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

enumerator.c - provides Enumerator class

$Author$

Copyright (C) 2001-2003 Akinori MUSHA

$Idaemons: /home/cvs/rb/enumerator/enumerator.c,v 1.1.1.1 2001/07/15 10:12:48 knu Exp $
$RoughId: enumerator.c,v 1.6 2003/07/27 11:03:24 nobu Exp $
$Id$

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

#include "ruby/ruby.h"

/*
* Document-class: Enumerator
*
* A class which provides a method `each' to be used as an Enumerable
* object.
*
* An enumerator can be created by following methods.
* - Kernel#to_enum
* - Kernel#enum_for
* - Enumerator.new
*
* Also, most iteration methods without a block returns an enumerator.
* For example, Array#map returns an enumerator if a block is not given.
* The enumerator has the with_index method.
* So ary.map.with_index works as follows.
*
* p %w[foo bar baz].map.with_index {|w,i| "#{i}:#{w}" }
* #=> ["0:foo", "1:bar", "2:baz"]
*
* An enumerator object can be used as an external iterator.
* I.e. Enumerator#next returns the next value of the iterator.
* Enumerator#next raises StopIteration at end.
*
* e = [1,2,3].each # returns an enumerator object.
* p e.next #=> 1
* p e.next #=> 2
* p e.next #=> 3
* p e.next #raises StopIteration
*
* An external iterator can be used to implement an internal iterator as follows.
*
* def ext_each(e)
* while true
* begin
* vs = e.next_values
* rescue StopIteration
* return $!.result
* end
* y = yield(*vs)
* e.feed y
* end
* end
*
* o = Object.new
* def o.each
* p yield
* p yield(1)
* p yield(1, 2)
* 3
* end
*
* # use o.each as an internal iterator directly.
* p o.each {|*x| p x; [:b, *x] }
* #=> [], [:b], [1], [:b, 1], [1, 2], [:b, 1, 2], 3
*
* # convert o.each to an external iterator for
* # implementing an internal iterator.
* p ext_each(o.to_enum) {|*x| p x; [:b, *x] }
* #=> [], [:b], [1], [:b, 1], [1, 2], [:b, 1, 2], 3
*
*/
VALUE rb_cEnumerator;
static ID id_rewind, id_each;
static VALUE sym_each;

VALUE rb_eStopIteration;

struct enumerator {
    VALUE obj;
    ID meth;
    VALUE args;
    VALUE fib;
    VALUE dst;
    VALUE lookahead;
    VALUE feedvalue;
    VALUE stop_exc;
};

static VALUE rb_cGenerator, rb_cYielder;

struct generator {
    VALUE proc;
};

struct yielder {
    VALUE proc;
};

static VALUE generator_allocate(VALUE klass);
static VALUE generator_init(VALUE obj, VALUE proc);

/*
* Enumerator
*/
static void
enumerator_mark(void *p)
{
    struct enumerator *ptr = p;
    rb_gc_mark(ptr->obj);
    rb_gc_mark(ptr->args);
    rb_gc_mark(ptr->fib);
    rb_gc_mark(ptr->dst);
    rb_gc_mark(ptr->lookahead);
    rb_gc_mark(ptr->feedvalue);
    rb_gc_mark(ptr->stop_exc);
}

#define enumerator_free RUBY_TYPED_DEFAULT_FREE

static size_t
enumerator_memsize(const void *p)
{
    return p ? sizeof(struct enumerator) : 0;
}

static const rb_data_type_t enumerator_data_type = {
    "enumerator",
    enumerator_mark,
    enumerator_free,
    enumerator_memsize,
};

static struct enumerator *
enumerator_ptr(VALUE obj)
{
    struct enumerator *ptr;

    TypedData_Get_Struct(obj, struct enumerator, &enumerator_data_type, ptr);
    if (!ptr || ptr->obj == Qundef) {
rb_raise(rb_eArgError, "uninitialized enumerator");
    }
    return ptr;
}

