Class: Enumerator::Lazy

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, ::Enumerator
Instance Chain: self, ::Enumerator, ::Enumerable
Inherits:	Enumerator ::Object Enumerator Enumerator::Lazy
Defined in:	enumerator.c

Overview

Lazy

Class Method Summary

.new(obj, size = nil) {|yielder, *values| ... } constructor

Creates a new Lazy enumerator.

::Enumerator - Inherited

.new	Creates a new ::Enumerator object, which can be used as an ::Enumerable.

Instance Method Summary

#chunk(*args) (also: #slice_before, #slice_after, #slice_when, #chunk_while)
#chunk_while(*args)

Alias for #chunk.
#collect

Alias for #map.
#collect_concat {|obj| ... } ⇒ Lazy

Alias for #flat_map.
#drop(n)
#drop_while
#enum_for(method = :each, *args) ⇒ Lazy

Alias for #to_enum.
#find_all

Alias for #select.
#flat_map {|obj| ... } ⇒ Lazy (also: #collect_concat)

Returns a new lazy enumerator with the concatenated results of running block once for every element in lazy.
#force(*args) ⇒ Array

Alias for Enumerable#to_a.
#grep(pattern)
#grep_v(pattern)
#lazy
#map (also: #collect)
#reject
#select (also: #find_all)
#slice_after(*args)

Alias for #chunk.
#slice_before(*args)

Alias for #chunk.
#slice_when(*args)

Alias for #chunk.
#take(n)
#take_while
#to_enum(method = :each, *args) ⇒ Lazy (also: #enum_for)

Similar to Object#to_enum, except it returns a lazy enumerator.
#uniq
#zip(*args)

::Enumerator - Inherited

#each	Iterates over the block according to how this ::Enumerator was constructed.
#each_with_index	Same as #with_index(0), i.e. there is no starting offset.
#each_with_object	Alias for #with_object.
#feed	Sets the value to be returned by the next yield inside `e`.
#inspect	Creates a printable version of e.
#next	Returns the next object in the enumerator, and move the internal position forward.
#next_values	Returns the next object as an array in the enumerator, and move the internal position forward.
#peek	Returns the next object in the enumerator, but doesn't move the internal position forward.
#peek_values	Returns the next object as an array, similar to #next_values, but doesn't move the internal position forward.
#rewind	Rewinds the enumeration sequence to the beginning.
#size	Returns the size of the enumerator, or `nil` if it can't be calculated lazily.
#with_index	Iterates the given block for each element with an index, which starts from `offset`.
#with_object	Iterates the given block for each element with an arbitrary object, `obj`, and returns `obj`
#initialize_copy

::Enumerable - Included

#all?	Passes each element of the collection to the given block.
#any?	Passes each element of the collection to the given block.
#chunk	Enumerates over the items, chunking them together based on the return value of the block.
#chunk_while	Creates an enumerator for each chunked elements.
#collect	Alias for Enumerable#map.
#collect_concat	Alias for Enumerable#flat_map.
#count	Returns the number of items in `enum` through enumeration.
#cycle	Calls block for each element of enum repeatedly n times or forever if none or `nil` is given.
#detect	Alias for Enumerable#find.
#drop	Drops first n elements from enum, and returns rest elements in an array.
#drop_while	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.
#each_cons	Iterates the given block for each array of consecutive <n> elements.
#each_entry	Calls block once for each element in `self`, passing that element as a parameter, converting multiple values from yield to an array.
#each_slice	Iterates the given block for each slice of <n> elements.
#each_with_index	Calls block with two arguments, the item and its index, for each item in enum.
#each_with_object	Iterates the given block for each element with an arbitrary object given, and returns the initially given object.
#entries	Alias for Enumerable#to_a.
#find	Passes each entry in enum to block.
#find_all	Alias for Enumerable#select.
#find_index	Compares each entry in enum with value or passes to block.
#first	Returns the first element, or the first `n` elements, of the enumerable.
#flat_map	Returns a new array with the concatenated results of running block once for every element in enum.
#grep	Returns an array of every element in enum for which `Pattern === element`.
#grep_v	Inverted version of Enumerable#grep.
#group_by	Groups the collection by result of the block.
#include?	Alias for Enumerable#member?.
#inject	Combines all elements of enum by applying a binary operation, specified by a block or a symbol that names a method or operator.
#lazy	Returns a lazy enumerator, whose methods map/collect, flat_map/collect_concat, select/find_all, reject, grep, grep_v, zip, take, take_while, drop, and drop_while enumerate values only on an as-needed basis.
#map	Returns a new array with the results of running block once for every element in enum.
#max	Returns the object in enum with the maximum value.
#max_by	Returns the object in enum that gives the maximum value from the given block.
#member?	Returns `true` if any member of enum equals obj.
#min	Returns the object in enum with the minimum value.
#min_by	Returns the object in enum that gives the minimum value from the given block.
#minmax	Returns a two element array which contains the minimum and the maximum value in the enumerable.
#minmax_by	Returns a two element array containing the objects in enum that correspond to the minimum and maximum values respectively from the given block.
#none?	Passes each element of the collection to the given block.
#one?	Passes each element of the collection to the given block.
#partition	Returns two arrays, the first containing the elements of enum for which the block evaluates to true, the second containing the rest.
#reduce	Alias for Enumerable#inject.
#reject	Returns an array for all elements of `enum` for which the given `block` returns `false`.
#reverse_each	Builds a temporary array and traverses that array in reverse order.
#select	Returns an array containing all elements of `enum` for which the given `block` returns a true value.
#slice_after	Creates an enumerator for each chunked elements.
#slice_before	Creates an enumerator for each chunked elements.
#slice_when	Creates an enumerator for each chunked elements.
#sort	Returns an array containing the items in enum sorted.
#sort_by	Sorts enum using a set of keys generated by mapping the values in enum through the given block.
#sum	Returns the sum of elements in an ::Enumerable.
#take	Returns first n elements from enum.
#take_while	Passes elements to the block until the block returns `nil` or `false`, then stops iterating and returns an array of all prior elements.
#to_a	Returns an array containing the items in enum.
#to_h	Returns the result of interpreting enum as a list of `[key, value]` pairs.
#uniq	Returns a new array by removing duplicate values in `self`.
#zip	Takes one element from enum and merges corresponding elements from each args.

