which equals to <i>obj</i>. If a block is
 * given, counts the number of elements yielding a true value.
 *
 * ary = [1, 2, 4, 2]
 * ary.count #=> 4
 * ary.count(2) #=> 2
 * ary.count{|x|x%2==0} #=> 3
 *
 */

static VALUE
rb_ary_count(int argc, VALUE *argv, VALUE ary)
{
 long i, n = 0;

 if (argc == 0) {
	VALUE v;

	if (!rb_block_given_p())
	 return LONG2NUM(RARRAY_LEN(ary));

	for (i = 0; i < RARRAY_LEN(ary); i++) {
	 v = RARRAY_PTR(ary)[i];
	 if (RTEST(rb_yield(v))) n++;
	}
 }
 else {
	VALUE obj;

	rb_scan_args(argc, argv, "1", &obj);
	if (rb_block_given_p()) {
	 rb_warn("given block not used");
	}
	for (i = 0; i < RARRAY_LEN(ary); i++) {
	 if (rb_equal(RARRAY_PTR(ary)[i], obj)) n++;
	}
 }

 return LONG2NUM(n);
}

static VALUE
flatten(VALUE ary, int level, int *modified)
{
 long i = 0;
 VALUE stack, result, tmp, elt;
 st_table *memo;
 st_data_t id;

 stack = ary_new(0, ARY_DEFAULT_SIZE);
 result = ary_new(0, RARRAY_LEN(ary));
 memo = st_init_numtable();
 st_insert(memo, (st_data_t)ary, (st_data_t)Qtrue);
 *modified = 0;

 while (1) {
	while (i < RARRAY_LEN(ary)) {
	 elt = RARRAY_PTR(ary)[i++];
	 tmp = rb_check_array_type(elt);
	 if (RBASIC(result)->klass) {
		rb_raise(rb_eRuntimeError, "flatten reentered");
	 }
	 if (NIL_P(tmp) || (level >= 0 && RARRAY_LEN(stack) / 2 >= level)) {
		rb_ary_push(result, elt);
	 }
	 else {
		*modified = 1;
		id = (st_data_t)tmp;
		if (st_lookup(memo, id, 0)) {
		 st_free_table(memo);
		 rb_raise(rb_eArgError, "tried to flatten recursive array");
		}
		st_insert(memo, id, (st_data_t)Qtrue);
		rb_ary_push(stack, ary);
		rb_ary_push(stack, LONG2NUM(i));
		ary = tmp;
		i = 0;
	 }
	}
	if (RARRAY_LEN(stack) == 0) {
	 break;
	}
	id = (st_data_t)ary;
	st_delete(memo, &id, 0);
	tmp = rb_ary_pop(stack);
	i = NUM2LONG(tmp);
	ary = rb_ary_pop(stack);
 }

 st_free_table(memo);

 RBASIC(result)->klass = rb_class_of(ary);
 return result;
}

/*
 * call-seq:
 * ary.flatten! -> ary or nil
 * ary.flatten!(level) -> array or nil
 *
 * Flattens +self+ in place.
 * Returns <code>nil</code> if no modifications were made (i.e.,
 * <i>ary</i> contains no subarrays.) If the optional <i>level</i>
 * argument determines the level of recursion to flatten.
 *
 * a = [ 1, 2, [3, [4, 5] ] ]
 * a.flatten! #=> [1, 2, 3, 4, 5]
 * a.flatten! #=> nil
 * a #=> [1, 2, 3, 4, 5]
 * a = [ 1, 2, [3, [4, 5] ] ]
 * a.flatten!(1) #=> [1, 2, 3, [4, 5]]
 */

static VALUE
rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
{
 int mod = 0, level = -1;
 VALUE result, lv;

 rb_scan_args(argc, argv, "01", &lv);
 rb_ary_modify_check(ary);
 if (!NIL_P(lv)) level = NUM2INT(lv);
 if (level == 0) return Qnil;

 result = flatten(ary, level, &mod);
 if (mod == 0) {
	ary_discard(result);
	return Qnil;
 }
 if (!(mod = ARY_EMBED_P(result))) rb_obj_freeze(result);
 rb_ary_replace(ary, result);
 if (mod) ARY_SET_EMBED_LEN(result, 0);

 return ary;
}

/*
 * call-seq:
 * ary.flatten -> new_ary
 * ary.flatten(level) -> new_ary
 *
 * Returns a new array that is a one-dimensional flattening of this
 * array (recursively). That is, for every element that is an array,
 * extract its elements into the new array. If the optional
 * <i>level</i> argument determines the level of recursion to flatten.
 *
 * s = [ 1, 2, 3 ] #=> [1, 2, 3]
 * t = [ 4, 5, 6, [7, 8] ] #=> [4, 5, 6, [7, 8]]
 * a = [ s, t, 9, 10 ] #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
 * a.flatten #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 * a = [ 1, 2, [3, [4, 5] ] ]
 * a.flatten(1) #=> [1, 2, 3, [4, 5]]
 */

static VALUE
rb_ary_flatten(int argc, VALUE *argv, VALUE ary)
{
 int mod = 0, level = -1;
 VALUE result, lv;

 rb_scan_args(argc, argv, "01", &lv);
 if (!NIL_P(lv)) level = NUM2INT(lv);
 if (level == 0) return ary_make_shared_copy(ary);

 result = flatten(ary, level, &mod);
 OBJ_INFECT(result, ary);

 return result;
}

#define OPTHASH_GIVEN_P(opts) \
 (argc > 0 && !NIL_P((opts) = rb_check_hash_type(argv[argc-1])) && (--argc, 1))
static VALUE sym_random;

