struct Slice(T)

Overview

A Slice is a Pointer with an associated size.

While a pointer is unsafe because no bound checks are performed when reading from and writing to it, reading from and writing to a slice involve bound checks. In this way, a slice is a safe alternative to Pointer.

A Slice can be created as read-only: trying to write to it will raise. For example the slice of bytes returned by String#to_slice is read-only.

Included Modules

Defined in:

slice.cr
slice/sort.cr
yaml/from_yaml.cr
yaml/to_yaml.cr

Constructors

Instance Method Summary

Macro Summary

Instance methods inherited from module Comparable(Slice(T))

<(other : T) : Bool <, <=(other : T) <=, <=>(other : T) <=>, ==(other : T) ==, >(other : T) : Bool >, >=(other : T) >=, clamp(min, max)
clamp(range : Range)
clamp

Instance methods inherited from module Indexable::Mutable(T)

[]=(index : Int, value : T) : T []=, fill(value : T, start : Int, count : Int) : self
fill(value : T, range : Range) : self
fill(value : T) : self
fill(start : Int, count : Int, & : Int32 -> T) : self
fill(range : Range, & : Int32 -> T) : self
fill(*, offset : Int = 0, & : Int32 -> T) : self
fill
, map!(& : T -> _) : self map!, map_with_index!(offset = 0, & : T, Int32 -> _) : self map_with_index!, reverse! : self reverse!, rotate!(n : Int = 1) : self rotate!, shuffle!(random : Random = Random::DEFAULT) : self shuffle!, sort! : self
sort!(&block : T, T -> U) : self forall U
sort!
, sort_by!(&block : T -> _) : self sort_by!, swap(index0 : Int, index1 : Int) : self swap, unsafe_put(index : Int, value : T) unsafe_put, unstable_sort! : self
unstable_sort!(&block : T, T -> U) : self forall U
unstable_sort!
, unstable_sort_by!(&block : T -> _) : self unstable_sort_by!, update(index : Int, & : T -> _) : T update

Instance methods inherited from module Indexable(T)

[](index : Int) [], []?(index : Int) []?, bsearch(& : T -> _) bsearch, bsearch_index(& : T, Int32 -> _) bsearch_index, cartesian_product(*others : Indexable) cartesian_product, combinations(size : Int = self.size) combinations, dig(index : Int, *subindexes) dig, dig?(index : Int, *subindexes) dig?, each(& : T -> )
each
each(*, start : Int, count : Int, & : T -> )
each(*, within range : Range, & : T -> )
each
, each_cartesian(*others : Indexable, &)
each_cartesian(*others : Indexable)
each_cartesian
, each_combination(size : Int = self.size, reuse = false, &) : Nil
each_combination(size : Int = self.size, reuse = false)
each_combination
, each_index(& : Int32 -> ) : Nil
each_index
each_index(*, start : Int, count : Int, &)
each_index
, each_permutation(size : Int = self.size, reuse = false, &) : Nil
each_permutation(size : Int = self.size, reuse = false)
each_permutation
, each_repeated_combination(size : Int = self.size, reuse = false, &) : Nil
each_repeated_combination(size : Int = self.size, reuse = false)
each_repeated_combination
, empty? : Bool empty?, equals?(other : Indexable, &) : Bool
equals?(other, &)
equals?
, fetch(index : Int, &)
fetch(index, default)
fetch
, first(&) first, hash(hasher) hash, index(object, offset : Int = 0)
index(offset : Int = 0, & : T -> )
index
, index!(obj, offset : Int = 0)
index!(offset : Int = 0, & : T -> )
index!
, join(separator : String | Char | Number = "") : String join, last : T
last(&)
last
, last? : T | Nil last?, permutations(size : Int = self.size) : Array(Array(T)) permutations, repeated_combinations(size : Int = self.size) : Array(Array(T)) repeated_combinations, reverse_each(& : T -> ) : Nil
reverse_each
reverse_each
, rindex(value, offset = size - 1)
rindex(offset = size - 1, & : T -> )
rindex
, rindex!(value, offset = size - 1)
rindex!(offset = size - 1, & : T -> )
rindex!
, sample(n : Int, random : Random = Random::DEFAULT) : Array(T)
sample(random : Random = Random::DEFAULT)
sample
, size size, to_a : Array(T) to_a, unsafe_fetch(index : Int) unsafe_fetch, values_at(*indexes : Int) values_at

Class methods inherited from module Indexable(T)

cartesian_product(indexables : Indexable(Indexable)) cartesian_product, each_cartesian(indexables : Indexable(Indexable), reuse = false, &)
each_cartesian(indexables : Indexable(Indexable), reuse = false)
each_cartesian

