BitArray

struct BitArray

Overview

BitArray is an array data structure that compactly stores bits.

Bits externally represented as Bools are stored internally as UInt32s. The total number of bits stored is set at creation and is immutable.

BitArray includes all the methods in Enumerable-

Example

require "bit_array"

ba = BitArray.new(12) # => "BitArray[000000000000]"
ba[2]                 # => false
0.upto(5) { |i| ba[i * 2] = true }
ba    # => "BitArray[101010101010]"
ba[2] # => true

Included Modules

Indexable(Bool)

Defined in:

bit_array.cr

Class Method Summary

.new(size, initial : Bool = false)
Create a new BitArray of size bits.

Instance Method Summary

#[]=(index, value : Bool)
Sets the bit at the given index.
#inspect(io : IO)
Creates a string representation of self.
#invert
Inverts all bits in the array.
#size : Int32
The number of bits the BitArray stores
#to_s(io : IO)
Creates a string representation of self.
#to_slice : Bytes
Returns a Bytes able to read and write bytes from a buffer.
#toggle(index)
Toggles the bit at the given index.
#unsafe_at(index : Int)

Instance methods inherited from module `Indexable(Bool)`

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Instance methods inherited from module `Enumerable(Bool)`

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Instance methods inherited from module `Iterable(Bool)`

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Instance methods inherited from struct `Struct`

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Instance methods inherited from struct `Value`

Instance methods inherited from class `Object`

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Class methods inherited from class `Object`

Class Method Detail

def self.new(size, initial : Bool = false)Source

Create a new BitArray of size bits.

initial optionally sets the starting value, true or false, for all bits in the array.

Instance Method Detail

def []=(index, value : Bool)Source

Sets the bit at the given index. Negative indices can be used to start counting from the end of the array. Raises IndexError if trying to access a bit outside the array's range-

ba = BitArray.new(5)
ba[3] = true

def inspect(io : IO)Source

Creates a string representation of self.

ba = BitArray.new(5)
ba.to_s # => "BitArray[00000]"

def invertSource

Inverts all bits in the array. Falses become true and vice versa.

ba = BitArray.new(5)
ba[2] = true; ba[3] = true
ba # => BitArray[00110]
ba.invert
ba # => BitArray[11001]

def size : Int32 Source

The number of bits the BitArray stores

def to_s(io : IO)Source

Creates a string representation of self.

ba = BitArray.new(5)
ba.to_s # => "BitArray[00000]"

def to_slice : Bytes Source

Returns a Bytes able to read and write bytes from a buffer. The slice will be long enough to hold all the bits groups in bytes despite the UInt32 internal representation. It's useful for reading and writing a bit array from a byte buffer directly.

def toggle(index)Source

Toggles the bit at the given index. A false bit becomes a true bit, and vice versa. Negative indices can be used to start counting from the end of the array. Raises IndexError if trying to access a bit outside the array's range-

ba = BitArray.new(5)
ba[3] # => false
ba.toggle(3)
ba[3] # => true

def unsafe_at(index : Int)Source

© 2012–2017 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.22.0/BitArray.html