util

Documentation

Overview

Package util is a very generic package that is used to contain simple functions that may be used in multiple packages, such as the simple random number generator.

Generic re-implementations of built-in Golang structs or functions also sometimes land in here.

This package is affected by the "stdrand" build tag, which will replace the "fastrand" implementation with the "math/rand" random struct.

Index

• Constants
• Variables
• func FastRand() uint32
• func FastRandN(n int) uint32
• func Itoa(v int64) string
• func Uitoa(v uint64) string
• func Uitoa16(v uint64) string
• type Builder
  • func (b *Builder) Cap() int
  • func (b *Builder) Grow(n int)
  • func (b *Builder) InsertByte(c byte) error
  • func (b *Builder) Len() int
  • func (b *Builder) Output() string
  • func (b *Builder) Reset()
  • func (b *Builder) String() string
  • func (b *Builder) Write(p []byte) (int, error)
  • func (b *Builder) WriteByte(c byte) error
  • func (b *Builder) WriteString(s string) (int, error)

Constants

const HexTable = "0123456789ABCDEF"

HexTable is a static string hex mapping constant string. This can be used multiple places to prevent reuse.

Variables

var Rand random

Rand is the custom Random number generator, based on the current time as a seed.

This struct is overridden by the tag "stdrand". By default, it will use the "unsafe" fastrand() implementation which is faster, but contains less entropy than the built-in, 'rand.Rand', which requires more memory and binary storage space.

Functions

func FastRand

func FastRand() uint32

FastRand is a fast thread local random function. This should be used in place instead of 'Rand.Uint32()'.

Taken from https://github.com/dgraph-io/ristretto/blob/master/z/rtutil.go Thanks!

func FastRandN

func FastRandN(n int) uint32

FastRandN is a fast thread local random function. This should be used in place instead of 'Rand.Uint32n()'.

This function will take a max value to specify.

func Itoa

func Itoa(v int64) string

Itoa converts val to a decimal string.

Similar to the "strconv" variant. Taken from the "internal/itoa" package.

func Uitoa

func Uitoa(v uint64) string

Uitoa converts val to a decimal string.

Similar to the "strconv" variant. Taken from the "internal/itoa" package.

func Uitoa16

func Uitoa16(v uint64) string

Uitoa16 converts val to a hexadecimal string.

Types

type Builder

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

A Builder is used to efficiently build a string using Write methods. It minimizes memory copying. The zero value is ready to use. Do not copy a non-zero Builder.

Re-implemented to remove UTF8 dependency and added some useful functions. Copy-check was also removed.

func (*Builder) Cap

func (b *Builder) Cap() int

Cap returns the capacity of the builder's underlying byte slice. It is the total space allocated for the string being built and includes any bytes already written.

func (*Builder) Grow

func (b *Builder) Grow(n int)

Grow grows b's capacity, if necessary, to guarantee space for another n bytes.

After Grow(n), at least n bytes can be written to b without another allocation. If n is negative, Grow is a NOP.

func (*Builder) InsertByte

func (b *Builder) InsertByte(c byte) error

InsertByte appends the byte c to b's buffer at the zero position.

The returned error is always nil.

func (*Builder) Len

func (b *Builder) Len() int

Len returns the number of accumulated bytes; b.Len() == len(b.String()).

func (*Builder) Output

func (b *Builder) Output() string

Output returns the accumulated string, then resets the value of this Builder.

func (*Builder) Reset

func (b *Builder) Reset()

Reset resets the Builder to be empty.

func (*Builder) String

func (b *Builder) String() string

String returns the accumulated string.

func (*Builder) Write

func (b *Builder) Write(p []byte) (int, error)

Write appends the contents of p to b's buffer.

Write always returns len(p), nil.

func (*Builder) WriteByte

func (b *Builder) WriteByte(c byte) error

WriteByte appends the byte c to b's buffer.

The returned error is always nil.

func (*Builder) WriteString

func (b *Builder) WriteString(s string) (int, error)

WriteString appends the contents of s to b's buffer.

It returns the length of s and a nil error.