Instance methods inherited from module Enumerable(T)

accumulate(initial : U) : Array(U) forall U
accumulate : Array(T)
accumulate(initial : U, &block : U, T -> U) : Array(U) forall U
accumulate(&block : T, T -> T) : Array(T)
accumulate
, all?(& : T -> ) : Bool
all?(pattern) : Bool
all? : Bool
all?
, any?(& : T -> ) : Bool
any?(pattern) : Bool
any? : Bool
any?
, chunks(&block : T -> U) forall U chunks, compact_map(& : T -> _) compact_map, count(& : T -> ) : Int32
count(item) : Int32
count
, cycle(n, & : T -> ) : Nil
cycle(& : T -> ) : Nil
cycle
, each(& : T -> ) each, each_cons(count : Int, reuse = false, &) each_cons, each_cons_pair(& : T, T -> ) : Nil each_cons_pair, each_slice(count : Int, reuse = false, &) each_slice, each_with_index(offset = 0, &) each_with_index, each_with_object(obj : U, & : T, U -> ) : U forall U each_with_object, empty? : Bool empty?, find(if_none = nil, & : T -> ) find, find!(& : T -> ) : T find!, first(&)
first(count : Int) : Array(T)
first : T
first
, first? : T | Nil first?, flat_map(& : T -> _) flat_map, group_by(& : 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, &) forall U
in_groups_of
, includes?(obj) : Bool includes?, index(& : T -> ) : Int32 | Nil
index(obj) : Int32 | Nil
index
, index!(& : T -> ) : Int32
index!(obj) : Int32
index!
, index_by(& : T -> U) : Hash(U, T) forall U index_by, join(io : IO, separator = "") : Nil
join(separator, io : IO) : Nil
join(separator = "") : String
join(io : IO, separator = "", & : T, IO -> )
join(separator, io : IO, &)
join(separator = "", & : T -> )
join
, map(& : T -> U) : Array(U) forall U map, map_with_index(offset = 0, & : T, Int32 -> U) : Array(U) forall U map_with_index, max : T max, max? : T | Nil max?, max_by(& : T -> U) : T forall U max_by, max_by?(& : T -> U) : T | Nil forall U max_by?, max_of(& : T -> U) : U forall U max_of, max_of?(& : T -> U) : U | Nil forall U max_of?, min : T min, min? : T | Nil min?, min_by(& : T -> U) : T forall U min_by, min_by?(& : T -> U) : T | Nil forall U min_by?, min_of(& : T -> U) : U forall U min_of, min_of?(& : T -> U) : U | Nil forall U min_of?, minmax : Tuple(T, T) minmax, minmax? : Tuple(T | Nil, T | Nil) minmax?, minmax_by(& : T -> U) : Tuple(T, T) forall U minmax_by, minmax_by?(& : T -> U) : Tuple(T, T) | Tuple(Nil, Nil) forall U minmax_by?, minmax_of(& : T -> U) : Tuple(U, U) forall U minmax_of, minmax_of?(& : T -> U) : Tuple(U, U) | Tuple(Nil, Nil) forall U minmax_of?, none?(& : T -> ) : Bool
none?(pattern) : Bool
none? : Bool
none?
, one?(& : T -> ) : Bool
one?(pattern) : Bool
one? : Bool
one?
, partition(& : T -> ) : Tuple(Array(T), Array(T)) partition, product(initial : Number)
product
product(initial : Number, & : T -> )
product(& : T -> _)
product
, reduce(memo, &)
reduce(&)
reduce
, reduce?(&) reduce?, reject(& : T -> )
reject(type : U.class) forall U
reject(pattern) : Array(T)
reject
, sample(n : Int, random : Random = Random::DEFAULT) : Array(T)
sample(random : Random = Random::DEFAULT) : T
sample
, select(& : T -> )
select(type : U.class) : Array(U) forall U
select(pattern) : Array(T)
select
, size : Int32 size, skip(count : Int) skip, skip_while(& : T -> ) : Array(T) skip_while, sum(initial)
sum
sum(initial, & : T -> )
sum(& : T -> )
sum
, take_while(& : T -> ) : Array(T) take_while, tally(hash)
tally : Hash(T, Int32)
tally
, tally_by(hash, &)
tally_by(&block : T -> U) : Hash(U, Int32) forall U
tally_by
, to_a to_a, to_h
to_h(& : T -> Tuple(K, V)) forall K, V
to_h
, to_set : Set(T) to_set, zip(*others : Indexable | Iterable | Iterator, &)
zip(*others : Indexable | Iterable | Iterator)
zip
, zip?(*others : Indexable | Iterable | Iterator, &)
zip?(*others : Indexable | Iterable | Iterator)
zip?

