JezK
Edit File: enumerable.rbs
# <!-- rdoc-file=enum.c --> # ## What's Here # # Module Enumerable provides methods that are useful to a collection class for: # * [Querying](#module-Enumerable-label-Methods+for+Querying) # * [Fetching](#module-Enumerable-label-Methods+for+Fetching) # * [Searching](#module-Enumerable-label-Methods+for+Searching) # * [Sorting](#module-Enumerable-label-Methods+for+Sorting) # * [Iterating](#module-Enumerable-label-Methods+for+Iterating) # * [And more....](#module-Enumerable-label-Other+Methods) # # # ### Methods for Querying # # These methods return information about the Enumerable other than the elements # themselves: # # #include?, #member? # : Returns `true` if self == object, `false` otherwise. # #all? # : Returns `true` if all elements meet a specified criterion; `false` # otherwise. # #any? # : Returns `true` if any element meets a specified criterion; `false` # otherwise. # #none? # : Returns `true` if no element meets a specified criterion; `false` # otherwise. # #one? # : Returns `true` if exactly one element meets a specified criterion; `false` # otherwise. # #count # : Returns the count of elements, based on an argument or block criterion, if # given. # #tally # : Returns a new Hash containing the counts of occurrences of each element. # # # ### Methods for Fetching # # These methods return entries from the Enumerable, without modifying it: # # *Leading, trailing, or all elements*: # #entries, #to_a # : Returns all elements. # #first # : Returns the first element or leading elements. # #take # : Returns a specified number of leading elements. # #drop # : Returns a specified number of trailing elements. # #take_while # : Returns leading elements as specified by the given block. # #drop_while # : Returns trailing elements as specified by the given block. # # # *Minimum and maximum value elements*: # #min # : Returns the elements whose values are smallest among the elements, as # determined by `<=>` or a given block. # #max # : Returns the elements whose values are largest among the elements, as # determined by `<=>` or a given block. # #minmax # : Returns a 2-element Array containing the smallest and largest elements. # #min_by # : Returns the smallest element, as determined by the given block. # #max_by # : Returns the largest element, as determined by the given block. # #minmax_by # : Returns the smallest and largest elements, as determined by the given # block. # # # *Groups, slices, and partitions*: # #group_by # : Returns a Hash that partitions the elements into groups. # #partition # : Returns elements partitioned into two new Arrays, as determined by the # given block. # #slice_after # : Returns a new Enumerator whose entries are a partition of `self`, based # either on a given `object` or a given block. # #slice_before # : Returns a new Enumerator whose entries are a partition of `self`, based # either on a given `object` or a given block. # #slice_when # : Returns a new Enumerator whose entries are a partition of `self` based on # the given block. # #chunk # : Returns elements organized into chunks as specified by the given block. # #chunk_while # : Returns elements organized into chunks as specified by the given block. # # # ### Methods for Searching and Filtering # # These methods return elements that meet a specified criterion. # # #find, #detect # : Returns an element selected by the block. # #find_all, #filter, #select # : Returns elements selected by the block. # #find_index # : Returns the index of an element selected by a given object or block. # #reject # : Returns elements not rejected by the block. # #uniq # : Returns elements that are not duplicates. # # # ### Methods for Sorting # # These methods return elements in sorted order. # # #sort # : Returns the elements, sorted by `<=>` or the given block. # #sort_by # : Returns the elements, sorted by the given block. # # # ### Methods for Iterating # # #each_entry # : Calls the block with each successive element (slightly different from # #each). # #each_with_index # : Calls the block with each successive element and its index. # #each_with_object # : Calls the block with each successive element and a given object. # #each_slice # : Calls the block with successive non-overlapping slices. # #each_cons # : Calls the block with successive overlapping slices. (different from # #each_slice). # #reverse_each # : Calls the block with each successive element, in reverse order. # # # ### Other Methods # # #map, #collect # : Returns objects returned by the block. # #filter_map # : Returns truthy objects returned by the block. # #flat_map, #collect_concat # : Returns flattened objects returned by the block. # #grep # : Returns elements selected by a given object or objects returned by a given # block. # #grep_v # : Returns elements selected by a given object or objects returned by a given # block. # #reduce, #inject # : Returns the object formed by combining all elements. # #sum # : Returns the sum of the elements, using method +++. # #zip # : Combines each element with elements from other enumerables; returns the # n-tuples or calls the block with each. # #cycle # : Calls the block with each element, cycling repeatedly. # # # ## Usage # # To use module Enumerable in a collection class: # # * Include it: # # include Enumerable # # * Implement method `#each` which must yield successive elements of the # collection. The method will be called by almost any Enumerable method. # # # Example: # # class Foo # include Enumerable # def each # yield 1 # yield 1, 2 # yield # end # end # Foo.new.each_entry{ |element| p element } # # Output: # # 1 # [1, 2] # nil # # ## Enumerable in Ruby Core Classes # Some Ruby classes include Enumerable: # * Array # * Dir # * Hash # * IO # * Range # * Set # * Struct # # Virtually all methods in Enumerable call method `#each` in the including # class: # * `Hash#each` yields the next key-value pair as a 2-element Array. # * `Struct#each` yields the next name-value pair as a 2-element Array. # * For the other classes above, `#each` yields the next object from the # collection. # # # ## About the Examples # The example code snippets for the Enumerable methods: # * Always show the use of one or more Array-like classes (often Array # itself). # * Sometimes show the use of a Hash-like class. For some methods, though, the # usage would not make sense, and so it is not shown. Example: #tally would # find exactly one of each Hash entry. # module Enumerable[unchecked out Elem] : _Each[Elem] # <!-- # rdoc-file=enum.c # - all? -> true or false # - all?(pattern) -> true or false # - all? {|element| ... } -> true or false # --> # Returns whether every element meets a given criterion. # # With no argument and no block, returns whether every element is truthy: # # (1..4).all? # => true # %w[a b c d].all? # => true # [1, 2, nil].all? # => false # ['a','b', false].all? # => false # [].all? # => true # # With argument `pattern` and no block, returns whether for each element # `element`, `pattern === element`: # # (1..4).all?(Integer) # => true # (1..4).all?(Numeric) # => true # (1..4).all?(Float) # => false # %w[bar baz bat bam].all?(/ba/) # => true # %w[bar baz bat bam].all?(/bar/) # => false # %w[bar baz bat bam].all?('ba') # => false # {foo: 0, bar: 1, baz: 2}.all?(Array) # => true # {foo: 0, bar: 1, baz: 2}.all?(Hash) # => false # [].all?(Integer) # => true # # With a block given, returns whether the block returns a truthy value for every # element: # # (1..4).all? {|element| element < 5 } # => true # (1..4).all? {|element| element < 4 } # => false # {foo: 0, bar: 1, baz: 2}.all? {|key, value| value < 3 } # => true # {foo: 0, bar: 1, baz: 2}.all? {|key, value| value < 2 } # => false # # Related: #any?, #none? #one?. # def all?: () -> bool | () { (Elem) -> boolish } -> bool # <!-- # rdoc-file=enum.c # - any? -> true or false # - any?(pattern) -> true or false # - any? {|element| ... } -> true or false # --> # Returns whether any element meets a given criterion. # # With no argument and no block, returns whether any element is truthy: # # (1..4).any? # => true # %w[a b c d].any? # => true # [1, false, nil].any? # => true # [].any? # => false # # With argument `pattern` and no block, returns whether for any element # `element`, `pattern === element`: # # [nil, false, 0].any?(Integer) # => true # [nil, false, 0].any?(Numeric) # => true # [nil, false, 0].any?(Float) # => false # %w[bar baz bat bam].any?(/m/) # => true # %w[bar baz bat bam].any?(/foo/) # => false # %w[bar baz bat bam].any?('ba') # => false # {foo: 0, bar: 1, baz: 2}.any?(Array) # => true # {foo: 0, bar: 1, baz: 2}.any?(Hash) # => false # [].any?