module Enumerable
Constants
- Arguments
This is a simple reimplementation of the core Enumerable module to allow its methods to take and pass-on arbitrary arguments to the underlying each call. This library uses Enumerator and scans Enumerable so it can alwasy stay in sync.
NOTE: Any Enumerable method with a negative arity cannot pass arguments due to ambiguity in the argument count. So the methods inject and zip do NOT work this way, but simply work as they do in Enumerable. However, The methods find and detect have been made modified to work by removing its rarely used optional parameter and providing instead an optional keyword parameter (:ifnone => …). Please keep these difference in mind.
Example
require 'enumargs' class T include Enumerable::Argumentable def initialize(arr) @arr = arr end def each(n) arr.each{ |e| yield(e+n) } end end t = T.new([1,2,3]) t.collect(4) #=> [5,6,7]
Public Instance Methods
Accumulate a set of a set. For example, in an ORM design where `Group has_many User` we might have something equivalent to the following.
Group = Struct.new(:users) User = Struct.new(:name, :friends) user1 = User.new('John', []) user2 = User.new('Jane', ['Jill']) user3 = User.new('Joe' , ['Jack', 'Jim']) group1 = Group.new([user1, user2]) group2 = Group.new([user2, user3]) groups = [group1, group2]
Now we can accumulate the users of all groups.
groups.accumulate.users #=> [user1, user2, user3]
You may pass an argument to perform chains, e.g. the following returns the names of users from all groups.
groups.accumulate(2).users.name #=> ['John','Jane','Joe']
Or we can gather all the friends of all users in groups.
groups.accumulate(2).users.friends #=> ['Jill','Jack','Jim']
This is more convenient then the equivalent.
groups.accumulate.users.accumulate.friends #=> ['Jill','Jack','Jim']
CREDIT: George Moshchovitis, Daniel Emirikol, Robert Dober
# File lib/core/facets/enumerable/accumulate.rb, line 42 def accumulate(iterations=1) return self if iterations == 0 Functor.new do |op, *args| result = [] each { |x| result << x.send(op, *args) } result.flatten.uniq.accumulate(iterations - 1) end end
Same as accumulate, but does not apply uniq to final result.
groups.accumulate_all(2).users.friends #=> ['Jill', 'Jill','Jack','Jim']
# File lib/core/facets/enumerable/accumulate.rb, line 56 def accumulate_all(iterations=1) return self if iterations == 0 Functor.new do |op, *args| result = [] each { |x| result << x.send(op, *args) } result.flatten.accumulate_all(iterations - 1) end end
Returns an elemental object. This allows you to map a method on to every element.
r = [1,2,3].apply.+ r #=> 6
# File lib/core/facets/enumerable/apply.rb, line 12 def apply #Functor.new do |sym, *args, &blk| # inject{ |r, e| r.__send__(sym, e, *args, &blk) } #end per(:inject) end
Clusters together adjacent elements into a list of sub-arrays.
[2,2,2,3,3,4,2,2,1].cluster{ |x| x } => [[2, 2, 2], [3, 3], [4], [2, 2], [1]] ["dog", "duck", "cat", "dude"].cluster{ |x| x[0] } => [["dog", "duck"], ["cat"], ["dude"]]
@author Oleg K
# File lib/core/facets/enumerable/cluster.rb, line 13 def cluster cluster = [] each do |element| if cluster.last && yield(cluster.last.last) == yield(element) cluster.last << element else cluster << [element] end end cluster end
A more versitle compact method. It can be used to collect and filter items out in one single step.
c = [1,2,3].compact_map do |n| n < 2 ? nil : n end c #=> [2,3]
CREDIT: Trans
DEPRECATE: This method should probably be removed b/c purge does almost the same thing and enum.map{}.compact works too.
# File lib/core/facets/enumerable/compact_map.rb, line 17 def compact_map(&block) y = [] if block_given? each do |*a| r = yield(*a) y << r unless r.nil? end else each do |r| y << r unless r.nil? end end y end
Without a block: wrap the Enumerable object in such a way that map, select and similar operations are performed “horizontally” across a series of blocks, instead of building an array of results at each step. This reduces memory usage, allows partial results to be provided early, and permits working with infinite series.
a = (1..1_000_000_000).defer.select{ |i| i % 2 == 0 }. map{ |i| i + 100 }. take(10).to_a
With a block: the block acts as an arbitrary filter on the data. Unlike map, it can choose to drop elements from the result, and/or add additional ones. The first object passed to the block is the receiver of the output.