/*
* call-seq:
* obj.to_enum(method = :each, *args)
* obj.enum_for(method = :each, *args)
*
* Returns Enumerator.new(self, method, *args).
*
* e.g.:
*
* str = "xyz"
*
* enum = str.enum_for(:each_byte)
* a = enum.map {|b| '%02x' % b } #=> ["78", "79", "7a"]
*
* # protects an array from being modified
* a = [1, 2, 3]
* some_method(a.to_enum)
*
*/
static VALUE
obj_to_enum(int argc, VALUE *argv, VALUE obj)
{
    VALUE meth = sym_each;

    if (argc > 0) {
--argc;
meth = *argv++;
    }
    return rb_enumeratorize(obj, meth, argc, argv);
}

static VALUE
enumerator_allocate(VALUE klass)
{
    struct enumerator *ptr;
    VALUE enum_obj;

    enum_obj = TypedData_Make_Struct(klass, struct enumerator, &enumerator_data_type, ptr);
    ptr->obj = Qundef;

    return enum_obj;
}

static VALUE
enumerator_init(VALUE enum_obj, VALUE obj, VALUE meth, int argc, VALUE *argv)
{
    struct enumerator *ptr;

    TypedData_Get_Struct(enum_obj, struct enumerator, &enumerator_data_type, ptr);

    if (!ptr) {
rb_raise(rb_eArgError, "unallocated enumerator");
    }

    ptr->obj = obj;
    ptr->meth = rb_to_id(meth);
    if (argc) ptr->args = rb_ary_new4(argc, argv);
    ptr->fib = 0;
    ptr->dst = Qnil;
    ptr->lookahead = Qundef;
    ptr->feedvalue = Qundef;
    ptr->stop_exc = Qfalse;

    return enum_obj;
}

/*
* call-seq:
* Enumerator.new(obj, method = :each, *args)
* Enumerator.new { |y| ... }
*
* Creates a new Enumerator object, which is to be used as an
* Enumerable object iterating in a given way.
*
* In the first form, a generated Enumerator iterates over the given
* object using the given method with the given arguments passed.
* Use of this form is discouraged. Use Kernel#enum_for(), alias
* to_enum, instead.
*
* e = Enumerator.new(ObjectSpace, :each_object)
* #-> ObjectSpace.enum_for(:each_object)
*
* e.select { |obj| obj.is_a?(Class) } #=> array of all classes
*
* In the second form, iteration is defined by the given block, in
* which a "yielder" object given as block parameter can be used to
* yield a value by calling the +yield+ method, alias +<<+.
*
* fib = Enumerator.new { |y|
* a = b = 1
* loop {
* y << a
* a, b = b, a + b
* }
* }
*
* p fib.take(10) #=> [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
*/
static VALUE
enumerator_initialize(int argc, VALUE *argv, VALUE obj)
{
    VALUE recv, meth = sym_each;

    if (argc == 0) {
if (!rb_block_given_p())
rb_raise(rb_eArgError, "wrong number of argument (0 for 1+)");

recv = generator_init(generator_allocate(rb_cGenerator), rb_block_proc());
    }
    else {
recv = *argv++;
if (--argc) {
meth = *argv++;
--argc;
}
    }

    return enumerator_init(obj, recv, meth, argc, argv);
}

/* :nodoc: */
static VALUE
enumerator_init_copy(VALUE obj, VALUE orig)
{
    struct enumerator *ptr0, *ptr1;

    ptr0 = enumerator_ptr(orig);
    if (ptr0->fib) {
/* Fibers cannot be copied */
rb_raise(rb_eTypeError, "can't copy execution context");
    }

    TypedData_Get_Struct(obj, struct enumerator, &enumerator_data_type, ptr1);

    if (!ptr1) {
rb_raise(rb_eArgError, "unallocated enumerator");
    }

    ptr1->obj = ptr0->obj;
    ptr1->meth = ptr0->meth;
    ptr1->args = ptr0->args;
    ptr1->fib = 0;
    ptr1->lookahead = Qundef;
    ptr1->feedvalue = Qundef;

    return obj;
}

VALUE
rb_enumeratorize(VALUE obj, VALUE meth, int argc, VALUE *argv)
{
    return enumerator_init(enumerator_allocate(rb_cEnumerator), obj, meth, argc, argv);
}

static VALUE
enumerator_block_call(VALUE obj, rb_block_call_func *func, VALUE arg)
{
    int argc = 0;
    VALUE *argv = 0;
    const struct enumerator *e = enumerator_ptr(obj);
    ID meth = e->meth;

    if (e->args) {
argc = RARRAY_LENINT(e->args);
argv = RARRAY_PTR(e->args);
    }
    return rb_block_call(e->obj, meth, argc, argv, func, arg);
}

