Enumerator::Lazy
class Enumerator::Lazy
Public Class Methods
new(obj, size=nil) { |yielder, *values| ... } Show source
Creates a new Lazy enumerator- When the enumerator is actually enumerated (e-g- by calling force), obj will be enumerated and each value passed to the given block- The block can yield values back using yielder- For example, to create a method filter_map in both lazy and non-lazy fashions:
module Enumerable
def filter_map(&block)
map(&block).compact
end
end
class Enumerator::Lazy
def filter_map
Lazy.new(self) do |yielder, *values|
result = yield *values
yielder << result if result
end
end
end
(1..Float::INFINITY).lazy.filter_map{|i| i*i if i.even?}.first(5)
# => [4, 16, 36, 64, 100]
static VALUE
lazy_initialize(int argc, VALUE *argv, VALUE self)
{
VALUE obj, size = Qnil;
VALUE generator;
rb_check_arity(argc, 1, 2);
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy new without a block");
}
obj = argv[0];
if (argc > 1) {
size = argv[1];
}
generator = generator_allocate(rb_cGenerator);
rb_block_call(generator, id_initialize, 0, 0, lazy_init_block_i, obj);
enumerator_init(self, generator, sym_each, 0, 0, 0, size);
rb_ivar_set(self, id_receiver, obj);
return self;
} Public Instance Methods
static VALUE
lazy_super(int argc, VALUE *argv, VALUE lazy)
{
return enumerable_lazy(rb_call_super(argc, argv));
} static VALUE
lazy_map(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy map without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_map_func, 0),
Qnil, lazy_receiver_size);
} collect_concat { |obj| block } → a_lazy_enumerator Show source
Returns a new lazy enumerator with the concatenated results of running block once for every element in lazy.
["foo", "bar"].lazy.flat_map {|i| i.each_char.lazy}.force
#=> ["f", "o", "o", "b", "a", "r"]
A value x returned by block is decomposed if either of the following conditions is true:
a) <i>x</i> responds to both each and force, which means that <i>x</i> is a lazy enumerator. b) <i>x</i> is an array or responds to to_ary.
Otherwise, x is contained as-is in the return value.
[{a:1}, {b:2}].lazy.flat_map {|i| i}.force
#=> [{:a=>1}, {:b=>2}]
static VALUE
lazy_flat_map(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy flat_map without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_flat_map_func, 0),
Qnil, 0);
} static VALUE
lazy_drop(VALUE obj, VALUE n)
{
long len = NUM2LONG(n);
if (len < 0) {
rb_raise(rb_eArgError, "attempt to drop negative size");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_drop_func, n),
rb_ary_new3(1, n), lazy_drop_size);
} static VALUE
lazy_drop_while(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy drop_while without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_drop_while_func, 0),
Qnil, 0);
} enum_for(method = :each, *args) → lazy_enum Show source
enum_for(method = :each, *args){|*args| block} → lazy_enum
Similar to Kernel#to_enum, except it returns a lazy enumerator. This makes it easy to define Enumerable methods that will naturally remain lazy if called from a lazy enumerator.
For example, continuing from the example in Kernel#to_enum:
# See Kernel#to_enum for the definition of repeat
r = 1..Float::INFINITY
r.repeat(2).first(5) # => [1, 1, 2, 2, 3]
r.repeat(2).class # => Enumerator
r.repeat(2).map{|n| n ** 2}.first(5) # => endless loop!
# works naturally on lazy enumerator:
r.lazy.repeat(2).class # => Enumerator::Lazy
r.lazy.repeat(2).map{|n| n ** 2}.first(5) # => [1, 1, 4, 4, 9]
static VALUE
lazy_to_enum(int argc, VALUE *argv, VALUE self)
{
VALUE lazy, meth = sym_each;
if (argc > 0) {
--argc;
meth = *argv++;
}
lazy = lazy_to_enum_i(self, meth, argc, argv, 0);
if (rb_block_given_p()) {
enumerator_ptr(lazy)->size = rb_block_proc();
}
return lazy;
} static VALUE
lazy_select(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy select without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_select_func, 0),
Qnil, 0);
} flat_map { |obj| block } → a_lazy_enumerator Show source
Returns a new lazy enumerator with the concatenated results of running block once for every element in lazy.