Class methods inherited from module Enumerable(T)

element_type(x) element_type

Instance methods inherited from module Iterable(T)

chunk(reuse = false, &block : T -> U) forall U chunk, chunk_while(reuse : Bool | Array(T) = false, &block : T, T -> B) forall B chunk_while, cycle(n)
cycle
cycle
, each each, each_cons(count : Int, reuse = false) each_cons, each_cons_pair each_cons_pair, each_slice(count : Int, reuse = false) each_slice, each_with_index(offset = 0) each_with_index, each_with_object(obj) each_with_object, slice_after(reuse : Bool | Array(T) = false, &block : T -> B) forall B
slice_after(pattern, reuse : Bool | Array(T) = false)
slice_after
, slice_before(reuse : Bool | Array(T) = false, &block : T -> B) forall B
slice_before(pattern, reuse : Bool | Array(T) = false)
slice_before
, slice_when(reuse : Bool | Array(T) = false, &block : T, T -> B) forall B slice_when

Instance methods inherited from struct Struct

==(other) : Bool ==, hash(hasher) hash, inspect(io : IO) : Nil inspect, pretty_print(pp) : Nil pretty_print, to_s(io : IO) : Nil to_s

Instance methods inherited from struct Value

==(other : JSON::Any)
==(other : YAML::Any)
==(other)
==
, dup dup

Instance methods inherited from class Object

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other)
===
, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash
hash
, in?(collection : Object) : Bool
in?(*values : Object) : Bool
in?
, inspect(io : IO) : Nil
inspect : String
inspect
, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message = nil) not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String
to_json
, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil
to_pretty_json
, to_s(io : IO) : Nil
to_s : String
to_s
, to_yaml(io : IO) : Nil
to_yaml : String
to_yaml
, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

Class methods inherited from class Object

from_json(string_or_io, root : String)
from_json(string_or_io)
from_json
, from_yaml(string_or_io : String | IO) from_yaml

Constructor Detail

def self.empty : self #

Creates an empty slice.

slice = Slice(UInt8).empty
slice.size # => 0

[View source]
def self.new(ctx : YAML::ParseContext, node : YAML::Nodes::Node) #

[View source]
def self.new(pointer : Pointer(T), size : Int, *, read_only : Bool = false) #

Creates a slice to the given pointer, bounded by the given size. This method does not allocate heap memory.

ptr = Pointer.malloc(9) { |i| ('a'.ord + i).to_u8 }

slice = Slice.new(ptr, 3)
slice.size # => 3
slice      # => Bytes[97, 98, 99]

String.new(slice) # => "abc"

[View source]
def self.new(size : Int, value : T, *, read_only = false) #

Allocates size * sizeof(T) bytes of heap memory initialized to value and returns a slice pointing to that memory.

The memory is allocated by the GC, so when there are no pointers to this memory, it will be automatically freed.

slice = Slice.new(3, 10)
slice # => Slice[10, 10, 10]

[View source]
def self.new(size : Int, *, read_only = false) #

Allocates size * sizeof(T) bytes of heap memory initialized to zero and returns a slice pointing to that memory.

The memory is allocated by the GC, so when there are no pointers to this memory, it will be automatically freed.

Only works for primitive integers and floats (UInt8, Int32, Float64, etc.)

slice = Slice(UInt8).new(3)
slice # => Bytes[0, 0, 0]

[View source]
def self.new(size : Int, *, read_only = false, &) #

Allocates size * sizeof(T) bytes of heap memory initialized to the value returned by the block (which is invoked once with each index in the range 0...size) and returns a slice pointing to that memory.

The memory is allocated by the GC, so when there are no pointers to this memory, it will be automatically freed.

slice = Slice.new(3) { |i| i + 10 }
slice # => Slice[10, 11, 12]

[View source]

Instance Method Detail

def +(offset : Int) : Slice(T) #

Returns a new slice that is offset elements apart from this slice.

slice = Slice.new(5) { |i| i + 10 }
slice # => Slice[10, 11, 12, 13, 14]

slice2 = slice + 2
slice2 # => Slice[12, 13, 14]

[View source]
def <=>(other : Slice(U)) forall U #

Combined comparison operator.

Returns a negative number, 0, or a positive number depending on whether self is less than other, equals other.

It compares the elements of both slices in the same position using the <=> operator. As soon as one of such comparisons returns a non-zero value, that result is the return value of the comparison.

If all elements are equal, the comparison is based on the size of the arrays.

Bytes[8] <=> Bytes[1, 2, 3] # => 7
Bytes[2] <=> Bytes[4, 2, 3] # => -2
Bytes[1, 2] <=> Bytes[1, 2] # => 0

[View source]
def ==(other : Slice(U)) : Bool forall U #

Returns true if self and other have the same size and all their elements are equal, false otherwise.