/*
* call-seq:
* enum.each {...}
*
* Iterates the given block using the object and the method specified
* in the first place. If no block is given, returns self.
*
*/
static VALUE
enumerator_each(VALUE obj)
{
    if (!rb_block_given_p()) return obj;
    return enumerator_block_call(obj, 0, obj);
}

static VALUE
enumerator_with_index_i(VALUE val, VALUE m, int argc, VALUE *argv)
{
    VALUE idx;
    VALUE *memo = (VALUE *)m;

    idx = INT2FIX(*memo);
    ++*memo;

    if (argc <= 1)
return rb_yield_values(2, val, idx);

    return rb_yield_values(2, rb_ary_new4(argc, argv), idx);
}

/*
* call-seq:
* e.with_index(offset = 0) {|(*args), idx| ... }
* e.with_index(offset = 0)
*
* Iterates the given block for each element with an index, which
* starts from +offset+. If no block is given, returns an enumerator.
*
*/
static VALUE
enumerator_with_index(int argc, VALUE *argv, VALUE obj)
{
    VALUE memo;

    rb_scan_args(argc, argv, "01", &memo);
    RETURN_ENUMERATOR(obj, argc, argv);
    memo = NIL_P(memo) ? 0 : (VALUE)NUM2LONG(memo);
    return enumerator_block_call(obj, enumerator_with_index_i, (VALUE)&memo);
}

/*
* call-seq:
* e.each_with_index {|(*args), idx| ... }
* e.each_with_index
*
* Same as Enumerator#with_index, except each_with_index does not
* receive an offset argument.
*
*/
static VALUE
enumerator_each_with_index(VALUE obj)
{
    return enumerator_with_index(0, NULL, obj);
}

static VALUE
enumerator_with_object_i(VALUE val, VALUE memo, int argc, VALUE *argv)
{
    if (argc <= 1)
return rb_yield_values(2, val, memo);

    return rb_yield_values(2, rb_ary_new4(argc, argv), memo);
}

/*
* call-seq:
* e.with_object(obj) {|(*args), memo_obj| ... }
* e.with_object(obj)
*
* Iterates the given block for each element with an arbitrary
* object given, and returns the initially given object.
*
* If no block is given, returns an enumerator.
*
*/
static VALUE
enumerator_with_object(VALUE obj, VALUE memo)
{
    RETURN_ENUMERATOR(obj, 1, &memo);
    enumerator_block_call(obj, enumerator_with_object_i, memo);

    return memo;
}

static VALUE
next_ii(VALUE i, VALUE obj, int argc, VALUE *argv)
{
    struct enumerator *e = enumerator_ptr(obj);
    VALUE feedvalue = Qnil;
    VALUE args = rb_ary_new4(argc, argv);
    rb_fiber_yield(1, &args);
    if (e->feedvalue != Qundef) {
        feedvalue = e->feedvalue;
        e->feedvalue = Qundef;
    }
    return feedvalue;
}

static VALUE
next_i(VALUE curr, VALUE obj)
{
    struct enumerator *e = enumerator_ptr(obj);
    VALUE nil = Qnil;
    VALUE result;

    result = rb_block_call(obj, id_each, 0, 0, next_ii, obj);
    e->stop_exc = rb_exc_new2(rb_eStopIteration, "iteration reached an end");
    rb_ivar_set(e->stop_exc, rb_intern("result"), result);
    return rb_fiber_yield(1, &nil);
}

static void
next_init(VALUE obj, struct enumerator *e)
{
    VALUE curr = rb_fiber_current();
    e->dst = curr;
    e->fib = rb_fiber_new(next_i, obj);
    e->lookahead = Qundef;
}

static VALUE
get_next_values(VALUE obj, struct enumerator *e)
{
    VALUE curr, vs;

    if (e->stop_exc)
rb_exc_raise(e->stop_exc);

    curr = rb_fiber_current();

    if (!e->fib || !rb_fiber_alive_p(e->fib)) {
next_init(obj, e);
    }

    vs = rb_fiber_resume(e->fib, 1, &curr);
    if (e->stop_exc) {
e->fib = 0;
e->dst = Qnil;
e->lookahead = Qundef;
e->feedvalue = Qundef;
rb_exc_raise(e->stop_exc);
    }
    return vs;
}

