struct Range(B, E)

• Range(B, E)
• Struct
• Value
• Object

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)
(x..) # an endless range, in mathematics: >= x
..y   # a beginless inclusive range, in mathematics: <= y
...y  # a beginless exclusive range, in mathematics: < 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

• Enumerable(B)
• Iterable(B)

Defined in:

Instance Method Summary

• #overlaps?(other : Range) : Bool

  Compare two ranges and see if they overlap each other ` (1..5).overlaps?(4..6) # => true (1..5).overlaps?(7..9) # => false `

Instance Method Detail

 (1..5).overlaps?(4..6) # => true
 (1..5).overlaps?(7..9) # => false