(Integer) # => false # # With a block given, returns whether the block returns a truthy value for any # element: # # (1..4).any? {|element| element < 2 } # => true # (1..4).any? {|element| element < 1 } # => false # {foo: 0, bar: 1, baz: 2}.any? {|key, value| value < 1 } # => true # {foo: 0, bar: 1, baz: 2}.any? {|key, value| value < 0 } # => false # # Related: #all?, #none?, #one?. # def any?: () -> bool | () { (Elem) -> boolish } -> bool # <!-- # rdoc-file=enum.c # - map {|element| ... } -> array # - map -> enumerator # --> # Returns an array of objects returned by the block. # # With a block given, calls the block with successive elements; returns an array # of the objects returned by the block: # # (0..4).map {|i| i*i } # => [0, 1, 4, 9, 16] # {foo: 0, bar: 1, baz: 2}.map {|key, value| value*2} # => [0, 2, 4] # # With no block given, returns an Enumerator. # def collect: [U] () { (Elem arg0) -> U } -> ::Array[U] | () -> ::Enumerator[Elem, ::Array[untyped]] # <!-- rdoc-file=enum.c --> # Returns an array of flattened objects returned by the block. # # With a block given, calls the block with successive elements; returns a # flattened array of objects returned by the block: # # [0, 1, 2, 3].flat_map {|element| -element } # => [0, -1, -2, -3] # [0, 1, 2, 3].flat_map {|element| [element, -element] } # => [0, 0, 1, -1, 2, -2, 3, -3] # [[0, 1], [2, 3]].flat_map {|e| e + [100] } # => [0, 1, 100, 2, 3, 100] # {foo: 0, bar: 1, baz: 2}.flat_map {|key, value| [key, value] } # => [:foo, 0, :bar, 1, :baz, 2] # # With no block given, returns an Enumerator. # # Alias: #collect_concat. # def collect_concat: [U] () { (Elem) -> (::Array[U] | U) } -> ::Array[U] | () -> ::Enumerator[Elem, ::Array[untyped]] # <!-- # rdoc-file=enum.c # - compact -> array # --> # Returns an array of all non-`nil` elements: # # a = [nil, 0, nil, 'a', false, nil, false, nil, 'a', nil, 0, nil] # a.compact # => [0, "a", false, false, "a", 0] # def compact: () -> Array[Elem] # <!-- # rdoc-file=enum.c # - count -> integer # - count(object) -> integer # - count {|element| ... } -> integer # --> # Returns the count of elements, based on an argument or block criterion, if # given. # # With no argument and no block given, returns the number of elements: # # [0, 1, 2].count # => 3 # {foo: 0, bar: 1, baz: 2}.count # => 3 # # With argument `object` given, returns the number of elements that are `==` to # `object`: # # [0, 1, 2, 1].count(1) # => 2 # # With a block given, calls the block with each element and returns the number # of elements for which the block returns a truthy value: # # [0, 1, 2, 3].count {|element| element < 2} # => 2 # {foo: 0, bar: 1, baz: 2}.count {|key, value| value < 2} # => 2 # def count: () -> Integer | (Elem) -> Integer | () { (Elem) -> boolish } -> Integer # <!-- # rdoc-file=enum.c # - cycle(n = nil) {|element| ...} -> nil # - cycle(n = nil) -> enumerator # --> # When called with positive integer argument `n` and a block, calls the block # with each element, then does so again, until it has done so `n` times; returns # `nil`: # # a = [] # (1..4).cycle(3) {|element| a.push(element) } # => nil # a # => [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4] # a = [] # ('a'..'d').cycle(2) {|element| a.push(element) } # a # => ["a", "b", "c", "d", "a", "b", "c", "d"] # a = [] # {foo: 0, bar: 1, baz: 2}.cycle(2) {|element| a.push(element) } # a # => [[:foo, 0], [:bar, 1], [:baz, 2], [:foo, 0], [:bar, 1], [:baz, 2]] # # If count is zero or negative, does not call the block. # # When called with a block and `n` is `nil`, cycles forever. # # When no block is given, returns an Enumerator. # def cycle: (?Integer n) { (Elem arg0) -> untyped } -> NilClass | (?Integer n) -> ::Enumerator[Elem, NilClass] # <!-- rdoc-file=enum.c --> # Returns the first element for which the block returns a truthy value. # # With a block given, calls the block with successive elements of the # collection; returns the first element for which the block returns a truthy # value: # # (0..9).find {|element| element > 2} # => 3 # # If no such element is found, calls `if_none_proc` and returns its return # value. # # (0..9).find(proc {false}) {|element| element > 12} # => false # {foo: 0, bar: 1, baz: 2}.find {|key, value| key.start_with?('b') } # => [:bar, 1] # {foo: 0, bar: 1, baz: 2}.find(proc {[]}) {|key, value| key.start_with?('c') } # => [] # # With no block given, returns an Enumerator. # def detect: (?Proc ifnone) { (Elem) -> boolish } -> Elem? | (?Proc ifnone) -> ::Enumerator[Elem, Elem?] # <!-- # rdoc-file=enum.c # - drop(n) -> array # --> # For positive integer `n`, returns an array containing all but the first `n` # elements: # # r = (1..4) # r.drop(3) # => [4] # r.drop(2) # => [3, 4] # r.drop(1) # => [2, 3, 4] # r.drop(0) # => [1, 2, 3, 4] # r.drop(50) # => [] # # h = {foo: 0, bar: 1, baz: 2, bat: 3} # h.drop(2) # => [[:baz, 2], [:bat, 3]] # def drop: (Integer n) -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - drop_while {|element| ... } -> array # - drop_while -> enumerator # --> # Calls the block with successive elements as long as the block returns a truthy # value; returns an array of all elements after that point: # # (1..4).drop_while{|i| i < 3 } # => [3, 4] # h = {foo: 0, bar: 1, baz: 2} # a = h.drop_while{|element| key, value = *element; value < 2 } # a # => [[:baz, 2]] # # With no block given, returns an Enumerator. # def drop_while: () { (Elem) -> boolish } -> ::Array[Elem] | () -> ::Enumerator[Elem, ::Array[Elem]] # <!-- # rdoc-file=enum.c # - each_cons(n) { ... } -> self # - each_cons(n) -> enumerator # --> # Calls the block with each successive overlapped `n`-tuple of elements; returns # `self`: # # a = [] # (1..5).each_cons(3) {|element| a.push(element) } # a # => [[1, 2, 3], [2, 3, 4], [3, 4, 5]] # # a = [] # h = {foo: 0, bar: 1, baz: 2, bam: 3} # h.each_cons(2) {|element| a.push(element) } # a # => [[[:foo, 0], [:bar, 1]], [[:bar, 1], [:baz, 2]], [[:baz, 2], [:bam, 3]]] # # With no block given, returns an Enumerator. # def each_cons: (Integer n) { (::Array[Elem]) -> void } -> self | (Integer n) -> ::Enumerator[::Array[Elem], self] # <!-- # rdoc-file=enum.c # - each_with_index(*args) {|element, i| ..... } -> self # - each_with_index(*args) -> enumerator # --> # With a block given, calls the block with each element and its index; returns # `self`: # # h = {} # (1..4).each_with_index {|element, i| h[element] = i } # => 1..4 # h # => {1=>0, 2=>1, 3=>2, 4=>3} # # h = {} # %w[a b c d].each_with_index {|element, i| h[element] = i } # # => ["a", "b", "c", "d"] # h # => {"a"=>0, "b"=>1, "c"=>2, "d"=>3} # # a = [] # h = {foo: 0, bar: 1, baz: 2} # h.each_with_index {|element, i| a.push([i, element]) } # # => {:foo=>0, :bar=>1, :baz=>2} # a # => [[0, [:foo, 0]], [1, [:bar, 1]], [2, [:baz, 2]]] # # With no block given, returns an Enumerator. # def each_with_index: () { (Elem, Integer index) -> untyped } -> self | () -> ::Enumerator[[ Elem, Integer ], self] # <!-- # rdoc-file=enum.c # - each_with_object(object) { |(*args), memo_object| ... } -> object # - each_with_object(object) -> enumerator # --> # Calls the block once for each element, passing both the element and the given # object: # # (1..4).each_with_object([]) {|i, a| a.push(i**2) } # => [1, 4, 9, 16] # h.each_with_object({}) {|element, h| k, v = *element; h[v] = k } # # => {0=>:foo, 1=>:bar, 2=>:baz} # # With no block given, returns an Enumerator. # def each_with_object: [U] (U obj) { (Elem, U obj) -> untyped } -> U | [U] (U obj) -> ::Enumerator[[ Elem, U ], U] # <!-- rdoc-file=enum.c --> # Returns an array containing the items in `self`: # # (0..4).to_a # => [0, 1, 2, 3, 4] # # Enumerable#entries is an alias for Enumerable#to_a. # def entries: () -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - select {|element| ... } -> array # - select -> enumerator # --> # Returns an array containing elements selected by the block. # # With a block given, calls the block with successive elements; returns an array # of those elements for which the block returns a truthy value: # # (0..9).select {|element| element % 3 == 0 } # => [0, 3, 6, 9] # a = {foo: 0, bar: 1, baz: 2}.select {|key, value| key.start_with?('b') } # a # => {:bar=>1, :baz=>2} # # With no block given, returns an Enumerator. # # Related: #reject. # def find_all: () { (Elem) -> boolish } -> ::Array[Elem] | () -> ::Enumerator[Elem, ::Array[Elem]] # <!-- rdoc-file=enum.c --> # Returns an array containing elements selected by the block. # # With a block given, calls the block with successive elements; returns an array # of those elements for which the block returns a truthy value: # # (0..9).select {|element| element % 3 == 0 } # => [0, 3, 6, 9] # a = {foo: 0, bar: 1, baz: 2}.select {|key, value| key.start_with?