Constructor Details

.new(obj, size = nil) {|yielder, *values| ... }

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]

[ GitHub ]

# File 'enumerator.c', line 1551


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;
}

Instance Method Details

#chunk(*args) Also known as: #slice_before, #slice_after, #slice_when, #chunk_while

[ GitHub ]

# File 'enumerator.c', line 2277


static VALUE
lazy_super(int argc, VALUE *argv, VALUE lazy)
{
    return enumerable_lazy(rb_call_super(argc, argv));
}

#chunk_while(*args)

Alias for #chunk.

#collect

Alias for #map.

#collect_concat {|obj| ... } ⇒ `Lazy` #flat_map {|obj| ... } ⇒ `Lazy`

Alias for #flat_map.

#drop(n)

[ GitHub ]

# File 'enumerator.c', line 2188


static VALUE
lazy_drop(VALUE obj, VALUE n)
{
    long len = NUM2LONG(n);
    VALUE argv[2];
    argv[0] = sym_each;
    argv[1] = n;

    if (len < 0) {
	rb_raise(rb_eArgError, "attempt to drop negative size");
    }

    return lazy_add_method(obj, 2, argv, n, rb_ary_new3(1, n), &lazy_drop_funcs);
}

#drop_while

[ GitHub ]

# File 'enumerator.c', line 2225


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_add_method(obj, 0, 0, Qfalse, Qnil, &lazy_drop_while_funcs);
}

#to_enum(method = :each, args) ⇒ `Lazy` #enum_for(method = :each, args) ⇒ `Lazy` #to_enum(method = :each, args) {|args| ... } ⇒ `Lazy` #enum_for(method = :each, args) {|args| ... } ⇒ `Lazy`

Alias for #to_enum.

#find_all

Alias for #select.

#collect_concat {|obj| ... } ⇒ `Lazy` #flat_map {|obj| ... } ⇒ `Lazy`
Also known as: #collect_concat

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}]

[ GitHub ]

# File 'enumerator.c', line 1845


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_proc, 0),
			   Qnil, 0);
}

#force(*args) ⇒ Array

Alias for Enumerable#to_a.

#grep(pattern)

[ GitHub ]

# File 'enumerator.c', line 1932


static VALUE
lazy_grep(VALUE obj, VALUE pattern)
{
    const lazyenum_funcs *const funcs = rb_block_given_p() ?
	&lazy_grep_iter_funcs : &lazy_grep_funcs;
    return lazy_add_method(obj, 0, 0, pattern, rb_ary_new3(1, pattern), funcs);
}

#grep_v(pattern)

[ GitHub ]

# File 'enumerator.c', line 1964


static VALUE
lazy_grep_v(VALUE obj, VALUE pattern)
{
    return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
					 rb_block_given_p() ?
					 lazy_grep_v_iter : lazy_grep_v_func,
					 pattern),
			   rb_ary_new3(1, pattern), 0);
}

#lazy

[ GitHub ]

# File 'enumerator.c', line 2283


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

#map Also known as: #collect

[ GitHub ]

# File 'enumerator.c', line 1762


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_add_method(obj, 0, 0, Qnil, Qnil, &lazy_map_funcs);
}

#reject

[ GitHub ]

# File 'enumerator.c', line 1891


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_add_method(obj, 0, 0, Qnil, Qnil, &lazy_reject_funcs);
}

#select Also known as: #find_all

[ GitHub ]

# File 'enumerator.c', line 1869


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_add_method(obj, 0, 0, Qnil, Qnil, &lazy_select_funcs);
}

#slice_after(*args)

Alias for #chunk.

