simple8b

Documentation

Overview

Package simple8b implements the 64bit integer encoding algoritm as published by Ann and Moffat in "Index compression using 64-bit words", Softw. Pract. Exper. 2010; 40:131–147

It is capable of encoding multiple integers with values betweeen 0 and to 1^60 -1, in a single word.

Index

• Constants
• func Count(v uint64) (int, error)
• func CountBytes(b []byte) (int, error)
• func CountBytesBetween(b []byte, min, max uint64) (int, error)
• func Decode(dst *[240]uint64, v uint64) (n int, err error)
• func DecodeAll(dst, src []uint64) (value int, err error)
• func Encode(src []uint64) (value uint64, n int, err error)
• func EncodeAll(src []uint64) ([]uint64, error)
• func ForEach(b []byte, fn func(v uint64) bool) error
• type Decoder
  • func NewDecoder(b []byte) *Decoder
  • func (d *Decoder) Next() bool
  • func (d *Decoder) Read() uint64
  • func (d *Decoder) SetBytes(b []byte)
• type Encoder
  • func NewEncoder() *Encoder
  • func (e *Encoder) Bytes() ([]byte, error)
  • func (e *Encoder) Reset()
  • func (e *Encoder) SetValues(v []uint64)
  • func (e *Encoder) Write(v uint64) error

Constants

const MaxValue = (1 << 60) - 1

Functions

func Count

func Count(v uint64) (int, error)

Count returns the number of integers encoded within an uint64

func CountBytes

func CountBytes(b []byte) (int, error)

Count returns the number of integers encoded in the byte slice

func CountBytesBetween

func CountBytesBetween(b []byte, min, max uint64) (int, error)

func Decode

func Decode(dst *[240]uint64, v uint64) (n int, err error)

func DecodeAll

func DecodeAll(dst, src []uint64) (value int, err error)

Decode writes the uncompressed values from src to dst. It returns the number of values written or an error.

func Encode

func Encode(src []uint64) (value uint64, n int, err error)

Encode packs as many values into a single uint64. It returns the packed uint64, how many values from src were packed, or an error if the values exceed the maximum value range.

func EncodeAll

func EncodeAll(src []uint64) ([]uint64, error)

Encode returns a packed slice of the values from src. If a value is over 1 << 60, an error is returned. The input src is modified to avoid extra allocations. If you need to re-use, use a copy.

func ForEach

func ForEach(b []byte, fn func(v uint64) bool) error

Types

type Decoder

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

Decoder converts a compressed byte slice to a stream of unsigned 64bit integers.

func NewDecoder

func NewDecoder(b []byte) *Decoder

NewDecoder returns a Decoder from a byte slice

func (*Decoder) Next

func (d *Decoder) Next() bool

Next returns true if there are remaining values to be read. Successive calls to Next advance the current element pointer.

func (*Decoder) Read

func (d *Decoder) Read() uint64

Read returns the current value. Successive calls to Read return the same value.

func (*Decoder) SetBytes

func (d *Decoder) SetBytes(b []byte)

type Encoder

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

Encoder converts a stream of unsigned 64bit integers to a compressed byte slice.

func NewEncoder

func NewEncoder() *Encoder

NewEncoder returns an Encoder able to convert uint64s to compressed byte slices

func (*Encoder) Bytes

func (e *Encoder) Bytes() ([]byte, error)

func (*Encoder) Reset

func (e *Encoder) Reset()

func (*Encoder) SetValues

func (e *Encoder) SetValues(v []uint64)

func (*Encoder) Write

func (e *Encoder) Write(v uint64) error