["foo", "bar"].lazy.flat_map {|i| i.each_char.lazy}.force
#=> ["f", "o", "o", "b", "a", "r"]
A value x returned by block is decomposed if either of the following conditions is true:
a) <i>x</i> responds to both each and force, which means that <i>x</i> is a lazy enumerator. b) <i>x</i> is an array or responds to to_ary.
Otherwise, x is contained as-is in the return value.
[{a:1}, {b:2}].lazy.flat_map {|i| i}.force
#=> [{:a=>1}, {:b=>2}]
static VALUE
lazy_flat_map(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy flat_map without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_flat_map_func, 0),
Qnil, 0);
} static VALUE
lazy_grep(VALUE obj, VALUE pattern)
{
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
rb_block_given_p() ?
lazy_grep_iter : lazy_grep_func,
pattern),
rb_ary_new3(1, pattern), 0);
} static VALUE
lazy_lazy(VALUE obj)
{
return obj;
} static VALUE
lazy_map(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy map without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_map_func, 0),
Qnil, lazy_receiver_size);
} static VALUE
lazy_reject(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy reject without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_reject_func, 0),
Qnil, 0);
} static VALUE
lazy_select(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy select without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_select_func, 0),
Qnil, 0);
} static VALUE
lazy_super(int argc, VALUE *argv, VALUE lazy)
{
return enumerable_lazy(rb_call_super(argc, argv));
} static VALUE
lazy_super(int argc, VALUE *argv, VALUE lazy)
{
return enumerable_lazy(rb_call_super(argc, argv));
} static VALUE
lazy_super(int argc, VALUE *argv, VALUE lazy)
{
return enumerable_lazy(rb_call_super(argc, argv));
} static VALUE
lazy_take(VALUE obj, VALUE n)
{
long len = NUM2LONG(n);
VALUE lazy;
if (len < 0) {
rb_raise(rb_eArgError, "attempt to take negative size");
}
if (len == 0) {
VALUE len = INT2FIX(0);
lazy = lazy_to_enum_i(obj, sym_cycle, 1, &len, 0);
}
else {
lazy = rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_take_func, n);
}
return lazy_set_method(lazy, rb_ary_new3(1, n), lazy_take_size);
} static VALUE
lazy_take_while(VALUE obj)
{
if (!rb_block_given_p()) {
rb_raise(rb_eArgError, "tried to call lazy take_while without a block");
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
lazy_take_while_func, 0),
Qnil, 0);
} to_enum(method = :each, *args) → lazy_enum Show source
to_enum(method = :each, *args) {|*args| block} → lazy_enum
Similar to Kernel#to_enum, except it returns a lazy enumerator. This makes it easy to define Enumerable methods that will naturally remain lazy if called from a lazy enumerator.
For example, continuing from the example in Kernel#to_enum:
# See Kernel#to_enum for the definition of repeat
r = 1..Float::INFINITY
r.repeat(2).first(5) # => [1, 1, 2, 2, 3]
r.repeat(2).class # => Enumerator
r.repeat(2).map{|n| n ** 2}.first(5) # => endless loop!
# works naturally on lazy enumerator:
r.lazy.repeat(2).class # => Enumerator::Lazy
r.lazy.repeat(2).map{|n| n ** 2}.first(5) # => [1, 1, 4, 4, 9]
static VALUE
lazy_to_enum(int argc, VALUE *argv, VALUE self)
{
VALUE lazy, meth = sym_each;
if (argc > 0) {
--argc;
meth = *argv++;
}
lazy = lazy_to_enum_i(self, meth, argc, argv, 0);
if (rb_block_given_p()) {
enumerator_ptr(lazy)->size = rb_block_proc();
}
return lazy;
} static VALUE
lazy_zip(int argc, VALUE *argv, VALUE obj)
{
VALUE ary, v;
long i;
rb_block_call_func *func = lazy_zip_arrays_func;
if (rb_block_given_p()) {
return rb_call_super(argc, argv);
}
ary = rb_ary_new2(argc);
for (i = 0; i < argc; i++) {
v = rb_check_array_type(argv[i]);
if (NIL_P(v)) {
for (; i < argc; i++) {
if (!rb_respond_to(argv[i], id_each)) {
rb_raise(rb_eTypeError, "wrong argument type %s (must respond to :each)",
rb_obj_classname(argv[i]));
}
}
ary = rb_ary_new4(argc, argv);
func = lazy_zip_func;
break;
}
rb_ary_push(ary, v);
}
return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
func, ary),
ary, lazy_receiver_size);
}
Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.