(1..1_000_000_000). defer { |out,i| out << i if i % 2 == 0 }. # like select defer { |out,i| out << i + 100 }. # like map take(10).to_a
Use a method like to_a or to_h at the end of the chain when you want an Array or Hash built with the results, or each{…} if you just want to output each result and discard it.
# File lib/core/facets/enumerable/defer.rb, line 29 def defer(&blk) if block_given? Denumerator.new do |output| each do |*input| yield(output, *input) end end else Denumerator.new do |output| each do |*input| output.yield(*input) end end end end
Iterate through slices. If slice steps
is not given, the arity
of the block is used.
x = [] [1,2,3,4].each_by{ |a,b| x << [a,b] } x #=> [ [1,2], [3,4] ] x = [] [1,2,3,4,5,6].each_by(3){ |a| x << a } x #=> [ [1,2,3], [4,5,6] ]
This is just like each_slice, except that it will check the arity of the block. If each_slice ever suppots this this method can be deprecated.
CREDIT: Trans
# File lib/core/facets/enumerable/each_by.rb, line 22 def each_by(steps=nil, &block) if steps each_slice(steps, &block) else steps = block.arity.abs each_slice(steps, &block) #each_slice(steps) {|i| block.call(*i)} end end
Long-term for ewise.
a = [1,2] (a.elementwise + 3) #=> [4,5] (a.elementwise + [4,5]) #=> [5,7]
Returns an elemental object. This allows you to map a method on to every element.
r = [1,2,3].every + 3 r #=> [4,5,6]
# File lib/core/facets/enumerable/every.rb, line 11 def every per(:map) end
In place version of every.
# File lib/core/facets/enumerable/every.rb, line 17 def every! raise NoMethodError unless respond_to?(:map!) per(:map!) end
Returns an elementwise Functor designed to make R-like elementwise operations possible. This is very much like the every method, but it treats array argument specially.
([1,2].ewise + 3) #=> [4,5]
Vector to vector
([1,2].ewise + [4,5]) #=> [5,7]
Special thanks to Martin DeMello for helping to develop this.
# File lib/core/facets/enumerable/ewise.rb, line 19 def ewise(count=1) Functor.new do |op,*args| if args.empty? r = self count.times do r = r.collect{ |a| a.send(op) } end r else r = args.collect do |arg| if Array === arg #arg.kind_of?(Enumerable) x = self count.times do ln = (arg.length > length ? length : arg.length ) x = x.slice(0...ln) x = x.zip(arg[0...ln]) x = x.collect{ |a,b| a.send(op,b) } #x = x.collect{ |a,b| b ? a.send(op,b) : nil } end x else x = self count.times do x = x.collect{ |a| a.send(op,arg) } end x end end r.flatten! if args.length == 1 r end end end
The inverse of include?.
[:a, :b].exclude?(:c) #=> true [:a, :b].exclude?(:a) #=> false
# File lib/core/facets/enumerable/exclude.rb, line 10 def exclude?(object) !include?(object) end
Expand all elements of an Enumerable object.
[0, 2..3, 5..7].expand #=> [0,[2, 3],[5,6,7]]
CREDIT: Trans
# File lib/core/facets/enumerable/expand.rb, line 8 def expand map do |x| (Enumerable === x ? x.expand : x) end end
The block acts as an arbitrary filter on the data. Unlike map, it can choose to drop elements from the result and/or add additional elements. The first object passed to the block is the receiver of the output.
x = (1..10000) x = x.filter{ |out,i| out << i if i % 2 == 0 } # like select x = x.filter{ |out,i| out << i + 100 } # like map x = x.take(3) x #=> [102, 104, 106]
This is very similar to each_with_object, but filter handles argument better by reversing their order and using the splat operator. (This was also once known as injecting.)
CREDIT: David Black, Louis J Scoras
# File lib/core/facets/enumerable/filter.rb, line 21 def filter(output=[]) #:yeild: if block_given? each do |*input| yield(output, *input) end output else to_enum(:filter) end end
Yield each element to the block and return the result of the block when that result evaluates as true, terminating early like detect and find.
obj1 = Object.new obj2 = Object.new def obj1.foo?; false; end def obj2.foo?; true ; end def obj1.foo ; "foo1"; end def obj2.foo ; "foo2"; end [obj1, obj2].find_yield{ |obj| obj.foo if obj.foo? } #=> "foo2"
Another example.
