Add to_string and to_wstring methods

src/xtd.core.native.win32/include/xtd/native/win32/strings.h

@@ -124,13 +124,72 @@ namespace xtd::native {
         std::transform(result.begin(), result.end(), result.begin(), ::tolower);
         return result;
       }
-
+
+      static std::string to_string(const std::wstring& str) { return to_string(str.c_str()); }
+      static std::string to_string(const wchar_t* str) {
+        std::string out;
+        unsigned int codepoint = 0;
+        while (*str != 0) {
+          wchar_t character = static_cast<wchar_t>(*str);
+          if (character >= 0xd800 && character <= 0xdbff)
+            codepoint = ((character - 0xd800) << 10) + 0x10000;
+          else {
+            if (character >= 0xdc00 && character <= 0xdfff)
+              codepoint |= character - 0xdc00;
+            else
+              codepoint = character;
+
+            if (codepoint <= 0x7f)
+              out.append(1, static_cast<char>(codepoint));
+            else if (codepoint <= 0x7ff) {
+              out.append(1, static_cast<char>(0xc0 | ((codepoint >> 6) & 0x1f)));
+              out.append(1, static_cast<char>(0x80 | (codepoint & 0x3f)));
+            } else if (codepoint <= 0xffff) {
+              out.append(1, static_cast<char>(0xe0 | ((codepoint >> 12) & 0x0f)));
+              out.append(1, static_cast<char>(0x80 | ((codepoint >> 6) & 0x3f)));
+              out.append(1, static_cast<char>(0x80 | (codepoint & 0x3f)));
+            } else {
+              out.append(1, static_cast<char>(0xf0 | ((codepoint >> 18) & 0x07)));
+              out.append(1, static_cast<char>(0x80 | ((codepoint >> 12) & 0x3f)));
+              out.append(1, static_cast<char>(0x80 | ((codepoint >> 6) & 0x3f)));
+              out.append(1, static_cast<char>(0x80 | (codepoint & 0x3f)));
+            }
+            codepoint = 0;
+          }
+          ++str;
+        }
+        return out;
+      }
+
       static const std::string to_upper(const std::string& str) noexcept {
         auto result = str;
         std::transform(result.begin(), result.end(), result.begin(), ::toupper);
         return result;
       }
-
+
+      static std::wstring to_wstring(const std::string& str) { return to_wstring(str.c_str()); }
+      static std::wstring to_wstring(const char* str) {
+        std::wstring out;
+        char32_t codepoint = 0;
+        while (*str != 0) {
+          unsigned char ch = static_cast<unsigned char>(*str);
+          if (ch <= 0x7f) codepoint = ch;
+          else if (ch <= 0xbf) codepoint = (codepoint << 6) | (ch & 0x3f);
+          else if (ch <= 0xdf) codepoint = ch & 0x1f;
+          else if (ch <= 0xef) codepoint = ch & 0x0f;
+          else codepoint = ch & 0x07;
+          ++str;
+          if (((*str & 0xc0) != 0x80) && (codepoint <= 0x10ffff)) {
+            if (codepoint > 0xffff) {
+              out.append(1, static_cast<wchar_t>(0xd800 + (static_cast<char16_t>(codepoint) >> 10)));
+              out.append(1, static_cast<wchar_t>(0xdc00 + (static_cast<char16_t>(codepoint) & 0x03ff)));
+            } else if (codepoint < 0xd800 || codepoint >= 0xe000)
+              out.append(1, static_cast<wchar_t>(codepoint));
+          }
+        }
+        return out;
+      }
+
       static std::string trim_end(const std::string& str, const std::vector<char>& trim_chars) noexcept {
         if (!str.size()) return str;
         auto result = str;