('b') } # a # => {:bar=>1, :baz=>2} # # With no block given, returns an Enumerator. # # Related: #reject. # alias select find_all # <!-- rdoc-file=enum.c --> # Returns an array containing elements selected by the block. # # With a block given, calls the block with successive elements; returns an array # of those elements for which the block returns a truthy value: # # (0..9).select {|element| element % 3 == 0 } # => [0, 3, 6, 9] # a = {foo: 0, bar: 1, baz: 2}.select {|key, value| key.start_with?('b') } # a # => {:bar=>1, :baz=>2} # # With no block given, returns an Enumerator. # # Related: #reject. # alias filter find_all # <!-- # rdoc-file=enum.c # - find_index(object) -> integer or nil # - find_index {|element| ... } -> integer or nil # - find_index -> enumerator # --> # Returns the index of the first element that meets a specified criterion, or # `nil` if no such element is found. # # With argument `object` given, returns the index of the first element that is # `==` `object`: # # ['a', 'b', 'c', 'b'].find_index('b') # => 1 # # With a block given, calls the block with successive elements; returns the # first element for which the block returns a truthy value: # # ['a', 'b', 'c', 'b'].find_index {|element| element.start_with?('b') } # => 1 # {foo: 0, bar: 1, baz: 2}.find_index {|key, value| value > 1 } # => 2 # # With no argument and no block given, returns an Enumerator. # def find_index: (untyped value) -> Integer? | () { (Elem) -> boolish } -> Integer? | () -> ::Enumerator[Elem, Integer?] # <!-- # rdoc-file=enum.c # - first -> element or nil # - first(n) -> array # --> # Returns the first element or elements. # # With no argument, returns the first element, or `nil` if there is none: # # (1..4).first # => 1 # %w[a b c].first # => "a" # {foo: 1, bar: 1, baz: 2}.first # => [:foo, 1] # [].first # => nil # # With integer argument `n`, returns an array containing the first `n` elements # that exist: # # (1..4).first(2) # => [1, 2] # %w[a b c d].first(3) # => ["a", "b", "c"] # %w[a b c d].first(50) # => ["a", "b", "c", "d"] # {foo: 1, bar: 1, baz: 2}.first(2) # => [[:foo, 1], [:bar, 1]] # [].first(2) # => [] # def first: () -> Elem? | (_ToInt n) -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - grep(pattern) -> array # - grep(pattern) {|element| ... } -> array # --> # Returns an array of objects based elements of `self` that match the given # pattern. # # With no block given, returns an array containing each element for which # `pattern === element` is `true`: # # a = ['foo', 'bar', 'car', 'moo'] # a.grep(/ar/) # => ["bar", "car"] # (1..10).grep(3..8) # => [3, 4, 5, 6, 7, 8] # ['a', 'b', 0, 1].grep(Integer) # => [0, 1] # # With a block given, calls the block with each matching element and returns an # array containing each object returned by the block: # # a = ['foo', 'bar', 'car', 'moo'] # a.grep(/ar/) {|element| element.upcase } # => ["BAR", "CAR"] # # Related: #grep_v. # def grep: (untyped arg0) -> ::Array[Elem] | [U] (untyped arg0) { (Elem arg0) -> U } -> ::Array[U] # <!-- # rdoc-file=enum.c # - grep_v(pattern) -> array # - grep_v(pattern) {|element| ... } -> array # --> # Returns an array of objects based on elements of `self` that *don't* match the # given pattern. # # With no block given, returns an array containing each element for which # `pattern === element` is `false`: # # a = ['foo', 'bar', 'car', 'moo'] # a.grep_v(/ar/) # => ["foo", "moo"] # (1..10).grep_v(3..8) # => [1, 2, 9, 10] # ['a', 'b', 0, 1].grep_v(Integer) # => ["a", "b"] # # With a block given, calls the block with each non-matching element and returns # an array containing each object returned by the block: # # a = ['foo', 'bar', 'car', 'moo'] # a.grep_v(/ar/) {|element| element.upcase } # => ["FOO", "MOO"] # # Related: #grep. # def grep_v: (untyped) -> ::Array[Elem] | [U] (untyped) { (Elem) -> U } -> ::Array[U] # <!-- # rdoc-file=enum.c # - group_by {|element| ... } -> hash # - group_by -> enumerator # --> # With a block given returns a hash: # # * Each key is a return value from the block. # * Each value is an array of those elements for which the block returned that # key. # # # Examples: # # g = (1..6).group_by {|i| i%3 } # g # => {1=>[1, 4], 2=>[2, 5], 0=>[3, 6]} # h = {foo: 0, bar: 1, baz: 0, bat: 1} # g = h.group_by {|key, value| value } # g # => {0=>[[:foo, 0], [:baz, 0]], 1=>[[:bar, 1], [:bat, 1]]} # # With no block given, returns an Enumerator. # def group_by: [U] () { (Elem arg0) -> U } -> ::Hash[U, ::Array[Elem]] | () -> ::Enumerator[Elem, ::Array[Elem]] # <!-- rdoc-file=enum.c --> # Returns whether for any element `object == element`: # # (1..4).include?(2) # => true # (1..4).include?(5) # => false # (1..4).include?('2') # => false # %w[a b c d].include?('b') # => true # %w[a b c d].include?('2') # => false # {foo: 0, bar: 1, baz: 2}.include?(:foo) # => true # {foo: 0, bar: 1, baz: 2}.include?('foo') # => false # {foo: 0, bar: 1, baz: 2}.include?(0) # => false # # Enumerable#member? is an alias for Enumerable#include?. # def include?: (Elem arg0) -> bool # <!-- # rdoc-file=enum.c # - inject(symbol) -> object # - inject(initial_operand, symbol) -> object # - inject {|memo, operand| ... } -> object # - inject(initial_operand) {|memo, operand| ... } -> object # --> # Returns an object formed from operands via either: # # * A method named by `symbol`. # * A block to which each operand is passed. # # # With method-name argument `symbol`, combines operands using the method: # # # Sum, without initial_operand. # (1..4).inject(:+) # => 10 # # Sum, with initial_operand. # (1..4).inject(10, :+) # => 20 # # With a block, passes each operand to the block: # # # Sum of squares, without initial_operand. # (1..4).inject {|sum, n| sum + n*n } # => 30 # # Sum of squares, with initial_operand. # (1..4).inject(2) {|sum, n| sum + n*n } # => 32 # # **Operands** # # If argument `initial_operand` is not given, the operands for `inject` are # simply the elements of `self`. Example calls and their operands: # # `(1..4).inject(:+)` # : `[1, 2, 3, 4]`. # # `(1...4).inject(:+)` # : `[1, 2, 3]`. # # `('a'..'d').inject(:+)` # : `['a', 'b', 'c', 'd']`. # # `('a'...'d').inject(:+)` # : `['a', 'b', 'c']`. # # # # Examples with first operand (which is `self.first`) of various types: # # # Integer. # (1..4).inject(:+) # => 10 # # Float. # [1.0, 2, 3, 4].inject(:+) # => 10.0 # # Character. # ('a'..'d').inject(:+) # => "abcd" # # Complex. # [Complex(1, 2), 3, 4].inject(:+) # => (8+2i) # # If argument `initial_operand` is given, the operands for `inject` are that # value plus the elements of `self`. Example calls their operands: # # `(1..4).inject(10, :+)` # : `[10, 1, 2, 3, 4]`. # # `(1...4).inject(10, :+)` # : `[10, 1, 2, 3]`. # # `('a'..'d').inject('e', :+)` # : `['e', 'a', 'b', 'c', 'd']`. # # `('a'...'d').inject('e', :+)` # : `['e', 'a', 'b', 'c']`. # # # # Examples with `initial_operand` of various types: # # # Integer. # (1..4).inject(2, :+) # => 12 # # Float. # (1..4).inject(2.0, :+) # => 12.0 # # String. # ('a'..'d').inject('foo', :+) # => "fooabcd" # # Array. # %w[a b c].inject(['x'], :push) # => ["x", "a", "b", "c"] # # Complex. # (1..4).inject(Complex(2, 2), :+) # => (12+2i) # # **Combination by Given \Method** # # If the method-name argument `symbol` is given, the operands are combined by # that method: # # * The first and second operands are combined. # * That result is combined with the third operand. # * That result is combined with the fourth operand. # * And so on. # # # The return value from `inject` is the result of the last combination. # # This call to `inject` computes the sum of the operands: # # (1..4).inject(:+) # => 10 # # Examples with various methods: # # # Integer addition. # (1..4).inject(:+) # => 10 # # Integer multiplication. # (1..4).inject(:*) # => 24 # # Character range concatenation. # ('a'..'d').inject('', :+) # => "abcd" # # String array concatenation. # %w[foo bar baz].inject('', :+) # => "foobarbaz" # # Hash update. # h = [{foo: 0, bar: 1}, {baz: 2}, {bat: 3}].inject(:update) # h # => {:foo=>0, :bar=>1, :baz=>2, :bat=>3} # # Hash conversion to nested arrays. # h = {foo: 0, bar: 1}.inject([], :push) # h # => [[:foo, 0], [:bar, 1]] # # **Combination by Given Block** # # If a block is given, the operands are passed to the block: # # * The first call passes the first and second operands. # * The second call passes the result of the first call, along with the third # operand. # * The third call passes the result of the second call, along with the fourth # operand. # * And so on. # # # The return value from `inject` is the return value from the last block call. # # This call to `inject` gives a block that writes the memo and element, and also # sums the elements: # # (1..4).inject do |memo, element| # p "Memo: #{memo}; element: #{element}" # memo + element # end # => 10 # # Output: # # "Memo: 1; element: 2" # "Memo: 3; element: 3" # "Memo: 6; element: 4" # # Enumerable#reduce is an alias for Enumerable#inject. # def inject: (untyped init, Symbol method) -> untyped | (Symbol method) -> untyped | [A] (A initial) { (A, Elem) -> A } -> A | () { (Elem, Elem) -> Elem } -> Elem # <!