[1,2,3,4,5].find_yield{ |i| j = i+1; j if j % 4 == 0 } #=> 4
If the block is never true, return the object given in the first parameter, or nil if none specified.
[1,2,3].find_yield{ |_| false } #=> nil [false].find_yield(1){ |_| false } #=> 1
# File lib/core/facets/enumerable/find_yield.rb, line 28 def find_yield(fallback=nil) #:yield: each do |member| result = yield(member) return result if result end fallback end
Generates a hash mapping each unique symbol in the array to the absolute frequency it appears.
[:a,:a,:b,:c,:c,:c].frequency #=> {:a=>2,:b=>1,:c=>3}
CREDIT: Brian Schröder
# File lib/core/facets/enumerable/frequency.rb, line 18 def frequency p = Hash.new(0); each{ |v| p[v] += 1 }; p end
Like `#map`/`#collect`, but generates a Hash. The block is expected to return two values: the key and the value for the new hash.
numbers = (1..3) squares = numbers.graph{ |n| [n, n*n] } # { 1=>1, 2=>4, 3=>9 } sq_roots = numbers.graph{ |n| [n*n, n] } # { 1=>1, 4=>2, 9=>3 }
CREDIT: Andrew Dudzik (adudzik), Trans
# File lib/core/facets/enumerable/graph.rb, line 12 def graph(&yld) if yld h = {} each do |*kv| r = yld[*kv] case r when Hash nk, nv = *r.to_a[0] when Range nk, nv = r.first, r.last else nk, nv = *r end h[nk] = nv end h else Enumerator.new(self,:graph) end end
The hashify methods is a higher-order message used to convert an enumerable object into a hash. Converting an enumerable object into a hash is not a one-to-one conversion, for this reason hashify is used to provide variant approches for the conversion most suited to the use case at hand. Here are some (but not a complete set of) examples.
If the enumerable is a collection of perfect pairs, like that which Hash#to_a generates, then assoc can be used.
a = [ [:a,1], [:b,2] ] a.hashify.assoc #=> { :a=>1, :b=>2 }
If it it contains only arrays, but are not perfect pairs, then concat can be used.
a = [ [:a,1,2], [:b,2], [:c], [:d] ] a.hashify.concat #=> { :a=>[1,2], :b=>[2], :c=>[], :d=>[] }
If the array contains objects other then arrays then the splat method might do the trick.
a = [ [:a,1,2], 2, :b, [:c,3], 9 ] a.hashify.splat #=> { [:a,1,2]=>2, :b=>[:c,3], 9=>nil }
Also, the particular dispatch can be left up the Hashify using the auto method. See Hashify#auto for details on this.
TODO: This method takes arguments only for the sake of the old method which has been deprecated. These will be removed eventually.
CREDIT: Robert Klemme, Sandor Szücs, Trans
# File lib/core/facets/enumerable/hashify.rb, line 40 def hashify(val=nil, &block) if val warn "The old Enumerable#hashify method has been be deprecated. Use #value_by instead." value_by{ val } end if block warn "The old Enumerable#hashify method has been be deprecated. Use #value_by instead." value_by(&block) end Hashifier.new(self) end
Apply each element of an enumerable ot a hash by iterating over each element and yielding the hash and element.
[1,2,3].hinge{|h,e| h[e] = e+1 } #=> {1=>2, 2=>3, 3=>4}
TODO: #hinge will get a new name.
# File lib/core/facets/enumerable/hinge.rb, line 12 def hinge(init={}) h = init each{ |v| yield(h,v) } h end
The same as include? but tested using === instead of #==.
[1, 2, "a"].incase?(2) #=> true [1, 2, "a"].incase?(String) #=> true [1, 2, "a"].incase?(3) #=> false
Why the name `incase`? Because the method uses case-equality. Along with the alliteration for “in case” and the similarity with “include?”, it seemed like the perfect fit.
@author Lavir the Whiolet
# File lib/core/facets/enumerable/incase.rb, line 15 def incase?(what) any? { |x| what === x } end
Convert enumerable into a Hash, iterating over each member where the provided block must return the key to by used to map to the value.