Bytes[1, 2] == Bytes[1, 2]    # => true
Bytes[1, 3] == Bytes[1, 2]    # => false
Bytes[1, 2] == Bytes[1, 2, 3] # => false

[View source]
def [](start : Int, count : Int) : Slice(T) #

Returns a new slice that starts at start elements from this slice's start, and of count size.

Raises IndexError if the new slice falls outside this slice.

slice = Slice.new(5) { |i| i + 10 }
slice # => Slice[10, 11, 12, 13, 14]

slice[1, 3]  # => Slice[11, 12, 13]
slice[1, 33] # raises IndexError

[View source]
def [](range : Range) : Slice(T) #

Returns a new slice with the elements in the given range.

The first element in the returned slice is self[range.begin] followed by the next elements up to index range.end (or self[range.end - 1] if the range is exclusive). If there are fewer elements in self, the returned slice is shorter than range.size.

a = Slice["a", "b", "c", "d", "e"]
a[1..3] # => Slice["b", "c", "d"]

Negative indices count backward from the end of the slice (-1 is the last element). Additionally, an empty slice is returned when the starting index for an element range is at the end of the slice.

Raises IndexError if the new slice falls outside this slice.

slice = Slice.new(5) { |i| i + 10 }
slice # => Slice[10, 11, 12, 13, 14]

slice[1..3]  # => Slice[11, 12, 13]
slice[1..33] # raises IndexError

[View source]
def []=(index : Int, value : T) : T #

Sets the given value at the given index. Returns value.

Negative indices can be used to start counting from the end of the container. Raises IndexError if trying to set an element outside the container's range.

ary = [1, 2, 3]
ary[0] = 5
ary # => [5, 2, 3]

ary[3] = 5 # raises IndexError

Raises if this slice is read-only.


[View source]
def []?(start : Int, count : Int) : Slice(T) | Nil #

Returns a new slice that starts at start elements from this slice's start, and of count size.

Returns nil if the new slice falls outside this slice.

slice = Slice.new(5) { |i| i + 10 }
slice # => Slice[10, 11, 12, 13, 14]

slice[1, 3]?  # => Slice[11, 12, 13]
slice[1, 33]? # => nil

[View source]
def []?(range : Range) #

Returns a new slice with the elements in the given range.

Negative indices count backward from the end of the slice (-1 is the last element). Additionally, an empty slice is returned when the starting index for an element range is at the end of the slice.

Returns nil if the new slice falls outside this slice.

slice = Slice.new(5) { |i| i + 10 }
slice # => Slice[10, 11, 12, 13, 14]

slice[1..3]?  # => Slice[11, 12, 13]
slice[1..33]? # => nil

[View source]
def bytesize : Int32 #

[View source]
def clone #

Returns a deep copy of this slice.

This method allocates memory for the slice copy and stores the return values from calling #clone on each item.


[View source]
def copy_from(source : Pointer(T), count) #

[View source]
def copy_from(source : self) #

Copies the contents of source into this slice.

Raises IndexError if the destination slice cannot fit the data being transferred.


[View source]
def copy_to(target : Pointer(T), count) #

[View source]
def copy_to(target : self) #

Copies the contents of this slice into target.

Raises IndexError if the destination slice cannot fit the data being transferred e.g. dest.size < self.size.

src = Slice['a', 'a', 'a']
dst = Slice['b', 'b', 'b', 'b', 'b']
src.copy_to dst
dst             # => Slice['a', 'a', 'a', 'b', 'b']
dst.copy_to src # raises IndexError

[View source]
def dup #

Returns a shallow copy of this slice.

This method allocates memory for the slice copy and duplicates the values.


[View source]
def fill(value : T, start : Int, count : Int) : self #

Replaces count or less (if there aren't enough) elements starting at the given start index with value. Returns self.

Negative values of start count from the end of the container.

Raises IndexError if the start index is out of range.

Raises ArgumentError if count is negative.

array = [1, 2, 3, 4, 5]
array.fill(9, 2, 2) # => [1, 2, 9, 9, 5]
array               # => [1, 2, 9, 9, 5]

Raises if this slice is read-only.


[View source]
def fill(value : T, range : Range) : self #

Replaces the elements within the given range with value. Returns self.

Negative indices count backward from the end of the container.

Raises IndexError if the starting index is out of range.

array = [1, 2, 3, 4, 5]
array.fill(9, 2..3) # => [1, 2, 9, 9, 5]
array               # => [1, 2, 9, 9, 5]

Raises if this slice is read-only.


[View source]
def fill(value : T) : self #

Replaces every element in self with the given value. Returns self.

array = [1, 2, 3, 4]
array.fill(2) # => [2, 2, 2, 2]
array         # => [2, 2, 2, 2]

Raises if this slice is read-only.