#define RAND_UPTO(max) (long)(rb_random_real(randgen)*(max))

/*
 * call-seq:
 * ary.shuffle! -> ary
 * ary.shuffle!(random: rng) -> ary
 *
 * Shuffles elements in +self+ in place.
 * If +rng+ is given, it will be used as the random number generator.
 */

static VALUE
rb_ary_shuffle_bang(int argc, VALUE *argv, VALUE ary)
{
 VALUE *ptr, opts, *snap_ptr, randgen = rb_cRandom;
 long i, snap_len;

 if (OPTHASH_GIVEN_P(opts)) {
	randgen = rb_hash_lookup2(opts, sym_random, randgen);
 }
 if (argc > 0) {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
 }
 rb_ary_modify(ary);
 i = RARRAY_LEN(ary);
 ptr = RARRAY_PTR(ary);
 snap_len = i;
 snap_ptr = ptr;
 while (i) {
	long j = RAND_UPTO(i);
	VALUE tmp;
	if (snap_len != RARRAY_LEN(ary) || snap_ptr != RARRAY_PTR(ary)) {
	 rb_raise(rb_eRuntimeError, "modified during shuffle");
	}
	tmp = ptr[--i];
	ptr[i] = ptr[j];
	ptr[j] = tmp;
 }
 return ary;
}


/*
 * call-seq:
 * ary.shuffle -> new_ary
 * ary.shuffle(random: rng) -> new_ary
 *
 * Returns a new array with elements of this array shuffled.
 *
 * a = [ 1, 2, 3 ] #=> [1, 2, 3]
 * a.shuffle #=> [2, 3, 1]
 *
 * If +rng+ is given, it will be used as the random number generator.
 *
 * a.shuffle(random: Random.new(1)) #=> [1, 3, 2]
 */

static VALUE
rb_ary_shuffle(int argc, VALUE *argv, VALUE ary)
{
 ary = rb_ary_dup(ary);
 rb_ary_shuffle_bang(argc, argv, ary);
 return ary;
}


/*
 * call-seq:
 * ary.sample -> obj
 * ary.sample(random: rng) -> obj
 * ary.sample(n) -> new_ary
 * ary.sample(n, random: rng) -> new_ary
 *
 * Choose a random element or +n+ random elements from the array. The elements
 * are chosen by using random and unique indices into the array in order to
 * ensure that an element doesn't repeat itself unless the array already
 * contained duplicate elements. If the array is empty the first form returns
 * <code>nil</code> and the second form returns an empty array.
 *
 * If +rng+ is given, it will be used as the random number generator.
 */


static VALUE
rb_ary_sample(int argc, VALUE *argv, VALUE ary)
{
 VALUE nv, result, *ptr;
 VALUE opts, randgen = rb_cRandom;
 long n, len, i, j, k, idx[10];
 double rnds[numberof(idx)];

 if (OPTHASH_GIVEN_P(opts)) {
	randgen = rb_hash_lookup2(opts, sym_random, randgen);
 }
 ptr = RARRAY_PTR(ary);
 len = RARRAY_LEN(ary);
 if (argc == 0) {
	if (len == 0) return Qnil;
	if (len == 1) {
	 i = 0;
	}
	else {
	 double x = rb_random_real(randgen);
	 if ((len = RARRAY_LEN(ary)) == 0) return Qnil;
	 i = (long)(x * len);
	}
	return RARRAY_PTR(ary)[i];
 }
 rb_scan_args(argc, argv, "1", &nv);
 n = NUM2LONG(nv);
 if (n < 0) rb_raise(rb_eArgError, "negative sample number");
 if (n > len) n = len;
 if (n <= numberof(idx)) {
	for (i = 0; i < n; ++i) {
	 rnds[i] = rb_random_real(randgen);
	}
 }
 len = RARRAY_LEN(ary);
 ptr = RARRAY_PTR(ary);
 if (n > len) n = len;
 switch (n) {
 case 0:
	return rb_ary_new2(0);
 case 1:
	i = (long)(rnds[0] * len);
	return rb_ary_new4(1, &ptr[i]);
 case 2:
	i = (long)(rnds[0] * len);
	j = (long)(rnds[1] * (len-1));
	if (j >= i) j++;
	return rb_ary_new3(2, ptr[i], ptr[j]);
 case 3:
	i = (long)(rnds[0] * len);
	j = (long)(rnds[1] * (len-1));
	k = (long)(rnds[2] * (len-2));
	{
	 long l = j, g = i;
	 if (j >= i) l = i, g = ++j;
	 if (k >= l && (++k >= g)) ++k;
	}
	return rb_ary_new3(3, ptr[i], ptr[j], ptr[k]);
 }
 if (n <= numberof(idx)) {
	VALUE *ptr_result;
	long sorted[numberof(idx)];
	sorted[0] = idx[0] = (long)(rnds[0] * len);
	for (i=1; i<n; i++) {
	 k = (long)(rnds[i] * --len);
	 for (j = 0; j < i; ++j) {
		if (k < sorted[j]) break;
		++k;
	 }
	 memmove(&sorted[j+1], &sorted[j], sizeof(sorted[0])*(i-j));
	 sorted[j] = idx[i] = k;
	}
	result = rb_ary_new2(n);
	ptr_result = RARRAY_PTR(result);
	for (i=0; i<n; i++) {
	 ptr_result[i] = ptr[idx[i]];
	}
 }
 else {
	VALUE *ptr_result;
	result = rb_ary_new4(len, ptr);
	RBASIC(result)->klass = 0;
	ptr_result = RARRAY_PTR(result);
	RB_GC_GUARD(ary);
	for (i=0; i<n; i++) {
	 j = RAND_UPTO(len-i) + i;
	 nv = ptr_result[j];
	 ptr_result[j] = ptr_result[i];
	 ptr_result[i] = nv;
	}
	RBASIC(result)->klass = rb_cArray;
 }
 ARY_SET_LEN(result, n);