-- # rdoc-file=enum.c # - max -> element # - max(n) -> array # - max {|a, b| ... } -> element # - max(n) {|a, b| ... } -> array # --> # Returns the element with the maximum element according to a given criterion. # The ordering of equal elements is indeterminate and may be unstable. # # With no argument and no block, returns the maximum element, using the # elements' own method `<=>` for comparison: # # (1..4).max # => 4 # (-4..-1).max # => -1 # %w[d c b a].max # => "d" # {foo: 0, bar: 1, baz: 2}.max # => [:foo, 0] # [].max # => nil # # With positive integer argument `n` given, and no block, returns an array # containing the first `n` maximum elements that exist: # # (1..4).max(2) # => [4, 3] # (-4..-1).max(2) # => [-1, -2] # %w[d c b a].max(2) # => ["d", "c"] # {foo: 0, bar: 1, baz: 2}.max(2) # => [[:foo, 0], [:baz, 2]] # [].max(2) # => [] # # With a block given, the block determines the maximum elements. The block is # called with two elements `a` and `b`, and must return: # # * A negative integer if `a < b`. # * Zero if `a == b`. # * A positive integer if `a > b`. # # # With a block given and no argument, returns the maximum element as determined # by the block: # # %w[xxx x xxxx xx].max {|a, b| a.size <=> b.size } # => "xxxx" # h = {foo: 0, bar: 1, baz: 2} # h.max {|pair1, pair2| pair1[1] <=> pair2[1] } # => [:baz, 2] # [].max {|a, b| a <=> b } # => nil # # With a block given and positive integer argument `n` given, returns an array # containing the first `n` maximum elements that exist, as determined by the # block. # # %w[xxx x xxxx xx].max(2) {|a, b| a.size <=> b.size } # => ["xxxx", "xxx"] # h = {foo: 0, bar: 1, baz: 2} # h.max(2) {|pair1, pair2| pair1[1] <=> pair2[1] } # # => [[:baz, 2], [:bar, 1]] # [].max(2) {|a, b| a <=> b } # => [] # # Related: #min, #minmax, #max_by. # def max: () -> Elem? | () { (Elem arg0, Elem arg1) -> Integer } -> Elem? | (Integer arg0) -> ::Array[Elem] | (Integer arg0) { (Elem arg0, Elem arg1) -> Integer } -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - max_by {|element| ... } -> element # - max_by(n) {|element| ... } -> array # - max_by -> enumerator # - max_by(n) -> enumerator # --> # Returns the elements for which the block returns the maximum values. # # With a block given and no argument, returns the element for which the block # returns the maximum value: # # (1..4).max_by {|element| -element } # => 1 # %w[a b c d].max_by {|element| -element.ord } # => "a" # {foo: 0, bar: 1, baz: 2}.max_by {|key, value| -value } # => [:foo, 0] # [].max_by {|element| -element } # => nil # # With a block given and positive integer argument `n` given, returns an array # containing the `n` elements for which the block returns maximum values: # # (1..4).max_by(2) {|element| -element } # # => [1, 2] # %w[a b c d].max_by(2) {|element| -element.ord } # # => ["a", "b"] # {foo: 0, bar: 1, baz: 2}.max_by(2) {|key, value| -value } # # => [[:foo, 0], [:bar, 1]] # [].max_by(2) {|element| -element } # # => [] # # Returns an Enumerator if no block is given. # # Related: #max, #minmax, #min_by. # def max_by: () -> ::Enumerator[Elem, Elem?] | () { (Elem arg0) -> (Comparable | ::Array[untyped]) } -> Elem? | (Integer arg0) -> ::Enumerator[Elem, ::Array[Elem]] | (Integer arg0) { (Elem arg0) -> (Comparable | ::Array[untyped]) } -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - min -> element # - min(n) -> array # - min {|a, b| ... } -> element # - min(n) {|a, b| ... } -> array # --> # Returns the element with the minimum element according to a given criterion. # The ordering of equal elements is indeterminate and may be unstable. # # With no argument and no block, returns the minimum element, using the # elements' own method `<=>` for comparison: # # (1..4).min # => 1 # (-4..-1).min # => -4 # %w[d c b a].min # => "a" # {foo: 0, bar: 1, baz: 2}.min # => [:bar, 1] # [].min # => nil # # With positive integer argument `n` given, and no block, returns an array # containing the first `n` minimum elements that exist: # # (1..4).min(2) # => [1, 2] # (-4..-1).min(2) # => [-4, -3] # %w[d c b a].min(2) # => ["a", "b"] # {foo: 0, bar: 1, baz: 2}.min(2) # => [[:bar, 1], [:baz, 2]] # [].min(2) # => [] # # With a block given, the block determines the minimum elements. The block is # called with two elements `a` and `b`, and must return: # # * A negative integer if `a < b`. # * Zero if `a == b`. # * A positive integer if `a > b`. # # # With a block given and no argument, returns the minimum element as determined # by the block: # # %w[xxx x xxxx xx].min {|a, b| a.size <=> b.size } # => "x" # h = {foo: 0, bar: 1, baz: 2} # h.min {|pair1, pair2| pair1[1] <=> pair2[1] } # => [:foo, 0] # [].min {|a, b| a <=> b } # => nil # # With a block given and positive integer argument `n` given, returns an array # containing the first `n` minimum elements that exist, as determined by the # block. # # %w[xxx x xxxx xx].min(2) {|a, b| a.size <=> b.size } # => ["x", "xx"] # h = {foo: 0, bar: 1, baz: 2} # h.min(2) {|pair1, pair2| pair1[1] <=> pair2[1] } # # => [[:foo, 0], [:bar, 1]] # [].min(2) {|a, b| a <=> b } # => [] # # Related: #min_by, #minmax, #max. # def min: () -> Elem? | () { (Elem arg0, Elem arg1) -> Integer } -> Elem? | (Integer arg0) -> ::Array[Elem] | (Integer arg0) { (Elem arg0, Elem arg1) -> Integer } -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - min_by {|element| ... } -> element # - min_by(n) {|element| ... } -> array # - min_by -> enumerator # - min_by(n) -> enumerator # --> # Returns the elements for which the block returns the minimum values. # # With a block given and no argument, returns the element for which the block # returns the minimum value: # # (1..4).min_by {|element| -element } # => 4 # %w[a b c d].min_by {|element| -element.ord } # => "d" # {foo: 0, bar: 1, baz: 2}.min_by {|key, value| -value } # => [:baz, 2] # [].min_by {|element| -element } # => nil # # With a block given and positive integer argument `n` given, returns an array # containing the `n` elements for which the block returns minimum values: # # (1..4).min_by(2) {|element| -element } # # => [4, 3] # %w[a b c d].min_by(2) {|element| -element.ord } # # => ["d", "c"] # {foo: 0, bar: 1, baz: 2}.min_by(2) {|key, value| -value } # # => [[:baz, 2], [:bar, 1]] # [].min_by(2) {|element| -element } # # => [] # # Returns an Enumerator if no block is given. # # Related: #min, #minmax, #max_by. # def min_by: () -> ::Enumerator[Elem, Elem?] | () { (Elem arg0) -> (Comparable | ::Array[untyped]) } -> Elem? | (Integer arg0) -> ::Enumerator[Elem, ::Array[Elem]] | (Integer arg0) { (Elem arg0) -> (Comparable | ::Array[untyped]) } -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - minmax -> [minimum, maximum] # - minmax {|a, b| ... } -> [minimum, maximum] # --> # Returns a 2-element array containing the minimum and maximum elements # according to a given criterion. The ordering of equal elements is # indeterminate and may be unstable. # # With no argument and no block, returns the minimum and maximum elements, using # the elements' own method `<=>` for comparison: # # (1..4).minmax # => [1, 4] # (-4..-1).minmax # => [-4, -1] # %w[d c b a].minmax # => ["a", "d"] # {foo: 0, bar: 1, baz: 2}.minmax # => [[:bar, 1], [:foo, 0]] # [].minmax # => [nil, nil] # # With a block given, returns the minimum and maximum elements as determined by # the block: # # %w[xxx x xxxx xx].minmax {|a, b| a.size <=> b.size } # => ["x", "xxxx"] # h = {foo: 0, bar: 1, baz: 2} # h.minmax {|pair1, pair2| pair1[1] <=> pair2[1] } # # => [[:foo, 0], [:baz, 2]] # [].minmax {|a, b| a <=> b } # => [nil, nil] # # Related: #min, #max, #minmax_by. # def minmax: () -> [ Elem?, Elem? ] | () { (Elem arg0, Elem arg1) -> Integer } -> [ Elem?, Elem? ] # <!-- # rdoc-file=enum.c # - minmax_by {|element| ... } -> [minimum, maximum] # - minmax_by -> enumerator # --> # Returns a 2-element array containing the elements for which the block returns # minimum and maximum values: # # (1..4).minmax_by {|element| -element } # # => [4, 1] # %w[a b c d].minmax_by {|element| -element.ord } # # => ["d", "a"] # {foo: 0, bar: 1, baz: 2}.minmax_by {|key, value| -value } # # => [[:baz, 2], [:foo, 0]] # [].minmax_by {|element| -element } # # => [nil, nil] # # Returns an Enumerator if no block is given. # # Related: #max_by, #minmax, #min_by. # def minmax_by: () -> [ Elem?, Elem? ] | () { (Elem arg0) -> (Comparable | ::Array[untyped]) } -> [ Elem?, Elem? ] # <!