feat: first version.

stringcase/stringcase.go

@@ -0,0 +1,119 @@
+package stringcase
+
+import (
+	"strings"
+	"unicode"
+)
+
+// ToSnakeCase 把字符转换为 蛇形命名法（snake_case）
+func ToSnakeCase(input string) string {
+	if input == "" {
+		return input
+	}
+	if len(input) == 1 {
+		return strings.ToLower(input)
+	}
+
+	input = strings.Replace(input, " ", "", -1)
+
+	source := []rune(input)
+	dist := strings.Builder{}
+	dist.Grow(len(input) + len(input)/3) // avoid reallocation memory, 33% ~ 50% is recommended
+	skipNext := false
+	for i := 0; i < len(source); i++ {
+		cur := source[i]
+		switch cur {
+		case '-', '_':
+			dist.WriteRune('_')
+			skipNext = true
+			continue
+		}
+		if unicode.IsLower(cur) || unicode.IsDigit(cur) {
+			dist.WriteRune(cur)
+			continue
+		}
+
+		if i == 0 {
+			dist.WriteRune(unicode.ToLower(cur))
+			continue
+		}
+
+		last := source[i-1]
+		if (!unicode.IsLetter(last)) || unicode.IsLower(last) {
+			if skipNext {
+				skipNext = false
+			} else {
+				dist.WriteRune('_')
+			}
+			dist.WriteRune(unicode.ToLower(cur))
+			continue
+		}
+		// last is upper case
+		if i < len(source)-1 {
+			next := source[i+1]
+			if unicode.IsLower(next) {
+				if skipNext {
+					skipNext = false
+				} else {
+					dist.WriteRune('_')
+				}
+				dist.WriteRune(unicode.ToLower(cur))
+				continue
+			}
+		}
+		dist.WriteRune(unicode.ToLower(cur))
+	}
+
+	return dist.String()
+}
+
+// ToPascalCase 把字符转换为 帕斯卡命名/大驼峰命名法（CamelCase）
+func ToPascalCase(input string) string {
+	return toCamelCase(input, true)
+}
+
+// ToLowCamelCase 把字符转换为 小驼峰命名法（lowerCamelCase）
+func ToLowCamelCase(input string) string {
+	return toCamelCase(input, false)
+}
+
+func toCamelCase(s string, initCase bool) string {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return s
+	}
+
+	var uppercaseAcronym = map[string]string{}
+	if a, ok := uppercaseAcronym[s]; ok {
+		s = a
+	}
+
+	n := strings.Builder{}
+	n.Grow(len(s))
+	capNext := initCase
+	for i, v := range []byte(s) {
+		vIsCap := v >= 'A' && v <= 'Z'
+		vIsLow := v >= 'a' && v <= 'z'
+		if capNext {
+			if vIsLow {
+				v += 'A'
+				v -= 'a'
+			}
+		} else if i == 0 {
+			if vIsCap {
+				v += 'a'
+				v -= 'A'
+			}
+		}
+		if vIsCap || vIsLow {
+			n.WriteByte(v)
+			capNext = false
+		} else if vIsNum := v >= '0' && v <= '9'; vIsNum {
+			n.WriteByte(v)
+			capNext = true
+		} else {
+			capNext = v == '_' || v == ' ' || v == '-' || v == '.'
+		}
+	}
+	return n.String()
+}

stringcase/stringcase_test.go

@@ -0,0 +1,24 @@
+package stringcase
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestToLowCamelCase(t *testing.T) {
+	fmt.Println(ToLowCamelCase("snake_case"))
+	fmt.Println(ToLowCamelCase("CamelCase"))
+	fmt.Println(ToLowCamelCase("lowerCamelCase"))
+}
+
+func TestToPascalCase(t *testing.T) {
+	fmt.Println(ToPascalCase("snake_case"))
+	fmt.Println(ToPascalCase("CamelCase"))
+	fmt.Println(ToPascalCase("lowerCamelCase"))
+}
+
+func TestToSnakeCase(t *testing.T) {
+	fmt.Println(ToSnakeCase("snake_case"))
+	fmt.Println(ToSnakeCase("CamelCase"))
+	fmt.Println(ToSnakeCase("lowerCamelCase"))
+}