/*
* call-seq:
* e.next_values -> array
*
* Returns the next object as an array in the enumerator,
* and move the internal position forward.
* When the position reached at the end, StopIteration is raised.
*
* This method can be used to distinguish <code>yield</code> and <code>yield nil</code>.
*
* o = Object.new
* def o.each
* yield
* yield 1
* yield 1, 2
* yield nil
* yield [1, 2]
* end
* e = o.to_enum
* p e.next_values
* p e.next_values
* p e.next_values
* p e.next_values
* p e.next_values
* e = o.to_enum
* p e.next
* p e.next
* p e.next
* p e.next
* p e.next
*
* ## yield args next_values next
* # yield [] nil
* # yield 1 [1] 1
* # yield 1, 2 [1, 2] [1, 2]
* # yield nil [nil] nil
* # yield [1, 2] [[1, 2]] [1, 2]
*
* Note that enumeration sequence by next_values method does not affect other
* non-external enumeration methods, unless underlying iteration
* methods itself has side-effect, e.g. IO#each_line.
*
*/

static VALUE
enumerator_next_values(VALUE obj)
{
    struct enumerator *e = enumerator_ptr(obj);
    VALUE vs;

    if (e->lookahead != Qundef) {
        vs = e->lookahead;
        e->lookahead = Qundef;
        return vs;
    }

    return get_next_values(obj, e);
}

static VALUE
ary2sv(VALUE args, int dup)
{
    if (TYPE(args) != T_ARRAY)
        return args;

    switch (RARRAY_LEN(args)) {
      case 0:
        return Qnil;

      case 1:
        return RARRAY_PTR(args)[0];

      default:
        if (dup)
            return rb_ary_dup(args);
        return args;
    }
}

/*
* call-seq:
* e.next -> object
*
* Returns the next object in the enumerator, and move the internal
* position forward. When the position reached at the end, StopIteration
* is raised.
*
* a = [1,2,3]
* e = a.to_enum
* p e.next #=> 1
* p e.next #=> 2
* p e.next #=> 3
* p e.next #raises StopIteration
*
* Note that enumeration sequence by next method does not affect other
* non-external enumeration methods, unless underlying iteration
* methods itself has side-effect, e.g. IO#each_line.
*
*/

static VALUE
enumerator_next(VALUE obj)
{
    VALUE vs = enumerator_next_values(obj);
    return ary2sv(vs, 0);
}

static VALUE
enumerator_peek_values(VALUE obj)
{
    struct enumerator *e = enumerator_ptr(obj);

    if (e->lookahead == Qundef) {
        e->lookahead = get_next_values(obj, e);
    }
    return e->lookahead;
}

/*
* call-seq:
* e.peek_values -> array
*
* Returns the next object as an array in the enumerator,
* but don't move the internal position forward.
* When the position reached at the end, StopIteration is raised.
*
* o = Object.new
* def o.each
* yield
* yield 1
* yield 1, 2
* end
* e = o.to_enum
* p e.peek_values #=> []
* e.next
* p e.peek_values #=> [1]
* p e.peek_values #=> [1]
* e.next
* p e.peek_values #=> [1, 2]
* e.next
* p e.peek_values # raises StopIteration
*
*/

static VALUE
enumerator_peek_values_m(VALUE obj)
{
    return rb_ary_dup(enumerator_peek_values(obj));
}

/*
* call-seq:
* e.peek -> object
*
* Returns the next object in the enumerator, but don't move the internal
* position forward. When the position reached at the end, StopIteration
* is raised.
*
* a = [1,2,3]
* e = a.to_enum
* p e.next #=> 1
* p e.peek #=> 2
* p e.peek #=> 2
* p e.peek #=> 2
* p e.next #=> 2
* p e.next #=> 3
* p e.next #raises StopIteration
*
*/

static VALUE
enumerator_peek(VALUE obj)
{
    VALUE vs = enumerator_peek_values(obj);
    return ary2sv(vs, 1);
}

