Class: Enumerator::Lazy

Inherits:
Enumerator show all
Defined in:
enumerator.c,
enumerator.c

Overview

Enumerator::Lazy is a special type of Enumerator, that allows constructing chains of operations without evaluating them immediately, and evaluating values on as-needed basis. In order to do so it redefines most of Enumerable methods so that they just construct another lazy enumerator.

Enumerator::Lazy can be constructed from any Enumerable with the Enumerable#lazy method.

lazy = (1..Float::INFINITY).lazy.select(&:odd?).drop(10).take_while { |i| i < 30 }
# => #<Enumerator::Lazy: #<Enumerator::Lazy: #<Enumerator::Lazy: #<Enumerator::Lazy: 1..Infinity>:select>:drop(10)>:take_while>

The real enumeration is performed when any non-redefined Enumerable method is called, like Enumerable#first or Enumerable#to_a (the latter is aliased as #force for more semantic code):

lazy.first(2)
#=> [21, 23]

lazy.force
#=> [21, 23, 25, 27, 29]

Note that most Enumerable methods that could be called with or without a block, on Enumerator::Lazy will always require a block:

[1, 2, 3].map       #=> #<Enumerator: [1, 2, 3]:map>
[1, 2, 3].lazy.map  # ArgumentError: tried to call lazy map without a block

This class allows idiomatic calculations on long or infinite sequences, as well as chaining of calculations without constructing intermediate arrays.

Example for working with a slowly calculated sequence:

require 'open-uri'

# This will fetch all URLs before selecting
# necessary data
URLS.map { |u| JSON.parse(open(u).read) }
  .select { |data| data.key?('stats') }
  .first(5)

# This will fetch URLs one-by-one, only till
# there is enough data to satisfy the condition
URLS.lazy.map { |u| JSON.parse(open(u).read) }
  .select { |data| data.key?('stats') }
  .first(5)

Ending a chain with “.eager” generates a non-lazy enumerator, which is suitable for returning or passing to another method that expects a normal enumerator.

def active_items
  groups
    .lazy
    .flat_map(&:items)
    .reject(&:disabled)
    .eager
end

# This works lazily; if a checked item is found, it stops
# iteration and does not look into remaining groups.
first_checked = active_items.find(&:checked)

# This returns an array of items like a normal enumerator does.
all_checked = active_items.select(&:checked)

Instance Method Summary collapse

Methods inherited from Enumerator

#+, #each, #each_with_index, #each_with_object, #feed, #initialize_copy, #inspect, #next, #next_values, #peek, #peek_values, produce, #rewind, #size, #with_object

Methods included from Enumerable

#all?, #any?, #chain, #count, #cycle, #detect, #each_cons, #each_entry, #each_slice, #each_with_index, #each_with_object, #entries, #find, #find_index, #first, #group_by, #include?, #inject, #max, #max_by, #member?, #min, #min_by, #minmax, #minmax_by, #none?, #one?, #partition, #reduce, #reverse_each, #sort, #sort_by, #sum, #tally, #to_h

Constructor Details

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

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 “filter+map” enumerator:

def filter_map(sequence)
  Lazy.new(sequence) do |yielder, *values|
    result = yield *values
    yielder << result if result
  end
end

filter_map(1..Float::INFINITY) {|i| i*i if i.even?}.first(5)
#=> [4, 16, 36, 64, 100]

Yields:

  • (yielder, *values)


1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
# File 'enumerator.c', line 1764

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, 0);
    rb_ivar_set(self, id_receiver, obj);

    return self;
}

Instance Method Details

#with_index(offset = 0) {|(*args), idx| ... } ⇒ Object (private) #with_index(offset = 0) ⇒ Object (private)

Iterates the given block for each element with an index, which starts from offset. If no block is given, returns a new Enumerator that includes the index, starting from offset

offset

the starting index to use

Overloads:

  • #with_index(offset = 0) {|(*args), idx| ... } ⇒ Object

    Yields:

    • ((*args), idx)


666
667
668
669
670
671
672
673
674
675
# File 'enumerator.c', line 666

static VALUE
enumerator_with_index(int argc, VALUE *argv, VALUE obj)
{
    VALUE memo;

    rb_check_arity(argc, 0, 1);
    RETURN_SIZED_ENUMERATOR(obj, argc, argv, enumerator_enum_size);
    memo = (!argc || NIL_P(memo = argv[0])) ? INT2FIX(0) : rb_to_int(memo);
    return enumerator_block_call(obj, enumerator_with_index_i, (VALUE)MEMO_NEW(memo, 0, 0));
}

#chunk {|elt| ... } ⇒ Object

Like Enumerable#chunk, but chains operation to be lazy-evaluated.

