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Copy pathgrand.go
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188 lines (174 loc) · 4.53 KB
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// Copyright 2017 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.
// Package grand provides high performance random bytes/number/string generation functionality.
package grand
import (
"encoding/binary"
"unsafe"
)
var (
letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" // 52
symbols = "!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~" // 32
digits = "0123456789" // 10
characters = letters + digits + symbols // 94
)
// Intn returns a int number which is between 0 and max: [0, max).
//
// Note that:
// 1. The <max> can only be greater than 0, or else it returns <max> directly;
// 2. The result is greater than or equal to 0, but less than <max>;
// 3. The result number is 32bit and less than math.MaxUint32.
func Intn(max int) int {
if max <= 0 {
return max
}
n := int(binary.LittleEndian.Uint32(<-bufferChan)) % max
if (max > 0 && n < 0) || (max < 0 && n > 0) {
return -n
}
return n
}
// B retrieves and returns random bytes of given length <n>.
func B(n int) []byte {
if n <= 0 {
return nil
}
i := 0
b := make([]byte, n)
for {
copy(b[i:], <-bufferChan)
i += 4
if i >= n {
break
}
}
return b
}
// N returns a random int between min and max: [min, max].
// The <min> and <max> also support negative numbers.
func N(min, max int) int {
if min >= max {
return min
}
if min >= 0 {
// Because Intn dose not support negative number,
// so we should first shift the value to left,
// then call Intn to produce the random number,
// and finally shift the result back to right.
return Intn(max-(min-0)+1) + (min - 0)
}
if min < 0 {
// Because Intn dose not support negative number,
// so we should first shift the value to right,
// then call Intn to produce the random number,
// and finally shift the result back to left.
return Intn(max+(0-min)+1) - (0 - min)
}
return 0
}
// S returns a random string which contains digits and letters, and its length is <n>.
// The optional parameter <symbols> specifies whether the result could contain symbols,
// which is false in default.
func S(n int, symbols ...bool) string {
if n <= 0 {
return ""
}
var (
b = make([]byte, n)
numberBytes = B(n)
)
for i := range b {
if len(symbols) > 0 && symbols[0] {
b[i] = characters[numberBytes[i]%94]
} else {
b[i] = characters[numberBytes[i]%62]
}
}
return *(*string)(unsafe.Pointer(&b))
}
// Str randomly picks and returns <n> count of chars from given string <s>.
// It also supports unicode string like Chinese/Russian/Japanese, etc.
func Str(s string, n int) string {
if n <= 0 {
return ""
}
var (
b = make([]rune, n)
runes = []rune(s)
)
if len(runes) <= 255 {
numberBytes := B(n)
for i := range b {
b[i] = runes[int(numberBytes[i])%len(runes)]
}
} else {
for i := range b {
b[i] = runes[Intn(len(runes))]
}
}
return string(b)
}
// Digits returns a random string which contains only digits, and its length is <n>.
func Digits(n int) string {
if n <= 0 {
return ""
}
var (
b = make([]byte, n)
numberBytes = B(n)
)
for i := range b {
b[i] = digits[numberBytes[i]%10]
}
return *(*string)(unsafe.Pointer(&b))
}
// Letters returns a random string which contains only letters, and its length is <n>.
func Letters(n int) string {
if n <= 0 {
return ""
}
var (
b = make([]byte, n)
numberBytes = B(n)
)
for i := range b {
b[i] = letters[numberBytes[i]%52]
}
return *(*string)(unsafe.Pointer(&b))
}
// Symbols returns a random string which contains only symbols, and its length is <n>.
func Symbols(n int) string {
if n <= 0 {
return ""
}
var (
b = make([]byte, n)
numberBytes = B(n)
)
for i := range b {
b[i] = symbols[numberBytes[i]%32]
}
return *(*string)(unsafe.Pointer(&b))
}
// Perm returns, as a slice of n int numbers, a pseudo-random permutation of the integers [0,n).
// TODO performance improving for large slice producing.
func Perm(n int) []int {
m := make([]int, n)
for i := 0; i < n; i++ {
j := Intn(i + 1)
m[i] = m[j]
m[j] = i
}
return m
}
// Meet randomly calculate whether the given probability <num>/<total> is met.
func Meet(num, total int) bool {
return Intn(total) < num
}
// MeetProb randomly calculate whether the given probability is met.
func MeetProb(prob float32) bool {
return Intn(1e7) < int(prob*1e7)
}