/*
* call-seq:
* e.feed obj -> nil
*
* Set the value for the next yield in the enumerator returns.
*
* If the value is not set, the yield returns nil.
*
* This value is cleared after used.
*
* o = Object.new
* def o.each
* # (2)
* x = yield
* p x #=> "foo"
* # (5)
* x = yield
* p x #=> nil
* # (7)
* x = yield
* # not reached
* p x
* end
* e = o.to_enum
* # (1)
* e.next
* # (3)
* e.feed "foo"
* # (4)
* e.next
* # (6)
* e.next
* # (8)
*
*/

static VALUE
enumerator_feed(VALUE obj, VALUE v)
{
    struct enumerator *e = enumerator_ptr(obj);

    if (e->feedvalue != Qundef) {
rb_raise(rb_eTypeError, "feed value already set");
    }
    e->feedvalue = v;

    return Qnil;
}

/*
* call-seq:
* e.rewind -> e
*
* Rewinds the enumeration sequence by the next method.
*
* If the enclosed object responds to a "rewind" method, it is called.
*/

static VALUE
enumerator_rewind(VALUE obj)
{
    struct enumerator *e = enumerator_ptr(obj);

    rb_check_funcall(e->obj, id_rewind, 0, 0);

    e->fib = 0;
    e->dst = Qnil;
    e->lookahead = Qundef;
    e->feedvalue = Qundef;
    e->stop_exc = Qfalse;
    return obj;
}

static VALUE
inspect_enumerator(VALUE obj, VALUE dummy, int recur)
{
    struct enumerator *e;
    const char *cname;
    VALUE eobj, str;
    int tainted, untrusted;

    TypedData_Get_Struct(obj, struct enumerator, &enumerator_data_type, e);

    cname = rb_obj_classname(obj);

    if (!e || e->obj == Qundef) {
return rb_sprintf("#<%s: uninitialized>", cname);
    }

    if (recur) {
str = rb_sprintf("#<%s: ...>", cname);
OBJ_TAINT(str);
return str;
    }

    eobj = e->obj;

    tainted = OBJ_TAINTED(eobj);
    untrusted = OBJ_UNTRUSTED(eobj);

    /* (1..100).each_cons(2) => "#<Enumerator: 1..100:each_cons(2)>" */
    str = rb_sprintf("#<%s: ", cname);
    rb_str_concat(str, rb_inspect(eobj));
    rb_str_buf_cat2(str, ":");
    rb_str_buf_cat2(str, rb_id2name(e->meth));

    if (e->args) {
long argc = RARRAY_LEN(e->args);
VALUE *argv = RARRAY_PTR(e->args);

rb_str_buf_cat2(str, "(");

while (argc--) {
VALUE arg = *argv++;

rb_str_concat(str, rb_inspect(arg));
rb_str_buf_cat2(str, argc > 0 ? ", " : ")");

if (OBJ_TAINTED(arg)) tainted = TRUE;
if (OBJ_UNTRUSTED(arg)) untrusted = TRUE;
}
    }

    rb_str_buf_cat2(str, ">");

    if (tainted) OBJ_TAINT(str);
    if (untrusted) OBJ_UNTRUST(str);
    return str;
}

/*
* call-seq:
* e.inspect -> string
*
* Create a printable version of <i>e</i>.
*/

static VALUE
enumerator_inspect(VALUE obj)
{
    return rb_exec_recursive(inspect_enumerator, obj, 0);
}

/*
* Yielder
*/
static void
yielder_mark(void *p)
{
    struct yielder *ptr = p;
    rb_gc_mark(ptr->proc);
}

#define yielder_free RUBY_TYPED_DEFAULT_FREE

static size_t
yielder_memsize(const void *p)
{
    return p ? sizeof(struct yielder) : 0;
}

static const rb_data_type_t yielder_data_type = {
    "yielder",
    yielder_mark,
    yielder_free,
    yielder_memsize,
};

static struct yielder *
yielder_ptr(VALUE obj)
{
    struct yielder *ptr;

