feat: merge some new functions from rc branch

random/random.go

@@ -8,22 +8,30 @@ import (
 	crand "crypto/rand"
 	"fmt"
 	"io"
+	"math"
 	"math/rand"
 	"time"
+	"unsafe"
+
+	"github.com/duke-git/lancet/mathutil"
 )
 
 const (
-	NUMERAL       = "0123456789"
-	LOWER_LETTERS = "abcdefghijklmnopqrstuvwxyz"
-	UPPER_LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-	LETTERS       = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	MaximumCapacity = math.MaxInt>>1 + 1
+	Numeral         = "0123456789"
+	LowwerLetters   = "abcdefghijklmnopqrstuvwxyz"
+	UpperLetters    = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	Letters         = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	SymbolChars     = "!@#$%^&*()_+-=[]{}|;':\",./<>?"
 )
 
+var rn = rand.NewSource(time.Now().UnixNano())
+
 func init() {
 	rand.Seed(time.Now().UnixNano())
 }
 
-// RandInt generate random int between min and max, maybe min,  not be max
+// RandInt generate random int between [min, max).
 func RandInt(min, max int) int {
 	if min == max {
 		return min
@@ -36,7 +44,23 @@ func RandInt(min, max int) int {
 	return rand.Intn(max-min) + min
 }
 
-// RandBytes generate random byte slice
+// RandFloat generate random float64 number between [min, max) with specific precision.
+func RandFloat(min, max float64, precision int) float64 {
+	if min == max {
+		return min
+	}
+
+	if max < min {
+		min, max = max, min
+	}
+
+	n := rand.Float64()*(max-min) + min
+
+	return mathutil.RoundToFloat(n, precision)
+}
+
+// RandBytes generate random byte slice.
+// Play: https://go.dev/play/p/EkiLESeXf8d
 func RandBytes(length int) []byte {
 	if length < 1 {
 		return []byte{}
@@ -46,48 +70,99 @@ func RandBytes(length int) []byte {
 	if _, err := io.ReadFull(crand.Reader, b); err != nil {
 		return nil
 	}
+
 	return b
 }
 
-// RandString generate random string
+// RandString generate random alpha string of specified length.
 func RandString(length int) string {
-	return random(LETTERS, length)
+	return random(Letters, length)
 }
 
-// RandUpper generate a random upper case string
+// RandUpper generate a random upper case string of specified length.
 func RandUpper(length int) string {
-	return random(UPPER_LETTERS, length)
+	return random(UpperLetters, length)
 }
 
-// RandLower generate a random lower case string
+// RandLower generate a random lower case string of specified length.
 func RandLower(length int) string {
-	return random(LOWER_LETTERS, length)
+	return random(LowwerLetters, length)
 }
 
-// RandNumeral generate a random numeral string
+// RandNumeral generate a random numeral string of specified length.
 func RandNumeral(length int) string {
-	return random(NUMERAL, length)
+	return random(Numeral, length)
 }
 
-// RandNumeralOrLetter generate a random numeral or letter string
+// RandNumeralOrLetter generate a random numeral or alpha string of specified length.
 func RandNumeralOrLetter(length int) string {
-	return random(NUMERAL+LETTERS, length)
+	return random(Numeral+Letters, length)
 }
 
-// random generate a random string based on given string range
-func random(s string, length int) string {
-	b := make([]byte, length)
+// RandSymbolChar generate a random symbol char of specified length.
+// symbol chars: !@#$%^&*()_+-=[]{}|;':\",./<>?.
+func RandSymbolChar(length int) string {
+	return random(SymbolChars, length)
+}
 
-	// fix: https://github.com/duke-git/lancet/issues/75
-	// r := rand.New(rand.NewSource(time.Now().UnixNano()))
-
-	for i := range b {
-		b[i] = s[rand.Int63()%int64(len(s))]
+// nearestPowerOfTwo 返回一个大于等于cap的最近的2的整数次幂，参考java8的hashmap的tableSizeFor函数
+func nearestPowerOfTwo(cap int) int {
+	n := cap - 1
+	n |= n >> 1
+	n |= n >> 2
+	n |= n >> 4
+	n |= n >> 8
+	n |= n >> 16
+	if n < 0 {
+		return 1
+	} else if n >= MaximumCapacity {
+		return MaximumCapacity
 	}
-	return string(b)
+	return n + 1
 }
 