 return result;
}


/*
 * call-seq:
 * ary.cycle(n=nil) {|obj| block } -> nil
 * ary.cycle(n=nil) -> an_enumerator
 *
 * Calls <i>block</i> for each element repeatedly _n_ times or
 * forever if none or +nil+ is given. If a non-positive number is
 * given or the array is empty, does nothing. Returns +nil+ if the
 * loop has finished without getting interrupted.
 *
 * If no block is given, an enumerator is returned instead.
 *
 *
 * a = ["a", "b", "c"]
 * a.cycle {|x| puts x } # print, a, b, c, a, b, c,.. forever.
 * a.cycle(2) {|x| puts x } # print, a, b, c, a, b, c.
 *
 */

static VALUE
rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
{
 long n, i;
 VALUE nv = Qnil;

 rb_scan_args(argc, argv, "01", &nv);

 RETURN_ENUMERATOR(ary, argc, argv);
 if (NIL_P(nv)) {
 n = -1;
 }
 else {
 n = NUM2LONG(nv);
 if (n <= 0) return Qnil;
 }

 while (RARRAY_LEN(ary) > 0 && (n < 0 || 0 < n--)) {
 for (i=0; i<RARRAY_LEN(ary); i++) {
 rb_yield(RARRAY_PTR(ary)[i]);
 }
 }
 return Qnil;
}

#define tmpbuf(n, size) rb_str_tmp_new((n)*(size))
#define tmpbuf_discard(s) (rb_str_resize((s), 0L), RBASIC(s)->klass = rb_cString)
#define tmpary(n) rb_ary_tmp_new(n)
#define tmpary_discard(a) (ary_discard(a), RBASIC(a)->klass = rb_cArray)

/*
 * Recursively compute permutations of r elements of the set [0..n-1].
 * When we have a complete permutation of array indexes, copy the values
 * at those indexes into a new array and yield that array.
 *
 * n: the size of the set
 * r: the number of elements in each permutation
 * p: the array (of size r) that we're filling in
 * index: what index we're filling in now
 * used: an array of booleans: whether a given index is already used
 * values: the Ruby array that holds the actual values to permute
 */
static void
permute0(long n, long r, long *p, long index, char *used, VALUE values)
{
 long i,j;
 for (i = 0; i < n; i++) {
	if (used[i] == 0) {
	 p[index] = i;
	 if (index < r-1) { /* if not done yet */
		used[i] = 1; /* mark index used */
		permute0(n, r, p, index+1, /* recurse */
			 used, values);
		used[i] = 0; /* index unused */
	 }
	 else {
		/* We have a complete permutation of array indexes */
		/* Build a ruby array of the corresponding values */
		/* And yield it to the associated block */
		VALUE result = rb_ary_new2(r);
		VALUE *result_array = RARRAY_PTR(result);
		const VALUE *values_array = RARRAY_PTR(values);

		for (j = 0; j < r; j++) result_array[j] = values_array[p[j]];
		ARY_SET_LEN(result, r);
		rb_yield(result);
		if (RBASIC(values)->klass) {
		 rb_raise(rb_eRuntimeError, "permute reentered");
		}
	 }
	}
 }
}

/*
 * call-seq:
 * ary.permutation { |p| block } -> ary
 * ary.permutation -> an_enumerator
 * ary.permutation(n) { |p| block } -> ary
 * ary.permutation(n) -> an_enumerator
 *
 * When invoked with a block, yield all permutations of length <i>n</i>
 * of the elements of <i>ary</i>, then return the array itself.
 * If <i>n</i> is not specified, yield all permutations of all elements.
 * The implementation makes no guarantees about the order in which
 * the permutations are yielded.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * Examples:
 *
 * a = [1, 2, 3]
 * a.permutation.to_a #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
 * a.permutation(1).to_a #=> [[1],[2],[3]]
 * a.permutation(2).to_a #=> [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]]
 * a.permutation(3).to_a #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
 * a.permutation(0).to_a #=> [[]] # one permutation of length 0
 * a.permutation(4).to_a #=> [] # no permutations of length 4
 */

