Add "String input" documentation

Doxyfile

@@ -970,7 +970,8 @@ INPUT                  = include/upa/url.h \
                          include/upa/url_result.h \
                          include/upa/url_search_params.h \
                          include/upa/url_percent_encode.h \
-                         README.md
+                         README.md \
+                         doc/string_input.md
 
 # This tag can be used to specify the character encoding of the source files
 # that Doxygen parses. Internally Doxygen uses the UTF-8 encoding. Doxygen uses

README.md

@@ -27,7 +27,7 @@ Upa URL contains features not specified in the standard:
 4. Experimental URLHost class (see proposal: https://github.com/whatwg/url/pull/288): `upa::url_host`
 5. The `upa::url_search_params` class has a few additional functions: `remove`, `remove_if`
 
-For string input, the library supports UTF-8, UTF-16, UTF-32 encodings and several string types, including `std::basic_string`, `std::basic_string_view`, null-terminated strings of any char type: `char`, `char8_t`, `char16_t`, `char32_t`, or `wchar_t`.
+For string input, the library supports UTF-8, UTF-16, UTF-32 encodings and several string types, including `std::basic_string`, `std::basic_string_view`, null-terminated strings of any char type: `char`, `char8_t`, `char16_t`, `char32_t`, or `wchar_t`. See ["String input"](doc/string_input.md) for more information.
 
 ## Installation
 

doc/string_input.md

@@ -0,0 +1,23 @@
+## String input
+
+For string input, the library supports UTF-8, UTF-16, UTF-32 encodings and several string types, including `std::basic_string`, `std::basic_string_view`, null-terminated strings of any char type: `char`, `char8_t`, `char16_t`, `char32_t`, or `wchar_t`.
+
+The ATL/MFC and Qt library string types are also supported. To use them you need to include the header files listed in the table below instead of `url.h`:
+
+| Library | Supported string types | Include instead of `url.h` |
+|-|-|-|
+| ATL/MFC | `CSimpleStringT`, `CStringT`, `CFixedStringT` | `url_for_atl.h` |
+| Qt | `QString`, `QStringView`, `QUtf8StringView` | `url_for_qt.h` |
+
+Qt example:
+```cpp
+#include "upa/url_for_qt.h"
+#include <QString>
+
+int main() {
+    QString str{"http://example.com/"};
+    upa::url url{str};
+    std::cout << url.href() << '\n';
+    return 0;
+}
+```

include/upa/url_for_atl.h

@@ -1,6 +1,10 @@
 // Copyright 2024 Rimas Misevičius
 // Distributed under the BSD-style license that can be
 // found in the LICENSE file.
+
+// This file can be included instead of url.h to allow strings of the
+// ATL/MFC classes CSimpleStringT, CStringT, CFixedStringT to be used
+// as string input in the functions of this library.
 //
 #ifndef UPA_URL_FOR_ATL_H
 #define UPA_URL_FOR_ATL_H

include/upa/url_for_qt.h

@@ -1,6 +1,10 @@
 // Copyright 2024 Rimas Misevičius
 // Distributed under the BSD-style license that can be
 // found in the LICENSE file.
+
+// This file can be included instead of url.h to allow strings of the
+// Qt classes QString, QStringView, QUtf8StringView to be used as string
+// input in the functions of this library.
 //
 #ifndef UPA_URL_FOR_QT_H
 #define UPA_URL_FOR_QT_H