add transformation in enum_to_string

README.md

@@ -24,6 +24,8 @@ using list_variant = [:form::util::create_variant(^list):];
 
 ## Enum to string 
 
+Transform enum directly to std::string
+
 ``` c++
 
 enum class Color { red, green, blue };
@@ -34,6 +36,27 @@ void EnumToString() {
 
 ```
 
+If you want to apply some pattern to the formatting of enum value name
+
+``` c++
+void EnumToString() { 
+  auto transform = [](std::string data) {
+    std::string out;
+    out += std::tolower(data[0]);
+    for (auto const c : data.substr(1, data.size())) {
+      if (std::isupper(c))
+        out += "-";
+      out += std::tolower(c);
+    }
+    return out;
+  };
+  form::enum_to_string(Decorator::Underline, transform) //  underline
+  form::enum_to_string(Decorator::DottedUnderline, transform) // dotted-underline
+}
+```
+
+`
+
 ## Variant type to string
 
 ``` c++

include/form/form.h

@@ -32,6 +32,12 @@ constexpr std::string enum_to_string(E value) {
   return result;
 }
 
+template <typename E>
+  requires std::is_enum_v<E>
+constexpr std::string enum_to_string(E value, auto transformation) {
+  return transformation(enum_to_string(value));
+}
+
 template <typename T> bool compare(T const &lhs, T const &rhs) {
   bool result = true;
   if constexpr (std::is_arithmetic_v<T>)

src/test.cpp

@@ -1,13 +1,5 @@
 #include "test.h"
 
-template <typename T>
-  requires form::util::is_one_of<T, Z>
-struct std::formatter<T> : std::formatter<std::string> {
-  auto format(const T &val, std::format_context &ctx) const {
-    return std::format_to(ctx.out(), "{}", form::format_univ(val));
-  }
-};
-
 int main() {
   form::run_tests<^form::tests>();
   form::run_tests<^form::round_trip_tests>();

src/test.h

@@ -322,6 +322,18 @@ using list_variant = [:form::util::create_variant(^list):];
 
 enum class Color { red, green, blue };
 
+enum class Decorator : uint8_t {
+  Underline,
+  DoubleUnderline,
+  CurlyUnderline,
+  DottedUnderline,
+  DashedUnderline,
+  Overline,
+  CrossedOut,
+  Framed,
+  Encircle,
+};
+
 namespace form::examples {
 bool VariantCreate() {
   list_variant v{list::CancelSelection{}};
@@ -335,6 +347,25 @@ bool VariantToString() {
 }
 
 bool EnumToString() { return form::enum_to_string(Color::red) == "red"; }
+
+bool EnumToStringWithTransform() {
+  bool res = true;
+  auto transform = [](std::string data) {
+    std::string out;
+    out += std::tolower(data[0]);
+    for (auto const c : data.substr(1, data.size())) {
+      if (std::isupper(c))
+        out += "-";
+      out += std::tolower(c);
+    }
+    return out;
+  };
+  res &= (form::enum_to_string(Decorator::Underline, transform) == "underline");
+  res &= (form::enum_to_string(Decorator::DottedUnderline, transform) ==
+          "dotted-underline");
+  return res;
+}
+
 } // namespace form::examples
 
 void ExampleConfig() {