Examples:
[:a,:b,:c].key_by{ |v| v.to_s } #=> {'a'=>:a, 'b'=>:b, 'c'=>:c}
TODO: How should this method behave with a Hash?
Returns: Hash
# File lib/core/facets/enumerable/key_by.rb, line 16 def key_by return to_enum(:key_by) unless block_given? h = {} each do |v| h[yield(v)] = v end return h end
Like group_by, but maps the second value returned from the block.
a = [1,2,3,4,5] a.map_by{ |e| [e % 2, e + 1] } #=> { 0=>[3,5], 1=>[2,4,6] }
Works well with a hash too.
h = {"A"=>1, "B"=>1, "C"=>1, "D"=>2, "E"=>2} h.map_by{ |k,v| [v, k.downcase] } #=> {1=>["a", "b", "c"], 2=>["d", "e"]}
If a second value is not returned, map_by acts like group_by.
h = {"A"=>1, "B"=>1, "C"=>1, "D"=>2, "E"=>2} h.map_by{ |k,v| v } #=> {1=>[["A",1], ["B",1], ["C",1]], 2=>[["D",2], ["E",2]]}
# File lib/core/facets/enumerable/map_by.rb, line 21 def map_by #:yield: res = {} each do |a| k,v = yield(*a) if v (res[k] ||= []) << v else (res[k] ||= []) << a end end res end
Alias for find_yield.
DEPRECATE: This has been renamed to find_yield.
Send a message to each element and collect the result.
[1,2,3].map_send(:+, 3) #=> [4,5,6]
CREDIT: Sean O'Halpin
# File lib/core/facets/enumerable/map_send.rb, line 9 def map_send(meth, *args, &block) map{|e| e.send(meth, *args, &block)} end
Map each element into another class via class constructor.
@param [#new] to_class
Generally a class, but any object that repsonds to #new.
# File lib/core/facets/enumerable/map_to.rb, line 8 def map_to(to_class) map{ |e| to_class.new(e) } end
Combines zip and map in a single efficient operation.
h = {} [1,2,3].map_with [:x,:y,:z] do |n,k| h[k] = n end h #=> {:x=>1, :y=>2, :z=>3}
@return [Hash]
@author Michael Kohl
# File lib/core/facets/enumerable/map_with.rb, line 14 def map_with(*arrays, &block) enum_for(:zip, *arrays).map(&block) end
Same as collect but with an iteration counter.
a = [1,2,3].collect_with_index { |e,i| e*i } a #=> [0,2,6]
CREDIT: Gavin Sinclair
# File lib/core/facets/enumerable/map_with_index.rb, line 10 def map_with_index r = [] each_with_index do |e, i| r << yield(e, i) end r end
Like `#map`/`#collect`, but generates a Hash. The block is expected to return two values: the key and the value for the new hash.
numbers = (1..3) squares = numbers.mash{ |n| [n, n*n] } # { 1=>1, 2=>4, 3=>9 } sq_roots = numbers.mash{ |n| [n*n, n] } # { 1=>1, 4=>2, 9=>3 }
CREDIT: Andrew Dudzik (adudzik), Trans
# File lib/core/facets/enumerable/mash.rb, line 12 def mash(&yld) if yld h = {} each do |*kv| r = yld[*kv] case r when Hash nk, nv = *r.to_a[0] when Range nk, nv = r.first, r.last else nk, nv = *r end h[nk] = nv end h else Enumerator.new(self,:graph) end end
Divide an array into groups by modulo of the index.
[2,4,6,8].modulate(2) #=> [[2,6],[4,8]]
CREDIT: Trans
NOTE: Would the better name for this be 'collate'?