static VALUE
rb_ary_permutation(int argc, VALUE *argv, VALUE ary)
{
 VALUE num;
 long r, n, i;

 n = RARRAY_LEN(ary); /* Array length */
 RETURN_ENUMERATOR(ary, argc, argv); /* Return enumerator if no block */
 rb_scan_args(argc, argv, "01", &num);
 r = NIL_P(num) ? n : NUM2LONG(num); /* Permutation size from argument */

 if (r < 0 || n < r) {
	/* no permutations: yield nothing */
 }
 else if (r == 0) { /* exactly one permutation: the zero-length array */
	rb_yield(rb_ary_new2(0));
 }
 else if (r == 1) { /* this is a special, easy case */
	for (i = 0; i < RARRAY_LEN(ary); i++) {
	 rb_yield(rb_ary_new3(1, RARRAY_PTR(ary)[i]));
	}
 }
 else { /* this is the general case */
	volatile VALUE t0 = tmpbuf(n,sizeof(long));
	long *p = (long*)RSTRING_PTR(t0);
	volatile VALUE t1 = tmpbuf(n,sizeof(char));
	char *used = (char*)RSTRING_PTR(t1);
	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
	RBASIC(ary0)->klass = 0;

	MEMZERO(used, char, n); /* initialize array */

	permute0(n, r, p, 0, used, ary0); /* compute and yield permutations */
	tmpbuf_discard(t0);
	tmpbuf_discard(t1);
	RBASIC(ary0)->klass = rb_cArray;
 }
 return ary;
}

/*
 * call-seq:
 * ary.combination(n) { |c| block } -> ary
 * ary.combination(n) -> an_enumerator
 *
 * When invoked with a block, yields all combinations of length <i>n</i>
 * of elements from <i>ary</i> and then returns <i>ary</i> itself.
 * The implementation makes no guarantees about the order in which
 * the combinations are yielded.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * Examples:
 *
 * a = [1, 2, 3, 4]
 * a.combination(1).to_a #=> [[1],[2],[3],[4]]
 * a.combination(2).to_a #=> [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
 * a.combination(3).to_a #=> [[1,2,3],[1,2,4],[1,3,4],[2,3,4]]
 * a.combination(4).to_a #=> [[1,2,3,4]]
 * a.combination(0).to_a #=> [[]] # one combination of length 0
 * a.combination(5).to_a #=> [] # no combinations of length 5
 *
 */

static VALUE
rb_ary_combination(VALUE ary, VALUE num)
{
 long n, i, len;

 n = NUM2LONG(num);
 RETURN_ENUMERATOR(ary, 1, &num);
 len = RARRAY_LEN(ary);
 if (n < 0 || len < n) {
	/* yield nothing */
 }
 else if (n == 0) {
	rb_yield(rb_ary_new2(0));
 }
 else if (n == 1) {
	for (i = 0; i < len; i++) {
	 rb_yield(rb_ary_new3(1, RARRAY_PTR(ary)[i]));
	}
 }
 else {
	volatile VALUE t0 = tmpbuf(n+1, sizeof(long));
	long *stack = (long*)RSTRING_PTR(t0);
	volatile VALUE cc = tmpary(n);
	VALUE *chosen = RARRAY_PTR(cc);
	long lev = 0;

	MEMZERO(stack, long, n);
	stack[0] = -1;
	for (;;) {
	 chosen[lev] = RARRAY_PTR(ary)[stack[lev+1]];
	 for (lev++; lev < n; lev++) {
		chosen[lev] = RARRAY_PTR(ary)[stack[lev+1] = stack[lev]+1];
	 }
	 rb_yield(rb_ary_new4(n, chosen));
	 if (RBASIC(t0)->klass) {
		rb_raise(rb_eRuntimeError, "combination reentered");
	 }
	 do {
		if (lev == 0) goto done;
		stack[lev--]++;
	 } while (stack[lev+1]+n == len+lev+1);
	}
 done:
	tmpbuf_discard(t0);
	tmpary_discard(cc);
 }
 return ary;
}

/*
 * Recursively compute repeated permutations of r elements of the set
 * [0..n-1].
 * When we have a complete repeated permutation of array indexes, copy the
 * values at those indexes into a new array and yield that array.
 *
 * n: the size of the set
 * r: the number of elements in each permutation
 * p: the array (of size r) that we're filling in
 * index: what index we're filling in now
 * values: the Ruby array that holds the actual values to permute
 */
static void
rpermute0(long n, long r, long *p, long index, VALUE values)
{
 long i, j;
 for (i = 0; i < n; i++) {
	p[index] = i;
	if (index < r-1) { /* if not done yet */
	 rpermute0(n, r, p, index+1, values); /* recurse */
	}
	else {
	 /* We have a complete permutation of array indexes */
	 /* Build a ruby array of the corresponding values */
	 /* And yield it to the associated block */
	 VALUE result = rb_ary_new2(r);
	 VALUE *result_array = RARRAY_PTR(result);
	 const VALUE *values_array = RARRAY_PTR(values);

	 for (j = 0; j < r; j++) result_array[j] = values_array[p[j]];
	 ARY_SET_LEN(result, r);
	 rb_yield(result);
	 if (RBASIC(values)->klass) {
		rb_raise(rb_eRuntimeError, "repeated permute reentered");
	 }
	}
 }
}