Yields:

  • (elt)


2768
2769
2770
2771
2772
# File 'enumerator.c', line 2768

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

#chunk_while {|elt_before, elt_after| ... } ⇒ Object

Like Enumerable#chunk_while, but chains operation to be lazy-evaluated.

Yields:

  • (elt_before, elt_after)


2768
2769
2770
2771
2772
# File 'enumerator.c', line 2768

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

#collect {|obj| ... } ⇒ Object #map {|obj| ... } ⇒ Object Also known as: _enumerable_collect

Like Enumerable#map, but chains operation to be lazy-evaluated.

(1..Float::INFINITY).lazy.map {|i| i**2 }
#=> #<Enumerator::Lazy: #<Enumerator::Lazy: 1..Infinity>:map>
(1..Float::INFINITY).lazy.map {|i| i**2 }.first(3)
#=> [1, 4, 9]

Overloads:

  • #collect {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #map {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2023
2024
2025
2026
2027
2028
2029
2030
2031
# File 'enumerator.c', line 2023

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);
}

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

Returns a new lazy enumerator with the concatenated results of running block once for every element in the lazy enumerator.

["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:

  • x responds to both each and force, which means that x is a lazy enumerator.

  • x 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}]

Overloads:

  • #collect_concat {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #flat_map {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
# File 'enumerator.c', line 2108

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);
}

#drop(n) ⇒ Object Also known as: _enumerable_drop

Like Enumerable#drop, but chains operation to be lazy-evaluated.



2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
# File 'enumerator.c', line 2550

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 {|obj| ... } ⇒ Object Also known as: _enumerable_drop_while

Like Enumerable#drop_while, but chains operation to be lazy-evaluated.

Yields:

  • (obj)


2594
2595
2596
2597
2598
2599
2600
2601
2602
# File 'enumerator.c', line 2594

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);
}

#eagerEnumerator

Returns a non-lazy Enumerator converted from the lazy enumerator.

Returns:



1963
1964
1965
1966
1967
1968
# File 'enumerator.c', line 1963

static VALUE
lazy_eager(VALUE self)
{
    return enumerator_init(enumerator_allocate(rb_cEnumerator),
                           self, sym_each, 0, 0, lazy_eager_size, Qnil, 0);
}

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

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 Object#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]

Overloads:

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

    Yields:

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

    Yields:

    • (*args)


1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
# File 'enumerator.c', line 1931

static VALUE
lazy_to_enum(int argc, VALUE *argv, VALUE self)
{
    VALUE lazy, meth = sym_each, super_meth;

    if (argc > 0) {
	--argc;
	meth = *argv++;
    }
    if (RTEST((super_meth = rb_hash_aref(lazy_use_super_method, meth)))) {
        meth = super_meth;
    }
    lazy = lazy_to_enum_i(self, meth, argc, argv, 0, PASS_KW_SPLAT);
    if (rb_block_given_p()) {
	enumerator_ptr(lazy)->size = rb_block_proc();
    }
    return lazy;
}

#find_all {|obj| ... } ⇒ Object #select {|obj| ... } ⇒ Object #filter {|obj| ... } ⇒ Object Also known as: _enumerable_filter

Like Enumerable#select, but chains operation to be lazy-evaluated.

Overloads:

  • #find_all {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #select {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #filter {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2140
2141
2142
2143
2144
2145
2146
2147
2148
# File 'enumerator.c', line 2140

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);
}

#filter_map {|obj| ... } ⇒ Object Also known as: _enumerable_filter_map

Like Enumerable#filter_map, but chains operation to be lazy-evaluated.