    TypedData_Get_Struct(obj, struct yielder, &yielder_data_type, ptr);
    if (!ptr || ptr->proc == Qundef) {
rb_raise(rb_eArgError, "uninitialized yielder");
    }
    return ptr;
}

/* :nodoc: */
static VALUE
yielder_allocate(VALUE klass)
{
    struct yielder *ptr;
    VALUE obj;

    obj = TypedData_Make_Struct(klass, struct yielder, &yielder_data_type, ptr);
    ptr->proc = Qundef;

    return obj;
}

static VALUE
yielder_init(VALUE obj, VALUE proc)
{
    struct yielder *ptr;

    TypedData_Get_Struct(obj, struct yielder, &yielder_data_type, ptr);

    if (!ptr) {
rb_raise(rb_eArgError, "unallocated yielder");
    }

    ptr->proc = proc;

    return obj;
}

/* :nodoc: */
static VALUE
yielder_initialize(VALUE obj)
{
    rb_need_block();

    return yielder_init(obj, rb_block_proc());
}

/* :nodoc: */
static VALUE
yielder_yield(VALUE obj, VALUE args)
{
    struct yielder *ptr = yielder_ptr(obj);

    return rb_proc_call(ptr->proc, args);
}

/* :nodoc: */
static VALUE yielder_yield_push(VALUE obj, VALUE args)
{
    yielder_yield(obj, args);
    return obj;
}

static VALUE
yielder_yield_i(VALUE obj, VALUE memo, int argc, VALUE *argv)
{
    return rb_yield_values2(argc, argv);
}

static VALUE
yielder_new(void)
{
    return yielder_init(yielder_allocate(rb_cYielder), rb_proc_new(yielder_yield_i, 0));
}

/*
* Generator
*/
static void
generator_mark(void *p)
{
    struct generator *ptr = p;
    rb_gc_mark(ptr->proc);
}

#define generator_free RUBY_TYPED_DEFAULT_FREE

static size_t
generator_memsize(const void *p)
{
    return p ? sizeof(struct generator) : 0;
}

static const rb_data_type_t generator_data_type = {
    "generator",
    generator_mark,
    generator_free,
    generator_memsize,
};

static struct generator *
generator_ptr(VALUE obj)
{
    struct generator *ptr;

    TypedData_Get_Struct(obj, struct generator, &generator_data_type, ptr);
    if (!ptr || ptr->proc == Qundef) {
rb_raise(rb_eArgError, "uninitialized generator");
    }
    return ptr;
}

/* :nodoc: */
static VALUE
generator_allocate(VALUE klass)
{
    struct generator *ptr;
    VALUE obj;

    obj = TypedData_Make_Struct(klass, struct generator, &generator_data_type, ptr);
    ptr->proc = Qundef;

    return obj;
}

static VALUE
generator_init(VALUE obj, VALUE proc)
{
    struct generator *ptr;

    TypedData_Get_Struct(obj, struct generator, &generator_data_type, ptr);

    if (!ptr) {
rb_raise(rb_eArgError, "unallocated generator");
    }

    ptr->proc = proc;

    return obj;
}

VALUE rb_obj_is_proc(VALUE proc);

/* :nodoc: */
static VALUE
generator_initialize(int argc, VALUE *argv, VALUE obj)
{
    VALUE proc;

    if (argc == 0) {
rb_need_block();

proc = rb_block_proc();
    } else {
rb_scan_args(argc, argv, "1", &proc);

if (!rb_obj_is_proc(proc))
rb_raise(rb_eTypeError,
"wrong argument type %s (expected Proc)",
rb_obj_classname(proc));

if (rb_block_given_p()) {
rb_warn("given block not used");
}
    }

    return generator_init(obj, proc);
}

/* :nodoc: */
static VALUE
generator_init_copy(VALUE obj, VALUE orig)
{
    struct generator *ptr0, *ptr1;

    ptr0 = generator_ptr(orig);