/*
 * call-seq:
 * ary.repeated_permutation(n) { |p| block } -> ary
 * ary.repeated_permutation(n) -> an_enumerator
 *
 * When invoked with a block, yield all repeated permutations of length
 * <i>n</i> of the elements of <i>ary</i>, then return the array itself.
 * The implementation makes no guarantees about the order in which
 * the repeated permutations are yielded.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * Examples:
 *
 * a = [1, 2]
 * a.repeated_permutation(1).to_a #=> [[1], [2]]
 * a.repeated_permutation(2).to_a #=> [[1,1],[1,2],[2,1],[2,2]]
 * a.repeated_permutation(3).to_a #=> [[1,1,1],[1,1,2],[1,2,1],[1,2,2],
 * # [2,1,1],[2,1,2],[2,2,1],[2,2,2]]
 * a.repeated_permutation(0).to_a #=> [[]] # one permutation of length 0
 */

static VALUE
rb_ary_repeated_permutation(VALUE ary, VALUE num)
{
 long r, n, i;

 n = RARRAY_LEN(ary); /* Array length */
 RETURN_ENUMERATOR(ary, 1, &num); /* Return enumerator if no block */
 r = NUM2LONG(num); /* Permutation size from argument */

 if (r < 0) {
	/* no permutations: yield nothing */
 }
 else if (r == 0) { /* exactly one permutation: the zero-length array */
	rb_yield(rb_ary_new2(0));
 }
 else if (r == 1) { /* this is a special, easy case */
	for (i = 0; i < RARRAY_LEN(ary); i++) {
	 rb_yield(rb_ary_new3(1, RARRAY_PTR(ary)[i]));
	}
 }
 else { /* this is the general case */
	volatile VALUE t0 = tmpbuf(r, sizeof(long));
	long *p = (long*)RSTRING_PTR(t0);
	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
	RBASIC(ary0)->klass = 0;

	rpermute0(n, r, p, 0, ary0); /* compute and yield repeated permutations */
	tmpbuf_discard(t0);
	RBASIC(ary0)->klass = rb_cArray;
 }
 return ary;
}

static void
rcombinate0(long n, long r, long *p, long index, long rest, VALUE values)
{
 long j;
 if (rest > 0) {
	for (; index < n; ++index) {
	 p[r-rest] = index;
	 rcombinate0(n, r, p, index, rest-1, values);
	}
 }
 else {
	VALUE result = rb_ary_new2(r);
	VALUE *result_array = RARRAY_PTR(result);
	const VALUE *values_array = RARRAY_PTR(values);

	for (j = 0; j < r; ++j) result_array[j] = values_array[p[j]];
	ARY_SET_LEN(result, r);
	rb_yield(result);
	if (RBASIC(values)->klass) {
	 rb_raise(rb_eRuntimeError, "repeated combination reentered");
	}
 }
}

/*
 * call-seq:
 * ary.repeated_combination(n) { |c| block } -> ary
 * ary.repeated_combination(n) -> an_enumerator
 *
 * When invoked with a block, yields all repeated combinations of
 * length <i>n</i> of elements from <i>ary</i> and then returns
 * <i>ary</i> itself.
 * The implementation makes no guarantees about the order in which
 * the repeated combinations are yielded.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * Examples:
 *
 * a = [1, 2, 3]
 * a.repeated_combination(1).to_a #=> [[1], [2], [3]]
 * a.repeated_combination(2).to_a #=> [[1,1],[1,2],[1,3],[2,2],[2,3],[3,3]]
 * a.repeated_combination(3).to_a #=> [[1,1,1],[1,1,2],[1,1,3],[1,2,2],[1,2,3],
 * # [1,3,3],[2,2,2],[2,2,3],[2,3,3],[3,3,3]]
 * a.repeated_combination(4).to_a #=> [[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,2],[1,1,2,3],
 * # [1,1,3,3],[1,2,2,2],[1,2,2,3],[1,2,3,3],[1,3,3,3],
 * # [2,2,2,2],[2,2,2,3],[2,2,3,3],[2,3,3,3],[3,3,3,3]]
 * a.repeated_combination(0).to_a #=> [[]] # one combination of length 0
 *
 */

static VALUE
rb_ary_repeated_combination(VALUE ary, VALUE num)
{
 long n, i, len;

 n = NUM2LONG(num); /* Combination size from argument */
 RETURN_ENUMERATOR(ary, 1, &num); /* Return enumerator if no block */
 len = RARRAY_LEN(ary);
 if (n < 0) {
	/* yield nothing */
 }
 else if (n == 0) {
	rb_yield(rb_ary_new2(0));
 }
 else if (n == 1) {
	for (i = 0; i < len; i++) {
	 rb_yield(rb_ary_new3(1, RARRAY_PTR(ary)[i]));
	}
 }
 else if (len == 0) {
	/* yield nothing */
 }
 else {
	volatile VALUE t0 = tmpbuf(n, sizeof(long));
	long *p = (long*)RSTRING_PTR(t0);
	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
	RBASIC(ary0)->klass = 0;

	rcombinate0(len, n, p, 0, n, ary0); /* compute and yield repeated combinations */
	tmpbuf_discard(t0);
	RBASIC(ary0)->klass = rb_cArray;
 }
 return ary;
}

