bitseq

Documentation

Overview

Package bitseq efficiently implements a general-purpose infinite sequence of bits.

Index

• Variables
• func Read(dest *Store, r io.Reader) error
• type Store
  • func (s *Store) Clear()
  • func (s Store) CountTrue() int
  • func (s *Store) Crop()
  • func (s Store) Get(index int) bool
  • func (s Store) NextFalse(after int) int
  • func (s Store) NextTrue(after int) (int, bool)
  • func (s Store) PrevTrue(before int) (int, bool)
  • func (s *Store) Set(index int, bit bool)
  • func (s Store) String() string
  • func (s Store) Write(w io.Writer) error

Variables

var ErrRange = errors.New("value out of range")

Functions

func Read

func Read(dest *Store, r io.Reader) error

Read reads an opaque binary representation from r into the provided Store, replacing its existing contents iff successful.

Important: While relatively robust against corrupt data, care should be taken when parsing arbitrary input. A malicious actor could craft an input that would allocate a large amount of memory, or attempt to extract information by continuing to consume from the reader. io.LimitReader may be helpful here.

Types

type Store

type Store struct {
	// contains filtered or unexported fields
}

Store is an "infinite" sequence of bits. Trailing zero bits do not necessarily consume any memory.

The zero-value Store is a useful value. The store is not suitable for concurrent use without additional synchronization.

func (*Store) Clear

func (s *Store) Clear()

Clear resets the sequence to zeroes.

func (Store) CountTrue

func (s Store) CountTrue() int

CountTrue returns the number of true bits in the store.

func (*Store) Crop

func (s *Store) Crop()

Crop attempts to reclaim any surplus backing memory consumed by trailing zero bits.

func (Store) Get

func (s Store) Get(index int) bool

Get looks up a bit at a given index, returning true iff it has been set. Panics if index is less than zero.

func (Store) NextFalse

func (s Store) NextFalse(after int) int

NextFalse returns the index of the next false bit found after the given index. To start at the beginning, start with NextFalse(-1).

func (Store) NextTrue

func (s Store) NextTrue(after int) (int, bool)

NextTrue returns the index of the next true bit found after the given index. To start at the beginning, start with NextTrue(-1). If the second return value is false, then the search has finished, and the remaining sequence is an infinite sequence of false bits.

func (Store) PrevTrue

func (s Store) PrevTrue(before int) (int, bool)

PrevTrue returns the index of the previous true bit found before the given index. To start at the end, start with PrevTrue(-1). If the second return value is false, then the search has finished, and the remaining sequence prefix is either empty or all false bits.

func (*Store) Set

func (s *Store) Set(index int, bit bool)

Set sets a bit to true or false at given index.

func (Store) String

func (s Store) String() string

String implements the stringer interface, and prints a bit sequence as '1' and '0' characters from left-to-right. Trailing zeroes are omitted.

func (Store) Write

func (s Store) Write(w io.Writer) error

Write writes an opaque binary representation of the Store into w.