Add comprehensive case conversion utilities

.cursor/commands/pr.md

@@ -0,0 +1,10 @@
+Create a Pull Request
+
+- Make sure local changes are committed and pushed, if not ask user to do it
+- Compare the current branch to origin/main
+- Read through the changes and commits
+- Raise a pull request using the gh cli, you might have to `unset GITHUB_TOKEN` if auth issues occur.
+- Don't ever fork, we work directly on the originally repo with branches
+- Use a succint title
+- Keep the description to the point and do not hallucinate
+- Use a temporary file for PR description and remove it later with rm linux command.

sx.go

@@ -169,13 +169,25 @@ func capitalizeWord(word string) string {
 }
 
 // joinWords joins words with a separator
-func joinWords(words []string, separator string, transform func(string, int) string) string {
+func joinWords(words []string, separator string, preserveEmpty bool, transform func(string, int) string) string {
 	if len(words) == 0 {
 		return ""
 	}
 
+	// Filter out empty words if not preserving them
+	wordsToUse := words
+	if !preserveEmpty {
+		var filteredWords []string
+		for _, word := range words {
+			if word != "" {
+				filteredWords = append(filteredWords, word)
+			}
+		}
+		wordsToUse = filteredWords
+	}
+
 	var result strings.Builder
-	for i, word := range words {
+	for i, word := range wordsToUse {
 		if i > 0 && separator != "" {
 			result.WriteString(separator)
 		}
@@ -215,14 +227,14 @@ func PascalCase[T StringOrStringSlice](input T, opts ...CaseOption) string {
 	switch v := any(input).(type) {
 	case string:
 		words := splitByCaseWithCustomSeparators(v, nil)
-		result := joinWords(words, "", func(word string, i int) string {
+		result := joinWords(words, "", false, func(word string, i int) string {
 			normalized := normalizeWord(word, options.Normalize)
 			return capitalizeWord(normalized)
 		})
 
 		return result
 	case []string:
-		result := joinWords(v, "", func(word string, i int) string {
+		result := joinWords(v, "", false, func(word string, i int) string {
 			normalized := normalizeWord(word, options.Normalize)
 			return capitalizeWord(normalized)
 		})
@@ -263,7 +275,7 @@ func CamelCase[T StringOrStringSlice](input T, opts ...CaseOption) string {
 			opt(&options)
 		}
 
-		result := joinWords(v, "", func(word string, i int) string {
+		result := joinWords(v, "", false, func(word string, i int) string {
 			normalized := normalizeWord(word, options.Normalize)
 			if i == 0 {
 				return lowercaseWord(normalized)
@@ -276,3 +288,73 @@ func CamelCase[T StringOrStringSlice](input T, opts ...CaseOption) string {
 		return ""
 	}
 }
+
+// KebabCase converts input to kebab-case
+func KebabCase[T StringOrStringSlice](input T, separator ...string) string {
+	sep := "-"
+	if len(separator) > 0 {
+		sep = separator[0]
+	}
+
+	switch v := any(input).(type) {
+	case string:
+		words := splitByCaseWithCustomSeparators(v, nil)
+		result := joinWords(words, sep, true, func(word string, i int) string {
+			return strings.ToLower(word)
+		})
+		return result
+	case []string:
+		result := joinWords(v, sep, true, func(word string, i int) string {
+			return strings.ToLower(word)
+		})
+		return result
+	default:
+		return ""
+	}
+}
+
+// SnakeCase converts input to snake_case
+func SnakeCase[T StringOrStringSlice](input T) string {
+	return KebabCase(input, "_")
+}
+
+// TrainCase converts input to Train-Case
+func TrainCase[T StringOrStringSlice](input T, opts ...CaseOption) string {
+	options := CaseConfig{}
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	switch v := any(input).(type) {
+	case string:
+		words := splitByCaseWithCustomSeparators(v, nil)
+		result := joinWords(words, "-", false, func(word string, i int) string {
+			normalized := normalizeWord(word, options.Normalize)
+			return capitalizeWord(normalized)
+		})
+		return result
+	case []string:
+		result := joinWords(v, "-", false, func(word string, i int) string {
+			normalized := normalizeWord(word, options.Normalize)
+			return capitalizeWord(normalized)
+		})
+		return result
+	default:
+		return ""
+	}
+}
+
+// FlatCase converts input to flatcase (no separators)
+func FlatCase[T StringOrStringSlice](input T) string {
+	return KebabCase(input, "")
+}
+
+// UpperFirst converts the first character to uppercase
+func UpperFirst(s string) string {
+	return capitalizeWord(s)
+}
+
+// LowerFirst converts the first character to lowercase
+func LowerFirst(s string) string {
+	return lowercaseWord(s)
+}