-- # rdoc-file=enum.c # - none? -> true or false # - none?(pattern) -> true or false # - none? {|element| ... } -> true or false # --> # Returns whether no element meets a given criterion. # # With no argument and no block, returns whether no element is truthy: # # (1..4).none? # => false # [nil, false].none? # => true # {foo: 0}.none? # => false # {foo: 0, bar: 1}.none? # => false # [].none? # => true # # With argument `pattern` and no block, returns whether for no element # `element`, `pattern === element`: # # [nil, false, 1.1].none?(Integer) # => true # %w[bar baz bat bam].none?(/m/) # => false # %w[bar baz bat bam].none?(/foo/) # => true # %w[bar baz bat bam].none?('ba') # => true # {foo: 0, bar: 1, baz: 2}.none?(Hash) # => true # {foo: 0}.none?(Array) # => false # [].none?(Integer) # => true # # With a block given, returns whether the block returns a truthy value for no # element: # # (1..4).none? {|element| element < 1 } # => true # (1..4).none? {|element| element < 2 } # => false # {foo: 0, bar: 1, baz: 2}.none? {|key, value| value < 0 } # => true # {foo: 0, bar: 1, baz: 2}.none? {|key, value| value < 1 } # => false # # Related: #one?, #all?, #any?. # def none?: () -> bool | () { (Elem) -> boolish } -> bool # <!-- # rdoc-file=enum.c # - one? -> true or false # - one?(pattern) -> true or false # - one? {|element| ... } -> true or false # --> # Returns whether exactly one element meets a given criterion. # # With no argument and no block, returns whether exactly one element is truthy: # # (1..1).one? # => true # [1, nil, false].one? # => true # (1..4).one? # => false # {foo: 0}.one? # => true # {foo: 0, bar: 1}.one? # => false # [].one? # => false # # With argument `pattern` and no block, returns whether for exactly one element # `element`, `pattern === element`: # # [nil, false, 0].one?(Integer) # => true # [nil, false, 0].one?(Numeric) # => true # [nil, false, 0].one?(Float) # => false # %w[bar baz bat bam].one?(/m/) # => true # %w[bar baz bat bam].one?(/foo/) # => false # %w[bar baz bat bam].one?('ba') # => false # {foo: 0, bar: 1, baz: 2}.one?(Array) # => false # {foo: 0}.one?(Array) # => true # [].one?(Integer) # => false # # With a block given, returns whether the block returns a truthy value for # exactly one element: # # (1..4).one? {|element| element < 2 } # => true # (1..4).one? {|element| element < 1 } # => false # {foo: 0, bar: 1, baz: 2}.one? {|key, value| value < 1 } # => true # {foo: 0, bar: 1, baz: 2}.one? {|key, value| value < 2 } # => false # # Related: #none?, #all?, #any?. # def one?: () -> bool | () { (Elem) -> boolish } -> bool # <!-- # rdoc-file=enum.c # - partition {|element| ... } -> [true_array, false_array] # - partition -> enumerator # --> # With a block given, returns an array of two arrays: # # * The first having those elements for which the block returns a truthy # value. # * The other having all other elements. # # # Examples: # # p = (1..4).partition {|i| i.even? } # p # => [[2, 4], [1, 3]] # p = ('a'..'d').partition {|c| c < 'c' } # p # => [["a", "b"], ["c", "d"]] # h = {foo: 0, bar: 1, baz: 2, bat: 3} # p = h.partition {|key, value| key.start_with?('b') } # p # => [[[:bar, 1], [:baz, 2], [:bat, 3]], [[:foo, 0]]] # p = h.partition {|key, value| value < 2 } # p # => [[[:foo, 0], [:bar, 1]], [[:baz, 2], [:bat, 3]]] # # With no block given, returns an Enumerator. # # Related: Enumerable#group_by. # def partition: () { (Elem) -> boolish } -> [ ::Array[Elem], ::Array[Elem] ] | () -> ::Enumerator[Elem, [ ::Array[Elem], ::Array[Elem] ]] # <!-- # rdoc-file=enum.c # - reject {|element| ... } -> array # - reject -> enumerator # --> # Returns an array of objects rejected by the block. # # With a block given, calls the block with successive elements; returns an array # of those elements for which the block returns `nil` or `false`: # # (0..9).reject {|i| i * 2 if i.even? } # => [1, 3, 5, 7, 9] # {foo: 0, bar: 1, baz: 2}.reject {|key, value| key if value.odd? } # => {:foo=>0, :baz=>2} # # When no block given, returns an Enumerator. # # Related: #select. # def reject: () { (Elem) -> boolish } -> ::Array[Elem] | () -> ::Enumerator[Elem, ::Array[Elem]] # <!-- # rdoc-file=enum.c # - reverse_each(*args) {|element| ... } -> self # - reverse_each(*args) -> enumerator # --> # With a block given, calls the block with each element, but in reverse order; # returns `self`: # # a = [] # (1..4).reverse_each {|element| a.push(-element) } # => 1..4 # a # => [-4, -3, -2, -1] # # a = [] # %w[a b c d].reverse_each {|element| a.push(element) } # # => ["a", "b", "c", "d"] # a # => ["d", "c", "b", "a"] # # a = [] # h.reverse_each {|element| a.push(element) } # # => {:foo=>0, :bar=>1, :baz=>2} # a # => [[:baz, 2], [:bar, 1], [:foo, 0]] # # With no block given, returns an Enumerator. # def reverse_each: () { (Elem arg0) -> untyped } -> void | () -> ::Enumerator[Elem, void] # <!-- # rdoc-file=enum.c # - sort -> array # - sort {|a, b| ... } -> array # --> # Returns an array containing the sorted elements of `self`. The ordering of # equal elements is indeterminate and may be unstable. # # With no block given, the sort compares using the elements' own method `<=>`: # # %w[b c a d].sort # => ["a", "b", "c", "d"] # {foo: 0, bar: 1, baz: 2}.sort # => [[:bar, 1], [:baz, 2], [:foo, 0]] # # With a block given, comparisons in the block determine the ordering. The block # is called with two elements `a` and `b`, and must return: # # * A negative integer if `a < b`. # * Zero if `a == b`. # * A positive integer if `a > b`. # # # Examples: # # a = %w[b c a d] # a.sort {|a, b| b <=> a } # => ["d", "c", "b", "a"] # h = {foo: 0, bar: 1, baz: 2} # h.sort {|a, b| b <=> a } # => [[:foo, 0], [:baz, 2], [:bar, 1]] # # See also #sort_by. It implements a Schwartzian transform which is useful when # key computation or comparison is expensive. # def sort: () -> ::Array[Elem] | () { (Elem arg0, Elem arg1) -> Integer } -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - sort_by {|element| ... } -> array # - sort_by -> enumerator # --> # With a block given, returns an array of elements of `self`, sorted according # to the value returned by the block for each element. The ordering of equal # elements is indeterminate and may be unstable. # # Examples: # # a = %w[xx xxx x xxxx] # a.sort_by {|s| s.size } # => ["x", "xx", "xxx", "xxxx"] # a.sort_by {|s| -s.size } # => ["xxxx", "xxx", "xx", "x"] # h = {foo: 2, bar: 1, baz: 0} # h.sort_by{|key, value| value } # => [[:baz, 0], [:bar, 1], [:foo, 2]] # h.sort_by{|key, value| key } # => [[:bar, 1], [:baz, 0], [:foo, 2]] # # With no block given, returns an Enumerator. # # The current implementation of #sort_by generates an array of tuples containing # the original collection element and the mapped value. This makes #sort_by # fairly expensive when the keysets are simple. # # require 'benchmark' # # a = (1..100000).map { rand(100000) } # # Benchmark.bm(10) do |b| # b.report("Sort") { a.sort } # b.report("Sort by") { a.sort_by { |a| a } } # end # # *produces:* # # user system total real # Sort 0.180000 0.000000 0.180000 ( 0.175469) # Sort by 1.980000 0.040000 2.020000 ( 2.013586) # # However, consider the case where comparing the keys is a non-trivial # operation. The following code sorts some files on modification time using the # basic #sort method. # # files = Dir["*"] # sorted = files.sort { |a, b| File.new(a).mtime <=> File.new(b).mtime } # sorted #=> ["mon", "tues", "wed", "thurs"] # # This sort is inefficient: it generates two new File objects during every # comparison. A slightly better technique is to use the Kernel#test method to # generate the modification times directly. # # files = Dir["*"] # sorted = files.sort { |a, b| # test(?M, a) <=> test(?M, b) # } # sorted #=> ["mon", "tues", "wed", "thurs"] # # This still generates many unnecessary Time objects. A more efficient technique # is to cache the sort keys (modification times in this case) before the sort. # Perl users often call this approach a Schwartzian transform, after Randal # Schwartz. We construct a temporary array, where each element is an array # containing our sort key along with the filename. We sort this array, and then # extract the filename from the result. # # sorted = Dir["*"].collect { |f| # [test(?M, f), f] # }.sort.collect { |f| f[1] } # sorted #=> ["mon", "tues", "wed", "thurs"] # # This is exactly what #sort_by does internally. # # sorted = Dir["*"].sort_by { |f| test(?M, f) } # sorted #=> ["mon", "tues", "wed", "thurs"] # # To produce the reverse of a specific order, the following can be used: # # ary.sort_by { ... }.reverse! # def sort_by: () { (Elem arg0) -> (Comparable | ::Array[untyped]) } -> ::Array[Elem] | () -> ::Enumerator[Elem, ::Array[Elem]] # <!