feat: add UpperKebabCase/UpperSnakeCase

strutil/string_internal.go

@@ -1,40 +1,98 @@
 package strutil
 
-import "strings"
+import "unicode"
 
-// splitWordsToLower split a string into worlds by uppercase char
-func splitWordsToLower(s string) []string {
-	var res []string
+func splitIntoStrings(s string, upperCase bool) []string {
+	var runes [][]rune
+	lastCharType := 0
+	charType := 0
 
-	upperIndexes := upperIndex(s)
-	l := len(upperIndexes)
-	if upperIndexes == nil || l == 0 {
-		if s != "" {
-			res = append(res, s)
+	// split into fields based on type of unicode character
+	for _, r := range s {
+		switch true {
+		case isLower(r):
+			charType = 1
+		case isUpper(r):
+			charType = 2
+		case isDigit(r):
+			charType = 3
+		default:
+			charType = 4
 		}
-		return res
-	}
-	for i := 0; i < l; i++ {
-		if i < l-1 {
-			res = append(res, strings.ToLower(s[upperIndexes[i]:upperIndexes[i+1]]))
+
+		if charType == lastCharType {
+			runes[len(runes)-1] = append(runes[len(runes)-1], r)
 		} else {
-			res = append(res, strings.ToLower(s[upperIndexes[i]:]))
+			runes = append(runes, []rune{r})
 		}
-	}
-	return res
-}
-
-// upperIndex get a int slice which elements are all the uppercase char index of a string
-func upperIndex(s string) []int {
-	var res []int
-	for i := 0; i < len(s); i++ {
-		if 64 < s[i] && s[i] < 91 {
-			res = append(res, i)
-		}
-	}
-	if len(s) > 0 && res != nil && res[0] != 0 {
-		res = append([]int{0}, res...)
+		lastCharType = charType
 	}
 
-	return res
+	for i := 0; i < len(runes)-1; i++ {
+		if isUpper(runes[i][0]) && isLower(runes[i+1][0]) {
+			runes[i+1] = append([]rune{runes[i][len(runes[i])-1]}, runes[i+1]...)
+			runes[i] = runes[i][:len(runes[i])-1]
+		}
+	}
+
+	// filter all none letters and none digit
+	var result []string
+	for _, rs := range runes {
+		if len(rs) > 0 && (unicode.IsLetter(rs[0]) || isDigit(rs[0])) {
+			if upperCase {
+				result = append(result, string(toUpperAll(rs)))
+			} else {
+				result = append(result, string(toLowerAll(rs)))
+			}
+		}
+	}
+
+	return result
+}
+
+// isDigit checks if a character is digit ('0' to '9')
+func isDigit(r rune) bool {
+	return r >= '0' && r <= '9'
+}
+
+// isLower checks if a character is lower case ('a' to 'z')
+func isLower(r rune) bool {
+	return r >= 'a' && r <= 'z'
+}
+
+// isUpper checks if a character is upper case ('A' to 'Z')
+func isUpper(r rune) bool {
+	return r >= 'A' && r <= 'Z'
+}
+
+// toLower converts a character  'A' to 'Z' to its lower case
+func toLower(r rune) rune {
+	if r >= 'A' && r <= 'Z' {
+		return r + 32
+	}
+	return r
+}
+
+// toLowerAll converts a character  'A' to 'Z' to its lower case
+func toLowerAll(rs []rune) []rune {
+	for i := range rs {
+		rs[i] = toLower(rs[i])
+	}
+	return rs
+}
+
+// toUpper converts a character  'a' to 'z' to its upper case
+func toUpper(r rune) rune {
+	if r >= 'a' && r <= 'z' {
+		return r - 32
+	}
+	return r
+}
+
+// toUpperAll converts a character  'a' to 'z' to its upper case
+func toUpperAll(rs []rune) []rune {
+	for i := range rs {
+		rs[i] = toUpper(rs[i])
+	}
+	return rs
 }