add CamelToSnake

internal/3rdparty/snaker/snaker.go

@@ -8,6 +8,44 @@ import (
 	"unicode"
 )
 
+// CamelToSnake converts a given string to snake case
+func CamelToSnake(s string) string {
+	var result string
+	var words []string
+	var lastPos int
+	rs := []rune(s)
+
+	for i := 0; i < len(rs); i++ {
+		if i > 0 && unicode.IsUpper(rs[i]) {
+			if initialism := startsWithInitialism(s[lastPos:]); initialism != "" {
+				words = append(words, initialism)
+
+				i += len(initialism) - 1
+				lastPos = i
+				continue
+			}
+
+			words = append(words, s[lastPos:i])
+			lastPos = i
+		}
+	}
+
+	// append the last word
+	if s[lastPos:] != "" {
+		words = append(words, s[lastPos:])
+	}
+
+	for k, word := range words {
+		if k > 0 {
+			result += "_"
+		}
+
+		result += strings.ToLower(word)
+	}
+
+	return result
+}
+
 // SnakeToCamel returns a string converted from snake case to uppercase
 func SnakeToCamel(s string, firstLetterUppercase ...bool) string {
 	upperCase := true
@@ -48,6 +86,18 @@ func snakeToCamel(s string, upperCase bool) string {
 	return result
 }
 
+// startsWithInitialism returns the initialism if the given string begins with it
+func startsWithInitialism(s string) string {
+	var initialism string
+	// the longest initialism is 5 char, the shortest 2
+	for i := 1; i <= 5; i++ {
+		if len(s) > i-1 && commonInitialisms[s[:i]] {
+			initialism = s[:i]
+		}
+	}
+	return initialism
+}
+
 func toLowerFirstLetter(s string) string {
 	if s == "" {
 		return s