-- # rdoc-file=enum.c # - take(n) -> array # --> # For non-negative integer `n`, returns the first `n` elements: # # r = (1..4) # r.take(2) # => [1, 2] # r.take(0) # => [] # # h = {foo: 0, bar: 1, baz: 2, bat: 3} # h.take(2) # => [[:foo, 0], [:bar, 1]] # def take: (Integer n) -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - take_while {|element| ... } -> array # - take_while -> enumerator # --> # Calls the block with successive elements as long as the block returns a truthy # value; returns an array of all elements up to that point: # # (1..4).take_while{|i| i < 3 } # => [1, 2] # h = {foo: 0, bar: 1, baz: 2} # h.take_while{|element| key, value = *element; value < 2 } # # => [[:foo, 0], [:bar, 1]] # # With no block given, returns an Enumerator. # def take_while: () { (Elem) -> boolish } -> ::Array[Elem] | () -> ::Enumerator[Elem, ::Array[Elem]] # <!-- # rdoc-file=enum.c # - to_h -> hash # - to_h {|element| ... } -> hash # --> # When `self` consists of 2-element arrays, returns a hash each of whose entries # is the key-value pair formed from one of those arrays: # # [[:foo, 0], [:bar, 1], [:baz, 2]].to_h # => {:foo=>0, :bar=>1, :baz=>2} # # When a block is given, the block is called with each element of `self`; the # block should return a 2-element array which becomes a key-value pair in the # returned hash: # # (0..3).to_h {|i| [i, i ** 2]} # => {0=>0, 1=>1, 2=>4, 3=>9} # # Raises an exception if an element of `self` is not a 2-element array, and a # block is not passed. # def to_h: () -> ::Hash[untyped, untyped] | [T, U] () { (Elem) -> [ T, U ] } -> ::Hash[T, U] # <!-- # rdoc-file=enum.c # - each_slice(n) { ... } -> self # - each_slice(n) -> enumerator # --> # Calls the block with each successive disjoint `n`-tuple of elements; returns # `self`: # # a = [] # (1..10).each_slice(3) {|tuple| a.push(tuple) } # a # => [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]] # # a = [] # h = {foo: 0, bar: 1, baz: 2, bat: 3, bam: 4} # h.each_slice(2) {|tuple| a.push(tuple) } # a # => [[[:foo, 0], [:bar, 1]], [[:baz, 2], [:bat, 3]], [[:bam, 4]]] # # With no block given, returns an Enumerator. # def each_slice: (Integer n) { (::Array[Elem]) -> void } -> self | (Integer n) -> ::Enumerator[::Array[Elem], self] interface _NotFound[T] def call: () -> T end # <!-- # rdoc-file=enum.c # - find(if_none_proc = nil) {|element| ... } -> object or nil # - find(if_none_proc = nil) -> enumerator # --> # Returns the first element for which the block returns a truthy value. # # With a block given, calls the block with successive elements of the # collection; returns the first element for which the block returns a truthy # value: # # (0..9).find {|element| element > 2} # => 3 # # If no such element is found, calls `if_none_proc` and returns its return # value. # # (0..9).find(proc {false}) {|element| element > 12} # => false # {foo: 0, bar: 1, baz: 2}.find {|key, value| key.start_with?('b') } # => [:bar, 1] # {foo: 0, bar: 1, baz: 2}.find(proc {[]}) {|key, value| key.start_with?('c') } # => [] # # With no block given, returns an Enumerator. # def find: () { (Elem) -> boolish } -> Elem? | () -> ::Enumerator[Elem, Elem?] | [T] (_NotFound[T] ifnone) { (Elem) -> boolish } -> (Elem | T) | [T] (_NotFound[T] ifnone) -> ::Enumerator[Elem, Elem | T] # <!-- # rdoc-file=enum.c # - flat_map {|element| ... } -> array # - flat_map -> enumerator # --> # Returns an array of flattened objects returned by the block. # # With a block given, calls the block with successive elements; returns a # flattened array of objects returned by the block: # # [0, 1, 2, 3].flat_map {|element| -element } # => [0, -1, -2, -3] # [0, 1, 2, 3].flat_map {|element| [element, -element] } # => [0, 0, 1, -1, 2, -2, 3, -3] # [[0, 1], [2, 3]].flat_map {|e| e + [100] } # => [0, 1, 100, 2, 3, 100] # {foo: 0, bar: 1, baz: 2}.flat_map {|key, value| [key, value] } # => [:foo, 0, :bar, 1, :baz, 2] # # With no block given, returns an Enumerator. # # Alias: #collect_concat. # def flat_map: [U] () { (Elem) -> (Array[U] | U) } -> Array[U] | () -> ::Enumerator[Elem, Array[untyped]] # <!-- rdoc-file=enum.c --> # Returns an array of objects returned by the block. # # With a block given, calls the block with successive elements; returns an array # of the objects returned by the block: # # (0..4).map {|i| i*i } # => [0, 1, 4, 9, 16] # {foo: 0, bar: 1, baz: 2}.map {|key, value| value*2} # => [0, 2, 4] # # With no block given, returns an Enumerator. # def map: [U] () { (Elem arg0) -> U } -> ::Array[U] | () -> ::Enumerator[Elem, ::Array[untyped]] # <!-- # rdoc-file=enum.c # - include?(object) -> true or false # --> # Returns whether for any element `object == element`: # # (1..4).include?(2) # => true # (1..4).include?(5) # => false # (1..4).include?('2') # => false # %w[a b c d].include?('b') # => true # %w[a b c d].include?('2') # => false # {foo: 0, bar: 1, baz: 2}.include?(:foo) # => true # {foo: 0, bar: 1, baz: 2}.include?('foo') # => false # {foo: 0, bar: 1, baz: 2}.include?(0) # => false # # Enumerable#member? is an alias for Enumerable#include?. # def member?: (Elem arg0) -> bool # <!-- rdoc-file=enum.c --> # Returns an object formed from operands via either: # # * A method named by `symbol`. # * A block to which each operand is passed. # # # With method-name argument `symbol`, combines operands using the method: # # # Sum, without initial_operand. # (1..4).inject(:+) # => 10 # # Sum, with initial_operand. # (1..4).inject(10, :+) # => 20 # # With a block, passes each operand to the block: # # # Sum of squares, without initial_operand. # (1..4).inject {|sum, n| sum + n*n } # => 30 # # Sum of squares, with initial_operand. # (1..4).inject(2) {|sum, n| sum + n*n } # => 32 # # **Operands** # # If argument `initial_operand` is not given, the operands for `inject` are # simply the elements of `self`. Example calls and their operands: # # `(1..4).inject(:+)` # : `[1, 2, 3, 4]`. # # `(1...4).inject(:+)` # : `[1, 2, 3]`. # # `('a'..'d').inject(:+)` # : `['a', 'b', 'c', 'd']`. # # `('a'...'d').inject(:+)` # : `['a', 'b', 'c']`. # # # # Examples with first operand (which is `self.first`) of various types: # # # Integer. # (1..4).inject(:+) # => 10 # # Float. # [1.0, 2, 3, 4].inject(:+) # => 10.0 # # Character. # ('a'..'d').inject(:+) # => "abcd" # # Complex. # [Complex(1, 2), 3, 4].inject(:+) # => (8+2i) # # If argument `initial_operand` is given, the operands for `inject` are that # value plus the elements of `self`. Example calls their operands: # # `(1..4).inject(10, :+)` # : `[10, 1, 2, 3, 4]`. # # `(1...4).inject(10, :+)` # : `[10, 1, 2, 3]`. # # `('a'..'d').inject('e', :+)` # : `['e', 'a', 'b', 'c', 'd']`. # # `('a'...'d').inject('e', :+)` # : `['e', 'a', 'b', 'c']`. # # # # Examples with `initial_operand` of various types: # # # Integer. # (1..4).inject(2, :+) # => 12 # # Float. # (1..4).inject(2.0, :+) # => 12.0 # # String. # ('a'..'d').inject('foo', :+) # => "fooabcd" # # Array. # %w[a b c].inject(['x'], :push) # => ["x", "a", "b", "c"] # # Complex. # (1..4).inject(Complex(2, 2), :+) # => (12+2i) # # **Combination by Given \Method** # # If the method-name argument `symbol` is given, the operands are combined by # that method: # # * The first and second operands are combined. # * That result is combined with the third operand. # * That result is combined with the fourth operand. # * And so on. # # # The return value from `inject` is the result of the last combination. # # This call to `inject` computes the sum of the operands: # # (1..4).inject(:+) # => 10 # # Examples with various methods: # # # Integer addition. # (1..4).inject(:+) # => 10 # # Integer multiplication. # (1..4).inject(:*) # => 24 # # Character range concatenation. # ('a'..'d').inject('', :+) # => "abcd" # # String array concatenation. # %w[foo bar baz].inject('', :+) # => "foobarbaz" # # Hash update. # h = [{foo: 0, bar: 1}, {baz: 2}, {bat: 3}].inject(:update) # h # => {:foo=>0, :bar=>1, :baz=>2, :bat=>3} # # Hash conversion to nested arrays. # h = {foo: 0, bar: 1}.inject([], :push) # h # => [[:foo, 0], [:bar, 1]] # # **Combination by Given Block** # # If a block is given, the operands are passed to the block: # # * The first call passes the first and second operands. # * The second call passes the result of the first call, along with the third # operand. # * The third call passes the result of the second call, along with the fourth # operand. # * And so on. # # # The return value from `inject` is the return value from the last block call. # # This call to `inject` gives a block that writes the memo and element, and also # sums the elements: # # (1..4).inject do |memo, element| # p "Memo: #{memo}; element: #{element}" # memo + element # end # => 10 # # Output: # # "Memo: 1; element: 2" # "Memo: 3; element: 3" # "Memo: 6; element: 4" # # Enumerable#reduce is an alias for Enumerable#inject. # alias reduce inject # <!