[View source]
def fill(start : Int, count : Int, & : Int32 -> T) : self #

Yields each index of self, starting at start and for count times (or less if there aren't enough elements), to the given block and then assigns the block's value in that position. Returns self.

Negative values of start count from the end of the container.

Has no effect if count is zero or negative.

Raises IndexError if start is outside the array range.

a = [1, 2, 3, 4, 5, 6]
a.fill(2, 3) { |i| i * i * i } # => [1, 2, 8, 27, 64, 6]

Raises if this slice is read-only.


[View source]
def fill(range : Range, & : Int32 -> T) : self #

Yields each index of self, in the given range, to the given block and then assigns the block's value in that position. Returns self.

Negative indices count backward from the end of the container.

Raises IndexError if the starting index is out of range.

a = [1, 2, 3, 4, 5, 6]
a.fill(2..4) { |i| i * i * i } # => [1, 2, 8, 27, 64, 6]

Raises if this slice is read-only.


[View source]
def fill(*, offset : Int = 0, & : Int32 -> T) : self #

Yields each index of self to the given block and then assigns the block's value in that position. Returns self.

Accepts an optional offset parameter, which tells the block to start counting from there.

array = [2, 1, 1, 1]
array.fill { |i| i * i }            # => [0, 1, 4, 9]
array                               # => [0, 1, 4, 9]
array.fill(offset: 3) { |i| i * i } # => [9, 16, 25, 36]
array                               # => [9, 16, 25, 36]

Raises if this slice is read-only.


[View source]
def hash(hasher) #

[View source]
def hexdump(io : IO) #

Writes a hexdump of this slice to the given io.

self must be a Slice(UInt8). To call this method on other Slices, #to_unsafe_bytes should be used first.

This method is specially useful for debugging binary data and incoming/outgoing data in protocols.

Returns the number of bytes written to io.

slice = UInt8.slice(97, 62, 63, 8, 255)
slice.hexdump(STDOUT)

Prints:

00000000  61 3e 3f 08 ff                                    a>?..

[View source]
def hexdump : String #

Returns a hexdump of this slice.

self must be a Slice(UInt8). To call this method on other Slices, #to_unsafe_bytes should be used first.

This method is specially useful for debugging binary data and incoming/outgoing data in protocols.

slice = UInt8.slice(97, 62, 63, 8, 255)
slice.hexdump # => "00000000  61 3e 3f 08 ff                                    a>?..\n"

# assume little-endian system
slice = Int16.slice(97, 62, 1000, -2)
slice.to_unsafe_bytes.hexdump # => "00000000  61 00 3e 00 e8 03 fe ff                           a.>.....\n"

[View source]
def hexstring : String #

Returns a hexstring representation of this slice.

self must be a Slice(UInt8). To call this method on other Slices, #to_unsafe_bytes should be used first.

UInt8.slice(97, 62, 63, 8, 255).hexstring # => "613e3f08ff"

# assume little-endian system
Int16.slice(97, 62, 1000, -2).to_unsafe_bytes.hexstring # => "61003e00e803feff"

[View source]
def index(object, offset : Int = 0) #
Description copied from module Indexable(T)

Returns the index of the first appearance of object in self starting from the given offset, or nil if object is not in self.

[1, 2, 3, 1, 2, 3].index(2, offset: 2) # => 4

[View source]
def inspect(io : IO) : Nil #
Description copied from struct Struct

Appends this struct's name and instance variables names and values to the given IO.

struct Point
  def initialize(@x : Int32, @y : Int32)
  end
end

p1 = Point.new 1, 2
p1.to_s    # "Point(@x=1, @y=2)"
p1.inspect # "Point(@x=1, @y=2)"

[View source]
def map(*, read_only = false, & : T -> _) #

Returns a new slice where elements are mapped by the given block.

slice = Slice[1, 2.5, "a"]
slice.map &.to_s # => Slice["1", "2.5", "a"]

[View source]
def map!(& : T -> _) : self #

Invokes the given block for each element of self, replacing the element with the value returned by the block. Returns self.

a = [1, 2, 3]
a.map! { |x| x * x }
a # => [1, 4, 9]

Raises if this slice is read-only.


[View source]
def map_with_index(offset = 0, *, read_only = false, & : T, Int32 -> _) #

Like #map, but the block gets passed both the element and its index.

Accepts an optional offset parameter, which tells it to start counting from there.


[View source]
def map_with_index!(offset = 0, & : T, Int32 -> _) : self #

Like #map!, but the block gets passed both the element and its index.

Accepts an optional offset parameter, which tells it to start counting from there.

gems = ["crystal", "pearl", "diamond"]
gems.map_with_index! { |gem, i| "#{i}: #{gem}" }
gems # => ["0: crystal", "1: pearl", "2: diamond"]

Raises if this slice is read-only.