/*
 * call-seq:
 * ary.product(other_ary, ...) -> new_ary
 * ary.product(other_ary, ...) { |p| block } -> ary
 *
 * Returns an array of all combinations of elements from all arrays.
 * The length of the returned array is the product of the length
 * of +self+ and the argument arrays.
 * If given a block, <i>product</i> will yield all combinations
 * and return +self+ instead.
 *
 *
 * [1,2,3].product([4,5]) #=> [[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]]
 * [1,2].product([1,2]) #=> [[1,1],[1,2],[2,1],[2,2]]
 * [1,2].product([3,4],[5,6]) #=> [[1,3,5],[1,3,6],[1,4,5],[1,4,6],
 * # [2,3,5],[2,3,6],[2,4,5],[2,4,6]]
 * [1,2].product() #=> [[1],[2]]
 * [1,2].product([]) #=> []
 */

static VALUE
rb_ary_product(int argc, VALUE *argv, VALUE ary)
{
 int n = argc+1; /* How many arrays we're operating on */
 volatile VALUE t0 = tmpary(n);
 volatile VALUE t1 = tmpbuf(n, sizeof(int));
 VALUE *arrays = RARRAY_PTR(t0); /* The arrays we're computing the product of */
 int *counters = (int*)RSTRING_PTR(t1); /* The current position in each one */
 VALUE result = Qnil; /* The array we'll be returning, when no block given */
 long i,j;
 long resultlen = 1;

 RBASIC(t0)->klass = 0;
 RBASIC(t1)->klass = 0;

 /* initialize the arrays of arrays */
 ARY_SET_LEN(t0, n);
 arrays[0] = ary;
 for (i = 1; i < n; i++) arrays[i] = Qnil;
 for (i = 1; i < n; i++) arrays[i] = to_ary(argv[i-1]);

 /* initialize the counters for the arrays */
 for (i = 0; i < n; i++) counters[i] = 0;

 /* Otherwise, allocate and fill in an array of results */
 if (rb_block_given_p()) {
	/* Make defensive copies of arrays; exit if any is empty */
	for (i = 0; i < n; i++) {
	 if (RARRAY_LEN(arrays[i]) == 0) goto done;
	 arrays[i] = ary_make_shared_copy(arrays[i]);
	}
 }
 else {
	/* Compute the length of the result array; return [] if any is empty */
	for (i = 0; i < n; i++) {
	 long k = RARRAY_LEN(arrays[i]), l = resultlen;
	 if (k == 0) {
		result = rb_ary_new2(0);
		goto done;
	 }
	 resultlen *= k;
	 if (resultlen < k || resultlen < l || resultlen / k != l) {
		rb_raise(rb_eRangeError, "too big to product");
	 }
	}
	result = rb_ary_new2(resultlen);
 }
 for (;;) {
	int m;
	/* fill in one subarray */
	VALUE subarray = rb_ary_new2(n);
	for (j = 0; j < n; j++) {
	 rb_ary_push(subarray, rb_ary_entry(arrays[j], counters[j]));
	}

	/* put it on the result array */
	if(NIL_P(result)) {
	 FL_SET(t0, FL_USER5);
	 rb_yield(subarray);
	 if (! FL_TEST(t0, FL_USER5)) {
		rb_raise(rb_eRuntimeError, "product reentered");
	 }
	 else {
		FL_UNSET(t0, FL_USER5);
	 }
	}
	else {
	 rb_ary_push(result, subarray);
	}

	/*
	 * Increment the last counter. If it overflows, reset to 0
	 * and increment the one before it.
	 */
	m = n-1;
	counters[m]++;
	while (counters[m] == RARRAY_LEN(arrays[m])) {
	 counters[m] = 0;
	 /* If the first counter overflows, we are done */
	 if (--m < 0) goto done;
	 counters[m]++;
	}
 }
done:
 tmpary_discard(t0);
 tmpbuf_discard(t1);

 return NIL_P(result) ? ary : result;
}

/*
 * call-seq:
 * ary.take(n) -> new_ary
 *
 * Returns first n elements from <i>ary</i>.
 *
 * a = [1, 2, 3, 4, 5, 0]
 * a.take(3) #=> [1, 2, 3]
 *
 */

static VALUE
rb_ary_take(VALUE obj, VALUE n)
{
 long len = NUM2LONG(n);
 if (len < 0) {
	rb_raise(rb_eArgError, "attempt to take negative size");
 }
 return rb_ary_subseq(obj, 0, len);
}

/*
 * call-seq:
 * ary.take_while {|arr| block } -> new_ary
 * ary.take_while -> an_enumerator
 *
 * Passes elements to the block until the block returns +nil+ or +false+,
 * then stops iterating and returns an array of all prior elements.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = [1, 2, 3, 4, 5, 0]
 * a.take_while {|i| i < 3 } #=> [1, 2]
 *
 */

static VALUE
rb_ary_take_while(VALUE ary)
{
 long i;

