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
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
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#===
.
Returns the object that defines the beginning of this range.
(1..10).begin # => 1
(1...10).begin # => 1
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.
Returns an Iterator
that cycles over the values of this range.
(1..3).cycle.first(5).to_a # => [1, 2, 3, 1, 2]
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
Returns an Iterator
over the elements of this range.
(1..3).each.skip(1).to_a # => [2, 3]
Returns the object that defines the end of the range.
(1..10).end # => 10
(1...10).end # => 10
Returns true
if this range excludes the end element.
(1..10).excludes_end? # => false
(1...10).excludes_end? # => true
Returns true
if the range is exclusive.
Returns false
otherwise (default).
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
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
Returns a reverse Iterator
over the elements of this range.
(1..3).reverse_each.skip(1).to_a # => [2, 1]
Returns an Iterator
that returns each nth element in this range.
(1..10).step(3).skip(1).to_a # => [4, 7, 10]
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
.
If self
is a Int
range, it provides O(1) implementation,
otherwise it is same as Enumerable#sum
.