class Deque(T)
Overview
A Deque ("double-ended queue") is a collection of objects of type T that behaves much like an Array.
Deque has a subset of Array's API. It performs better than an Array
when there are frequent insertions or deletions
of items near the beginning or the end.
The most typical use case of a Deque is a queue: use #push
to add items to the end of the queue and #shift
to get
and remove the item at the beginning of the queue.
This Deque is implemented with a dynamic array used as a circular buffer.
Included Modules
Defined in:
deque.crConstructors
-
.new(size : Int, value : T)
Creates a new
Deque
of the given size filled with the same value in each position. -
.new(initial_capacity : Int)
Creates a new empty
Deque
backed by a buffer that is initiallyinitial_capacity
big. -
.new(array : Array(T))
Creates a new
Deque
that copies its items from an Array. -
.new
Creates a new empty Deque
-
.new(size : Int, &block : Int32 -> T)
Creates a new
Deque
of the given size and invokes the block once for each index of the deque, assigning the block's value in that index.
Instance Method Summary
-
#+(other : Deque(U)) forall U
Concatenation.
-
#<<(value : T)
Alias for
#push
. -
#==(other : Deque)
Returns
true
if it is passed aDeque
andequals?
returnstrue
for both deques, the caller and the argument. -
#[]=(index : Int, value : T)
Sets the given value at the given index.
-
#clear
Removes all elements from
self
. -
#clone
Returns a new
Deque
that has this deque's elements cloned. -
#concat(other : Enumerable(T))
Appends the elements of other to
self
, and returnsself
. -
#delete(obj)
Removes all items from
self
that are equal to obj. -
#delete_at(index : Int)
Delete the item that is present at the index.
-
#dup
Returns a new
Deque
that has exactly this deque's elements. -
#each(&block) : Nil
Yields each item in this deque, from first to last.
-
#insert(index : Int, value : T)
Insert a new item before the item at index.
- #inspect(io : IO)
-
#pop(&block)
Removes and returns the last item, if not empty, otherwise executes the given block and returns its value.
-
#pop
Removes and returns the last item.
-
#pop(n : Int)
Removes the last n (at most) items in the deque.
-
#pop?
Removes and returns the last item, if not empty, otherwise
nil
. - #pretty_print(pp)
-
#push(value : T)
Adds an item to the end of the deque.
-
#rotate!(n : Int = 1)
Rotates this deque in place so that the element at n becomes first.
-
#shift(n : Int)
Removes the first n (at most) items in the deque.
-
#shift
Removes and returns the first item.
-
#shift(&block)
Removes and returns the first item, if not empty, otherwise executes the given block and returns its value.
-
#shift?
Removes and returns the first item, if not empty, otherwise
nil
. -
#size
Returns the number of elements in the deque.
-
#swap(i, j)
Swaps the items at the indices i and j.
- #to_s(io : IO)
- #unsafe_at(index : Int)
-
#unshift(value : T)
Adds an item to the beginning of the deque.
Instance methods inherited from module Comparable(Deque(T))
<(other : T)
<,
<=(other : T)
<=,
<=>(other : T)
<=>,
==(other : T)
==,
>(other : T)
>,
>=(other : T)
>=
Instance methods inherited from module Indexable(T)
[](index : Int)
[],
[]?(index : Int)
[]?,
at(index : Int, &block)at(index : Int) at, bsearch(&block) bsearch, bsearch_index(&block) bsearch_index, each(&block)
each
each(*, start : Int, count : Int, &block)
each(*, within range : Range(Int, Int), &block) each, each_index(*, start : Int, count : Int, &block)
each_index(&block) : Nil
each_index each_index, empty? empty?, equals?(other, &block)
equals?(other : Indexable, &block) equals?, first(&block)
first first, first? first?, hash(hasher) hash, index(object, offset : Int = 0)
index(offset : Int = 0, &block) index, last(&block)
last last, last? last?, reverse_each(&block) : Nil
reverse_each reverse_each, rindex(value, offset = size - 1)
rindex(offset = size - 1, &block) rindex, sample(random = Random::DEFAULT) sample, size size, to_a to_a, unsafe_at(index : Int) unsafe_at, values_at(*indexes : Int) values_at, zip(other : Indexable(U), &block : T, U -> ) forall U
zip(other : Indexable(U)) : Array(Tuple(T, U)) forall U zip, zip?(other : Indexable(U), &block : T, U? -> ) forall U
zip?(other : Indexable(U)) : Array(Tuple(T, U?)) forall U zip?