(1..).lazy.filter_map { |i| i * 2 if i.even? }.first(5)
#=> [4, 8, 12, 16, 20]

Yields:

  • (obj)


2174
2175
2176
2177
2178
2179
2180
2181
2182
# File 'enumerator.c', line 2174

static VALUE
lazy_filter_map(VALUE obj)
{
    if (!rb_block_given_p()) {
        rb_raise(rb_eArgError, "tried to call lazy filter_map without a block");
    }

    return lazy_add_method(obj, 0, 0, Qnil, Qnil, &lazy_filter_map_funcs);
}

#find_all {|obj| ... } ⇒ Object #select {|obj| ... } ⇒ Object #filter {|obj| ... } ⇒ Object Also known as: _enumerable_find_all

Like Enumerable#select, but chains operation to be lazy-evaluated.

Overloads:

  • #find_all {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #select {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #filter {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2140
2141
2142
2143
2144
2145
2146
2147
2148
# File 'enumerator.c', line 2140

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);
}

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

Returns a new lazy enumerator with the concatenated results of running block once for every element in the lazy enumerator.

["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:

  • x responds to both each and force, which means that x is a lazy enumerator.

  • x 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}]

Overloads:

  • #collect_concat {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #flat_map {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
# File 'enumerator.c', line 2108

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);
}

#grep(pattern) ⇒ Object #grep(pattern) {|obj| ... } ⇒ Object Also known as: _enumerable_grep

Like Enumerable#grep, but chains operation to be lazy-evaluated.

Overloads:

  • #grep(pattern) {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2252
2253
2254
2255
2256
2257
2258
# File 'enumerator.c', line 2252

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) ⇒ Object #grep_v(pattern) {|obj| ... } ⇒ Object Also known as: _enumerable_grep_v

Like Enumerable#grep_v, but chains operation to be lazy-evaluated.

Overloads:

  • #grep_v(pattern) {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2299
2300
2301
2302
2303
2304
2305
# File 'enumerator.c', line 2299

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

#lazyObject

Returns self.



2781
2782
2783
2784
2785
# File 'enumerator.c', line 2781

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

#collect {|obj| ... } ⇒ Object #map {|obj| ... } ⇒ Object Also known as: _enumerable_map

Like Enumerable#map, but chains operation to be lazy-evaluated.

(1..Float::INFINITY).lazy.map {|i| i**2 }
#=> #<Enumerator::Lazy: #<Enumerator::Lazy: 1..Infinity>:map>
(1..Float::INFINITY).lazy.map {|i| i**2 }.first(3)
#=> [1, 4, 9]

Overloads:

  • #collect {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #map {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2023
2024
2025
2026
2027
2028
2029
2030
2031
# File 'enumerator.c', line 2023

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 {|obj| ... } ⇒ Object Also known as: _enumerable_reject

Like Enumerable#reject, but chains operation to be lazy-evaluated.

Yields:

  • (obj)


2203
2204
2205
2206
2207
2208
2209
2210
2211
# File 'enumerator.c', line 2203

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);
}

#find_all {|obj| ... } ⇒ Object #select {|obj| ... } ⇒ Object #filter {|obj| ... } ⇒ Object Also known as: _enumerable_select

Like Enumerable#select, but chains operation to be lazy-evaluated.

Overloads:

  • #find_all {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #select {|obj| ... } ⇒ Object

    Yields:

    • (obj)
  • #filter {|obj| ... } ⇒ Object

    Yields:

    • (obj)


2140
2141
2142
2143
2144
2145
2146
2147
2148
# File 'enumerator.c', line 2140

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(pattern) ⇒ Object #slice_after {|elt| ... } ⇒ Object

Like Enumerable#slice_after, but chains operation to be lazy-evaluated.

Overloads:

  • #slice_after {|elt| ... } ⇒ Object

    Yields:

    • (elt)


2768
2769
2770
2771
2772
# File 'enumerator.c', line 2768

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

#slice_before(pattern) ⇒ Object #slice_before {|elt| ... } ⇒ Object

Like Enumerable#slice_before, but chains operation to be lazy-evaluated.