[View source]
def move_from(source : Pointer(T), count) #

[View source]
def move_from(source : self) #

Moves the contents of source into this slice. source and self may overlap; the copy is always done in a non-destructive manner.

Raises IndexError if the destination slice cannot fit the data being transferred.


[View source]
def move_to(target : Pointer(T), count) #

[View source]
def move_to(target : self) #

Moves the contents of this slice into target. target and self may overlap; the copy is always done in a non-destructive manner.

Raises IndexError if the destination slice cannot fit the data being transferred e.g. dest.size < self.size.

src = Slice['a', 'a', 'a']
dst = Slice['b', 'b', 'b', 'b', 'b']
src.move_to dst
dst             # => Slice['a', 'a', 'a', 'b', 'b']
dst.move_to src # raises IndexError

See also: Pointer#move_to.


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def pretty_print(pp) : Nil #

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def read_only? : Bool #

Returns true if this slice cannot be written to.


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def reverse! : self #

Reverses in-place all the elements of self. Returns self.

Raises if this slice is read-only.


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def rotate!(n : Int = 1) : self #

Shifts all elements of self to the left n times. Returns self.

a1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a3 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

a1.rotate!
a2.rotate!(1)
a3.rotate!(3)

a1 # => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
a2 # => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
a3 # => [3, 4, 5, 6, 7, 8, 9, 0, 1, 2]

Raises if this slice is read-only.


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def shuffle!(random : Random = Random::DEFAULT) : self #

Modifies self by randomizing the order of elements in the collection using the given random number generator. Returns self.

a = [1, 2, 3, 4, 5]
a.shuffle!(Random.new(42)) # => [3, 2, 4, 5, 1]
a                          # => [3, 2, 4, 5, 1]

Raises if this slice is read-only.


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def size : Int32 #

Returns the size of this slice.

Slice(UInt8).new(3).size # => 3

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def sort : self #

Returns a new instance with all elements sorted based on the return value of their comparison method T#<=> (see Comparable#<=>), using a stable sort algorithm.

a = Slice[3, 1, 2]
a.sort # => Slice[1, 2, 3]
a      # => Slice[3, 1, 2]

See #sort! for details on the sorting mechanism.

Raises ArgumentError if the comparison between any two elements returns nil.


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def sort(&block : T, T -> U) : self forall U #

Returns a new instance with all elements sorted based on the comparator in the given block, using a stable sort algorithm.

a = Slice[3, 1, 2]
b = a.sort { |a, b| b <=> a }

b # => Slice[3, 2, 1]
a # => Slice[3, 1, 2]

See Indexable::Mutable#sort!(&block : T, T -> U) for details on the sorting mechanism.

Raises ArgumentError if for any two elements the block returns nil.


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def sort! : self #

Sorts all elements in self based on the return value of the comparison method T#<=> (see Comparable#<=>), using a stable sort algorithm.

slice = Slice[3, 1, 2]
slice.sort!
slice # => Slice[1, 2, 3]

This sort operation modifies self. See #sort for a non-modifying option that allocates a new instance.

The sort mechanism is implemented as merge sort. It is stable, which is typically a good default.

Stability means that two elements which compare equal (i.e. a <=> b == 0) keep their original relation. Stable sort guarantees that [a, b].sort! always results in [a, b] (given they compare equal). With unstable sort, the result could also be [b, a].

If stability is expendable, #unstable_sort! provides a performance advantage over stable sort.

Raises ArgumentError if the comparison between any two elements returns nil.


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def sort!(&block : T, T -> U) : self forall U #

Sorts all elements in self based on the comparator in the given block, using a stable sort algorithm.

slice = Slice[3, 1, 2]
# This is a reverse sort (forward sort would be `a <=> b`)
slice.sort! { |a, b| b <=> a }
slice # => Slice[3, 2, 1]

The block must implement a comparison between two elements a and b, where a < b outputs a negative value, a == b outputs 0, and a > b outputs a positive value. The comparison operator (Comparable#<=>) can be used for this.

The block's output type must be <= Int32?, but returning an actual nil value is an error.

This sort operation modifies self. See #sort(&block : T, T -> U) for a non-modifying option that allocates a new instance.

The sort mechanism is implemented as merge sort. It is stable, which is typically a good default.

Stability means that two elements which compare equal (i.e. a <=> b == 0) keep their original relation. Stable sort guarantees that [a, b].sort! always results in [a, b] (given they compare equal). With unstable sort, the result could also be [b, a].

If stability is expendable, #unstable_sort!(&block : T, T -> U) provides a performance advantage over stable sort.