sx_test.go

@@ -369,3 +369,254 @@ func TestCamelCaseWithSlice(t *testing.T) {
 		})
 	}
 }
+
+func TestKebabCase(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		expected  string
+		separator string
+	}{
+		{
+			name:     "camelCase to kebab-case",
+			input:    "camelCase",
+			expected: "camel-case",
+		},
+		{
+			name:     "PascalCase to kebab-case",
+			input:    "PascalCase",
+			expected: "pascal-case",
+		},
+		{
+			name:     "snake_case to kebab-case",
+			input:    "snake_case",
+			expected: "snake-case",
+		},
+		{
+			name:     "XMLHttpRequest to kebab-case",
+			input:    "XMLHttpRequest",
+			expected: "xml-http-request",
+		},
+		{
+			name:      "custom separator",
+			input:     "camelCase",
+			expected:  "camel|case",
+			separator: "|",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "single word",
+			input:    "word",
+			expected: "word",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var result string
+
+			if tt.separator != "" {
+				result = sx.KebabCase(tt.input, tt.separator)
+			} else {
+				result = sx.KebabCase(tt.input)
+			}
+
+			if result != tt.expected {
+				t.Errorf("KebabCase(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestSnakeCase(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "camelCase to snake_case",
+			input:    "camelCase",
+			expected: "camel_case",
+		},
+		{
+			name:     "PascalCase to snake_case",
+			input:    "PascalCase",
+			expected: "pascal_case",
+		},
+		{
+			name:     "kebab-case to snake_case",
+			input:    "kebab-case",
+			expected: "kebab_case",
+		},
+		{
+			name:     "XMLHttpRequest to snake_case",
+			input:    "XMLHttpRequest",
+			expected: "xml_http_request",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "single word",
+			input:    "word",
+			expected: "word",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := sx.SnakeCase(tt.input)
+			if result != tt.expected {
+				t.Errorf("SnakeCase(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestTrainCase(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+		options  []sx.CaseOption
+	}{
+		{
+			name:     "camelCase to Train-Case",
+			input:    "camelCase",
+			expected: "Camel-Case",
+		},
+		{
+			name:     "snake_case to Train-Case",
+			input:    "snake_case",
+			expected: "Snake-Case",
+		},
+		{
+			name:     "XMLHttpRequest to Train-Case",
+			input:    "XMLHttpRequest",
+			expected: "XML-Http-Request",
+		},
+		{
+			name:     "XMLHttpRequest normalized",
+			input:    "XMLHttpRequest",
+			expected: "Xml-Http-Request",
+			options:  []sx.CaseOption{sx.WithNormalize(true)},
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "single word",
+			input:    "word",
+			expected: "Word",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := sx.TrainCase(tt.input, tt.options...)
+			if result != tt.expected {
+				t.Errorf("TrainCase(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestFlatCase(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "camelCase to flatcase",
+			input:    "camelCase",
+			expected: "camelcase",
+		},
+		{
+			name:     "PascalCase to flatcase",
+			input:    "PascalCase",
+			expected: "pascalcase",
+		},
+		{
+			name:     "kebab-case to flatcase",
+			input:    "kebab-case",
+			expected: "kebabcase",
+		},
+		{
+			name:     "XMLHttpRequest to flatcase",
+			input:    "XMLHttpRequest",
+			expected: "xmlhttprequest",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "single word",
+			input:    "Word",
+			expected: "word",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := sx.FlatCase(tt.input)
+			if result != tt.expected {
+				t.Errorf("FlatCase(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestEdgeCases(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		function func(string) string
+		expected string
+	}{
+		{
+			name:     "unicode characters",
+			input:    "helloWörld",
+			function: func(s string) string { return sx.CamelCase(s) },
+			expected: "helloWörld",
+		},
+		{
+			name:     "numbers in string",
+			input:    "html5Parser",
+			function: func(s string) string { return sx.PascalCase(s) },
+			expected: "Html5Parser",
+		},
+		{
+			name:     "consecutive uppercase",
+			input:    "HTTPSConnection",
+			function: func(s string) string { return sx.KebabCase(s) },
+			expected: "https-connection",
+		},
+		{
+			name:     "mixed separators",
+			input:    "hello_world-test.case/example",
+			function: func(s string) string { return sx.CamelCase(s) },
+			expected: "helloWorldTestCaseExample",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := tt.function(tt.input)
+			if result != tt.expected {
+				t.Errorf("Function(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}