# File lib/core/facets/enumerable/modulate.rb, line 11 def modulate(modulo) return to_a if modulo == 1 raise ArgumentError, 'bad modulo' if size % modulo != 0 r = Array.new(modulo, []) (0...size).each do |i| r[i % modulo] += [self[i]] end r end
Returns an array of elements for the elements that occur n times. Or according to the results of a given block.
a = [1,1,2,3,3,4,5,5] a.occur(1).sort #=> [2,4] a.occur(2).sort #=> [1,3,5] a.occur(3).sort #=> [] a.occur(1..1).sort #=> [2,4] a.occur(2..3).sort #=> [1,3,5] a.occur { |n| n == 1 }.sort #=> [2,4] a.occur { |n| n > 1 }.sort #=> [1,3,5]
# File lib/core/facets/enumerable/occur.rb, line 18 def occur(n=nil) #:yield: result = Hash.new { |hash, key| hash[key] = Array.new } each do |item| key = item result[key] << item end if block_given? result.reject! { |key, values| ! yield(values.size) } else raise ArgumentError unless n if Range === n result.reject! { |key, values| ! n.include?(values.size) } else result.reject! { |key, values| values.size != n } end end return result.values.flatten.uniq end
Returns the only element in the enumerable. Raises an IndexError if the enumreable has more then one element.
[5].only # => 5 expect IndexError do [1,2,3].only end expect IndexError do [].only end
CREDIT: Lavir the Whiolet, Gavin Sinclair, Noah Gibbs
# File lib/core/facets/enumerable/only.rb, line 18 def only first = false first_item = nil each do |item| if first raise IndexError, "not the only element of enumerable" else first = true first_item = item end end if first return first_item else raise IndexError, "not the only element of enumerable" end end
Does this Enumerable have the only element?
It differs from Enumerable#one? in that it does not check the items themselves. It checks the quantity only.
CREDIT: Lavir the Whiolet
# File lib/core/facets/enumerable/only.rb, line 45 def only? first = false each do |item| return false if first first = true end return first end
Similar to group_by but returns an array of the groups. Returned elements are sorted by block.
%w{this is a test}.organize_by {|x| x[0]} #=> [ ['a'], ['is'], ['this', 'test'] ]
CREDIT: Erik Veenstra
# File lib/core/facets/enumerable/organize_by.rb, line 11 def organize_by(&b) group_by(&b).sort.transpose.pop || [] # group_by(&b).values ? end
Like `each_slice(2)` but ensures the last element has a pair if odd sized.
[:a,1,:b,2,:c,3].pair.to_a #=> [[:a,1],[:b,2],[:c,3]]
# File lib/core/facets/enumerable/pair.rb, line 8 def pair(missing=nil) return to_enum(:pair) unless block_given? each_slice(2) do |kv| if kv.size == 1 yield kv.first, missing else yield kv.first, kv.last end end end
Per element meta-functor.
([1,2,3].per(:map) + 3) #=> [4,5,6] ([1,2,3].per(:select) > 1) #=> [2,3]
Using fluid notation.
([1,2,3].per.map + 3) #=> [4,5,6] ([1,2,3].per.select > 1) #=> [2,3]
# File lib/core/facets/enumerable/per.rb, line 21 def per(enum_method=nil, *enum_args) if enum_method Functor.new do |op, *args, &blk| __send__(enum_method || :map, *enum_args){ |x, *y| x.__send__(op, *y, *args, &blk) } end else Functor.new do |enumr_method, *enumr_args| Functor.new do |op, *args, &blk| __send__(enumr_method, *enumr_args){ |x, *y| x.__send__(op, *y, *args, &blk) } end end end end
A versitle compaction method. Like map but used to filter out multiple items in a single step.
Without trash
arguments nil
is assumed.
[1, nil, 2].purge #=> [1,2]
If trash
arguments are given, each argument is compared for a
match using #==.
(1..6).purge(3,4) #=> [1,2,5,6]
If a block is given, the yield is used in the matching condition instead of the element itsef.
(1..6).purge(0){ |n| n % 2 } #=> [1,3,5]
NOTE: This could just as well be an override of the core compact method, but to avoid potential issues associated with overriding core methods we use the alternate name purge.
CREDIT: Trans
# File lib/core/facets/enumerable/purge.rb, line 27 def purge(*trash, &block) trash = [nil] if trash.empty? r = [] if block_given? each do |e| y = yield(e) r << e unless trash.any?{|t| t == y} end else each do |e| r << e unless trash.any?{|t| t == e} end end r end
Returns a recursive functor, that allows enumerable methods to iterate through enumerable sub-elements. By default it only recurses over elements of the same type.
# File lib/core/facets/enumerable/recursively.rb, line 7 def recursively(*types, &block) Recursor.new(self, *types, &block) end
Squeeze out the same elements. This behaves like C++ unique(), removing equivalent elements that are concomitant to each other. To get a similar result with Array#uniq, the array would have to be sorted first.