Raises ArgumentError if for any two elements the block returns nil.


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def sort_by(&block : T -> _) : self #

Returns a new instance with all elements sorted by the output value of the block. The output values are compared via the comparison method T#<=> (see Comparable#<=>), using a stable sort algorithm.

a = Slice["apple", "pear", "fig"]
b = a.sort_by { |word| word.size }
b # => Slice["fig", "pear", "apple"]
a # => Slice["apple", "pear", "fig"]

If stability is expendable, #unstable_sort_by(&block : T -> _) provides a performance advantage over stable sort.

See Indexable::Mutable#sort_by!(&block : T -> _) for details on the sorting mechanism.

Raises ArgumentError if the comparison between any two comparison values returns nil.


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def sort_by!(&block : T -> _) : Slice(T) #

Modifies self by sorting all elements. The given block is called for each element, then the comparison method <=> is called on the object returned from the block to determine sort order.

a = Slice["apple", "pear", "fig"]
a.sort_by! { |word| word.size }
a # => Slice["fig", "pear", "apple"]

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def swap(index0 : Int, index1 : Int) : self #

Swaps the elements at index0 and index1. Returns self.

Negative indices can be used to start counting from the end of the container. Raises IndexError if either index is out of bounds.

a = ["first", "second", "third"]
a.swap(1, 2)  # => ["first", "third", "second"]
a             # => ["first", "third", "second"]
a.swap(0, -1) # => ["second", "third", "first"]
a             # => ["second", "third", "first"]
a.swap(2, 3)  # raises IndexError

Raises if this slice is read-only.


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def to_a #
Description copied from module Indexable(T)

Returns an Array with all the elements in the collection.

{1, 2, 3}.to_a # => [1, 2, 3]

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def to_s(io : IO) : Nil #
Description copied from struct Struct

Same as #inspect(io).


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def to_slice : self #

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def to_unsafe : Pointer(T) #

Returns this slice's pointer.

slice = Slice.new(3, 10)
slice.to_unsafe[0] # => 10

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def to_unsafe_bytes : Bytes #

Returns a new Bytes pointing at the same contents as self.

WARNING This method is unsafe: the returned slice is writable if self is also writable, and modifications through the returned slice may violate the binary representations of Crystal objects. Additionally, the same elements may produce different results depending on the system endianness.

# assume little-endian system
ints = Slice[0x01020304, 0x05060708]
bytes = ints.to_unsafe_bytes # => Bytes[0x04, 0x03, 0x02, 0x01, 0x08, 0x07, 0x06, 0x05]
bytes[2] = 0xAD
ints # => Slice[0x01AD0304, 0x05060708]

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def to_yaml(yaml : YAML::Nodes::Builder) : Nil #

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def unsafe_fetch(index : Int) : T #
Description copied from module Indexable(T)

Returns the element at the given index, without doing any bounds check.

Indexable makes sure to invoke this method with index in 0...size, so converting negative indices to positive ones is not needed here.

Clients never invoke this method directly. Instead, they access elements with #[](index) and #[]?(index).

This method should only be directly invoked if you are absolutely sure the index is in bounds, to avoid a bounds check for a small boost of performance.


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def unsafe_put(index : Int, value : T) #
Description copied from module Indexable::Mutable(T)

Sets the element at the given index to value, without doing any bounds check.

Indexable::Mutable makes sure to invoke this method with index in 0...size, so converting negative indices to positive ones is not needed here.

Clients never invoke this method directly. Instead, they modify elements with #[]=(index, value).

This method should only be directly invoked if you are absolutely sure the index is in bounds, to avoid a bounds check for a small boost of performance.


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def unsafe_slice_of(type : U.class) : Slice(U) forall U #

Returns a new Slice pointing at the same contents as self, but reinterpreted as elements of the given type.

The returned slice never refers to more memory than self; if the last bytes of self do not fit into a U, they are excluded from the returned slice.

WARNING This method is unsafe: elements are reinterpreted using #unsafe_as, and the resulting slice may not be properly aligned. Additionally, the same elements may produce different results depending on the system endianness.

# assume little-endian system
bytes = Bytes[0x01, 0x02, 0x03, 0x04, 0xFF, 0xFE]
bytes.unsafe_slice_of(Int8)  # => Slice[1_i8, 2_i8, 3_i8, 4_i8, -1_i8, -2_i8]
bytes.unsafe_slice_of(Int16) # => Slice[513_i16, 1027_i16, -257_i16]
bytes.unsafe_slice_of(Int32) # => Slice[0x04030201]

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def unstable_sort : self #

Returns a new instance with all elements sorted based on the return value of their comparison method T#<=> (see Comparable#<=>), using an unstable sort algorithm.

a = Slice[3, 1, 2]
a.unstable_sort # => Slice[1, 2, 3]
a               # => Slice[3, 1, 2]

See Indexable::Mutable#unstable_sort! for details on the sorting mechanism.