Instance methods inherited from module Enumerable(T)
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 module Iterable(T)
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 class Reference
==(other : self)==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup, hash(hasher) hash, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference)
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new
Instance methods inherited from class Object
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash(hasher)
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, unsafe_as(type : T.class) forall T unsafe_as
Constructor 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 : String | IO) : self from_yaml
Constructor Detail
Creates a new Deque
of the given size filled with the same value in each position.
Deque.new(3, 'a') # => Deque{'a', 'a', 'a'}
Creates a new empty Deque
backed by a buffer that is initially initial_capacity
big.
The initial_capacity
is useful to avoid unnecessary reallocations of the internal buffer in case of growth. If you
have an estimate of the maximum number of elements a deque will hold, you should initialize it with that capacity
for improved execution performance.
deq = Deque(Int32).new(5)
deq.size # => 0
Creates a new Deque
that copies its items from an Array.
Deque.new([1, 2, 3]) # => Deque{1, 2, 3}
Creates a new Deque
of the given size and invokes the block once for
each index of the deque, assigning the block's value in that index.
Deque.new(3) { |i| (i + 1) ** 2 } # => Deque{1, 4, 9}
Instance Method Detail
Concatenation. Returns a new Deque
built by concatenating
two deques together to create a third. The type of the new deque
is the union of the types of both the other deques.
Returns true
if it is passed a Deque
and equals?
returns true
for both deques, the caller and the argument.
deq = Deque{2, 3}
deq.unshift 1
deq == Deque{1, 2, 3} # => true
deq == Deque{2, 3} # => false
Sets the given value at the given index.
Raises IndexError
if the deque had no previous value at the given index.
Returns a new Deque
that has this deque's elements cloned.
That is, it returns a deep copy of this deque.
Use #dup
if you want a shallow copy.
Removes all items from self
that are equal to obj.
a = Deque{"a", "b", "b", "b", "c"}
a.delete("b") # => true
a # => Deque{"a", "c"}
Delete the item that is present at the index. Items to the right
of this one will have their indices decremented.
Raises IndexError
if trying to delete an element outside the deque's range.
a = Deque{1, 2, 3}
a.delete_at(1) # => 2
a # => Deque{1, 3}
Returns a new Deque
that has exactly this deque's elements.
That is, it returns a shallow copy of this deque.
Yields each item in this deque, from first to last.
Do not modify the deque while using this variant of #each
!
Insert a new item before the item at index. Items to the right of this one will have their indices incremented.
a = Deque{0, 1, 2}
a.insert(1, 7) # => Deque{0, 7, 1, 2}
Removes and returns the last item, if not empty, otherwise executes the given block and returns its value.
Removes and returns the last item. Raises IndexError
if empty.
a = Deque{1, 2, 3}
a.pop # => 3
a # => Deque{1, 2}
Adds an item to the end of the deque.
a = Deque{1, 2}
a.push 3 # => Deque{1, 2, 3}
Rotates this deque in place so that the element at n becomes first.
- For positive n, equivalent to
n.times { push(shift) }
. - For negative n, equivalent to
(-n).times { unshift(pop) }
.
Removes and returns the first item. Raises IndexError
if empty.
a = Deque{1, 2, 3}
a.shift # => 1
a # => Deque{2, 3}
Removes and returns the first item, if not empty, otherwise executes the given block and returns its value.
Adds an item to the beginning of the deque.
a = Deque{1, 2}
a.unshift 0 # => Deque{0, 1, 2}