gf/g/util/grand/grand.go

// 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 string generation functionality.
package grand

var (
    letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
    digits  = []rune("0123456789")
)

// 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)
}

// N returns a random int between min and max - [min, max].
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 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 to left.
		return Intn(max + (0 - min) + 1) - (0 - min)
	}
	return 0
}

// Deprecated.
// Alias of N.
func Rand (min, max int) int {
	return N(min, max)
}

// Str returns a random string which contains digits and letters, and its length is <n>.
func Str(n int) string {
	b := make([]rune, n)
	for i := range b {
		if Intn(2) == 1 {
			b[i] = digits[Intn(10)]
		} else {
			b[i] = letters[Intn(52)]
		}
	}
	return string(b)
}

// Deprecated.
// Alias of Str.
func RandStr(n int) string {
	return Str(n)
}

// Digits returns a random string which contains only digits, and its length is <n>.
func Digits(n int) string {
	b := make([]rune, n)
	for i := range b {
		b[i] = digits[Intn(10)]
	}
	return string(b)

}

// Deprecated.
// Alias of Digits.
func RandDigits(n int) string {
	return Digits(n)
}

// Letters returns a random string which contains only letters, and its length is <n>.
func Letters(n int) string {
	b := make([]rune, n)
	for i := range b {
		b[i] = letters[Intn(52)]
	}
	return string(b)

}

// Deprecated.
// Alias of Letters.
func RandLetters(n int) string {
	return Letters(n)
}

// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
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
}