Range
struct Range(B, E)
Overview
A Range
represents an interval: a set of values with a beginning and an end-
Ranges may be constructed using the usual .new
method or with literals:
x..y # an inclusive range, in mathematics: [x, y] x...y # an exclusive range, in mathematics: [x, y)
An easy way to remember which one is inclusive and which one is exclusive it to think of the extra dot as if it pushes y further away, thus leaving it outside of the range.
Ranges typically involve integers, but can be created using arbitrary objects as long as they define succ
(or pred
for #reverse_each
), to get the next element in the range, and <
and ==
, to know when the range reached the end:
# Represents a string of 'x's. struct Xs include Comparable(Xs) getter size def initialize(@size : Int32) end def succ Xs.new(@size + 1) end def <=>(other) @size <=> other.size end def inspect(io) @size.times { io << 'x' } end def to_s(io) io << @size << ' ' inspect(io) end end
An example of using Xs
to construct a range:
r = Xs.new(3)..Xs.new(6) r.to_s # => "xxx..xxxxxx" r.to_a # => [Xs.new(3), Xs.new(4), Xs.new(5), Xs.new(6)] r.includes?(Xs.new(5)) # => true
Included Modules
Defined in:
range.crrange/bsearch.cr
Class Method Summary
- .new(begin : B, end : E, exclusive : Bool = false)
Constructs a
Range
using the given beginning and end-
Instance Method Summary
- #===(value)
Same as
#includes?
, useful for thecase
expression. - #begin : B
Returns the object that defines the beginning of this range.
- #bsearch(&block)
By using binary search, returns the first value for which the passed block returns
true
. - #clone
- #covers?(value)
Same as
#includes?
. - #cycle
Returns an
Iterator
that cycles over the values of this range. - #each(&block) : Nil
Iterates over the elements of this range, passing each in turn to the block.
- #each
Returns an
Iterator
over the elements of this range. - #end : E
Returns the object that defines the end of the range.
- #excludes_end?
Returns
true
if this range excludes the end element. - #exclusive? : Bool
Returns
true
if the range is exclusive. - #includes?(value)
Returns
true
if this range includes the given value. - #reverse_each(&block) : Nil
Iterates over the elements of this range in reverse order, passing each in turn to the block.
- #reverse_each
Returns a reverse
Iterator
over the elements of this range. - #step(by = 1)
Returns an
Iterator
that returns each nth element in this range. - #step(by = 1, &block)
Iterates over this range, passing each nth element to the block.
- #sum(initial)
If
self
is aInt
range, it provides O(1) implementation, otherwise it is same asEnumerable#sum
.
Instance methods inherited from module Iterable(B)
chunk(reuse = false, &block : T -> U) forall U chunk, cycle(n)cycle cycle, each each, each_cons(count : Int, reuse = false) each_cons, each_slice(count : Int, reuse = false) each_slice, each_with_index(offset = 0) each_with_index, each_with_object(obj) each_with_object
Instance methods inherited from module Enumerable(B)
all?(&block)all? all?, any?(&block)
any? any?, chunks(&block : T -> U) forall U chunks, compact_map(&block) compact_map, count(&block)
count(item) count, cycle(n, &block)
cycle(&block) cycle, each(&block : T -> _) each, each_cons(count : Int, reuse = false, &block) each_cons, each_slice(count : Int, reuse = false, &block) each_slice, each_with_index(offset = 0, &block) each_with_index, each_with_object(obj, &block) each_with_object, find(if_none = nil, &block) find, first(count : Int)
first first, first? first?, flat_map(&block : T -> Array(U) | Iterator(U) | U) forall U flat_map, grep(pattern) grep, group_by(&block : T -> U) forall U group_by, in_groups_of(size : Int, filled_up_with : U = nil) forall U
in_groups_of(size : Int, filled_up_with : U = nil, reuse = false, &block) forall U in_groups_of, includes?(obj) includes?, index(&block)
index(obj) index, index_by(&block : T -> U) forall U index_by, join(separator, io)
join(separator = "")
join(separator, io, &block)