Calculation order is O(n).
Examples
[1,2,2,3,3,2,1].squeeze #=> [1,2,3,2,1] [1,2,2,3,3,2,1].sort.squeeze #=> [1,2,3] [1,2,2,3,3,2,1].squeeze(*[3]) #=> [1,2,2,3,2,1]
Returns [Array].
CREDIT: T. Yamada
# File lib/core/facets/enumerable/squeeze.rb, line 20 def squeeze(*limited_to) first = true r = [] # result c = nil # current each do |e| if !limited_to.empty? && !limited_to.include?(e) r << e elsif first || c != e r << e first = false c = e end end r end
Uses #+ to sum the enumerated elements.
[1,2,3].sum #=> 6 [3,3,3].sum #=> 9
Note that Facets' sum method is completely generic – it can work on any objects that respond to #+.
[[1],[2],[3]].sum #=> [1,2,3]
For this reason it is usually a good idea to provide a default value. Consider the difference between the two expressions below.
[].sum #=> nil [].sum(0) #=> 0
This default value also acts as an initial value.
[].sum(5) #=> 5 [1,2,3].sum(10) #=> 16
A block can also be passed to coax the elements before summation.
[1.1,2.2,3.3].sum(10.4, &:to_i) #=> 16.4
Notice the initial value is not effected by the block.
@author Dawid Marcin Grzesiak
# File lib/core/facets/enumerable/sum.rb, line 32 def sum(*identity, &block) if block_given? map(&block).sum(*identity) else reduce(*identity) { |sum, element| sum + element } end end
Like Enumerable#map but each iteration is processed via a separate thread.
CREDIT: Sean O'Halpin
# File lib/standard/facets/thread.rb, line 59 def threaded_map #:yield: map{ |e| Thread.new(e){ |t| yield(t) } }.map{ |t| t.value } end
Like #map_send but each iteration is processed via a separate thread.
CREDIT: Sean O'Halpin
# File lib/standard/facets/thread.rb, line 68 def threaded_map_send(meth, *args, &block) map{ |e| Thread.new(e){ |t| t.send(meth, *args, &block) } }.map{ |t| t.value } end
Take an associative array and unassociate it.
[[:a,1], [:b,2]].unassociate.to_a #=> [:a, [1], :b, [2]] [[:a,1], [:b,2]].unassociate(1).to_a #=> [:a, 1, :b, 2]
# File lib/core/facets/enumerable/unassociate.rb, line 8 def unassociate(index = 1..-1) return to_enum(:unassociate, index) unless block_given? each do |v| case v when Array yield v[0] yield v[index] else yield v yield nil end end end
Like uniq, but determines uniqueness based on a given block.
(-5..5).to_a.uniq_by {|i| i*i } #=> [-5, -4, -3, -2, -1, 0]
# File lib/core/facets/enumerable/uniq_by.rb, line 8 def uniq_by #:yield: h = {}; inject([]) {|a,x| h[yield(x)] ||= a << x} end
Create a hash whose keys are the enumerable's elements, with specified values.
If no block is given, the given parameter (default true) is used for all values, e.g.:
[1,2,3].value_by{ true } #=> {1=>true, 2=>true, 3=>true} [1,2,3].value_by{ "a" } #=> {1=>"a", 2=>"a", 3=>"a"}
If a block is given, each key's value is the result of running the block for that key, e.g.:
[1,2,3].value_by{ |n| "a"*n } #=> {1=>"a", 2=>"aa", 3=>"aaa"}
@author Ronen Barzel
# File lib/core/facets/enumerable/value_by.rb, line 18 def value_by return to_enum(:value_by) unless block_given? h = {} each { |item| h[item] = yield(item) } h end
Recursively iterate over all Enumerable elements, or subset given :type=>[type1, type2, …].
[1, 2, 8..9].visit{ |x| x.succ } # => [2, 3, [9, 10]]
# File lib/core/facets/enumerable/visit.rb, line 9 def visit(opts={}, &block) type = opts[:type] ? [opts[:type]].flatten : [Enumerable] skip = opts[:skip] map do |v| case v when String # b/c of 1.8 block.call(v) when *type v.visit(opts, &block) else if skip && Enumerable === v v else block.call(v) end end end end