Overloads:

  • #slice_before {|elt| ... } ⇒ Object

    Yields:

    • (elt)


2768
2769
2770
2771
2772
# File 'enumerator.c', line 2768

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

#slice_when {|elt_before, elt_after| ... } ⇒ Object

Like Enumerable#slice_when, but chains operation to be lazy-evaluated.

Yields:

  • (elt_before, elt_after)


2768
2769
2770
2771
2772
# File 'enumerator.c', line 2768

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

#take(n) ⇒ Object Also known as: _enumerable_take

Like Enumerable#take, but chains operation to be lazy-evaluated.



2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
# File 'enumerator.c', line 2454

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 {|obj| ... } ⇒ Object Also known as: _enumerable_take_while

Like Enumerable#take_while, but chains operation to be lazy-evaluated.

Yields:

  • (obj)


2496
2497
2498
2499
2500
2501
2502
2503
2504
# File 'enumerator.c', line 2496

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_aArray #forceArray Also known as: force

Expands lazy enumerator to an array. See Enumerable#to_a.

Overloads:



1795
1796
1797
# File 'enumerator.c', line 1795

static VALUE lazy_to_a(VALUE self)
{
}

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

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 Object#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]

Overloads:

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

    Yields:

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

    Yields:

    • (*args)


1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
# File 'enumerator.c', line 1931

static VALUE
lazy_to_enum(int argc, VALUE *argv, VALUE self)
{
    VALUE lazy, meth = sym_each, super_meth;

    if (argc > 0) {
	--argc;
	meth = *argv++;
    }
    if (RTEST((super_meth = rb_hash_aref(lazy_use_super_method, meth)))) {
        meth = super_meth;
    }
    lazy = lazy_to_enum_i(self, meth, argc, argv, 0, PASS_KW_SPLAT);
    if (rb_block_given_p()) {
	enumerator_ptr(lazy)->size = rb_block_proc();
    }
    return lazy;
}

#uniqObject #uniq {|item| ... } ⇒ Object Also known as: _enumerable_uniq

Like Enumerable#uniq, but chains operation to be lazy-evaluated.

Overloads:

  • #uniq {|item| ... } ⇒ Object

    Yields:

    • (item)


2649
2650
2651
2652
2653
2654
2655
# File 'enumerator.c', line 2649

static VALUE
lazy_uniq(VALUE obj)
{
    const lazyenum_funcs *const funcs =
        rb_block_given_p() ? &lazy_uniq_iter_funcs : &lazy_uniq_funcs;
    return lazy_add_method(obj, 0, 0, Qnil, Qnil, funcs);
}

#with_index(offset = 0) {|(*args), idx| ... } ⇒ Object #with_index(offset = 0) ⇒ Object

If a block is given, iterates the given block for each element with an index, which starts from offset, and returns a lazy enumerator that yields the same values (without the index).

If a block is not given, returns a new lazy enumerator that includes the index, starting from offset.

offset

the starting index to use

See Enumerator#with_index.

Overloads:

  • #with_index(offset = 0) {|(*args), idx| ... } ⇒ Object

    Yields:

    • ((*args), idx)


2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
# File 'enumerator.c', line 2701

static VALUE
lazy_with_index(int argc, VALUE *argv, VALUE obj)
{
    VALUE memo;

    rb_scan_args(argc, argv, "01", &memo);
    if (NIL_P(memo))
        memo = LONG2NUM(0);

    return lazy_add_method(obj, 0, 0, memo, rb_ary_new_from_values(1, &memo), &lazy_with_index_funcs);
}

#zip(arg, ...) ⇒ Object #zip(arg, ...) {|arr| ... } ⇒ nil Also known as: _enumerable_zip

Like Enumerable#zip, but chains operation to be lazy-evaluated. However, if a block is given to zip, values are enumerated immediately.

Overloads:

  • #zip(arg, ...) {|arr| ... } ⇒ nil

    Yields:

    • (arr)

    Returns:

    • (nil)


2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
# File 'enumerator.c', line 2379

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);
}