#slice_before(*args)

Alias for #chunk.

#slice_when(*args)

Alias for #chunk.

#take(n)

[ GitHub ]

# File 'enumerator.c', line 2106


static VALUE
lazy_take(VALUE obj, VALUE n)
{
    long len = NUM2LONG(n);
    int argc = 0;
    VALUE argv[2];

    if (len < 0) {
	rb_raise(rb_eArgError, "attempt to take negative size");
    }

    if (len == 0) {
       argv[0] = sym_cycle;
       argv[1] = INT2NUM(0);
       argc = 2;
    }

    return lazy_add_method(obj, argc, argv, n, rb_ary_new3(1, n), &lazy_take_funcs);
}

#take_while

[ GitHub ]

# File 'enumerator.c', line 2141


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_add_method(obj, 0, 0, Qnil, Qnil, &lazy_take_while_funcs);
}

#to_enum(method = :each, args) ⇒ `Lazy` #enum_for(method = :each, args) ⇒ `Lazy` #to_enum(method = :each, args) {|args| ... } ⇒ `Lazy` #enum_for(method = :each, args) {|args| ... } ⇒ `Lazy`
Also known as: #enum_for

Similar to Object#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 Object#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]

[ GitHub ]

# File 'enumerator.c', line 1706


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;
}

#uniq

[ GitHub ]

# File 'enumerator.c', line 2267


static VALUE
lazy_uniq(VALUE obj)
{
    rb_block_call_func *const func =
	rb_block_given_p() ? lazy_uniq_iter : lazy_uniq_func;
    return lazy_set_method(rb_block_call(rb_cLazy, id_new, 1, &obj,
					 func, 0),
			   0, 0);
}

#zip(*args)

[ GitHub ]

# File 'enumerator.c', line 2038


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 %"PRIsVALUE" (must respond to :each)",
			     rb_obj_class(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);
}

Class: Enumerator::Lazy

Overview

Class Method Summary

::Enumerator - Inherited

Instance Method Summary

::Enumerator - Inherited

::Enumerable - Included

Constructor Details

.new(obj, size = nil) {|yielder, *values| ... }

Instance Method Details

#chunk(*args) Also known as: #slice_before, #slice_after, #slice_when, #chunk_while

#chunk_while(*args)

#collect

#collect_concat {|obj| ... } ⇒ Lazy #flat_map {|obj| ... } ⇒ Lazy

#drop(n)

#drop_while

#to_enum(method = :each, *args) ⇒ Lazy #enum_for(method = :each, *args) ⇒ Lazy #to_enum(method = :each, *args) {|*args| ... } ⇒ Lazy #enum_for(method = :each, *args) {|*args| ... } ⇒ Lazy

#find_all

#collect_concat {|obj| ... } ⇒ Lazy #flat_map {|obj| ... } ⇒ Lazy Also known as: #collect_concat

#force(*args) ⇒ Array

#grep(pattern)

#grep_v(pattern)

#lazy

#map Also known as: #collect

#reject

#select Also known as: #find_all

#slice_after(*args)

#slice_before(*args)

#slice_when(*args)

#take(n)

#take_while

#to_enum(method = :each, *args) ⇒ Lazy #enum_for(method = :each, *args) ⇒ Lazy #to_enum(method = :each, *args) {|*args| ... } ⇒ Lazy #enum_for(method = :each, *args) {|*args| ... } ⇒ Lazy Also known as: #enum_for

#uniq

#zip(*args)

#collect_concat {|obj| ... } ⇒ `Lazy` #flat_map {|obj| ... } ⇒ `Lazy`

#to_enum(method = :each, args) ⇒ `Lazy` #enum_for(method = :each, args) ⇒ `Lazy` #to_enum(method = :each, args) {|args| ... } ⇒ `Lazy` #enum_for(method = :each, args) {|args| ... } ⇒ `Lazy`

#collect_concat {|obj| ... } ⇒ `Lazy` #flat_map {|obj| ... } ⇒ `Lazy`
Also known as: #collect_concat

#to_enum(method = :each, args) ⇒ `Lazy` #enum_for(method = :each, args) ⇒ `Lazy` #to_enum(method = :each, args) {|args| ... } ⇒ `Lazy` #enum_for(method = :each, args) {|args| ... } ⇒ `Lazy`
Also known as: #enum_for