-// UUIdV4 generate a random UUID of version 4 according to RFC 4122
+// random generate a random string based on given string range.
+func random(s string, length int) string {
+	// 仿照strings.Builder
+	// 创建一个长度为 length 的字节切片
+	bytes := make([]byte, length)
+	strLength := len(s)
+	if strLength <= 0 {
+		return ""
+	} else if strLength == 1 {
+		for i := 0; i < length; i++ {
+			bytes[i] = s[0]
+		}
+		return *(*string)(unsafe.Pointer(&bytes))
+	}
+	// s的字符需要使用多少个比特位数才能表示完
+	// letterIdBits := int(math.Ceil(math.Log2(strLength))),下面比上面的代码快
+	letterIdBits := int(math.Log2(float64(nearestPowerOfTwo(strLength))))
+	// 最大的字母id掩码
+	var letterIdMask int64 = 1<<letterIdBits - 1
+	// 可用次数的最大值
+	letterIdMax := 63 / letterIdBits
+	// 循环生成随机字符串
+	for i, cache, remain := length-1, rn.Int63(), letterIdMax; i >= 0; {
+		// 检查随机数生成器是否用尽所有随机数
+		if remain == 0 {
+			cache, remain = rn.Int63(), letterIdMax
+		}
+		// 从可用字符的字符串中随机选择一个字符
+		if idx := int(cache & letterIdMask); idx < strLength {
+			bytes[i] = s[idx]
+			i--
+		}
+		// 右移比特位数，为下次选择字符做准备
+		cache >>= letterIdBits
+		remain--
+	}
+	// 仿照strings.Builder用unsafe包返回一个字符串，避免拷贝
+	// 将字节切片转换为字符串并返回
+	return *(*string)(unsafe.Pointer(&bytes))
+}
+
+// UUIdV4 generate a random UUID of version 4 according to RFC 4122.
 func UUIdV4() (string, error) {
 	uuid := make([]byte, 16)
 
@@ -125,3 +200,136 @@ func RandUniqueIntSlice(n, min, max int) []int {
 
 	return nums
 }
+
+// RandFloats generate a slice of random float64 numbers of length n that do not repeat.
+func RandFloats(n int, min, max float64, precision int) []float64 {
+	nums := make([]float64, n)
+	used := make(map[float64]struct{}, n)
+	for i := 0; i < n; {
+		r := RandFloat(min, max, precision)
+		if _, use := used[r]; use {
+			continue
+		}
+		used[r] = struct{}{}
+		nums[i] = r
+		i++
+	}
+
+	return nums
+}
+
+// const (
+// 	NUMERAL       = "0123456789"
+// 	LOWER_LETTERS = "abcdefghijklmnopqrstuvwxyz"
+// 	UPPER_LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+// 	LETTERS       = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+// )
+
+// var rn = rand.NewSource(time.Now().UnixNano())
+
+// func init() {
+// 	rand.Seed(time.Now().UnixNano())
+// }
+
+// // RandInt generate random int between min and max, maybe min,  not be max
+// func RandInt(min, max int) int {
+// 	if min == max {
+// 		return min
+// 	}
+
+// 	if max < min {
+// 		min, max = max, min
+// 	}
+
+// 	return rand.Intn(max-min) + min
+// }
+
+// // RandBytes generate random byte slice
+// func RandBytes(length int) []byte {
+// 	if length < 1 {
+// 		return []byte{}
+// 	}
+// 	b := make([]byte, length)
+
+// 	if _, err := io.ReadFull(crand.Reader, b); err != nil {
+// 		return nil
+// 	}
+// 	return b
+// }
+
+// // RandString generate random string
+// func RandString(length int) string {
+// 	return random(LETTERS, length)
+// }
+
+// // RandUpper generate a random upper case string
+// func RandUpper(length int) string {
+// 	return random(UPPER_LETTERS, length)
+// }
+
+// // RandLower generate a random lower case string
+// func RandLower(length int) string {
+// 	return random(LOWER_LETTERS, length)
+// }
+
+// // RandNumeral generate a random numeral string
+// func RandNumeral(length int) string {
+// 	return random(NUMERAL, length)
+// }
+
+// // RandNumeralOrLetter generate a random numeral or letter string
+// func RandNumeralOrLetter(length int) string {
+// 	return random(NUMERAL+LETTERS, length)
+// }
+
+// // random generate a random string based on given string range
+// func random(s string, length int) string {
+// 	b := make([]byte, length)
+
+// 	// fix: https://github.com/duke-git/lancet/issues/75
+// 	// r := rand.New(rand.NewSource(time.Now().UnixNano()))
+
+// 	for i := range b {
+// 		b[i] = s[rand.Int63()%int64(len(s))]
+// 	}
+// 	return string(b)
+// }
+
+// // UUIdV4 generate a random UUID of version 4 according to RFC 4122
+// func UUIdV4() (string, error) {
+// 	uuid := make([]byte, 16)
+
+// 	n, err := io.ReadFull(crand.Reader, uuid)
+// 	if n != len(uuid) || err != nil {
+// 		return "", err
+// 	}
+
+// 	uuid[8] = uuid[8]&^0xc0 | 0x80
+// 	uuid[6] = uuid[6]&^0xf0 | 0x40
+
+// 	return fmt.Sprintf("%x-%x-%x-%x-%x", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:]), nil
+// }
+
+// // RandUniqueIntSlice generate a slice of random int of length n that do not repeat.
+// func RandUniqueIntSlice(n, min, max int) []int {
+// 	if min > max {
+// 		return []int{}
+// 	}
+// 	if n > max-min {
+// 		n = max - min
+// 	}
+
+// 	nums := make([]int, n)
+// 	used := make(map[int]struct{}, n)
+// 	for i := 0; i < n; {
+// 		r := RandInt(min, max)
+// 		if _, use := used[r]; use {
+// 			continue
+// 		}
+// 		used[r] = struct{}{}
+// 		nums[i] = r
+// 		i++
+// 	}
+
+// 	return nums
+// }