Further reorganise unicode.hpp

Create a unicode_cast<utf8::string, ucs4::char_t> specialisation.
Move remaining functions in the utils namespace to implemenation.

src/help.cpp

@@ -3347,7 +3347,7 @@ std::string get_first_word(const std::string &s)
 
 	ucs4::char_t firstchar = *ch;
 	if (font::is_cjk_char(firstchar)) {
-		re = utils::ucs4char_to_string(firstchar);
+		re = unicode_cast<utf8::string>(firstchar);
 	}
 	return re;
 }

src/hotkey/hotkey_item.cpp

@@ -462,7 +462,7 @@ void hotkey_item::save(config& item) const
 	if (get_hat()       >= 0) item["hat"]      = get_hat();
 	if (get_value()     >= 0) item["value"]    = get_value();
 	if (get_keycode()   >= 0) item["key"]      = SDL_GetKeyName(SDLKey(get_keycode()));
-	if (get_character() >= 0) item["key"]      = utils::ucs4char_to_string(get_character());
+	if (get_character() >= 0) item["key"]      = unicode_cast<utf8::string, ucs4::char_t>(get_character()); // Second template argument because get_character returns a signed int
 	if (get_mouse()     >= 0) item["mouse"]    = get_mouse();
 	if (get_button()    >= 0) item["button"]   = get_button();
 

src/serialization/unicode.cpp

@@ -52,7 +52,7 @@ size_t byte_size_from_ucs4_codepoint(ucs4::char_t ch)
 }
 } // anonymous namespace
 
-namespace utils {
+namespace implementation {
 std::string ucs4string_to_string(const ucs4::string &src)
 {
 	std::string ret;
@@ -139,7 +139,7 @@ utf16::string ucs4string_to_utf16string(const ucs4::string &src)
 	return res;
 }
 
-} // utils namespace
+} // implementation namespace
 
 namespace utf8 {
 
@@ -257,7 +257,7 @@ utf8::string lowercase(const utf8::string& s)
 {
 	if(!s.empty()) {
 		utf8::iterator itor(s);
-		std::string res;
+		utf8::string res;
 
 		for(;itor != utf8::iterator::end(s); ++itor) {
 			ucs4::char_t uchar = *itor;
@@ -265,7 +265,7 @@ utf8::string lowercase(const utf8::string& s)
 			if(uchar <= static_cast<ucs4::char_t>(std::numeric_limits<wchar_t>::max()) &&
 			   uchar >= static_cast<ucs4::char_t>(std::numeric_limits<wchar_t>::min()))
 				uchar = towlower(static_cast<wchar_t>(uchar));
-			res += utils::ucs4char_to_string(uchar);
+			res += unicode_cast<utf8::string>(uchar);
 		}
 
 		res.append(itor.substr().second, s.end());
@@ -327,10 +327,10 @@ utf8::string& truncate(utf8::string& str, const size_t size)
 
 void truncate_as_ucs4(utf8::string &str, const size_t size)
 {
-	ucs4::string u4_str = utils::string_to_ucs4string(str);
+	ucs4::string u4_str = unicode_cast<ucs4::string>(str);
 	if(u4_str.size() > size) {
 		u4_str.resize(size);
-		str = utils::ucs4string_to_string(u4_str);
+		str = unicode_cast<utf8::string>(u4_str);
 	}
 }
 

src/serialization/unicode.hpp

@@ -117,15 +117,12 @@ namespace utf8 {
 	void truncate_as_ucs4(utf8::string& str, const size_t size);
 } // end namespace utf8
 
-namespace utils {
+namespace implementation {
 	std::string ucs4string_to_string(const ucs4::string &);
 	ucs4::string string_to_ucs4string(const std::string &);
 	std::string ucs4char_to_string(const ucs4::char_t);
-
 	utf16::string ucs4string_to_utf16string(const ucs4::string &);
-
-
-} // end namespace utils
+} // end namespace implementation
 
 template <typename To, typename From> inline
 To unicode_cast(const From &) {
@@ -135,17 +132,22 @@ To unicode_cast(const From &) {
 
 template <> inline
 utf8::string unicode_cast<utf8::string, ucs4::string>(const ucs4::string &in) {
-	return utils::ucs4string_to_string(in);
+	return implementation::ucs4string_to_string(in);
 }
 
 template <> inline
 ucs4::string unicode_cast<ucs4::string, utf8::string>(const utf8::string &in) {
-	return utils::string_to_ucs4string(in);
+	return implementation::string_to_ucs4string(in);
+}
+
+template <> inline
+utf8::string unicode_cast<utf8::string, ucs4::char_t>(const ucs4::char_t &in) {
+	return implementation::ucs4char_to_string(in);
 }
 
 template <> inline
 utf16::string unicode_cast<utf16::string, ucs4::string>(const ucs4::string &in) {
-	return utils::ucs4string_to_utf16string(in);
+	return implementation::ucs4string_to_utf16string(in);
 }
 
 template <> inline

src/widgets/textbox.cpp

@@ -313,7 +313,7 @@ surface textbox::add_text_line(const ucs4::string& text, const SDL_Color& color)
 		if(char(*itor) == ' ') {
 			backup_itor = itor;
 		}
-		visible_string.append(utils::ucs4char_to_string(*itor));
+		visible_string.append(unicode_cast<utf8::string>(*itor));
 
 		if(char(*itor) == '\n') {
 			backup_itor = text.end();