-- # rdoc-file=enum.c # - to_a -> array # --> # Returns an array containing the items in `self`: # # (0..4).to_a # => [0, 1, 2, 3, 4] # # Enumerable#entries is an alias for Enumerable#to_a. # def to_a: () -> ::Array[Elem] # <!-- # rdoc-file=enumerator.c # - e.lazy -> lazy_enumerator # --> # Returns an Enumerator::Lazy, which redefines most Enumerable methods to # postpone enumeration and enumerate values only on an as-needed basis. # # ### Example # # The following program finds pythagorean triples: # # def pythagorean_triples # (1..Float::INFINITY).lazy.flat_map {|z| # (1..z).flat_map {|x| # (x..z).select {|y| # x**2 + y**2 == z**2 # }.map {|y| # [x, y, z] # } # } # } # end # # show first ten pythagorean triples # p pythagorean_triples.take(10).force # take is lazy, so force is needed # p pythagorean_triples.first(10) # first is eager # # show pythagorean triples less than 100 # p pythagorean_triples.take_while { |*, z| z < 100 }.force # def lazy: () -> Enumerator::Lazy[Elem, void] # <!-- # rdoc-file=enum.c # - uniq -> array # - uniq {|element| ... } -> array # --> # With no block, returns a new array containing only unique elements; the array # has no two elements `e0` and `e1` such that `e0.eql?(e1)`: # # %w[a b c c b a a b c].uniq # => ["a", "b", "c"] # [0, 1, 2, 2, 1, 0, 0, 1, 2].uniq # => [0, 1, 2] # # With a block, returns a new array containing only for which the block returns # a unique value: # # a = [0, 1, 2, 3, 4, 5, 5, 4, 3, 2, 1] # a.uniq {|i| i.even? ? i : 0 } # => [0, 2, 4] # a = %w[a b c d e e d c b a a b c d e] # a.uniq {|c| c < 'c' } # => ["a", "c"] # def uniq: () -> ::Array[Elem] | () { (Elem item) -> untyped } -> ::Array[Elem] # <!-- # rdoc-file=enum.c # - sum(initial_value = 0) -> number # - sum(initial_value = 0) {|element| ... } -> object # --> # With no block given, returns the sum of `initial_value` and the elements: # # (1..100).sum # => 5050 # (1..100).sum(1) # => 5051 # ('a'..'d').sum('foo') # => "fooabcd" # # Generally, the sum is computed using methods `+` and `each`; for performance # optimizations, those methods may not be used, and so any redefinition of those # methods may not have effect here. # # One such optimization: When possible, computes using Gauss's summation formula # *n(n+1)/2*: # # 100 * (100 + 1) / 2 # => 5050 # # With a block given, calls the block with each element; returns the sum of # `initial_value` and the block return values: # # (1..4).sum {|i| i*i } # => 30 # (1..4).sum(100) {|i| i*i } # => 130 # h = {a: 0, b: 1, c: 2, d: 3, e: 4, f: 5} # h.sum {|key, value| value.odd? ? value : 0 } # => 9 # ('a'..'f').sum('x') {|c| c < 'd' ? c : '' } # => "xabc" # def sum: () -> (Elem | Integer) | [T] () { (Elem arg0) -> T } -> (Integer | T) | [T] (?T arg0) -> (Elem | T) | [U] (?U arg0) { (Elem arg0) -> U } -> U # <!-- # rdoc-file=enum.c # - filter_map {|element| ... } -> array # - filter_map -> enumerator # --> # Returns an array containing truthy elements returned by the block. # # With a block given, calls the block with successive elements; returns an array # containing each truthy value returned by the block: # # (0..9).filter_map {|i| i * 2 if i.even? } # => [0, 4, 8, 12, 16] # {foo: 0, bar: 1, baz: 2}.filter_map {|key, value| key if value.even? } # => [:foo, :baz] # # When no block given, returns an Enumerator. # def filter_map: [U] () { (Elem elem) -> (nil | false | U) } -> ::Array[U] | () -> ::Enumerator[Elem, ::Array[untyped]] # <!-- # rdoc-file=enumerator.c # - e.chain(*enums) -> enumerator # --> # Returns an enumerator object generated from this enumerator and given # enumerables. # # e = (1..3).chain([4, 5]) # e.to_a #=> [1, 2, 3, 4, 5] # def chain: (*self enumerables) -> ::Enumerator::Chain[Elem] # <!-- # rdoc-file=enum.c # - tally -> new_hash # - tally(hash) -> hash # --> # Returns a hash containing the counts of equal elements: # # * Each key is an element of `self`. # * Each value is the number elements equal to that key. # # # With no argument: # # %w[a b c b c a c b].tally # => {"a"=>2, "b"=>3, "c"=>3} # # With a hash argument, that hash is used for the tally (instead of a new hash), # and is returned; this may be useful for accumulating tallies across multiple # enumerables: # # hash = {} # hash = %w[a c d b c a].tally(hash) # hash # => {"a"=>2, "c"=>2, "d"=>1, "b"=>1} # hash = %w[b a z].tally(hash) # hash # => {"a"=>3, "c"=>2, "d"=>1, "b"=>2, "z"=>1} # hash = %w[b a m].tally(hash) # hash # => {"a"=>4, "c"=>2, "d"=>1, "b"=>3, "z"=>1, "m"=> 1} # def tally: (?Hash[Elem, Integer] hash) -> ::Hash[Elem, Integer] # <!-- # rdoc-file=enum.c # - each_entry(*args) {|element| ... } -> self # - each_entry(*args) -> enumerator # --> # Calls the given block with each element, converting multiple values from yield # to an array; returns `self`: # # a = [] # (1..4).each_entry {|element| a.push(element) } # => 1..4 # a # => [1, 2, 3, 4] # # a = [] # h = {foo: 0, bar: 1, baz:2} # h.each_entry {|element| a.push(element) } # # => {:foo=>0, :bar=>1, :baz=>2} # a # => [[:foo, 0], [:bar, 1], [:baz, 2]] # # class Foo # include Enumerable # def each # yield 1 # yield 1, 2 # yield # end # end # Foo.new.each_entry {|yielded| p yielded } # # Output: # # 1 # [1, 2] # nil # # With no block given, returns an Enumerator. # def each_entry: () -> ::Enumerator[Elem, self] | () { (Elem arg0) -> untyped } -> self # <!-- # rdoc-file=enum.c # - zip(*other_enums) -> array # - zip(*other_enums) {|array| ... } -> nil # --> # With no block given, returns a new array `new_array` of size self.size whose # elements are arrays. Each nested array `new_array[n]` is of size # `other_enums.size+1`, and contains: # # * The `n`-th element of self. # * The `n`-th element of each of the `other_enums`. # # # If all `other_enums` and self are the same size, all elements are included in # the result, and there is no `nil`-filling: # # a = [:a0, :a1, :a2, :a3] # b = [:b0, :b1, :b2, :b3] # c = [:c0, :c1, :c2, :c3] # d = a.zip(b, c) # d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]] # # f = {foo: 0, bar: 1, baz: 2} # g = {goo: 3, gar: 4, gaz: 5} # h = {hoo: 6, har: 7, haz: 8} # d = f.zip(g, h) # d # => [ # # [[:foo, 0], [:goo, 3], [:hoo, 6]], # # [[:bar, 1], [:gar, 4], [:har, 7]], # # [[:baz, 2], [:gaz, 5], [:haz, 8]] # # ] # # If any enumerable in other_enums is smaller than self, fills to `self.size` # with `nil`: # # a = [:a0, :a1, :a2, :a3] # b = [:b0, :b1, :b2] # c = [:c0, :c1] # d = a.zip(b, c) # d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, nil], [:a3, nil, nil]] # # If any enumerable in other_enums is larger than self, its trailing elements # are ignored: # # a = [:a0, :a1, :a2, :a3] # b = [:b0, :b1, :b2, :b3, :b4] # c = [:c0, :c1, :c2, :c3, :c4, :c5] # d = a.zip(b, c) # d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]] # # When a block is given, calls the block with each of the sub-arrays (formed as # above); returns nil: # # a = [:a0, :a1, :a2, :a3] # b = [:b0, :b1, :b2, :b3] # c = [:c0, :c1, :c2, :c3] # a.zip(b, c) {|sub_array| p sub_array} # => nil # # Output: # # [:a0, :b0, :c0] # [:a1, :b1, :c1] # [:a2, :b2, :c2] # [:a3, :b3, :c3] # def zip: [Elem2] (::Enumerable[Elem2] enum) -> ::Array[[ Elem, Elem2 | nil ]] | [U, Elem2] (::Enumerable[Elem2]) { ([ Elem, Elem2 | nil ]) -> U } -> nil # <!-- # rdoc-file=enum.c # - chunk {|array| ... } -> enumerator # --> # Each element in the returned enumerator is a 2-element array consisting of: # # * A value returned by the block. # * An array ("chunk") containing the element for which that value was # returned, and all following elements for which the block returned the same # value: # # # So that: # # * Each block return value that is different from its predecessor begins a # new chunk. # * Each block return value that is the same as its predecessor continues the # same chunk. # # # Example: # # e = (0..10).chunk {|i| (i / 3).floor } # => #<Enumerator: ...> # # The enumerator elements. # e.next # => [0, [0, 1, 2]] # e.next # => [1, [3, 4, 5]] # e.next # => [2, [6, 7, 8]] # e.next # => [3, [9, 10]] # # Method `chunk` is especially useful for an enumerable that is already sorted. # This example counts words for each initial letter in a large array of words: # # # Get sorted words from a web page. # url = 'https://raw.githubusercontent.com/eneko/data-repository/master/data/words.txt' # words = URI::open(url).readlines # # Make chunks, one for each letter. # e = words.chunk {|word| word.upcase[0] } # => #<Enumerator: ...