 RETURN_ENUMERATOR(ary, 0, 0);
 for (i = 0; i < RARRAY_LEN(ary); i++) {
	if (!RTEST(rb_yield(RARRAY_PTR(ary)[i]))) break;
 }
 return rb_ary_take(ary, LONG2FIX(i));
}

/*
 * call-seq:
 * ary.drop(n) -> new_ary
 *
 * Drops first n elements from +ary+ and returns the rest of
 * the elements in an array.
 *
 * a = [1, 2, 3, 4, 5, 0]
 * a.drop(3) #=> [4, 5, 0]
 *
 */

static VALUE
rb_ary_drop(VALUE ary, VALUE n)
{
 VALUE result;
 long pos = NUM2LONG(n);
 if (pos < 0) {
	rb_raise(rb_eArgError, "attempt to drop negative size");
 }

 result = rb_ary_subseq(ary, pos, RARRAY_LEN(ary));
 if (result == Qnil) result = rb_ary_new();
 return result;
}

/*
 * call-seq:
 * ary.drop_while {|arr| block } -> new_ary
 * ary.drop_while -> an_enumerator
 *
 * Drops elements up to, but not including, the first element for
 * which the block returns +nil+ or +false+ and returns an array
 * containing the remaining elements.
 *
 * If no block is given, an enumerator is returned instead.
 *
 * a = [1, 2, 3, 4, 5, 0]
 * a.drop_while {|i| i < 3 } #=> [3, 4, 5, 0]
 *
 */

static VALUE
rb_ary_drop_while(VALUE ary)
{
 long i;

 RETURN_ENUMERATOR(ary, 0, 0);
 for (i = 0; i < RARRAY_LEN(ary); i++) {
	if (!RTEST(rb_yield(RARRAY_PTR(ary)[i]))) break;
 }
 return rb_ary_drop(ary, LONG2FIX(i));
}



/* Arrays are ordered, integer-indexed collections of any object.
 * Array indexing starts at 0, as in C or Java. A negative index is
 * assumed to be relative to the end of the array---that is, an index of -1
 * indicates the last element of the array, -2 is the next to last
 * element in the array, and so on.
 */

void
Init_Array(void)
{
#undef rb_intern
#define rb_intern(str) rb_intern_const(str)

 rb_cArray = rb_define_class("Array", rb_cObject);
 rb_include_module(rb_cArray, rb_mEnumerable);

 rb_define_alloc_func(rb_cArray, ary_alloc);
 rb_define_singleton_method(rb_cArray, "[]", rb_ary_s_create, -1);
 rb_define_singleton_method(rb_cArray, "try_convert", rb_ary_s_try_convert, 1);
 rb_define_method(rb_cArray, "initialize", rb_ary_initialize, -1);
 rb_define_method(rb_cArray, "initialize_copy", rb_ary_replace, 1);

 rb_define_method(rb_cArray, "inspect", rb_ary_inspect, 0);
 rb_define_alias(rb_cArray, "to_s", "inspect");
 rb_define_method(rb_cArray, "to_a", rb_ary_to_a, 0);
 rb_define_method(rb_cArray, "to_ary", rb_ary_to_ary_m, 0);
 rb_define_method(rb_cArray, "frozen?", rb_ary_frozen_p, 0);

 rb_define_method(rb_cArray, "==", rb_ary_equal, 1);
 rb_define_method(rb_cArray, "eql?", rb_ary_eql, 1);
 rb_define_method(rb_cArray, "hash", rb_ary_hash, 0);