join(separator = "", &block) join, map(&block : T -> U) forall U map, map_with_index(&block : T, Int32 -> U) forall U map_with_index, max max, max? max?, max_by(&block : T -> U) forall U max_by, max_by?(&block : T -> U) forall U max_by?, max_of(&block : T -> U) forall U max_of, max_of?(&block : T -> U) forall U max_of?, min min, min? min?, min_by(&block : T -> U) forall U min_by, min_by?(&block : T -> U) forall U min_by?, min_of(&block : T -> U) forall U min_of, min_of?(&block : T -> U) forall U min_of?, minmax minmax, minmax? minmax?, minmax_by(&block : T -> U) forall U minmax_by, minmax_by?(&block : T -> U) forall U minmax_by?, minmax_of(&block : T -> U) forall U minmax_of, minmax_of?(&block : T -> U) forall U minmax_of?, none?(&block)
none? none?, one?(&block) one?, partition(&block) partition, product(&block)
product(initial : Number, &block)
product
product(initial : Number) product, reduce(&block)
reduce(memo, &block) reduce, reject(&block : T -> ) reject, select(&block : T -> ) select, size size, skip(count : Int) skip, skip_while(&block) skip_while, sum(initial)
sum
sum(initial, &block)
sum(&block) sum, take_while(&block) take_while, to_a to_a, to_h to_h, to_set to_set
Instance methods inherited from struct Struct
==(other : self) : Bool ==, hash : Int32 hash, inspect(io : IO) : Nil inspect, pretty_print(pp) : Nil pretty_print, to_s(io) to_s Instance methods inherited from struct Value
==(other) ==, dup dup Instance methods inherited from class Object
!=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try
Class methods inherited from class Object
from_json(string_or_io, root : String) : selffrom_json(string_or_io) : self from_json, from_yaml(string_or_io) : self from_yaml
Class Method Detail
def self.new(begin : B, end : E, exclusive : Bool = false)Source
Constructs a Range
using the given beginning and end-
Range.new(1, 10) # => 1..10 Range.new(1, 10, exclusive: true) # => 1...10
Instance Method Detail
def ===(value)Source
Same as #includes?
, useful for the case
expression.
case 79 when 1..50 then puts "low" when 51..75 then puts "medium" when 76..100 then puts "high" end
Produces:
high
See also: Object#===
.
def begin : BSource
Returns the object that defines the beginning of this range.
(1..10).begin # => 1 (1...10).begin # => 1
def bsearch(&block)Source
By using binary search, returns the first value for which the passed block returns true
.
If the block returns false
, the finding value exists behind. If the block returns true
, the finding value is itself or exists infront.
(0..10).bsearch { |x| x >= 5 } # => 5 (0..Float64::INFINITY).bsearch { |x| x ** 4 >= 256 } # => 4
Returns nil
if the block didn't return true
for any value.
def covers?(value)Source
Same as #includes?
.
def cycleSource
Returns an Iterator
that cycles over the values of this range.
(1..3).cycle.first(5).to_a # => [1, 2, 3, 1, 2]
def each(&block) : NilSource
Iterates over the elements of this range, passing each in turn to the block.
(10..15).each { |n| print n, ' ' } # prints: 10 11 12 13 14 15
def eachSource
Returns an Iterator
over the elements of this range.
(1..3).each.skip(1).to_a # => [2, 3]
def end : ESource
Returns the object that defines the end of the range.
(1..10).end # => 10 (1...10).end # => 10
def excludes_end?Source
Returns true
if this range excludes the end element.
(1..10).excludes_end? # => false (1...10).excludes_end? # => true
def exclusive? : BoolSource
Returns true
if the range is exclusive. Returns false
otherwise (default).
def includes?(value)Source
Returns true
if this range includes the given value.
(1..10).includes?(4) # => true (1..10).includes?(10) # => true (1..10).includes?(11) # => false (1...10).includes?(9) # => true (1...10).includes?(10) # => false
def reverse_each(&block) : NilSource
Iterates over the elements of this range in reverse order, passing each in turn to the block.
(10...15).reverse_each { |n| print n, ' ' } # prints: 14 13 12 11 10
def reverse_eachSource
Returns a reverse Iterator
over the elements of this range.
(1..3).reverse_each.skip(1).to_a # => [2, 1]
def step(by = 1)Source
Returns an Iterator
that returns each nth element in this range.
(1..10).step(3).skip(1).to_a # => [4, 7, 10]
def step(by = 1, &block)Source
Iterates over this range, passing each nth element to the block.
range = Xs.new(1)..Xs.new(10) range.step(2) { |x| puts x } puts range.step(3) { |x| puts x }
Produces:
1 x 3 xxx 5 xxxxx 7 xxxxxxx 9 xxxxxxxxx 1 x 4 xxxx 7 xxxxxxx 10 xxxxxxxxxx
See Range
's overview for the definition of Xs
-
def sum(initial)Source
If self
is a Int
range, it provides O(1) implementation, otherwise it is same as Enumerable#sum
.
© 2012–2017 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.22.0/Range.html