Raises ArgumentError if the comparison between any two elements returns nil.


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def unstable_sort(&block : T, T -> U) : self forall U #

Returns a new instance with all elements sorted based on the comparator in the given block, using an unstable sort algorithm.

a = Slice[3, 1, 2]
b = a.unstable_sort { |a, b| b <=> a }

b # => Slice[3, 2, 1]
a # => Slice[3, 1, 2]

See Indexable::Mutable#unstable_sort!(&block : T, T -> U) for details on the sorting mechanism.

Raises ArgumentError if for any two elements the block returns nil.


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def unstable_sort! : self #

Sorts all elements in self based on the return value of the comparison method T#<=> (see Comparable#<=>), using an unstable sort algorithm..

slice = Slice[3, 1, 2]
slice.unstable_sort!
slice # => Slice[1, 2, 3]

This sort operation modifies self. See #unstable_sort for a non-modifying option that allocates a new instance.

The sort mechanism is implemented as introsort. It does not guarantee stability between equally comparing elements. This offers higher performance but may be unexpected in some situations.

Stability means that two elements which compare equal (i.e. a <=> b == 0) keep their original relation. Stable sort guarantees that [a, b].sort! always results in [a, b] (given they compare equal). With unstable sort, the result could also be [b, a].

If stability is necessary, use #sort! instead.

Raises ArgumentError if the comparison between any two elements returns nil.


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def unstable_sort!(&block : T, T -> U) : self forall U #

Sorts all elements in self based on the comparator in the given block, using an unstable sort algorithm.

slice = Slice[3, 1, 2]
# This is a reverse sort (forward sort would be `a <=> b`)
slice.unstable_sort! { |a, b| b <=> a }
slice # => Slice[3, 2, 1]

The block must implement a comparison between two elements a and b, where a < b outputs a negative value, a == b outputs 0, and a > b outputs a positive value. The comparison operator (Comparable#<=>) can be used for this.

The block's output type must be <= Int32?, but returning an actual nil value is an error.

This sort operation modifies self. See #unstable_sort(&block : T, T -> U) for a non-modifying option that allocates a new instance.

The sort mechanism is implemented as introsort. It does not guarantee stability between equally comparing elements. This offers higher performance but may be unexpected in some situations.

Stability means that two elements which compare equal (i.e. a <=> b == 0) keep their original relation. Stable sort guarantees that [a, b].sort! always results in [a, b] (given they compare equal). With unstable sort, the result could also be [b, a].

If stability is necessary, use #sort!(&block : T, T -> U) instead.

Raises ArgumentError if for any two elements the block returns nil.


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def unstable_sort_by(&block : T -> _) : self #

Returns a new instance with all elements sorted by the output value of the block. The output values are compared via the comparison method #<=> (see Comparable#<=>), using an unstable sort algorithm.

a = Slice["apple", "pear", "fig"]
b = a.unstable_sort_by { |word| word.size }
b # => Slice["fig", "pear", "apple"]
a # => Slice["apple", "pear", "fig"]

If stability is necessary, use #sort_by(&block : T -> _) instead.

See Indexable::Mutable#unstable_sort!(&block : T -> _) for details on the sorting mechanism.

Raises ArgumentError if the comparison between any two comparison values returns nil.


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def unstable_sort_by!(&block : T -> _) : Slice(T) #

Modifies self by sorting all elements. The given block is called for each element, then the comparison method <=> is called on the object returned from the block to determine sort order.

a = Slice["apple", "pear", "fig"]
a.sort_by! { |word| word.size }
a # => Slice["fig", "pear", "apple"]

This method does not guarantee stability between equally sorting elements. Which results in a performance advantage over stable sort.


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def update(index : Int, & : T -> _) : T #

Yields the current element at the given index and updates the value at that index with the block's value. Returns the new value.

Raises IndexError if trying to set an element outside the container's range.

array = [1, 2, 3]
array.update(1) { |x| x * 2 } # => 4
array                         # => [1, 4, 3]
array.update(5) { |x| x * 2 } # raises IndexError

Raises if this slice is read-only.


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Macro Detail

macro [](*args, read_only = false) #

Creates a new Slice with the given args. The type of the slice will be the union of the type of the given args.

The slice is allocated on the heap.

slice = Slice[1, 'a']
slice[0]    # => 1
slice[1]    # => 'a'
slice.class # => Slice(Char | Int32)

If T is a Number then this is equivalent to Number.slice (numbers will be coerced to the type T)

  • Number.slice is a convenient alternative for designating a specific numerical item type.

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