 rb_define_method(rb_cArray, "[]", rb_ary_aref, -1);
 rb_define_method(rb_cArray, "[]=", rb_ary_aset, -1);
 rb_define_method(rb_cArray, "at", rb_ary_at, 1);
 rb_define_method(rb_cArray, "fetch", rb_ary_fetch, -1);
 rb_define_method(rb_cArray, "first", rb_ary_first, -1);
 rb_define_method(rb_cArray, "last", rb_ary_last, -1);
 rb_define_method(rb_cArray, "concat", rb_ary_concat, 1);
 rb_define_method(rb_cArray, "<<", rb_ary_push, 1);
 rb_define_method(rb_cArray, "push", rb_ary_push_m, -1);
 rb_define_method(rb_cArray, "pop", rb_ary_pop_m, -1);
 rb_define_method(rb_cArray, "shift", rb_ary_shift_m, -1);
 rb_define_method(rb_cArray, "unshift", rb_ary_unshift_m, -1);
 rb_define_method(rb_cArray, "insert", rb_ary_insert, -1);
 rb_define_method(rb_cArray, "each", rb_ary_each, 0);
 rb_define_method(rb_cArray, "each_index", rb_ary_each_index, 0);
 rb_define_method(rb_cArray, "reverse_each", rb_ary_reverse_each, 0);
 rb_define_method(rb_cArray, "length", rb_ary_length, 0);
 rb_define_alias(rb_cArray, "size", "length");
 rb_define_method(rb_cArray, "empty?", rb_ary_empty_p, 0);
 rb_define_method(rb_cArray, "find_index", rb_ary_index, -1);
 rb_define_method(rb_cArray, "index", rb_ary_index, -1);
 rb_define_method(rb_cArray, "rindex", rb_ary_rindex, -1);
 rb_define_method(rb_cArray, "join", rb_ary_join_m, -1);
 rb_define_method(rb_cArray, "reverse", rb_ary_reverse_m, 0);
 rb_define_method(rb_cArray, "reverse!", rb_ary_reverse_bang, 0);
 rb_define_method(rb_cArray, "rotate", rb_ary_rotate_m, -1);
 rb_define_method(rb_cArray, "rotate!", rb_ary_rotate_bang, -1);
 rb_define_method(rb_cArray, "sort", rb_ary_sort, 0);
 rb_define_method(rb_cArray, "sort!", rb_ary_sort_bang, 0);
 rb_define_method(rb_cArray, "sort_by!", rb_ary_sort_by_bang, 0);
 rb_define_method(rb_cArray, "collect", rb_ary_collect, 0);
 rb_define_method(rb_cArray, "collect!", rb_ary_collect_bang, 0);
 rb_define_method(rb_cArray, "map", rb_ary_collect, 0);
 rb_define_method(rb_cArray, "map!", rb_ary_collect_bang, 0);
 rb_define_method(rb_cArray, "select", rb_ary_select, 0);
 rb_define_method(rb_cArray, "select!", rb_ary_select_bang, 0);
 rb_define_method(rb_cArray, "keep_if", rb_ary_keep_if, 0);
 rb_define_method(rb_cArray, "values_at", rb_ary_values_at, -1);
 rb_define_method(rb_cArray, "delete", rb_ary_delete, 1);
 rb_define_method(rb_cArray, "delete_at", rb_ary_delete_at_m, 1);
 rb_define_method(rb_cArray, "delete_if", rb_ary_delete_if, 0);
 rb_define_method(rb_cArray, "reject", rb_ary_reject, 0);
 rb_define_method(rb_cArray, "reject!", rb_ary_reject_bang, 0);
 rb_define_method(rb_cArray, "zip", rb_ary_zip, -1);
 rb_define_method(rb_cArray, "transpose", rb_ary_transpose, 0);
 rb_define_method(rb_cArray, "replace", rb_ary_replace, 1);
 rb_define_method(rb_cArray, "clear", rb_ary_clear, 0);
 rb_define_method(rb_cArray, "fill", rb_ary_fill, -1);
 rb_define_method(rb_cArray, "include?", rb_ary_includes, 1);
 rb_define_method(rb_cArray, "<=>", rb_ary_cmp, 1);

 rb_define_method(rb_cArray, "slice", rb_ary_aref, -1);
 rb_define_method(rb_cArray, "slice!", rb_ary_slice_bang, -1);

 rb_define_method(rb_cArray, "assoc", rb_ary_assoc, 1);
 rb_define_method(rb_cArray, "rassoc", rb_ary_rassoc, 1);

 rb_define_method(rb_cArray, "+", rb_ary_plus, 1);
 rb_define_method(rb_cArray, "*", rb_ary_times, 1);

 rb_define_method(rb_cArray, "-", rb_ary_diff, 1);
 rb_define_method(rb_cArray, "&", rb_ary_and, 1);
 rb_define_method(rb_cArray, "|", rb_ary_or, 1);

 rb_define_method(rb_cArray, "uniq", rb_ary_uniq, 0);
 rb_define_method(rb_cArray, "uniq!", rb_ary_uniq_bang, 0);
 rb_define_method(rb_cArray, "compact", rb_ary_compact, 0);
 rb_define_method(rb_cArray, "compact!", rb_ary_compact_bang, 0);
 rb_define_method(rb_cArray, "flatten", rb_ary_flatten, -1);
 rb_define_method(rb_cArray, "flatten!", rb_ary_flatten_bang, -1);
 rb_define_method(rb_cArray, "count", rb_ary_count, -1);
 rb_define_method(rb_cArray, "shuffle!", rb_ary_shuffle_bang, -1);
 rb_define_method(rb_cArray, "shuffle", rb_ary_shuffle, -1);
 rb_define_method(rb_cArray, "sample", rb_ary_sample, -1);
 rb_define_method(rb_cArray, "cycle", rb_ary_cycle, -1);
 rb_define_method(rb_cArray, "permutation", rb_ary_permutation, -1);
 rb_define_method(rb_cArray, "combination", rb_ary_combination, 1);
 rb_define_method(rb_cArray, "repeated_permutation", rb_ary_repeated_permutation, 1);
 rb_define_method(rb_cArray, "repeated_combination", rb_ary_repeated_combination, 1);
 rb_define_method(rb_cArray, "product", rb_ary_product, -1);

 rb_define_method(rb_cArray, "take", rb_ary_take, 1);
 rb_define_method(rb_cArray, "take_while", rb_ary_take_while, 0);
 rb_define_method(rb_cArray, "drop", rb_ary_drop, 1);
 rb_define_method(rb_cArray, "drop_while", rb_ary_drop_while, 0);

 id_cmp = rb_intern("<=>");
 sym_random = ID2SYM(rb_intern("random"));
}