> # # Display 'A' through 'F'. # e.each {|c, words| p [c, words.length]; break if c == 'F' } # # Output: # # ["A", 17096] # ["B", 11070] # ["C", 19901] # ["D", 10896] # ["E", 8736] # ["F", 6860] # # You can use the special symbol `:_alone` to force an element into its own # separate chuck: # # a = [0, 0, 1, 1] # e = a.chunk{|i| i.even? ? :_alone : true } # e.to_a # => [[:_alone, [0]], [:_alone, [0]], [true, [1, 1]]] # # For example, you can put each line that contains a URL into its own chunk: # # pattern = /http/ # open(filename) { |f| # f.chunk { |line| line =~ pattern ? :_alone : true }.each { |key, lines| # pp lines # } # } # # You can use the special symbol `:_separator` or `nil` to force an element to # be ignored (not included in any chunk): # # a = [0, 0, -1, 1, 1] # e = a.chunk{|i| i < 0 ? :_separator : true } # e.to_a # => [[true, [0, 0]], [true, [1, 1]]] # # Note that the separator does end the chunk: # # a = [0, 0, -1, 1, -1, 1] # e = a.chunk{|i| i < 0 ? :_separator : true } # e.to_a # => [[true, [0, 0]], [true, [1]], [true, [1]]] # # For example, the sequence of hyphens in svn log can be eliminated as follows: # # sep = "-"*72 + "\n" # IO.popen("svn log README") { |f| # f.chunk { |line| # line != sep || nil # }.each { |_, lines| # pp lines # } # } # #=> ["r20018 | knu | 2008-10-29 13:20:42 +0900 (Wed, 29 Oct 2008) | 2 lines\n", # # "\n", # # "* README, README.ja: Update the portability section.\n", # # "\n"] # # ["r16725 | knu | 2008-05-31 23:34:23 +0900 (Sat, 31 May 2008) | 2 lines\n", # # "\n", # # "* README, README.ja: Add a note about default C flags.\n", # # "\n"] # # ... # # Paragraphs separated by empty lines can be parsed as follows: # # File.foreach("README").chunk { |line| # /\A\s*\z/ !~ line || nil # }.each { |_, lines| # pp lines # } # def chunk: [U] () { (Elem elt) -> U } -> ::Enumerator[[ U, ::Array[Elem] ], void] | () -> ::Enumerator[Elem, ::Enumerator[[ untyped, ::Array[Elem] ], void]] # <!-- # rdoc-file=enum.c # - chunk_while {|element, next_element| ... } -> enumerator # --> # The returned Enumerator uses the block to partition elements into arrays # ("chunks"); it calls the block with each element and its successor; begins a # new chunk if and only if the block returns a truthy value: # # Example: # # a = [1, 2, 4, 9, 10, 11, 12, 15, 16, 19, 20, 21] # e = a.chunk_while {|i, j| j == i + 1 } # e.each {|array| p array } # # Output: # # [1, 2] # [4] # [9, 10, 11, 12] # [15, 16] # [19, 20, 21] # def chunk_while: () { (Elem elt_before, Elem elt_after) -> boolish } -> ::Enumerator[::Array[Elem], void] # <!-- # rdoc-file=enum.c # - slice_when {|element, next_element| ... } -> enumerator # --> # The returned enumerator uses the block to partition elements into arrays # ("slices"); it calls the block with each element and its successor; begins a # new slice if and only if the block returns a truthy value: # # a = [0, 1, 2, 4, 5, 6, 8, 9] # e = a.slice_when {|i, j| j != i + 1 } # e.each {|array| p array } # # Output: # # [0, 1, 2] # [4, 5, 6] # [8, 9] # def slice_when: () { (Elem elt_before, Elem elt_after) -> boolish } -> ::Enumerator[::Array[Elem], void] # <!-- # rdoc-file=enum.c # - slice_after(pattern) -> enumerator # - slice_after {|array| ... } -> enumerator # --> # With argument `pattern`, returns an enumerator that uses the pattern to # partition elements into arrays ("slices"). An element ends the current slice # if `element === pattern`: # # a = %w[foo bar fop for baz fob fog bam foy] # e = a.slice_after(/ba/) # => #<Enumerator: ...> # e.each {|array| p array } # # Output: # # ["foo", "bar"] # ["fop", "for", "baz"] # ["fob", "fog", "bam"] # ["foy"] # # With a block, returns an enumerator that uses the block to partition elements # into arrays. An element ends the current slice if its block return is a truthy # value: # # e = (1..20).slice_after {|i| i % 4 == 2 } # => #<Enumerator: ...> # e.each {|array| p array } # # Output: # # [1, 2] # [3, 4, 5, 6] # [7, 8, 9, 10] # [11, 12, 13, 14] # [15, 16, 17, 18] # [19, 20] # # Other methods of the Enumerator class and Enumerable module, such as `map`, # etc., are also usable. # # For example, continuation lines (lines end with backslash) can be concatenated # as follows: # # lines = ["foo\n", "bar\\\n", "baz\n", "\n", "qux\n"] # e = lines.slice_after(/(?<!\\)\n\z/) # p e.to_a # #=> [["foo\n"], ["bar\\\n", "baz\n"], ["\n"], ["qux\n"]] # p e.map {|ll| ll[0...-1].map {|l| l.sub(/\\\n\z/, "") }.join + ll.last } # #=>["foo\n", "barbaz\n", "\n", "qux\n"] # def slice_after: (untyped pattern) -> ::Enumerator[::Array[Elem], void] | () { (Elem elt) -> boolish } -> ::Enumerator[::Array[Elem], void] # <!-- # rdoc-file=enum.c # - slice_before(pattern) -> enumerator # - slice_before {|array| ... } -> enumerator # --> # With argument `pattern`, returns an enumerator that uses the pattern to # partition elements into arrays ("slices"). An element begins a new slice if # `element === pattern` (or if it is the first element). # # a = %w[foo bar fop for baz fob fog bam foy] # e = a.slice_before(/ba/) # => #<Enumerator: ...> # e.each {|array| p array } # # Output: # # ["foo"] # ["bar", "fop", "for"] # ["baz", "fob", "fog"] # ["bam", "foy"] # # With a block, returns an enumerator that uses the block to partition elements # into arrays. An element begins a new slice if its block return is a truthy # value (or if it is the first element): # # e = (1..20).slice_before {|i| i % 4 == 2 } # => #<Enumerator: ...> # e.each {|array| p array } # # Output: # # [1] # [2, 3, 4, 5] # [6, 7, 8, 9] # [10, 11, 12, 13] # [14, 15, 16, 17] # [18, 19, 20] # # Other methods of the Enumerator class and Enumerable module, such as `to_a`, # `map`, etc., are also usable. # # For example, iteration over ChangeLog entries can be implemented as follows: # # # iterate over ChangeLog entries. # open("ChangeLog") { |f| # f.slice_before(/\A\S/).each { |e| pp e } # } # # # same as above. block is used instead of pattern argument. # open("ChangeLog") { |f| # f.slice_before { |line| /\A\S/ === line }.each { |e| pp e } # } # # "svn proplist -R" produces multiline output for each file. They can be chunked # as follows: # # IO.popen([{"LC_ALL"=>"C"}, "svn", "proplist", "-R"]) { |f| # f.lines.slice_before(/\AProp/).each { |lines| p lines } # } # #=> ["Properties on '.':\n", " svn:ignore\n", " svk:merge\n"] # # ["Properties on 'goruby.c':\n", " svn:eol-style\n"] # # ["Properties on 'complex.c':\n", " svn:mime-type\n", " svn:eol-style\n"] # # ["Properties on 'regparse.c':\n", " svn:eol-style\n"] # # ... # # If the block needs to maintain state over multiple elements, local variables # can be used. For example, three or more consecutive increasing numbers can be # squashed as follows (see `chunk_while` for a better way): # # a = [0, 2, 3, 4, 6, 7, 9] # prev = a[0] # p a.slice_before { |e| # prev, prev2 = e, prev # prev2 + 1 != e # }.map { |es| # es.length <= 2 ? es.join(",") : "#{es.first}-#{es.last}" # }.join(",") # #=> "0,2-4,6,7,9" # # However local variables should be used carefully if the result enumerator is # enumerated twice or more. The local variables should be initialized for each # enumeration. Enumerator.new can be used to do it. # # # Word wrapping. This assumes all characters have same width. # def wordwrap(words, maxwidth) # Enumerator.new {|y| # # cols is initialized in Enumerator.new. # cols = 0 # words.slice_before { |w| # cols += 1 if cols != 0 # cols += w.length # if maxwidth < cols # cols = w.length # true # else # false # end # }.each {|ws| y.yield ws } # } # end # text = (1..20).to_a.join(" ") # enum = wordwrap(text.split(/\s+/), 10) # puts "-"*10 # enum.each { |ws| puts ws.join(" ") } # first enumeration. # puts "-"*10 # enum.each { |ws| puts ws.join(" ") } # second enumeration generates same result as the first. # puts "-"*10 # #=> ---------- # # 1 2 3 4 5 # # 6 7 8 9 10 # # 11 12 13 # # 14 15 16 # # 17 18 19 # # 20 # # ---------- # # 1 2 3 4 5 # # 6 7 8 9 10 # # 11 12 13 # # 14 15 16 # # 17 18 19 # # 20 # # ---------- # # mbox contains series of mails which start with Unix From line. So each mail # can be extracted by slice before Unix From line. # # # parse mbox # open("mbox") { |f| # f.slice_before { |line| # line.start_with? "From " # }.each { |mail| # unix_from = mail.shift # i = mail.index("\n") # header = mail[0...i] # body = mail[(i+1)..-1] # body.pop if body.last == "\n" # fields = header.slice_before { |line| !" \t".include?(line[0]) }.to_a # p unix_from # pp fields # pp body # } # } # # # split mails in mbox (slice before Unix From line after an empty line) # open("mbox") { |f| # emp = true # f.slice_before { |line| # prevemp = emp # emp = line == "\n" # prevemp && line.start_with?("From ") # }.each { |mail| # mail.pop if mail.last == "\n" # pp mail # } # } # def slice_before: (untyped pattern) -> ::Enumerator[::Array[Elem], void] | () { (Elem elt) -> boolish } -> ::Enumerator[::Array[Elem], void] end