    TypedData_Get_Struct(obj, struct generator, &generator_data_type, ptr1);

    if (!ptr1) {
rb_raise(rb_eArgError, "unallocated generator");
    }

    ptr1->proc = ptr0->proc;

    return obj;
}

/* :nodoc: */
static VALUE
generator_each(VALUE obj)
{
    struct generator *ptr = generator_ptr(obj);
    VALUE yielder;

    yielder = yielder_new();

    return rb_proc_call(ptr->proc, rb_ary_new3(1, yielder));
}

/*
* Document-class: StopIteration
*
* Raised to stop the iteration, in particular by Enumerator#next. It is
* rescued by Kernel#loop.
*
* loop do
* puts "Hello"
* raise StopIteration
* puts "World"
* end
* puts "Done!"
*
* <em>produces:</em>
*
* Hello
* Done!
*/

/*
* call-seq:
* stopiteration.result -> value
*
* Returns the return value of the iterator.
*
* o = Object.new
* def o.each
* yield 1
* yield 2
* yield 3
* 100
* end
* e = o.to_enum
* p e.next #=> 1
* p e.next #=> 2
* p e.next #=> 3
* begin
* e.next
* rescue StopIteration
* p $!.result #=> 100
* end
*
*/
static VALUE
stop_result(VALUE self)
{
    return rb_attr_get(self, rb_intern("result"));
}

void
Init_Enumerator(void)
{
    rb_define_method(rb_mKernel, "to_enum", obj_to_enum, -1);
    rb_define_method(rb_mKernel, "enum_for", obj_to_enum, -1);

    rb_cEnumerator = rb_define_class("Enumerator", rb_cObject);
    rb_include_module(rb_cEnumerator, rb_mEnumerable);

    rb_define_alloc_func(rb_cEnumerator, enumerator_allocate);
    rb_define_method(rb_cEnumerator, "initialize", enumerator_initialize, -1);
    rb_define_method(rb_cEnumerator, "initialize_copy", enumerator_init_copy, 1);
    rb_define_method(rb_cEnumerator, "each", enumerator_each, 0);
    rb_define_method(rb_cEnumerator, "each_with_index", enumerator_each_with_index, 0);
    rb_define_method(rb_cEnumerator, "each_with_object", enumerator_with_object, 1);
    rb_define_method(rb_cEnumerator, "with_index", enumerator_with_index, -1);
    rb_define_method(rb_cEnumerator, "with_object", enumerator_with_object, 1);
    rb_define_method(rb_cEnumerator, "next_values", enumerator_next_values, 0);
    rb_define_method(rb_cEnumerator, "peek_values", enumerator_peek_values_m, 0);
    rb_define_method(rb_cEnumerator, "next", enumerator_next, 0);
    rb_define_method(rb_cEnumerator, "peek", enumerator_peek, 0);
    rb_define_method(rb_cEnumerator, "feed", enumerator_feed, 1);
    rb_define_method(rb_cEnumerator, "rewind", enumerator_rewind, 0);
    rb_define_method(rb_cEnumerator, "inspect", enumerator_inspect, 0);

    rb_eStopIteration = rb_define_class("StopIteration", rb_eIndexError);
    rb_define_method(rb_eStopIteration, "result", stop_result, 0);

    /* Generator */
    rb_cGenerator = rb_define_class_under(rb_cEnumerator, "Generator", rb_cObject);
    rb_include_module(rb_cGenerator, rb_mEnumerable);
    rb_define_alloc_func(rb_cGenerator, generator_allocate);
    rb_define_method(rb_cGenerator, "initialize", generator_initialize, -1);
    rb_define_method(rb_cGenerator, "initialize_copy", generator_init_copy, 1);
    rb_define_method(rb_cGenerator, "each", generator_each, 0);

    /* Yielder */
    rb_cYielder = rb_define_class_under(rb_cEnumerator, "Yielder", rb_cObject);
    rb_define_alloc_func(rb_cYielder, yielder_allocate);
    rb_define_method(rb_cYielder, "initialize", yielder_initialize, 0);
    rb_define_method(rb_cYielder, "yield", yielder_yield, -2);
    rb_define_method(rb_cYielder, "<<", yielder_yield_push, -2);

    id_rewind = rb_intern("rewind");
    id_each = rb_intern("each");
    sym_each = ID2SYM(id_each);

    rb_provide("enumerator.so"); /* for backward compatibility */
}
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