File: Make path a first-class object, add some methods from C++17.

firmware/application/file.cpp

@@ -139,18 +139,12 @@ static std::filesystem::path find_last_file_matching_pattern(const std::filesyst
 	return last_match;
 }
 
-static std::filesystem::path remove_filename_extension(const std::filesystem::path& filename) {
-	const auto extension_index = filename.find_last_of('.');
-	return filename.substr(0, extension_index);
-}
-
-static std::filesystem::path increment_filename_stem_ordinal(const std::filesystem::path& filename_stem) {
-	std::filesystem::path result { filename_stem };
-
-	auto it = result.rbegin();
+static std::filesystem::path increment_filename_stem_ordinal(std::filesystem::path path) {
+	auto t = path.replace_extension().native();
+	auto it = t.rbegin();
 
 	// Increment decimal number before the extension.
-	for(; it != result.rend(); ++it) {
+	for(; it != t.rend(); ++it) {
 		const auto c = *it;
 		if( c < '0' ) {
 			return { };
@@ -164,19 +158,18 @@ static std::filesystem::path increment_filename_stem_ordinal(const std::filesyst
 		}
 	}
 
-	return result;
+	return t;
 }
 
-std::filesystem::path next_filename_stem_matching_pattern(const std::filesystem::path& filename_stem_pattern) {
-	const auto filename = find_last_file_matching_pattern(filename_stem_pattern + u".*");
-	auto filename_stem = remove_filename_extension(filename);
-	if( filename_stem.empty() ) {
-		filename_stem = filename_stem_pattern;
-		std::replace(std::begin(filename_stem), std::end(filename_stem), '?', '0');
+std::filesystem::path next_filename_stem_matching_pattern(std::filesystem::path filename_pattern) {
+	const auto next_filename = find_last_file_matching_pattern(filename_pattern.replace_extension(u".*"));
+	if( next_filename.empty() ) {
+		auto pattern_s = filename_pattern.replace_extension().native();
+		std::replace(std::begin(pattern_s), std::end(pattern_s), '?', '0');
+		return pattern_s;
 	} else {
-		filename_stem = increment_filename_stem_ordinal(filename_stem);
+		return increment_filename_stem_ordinal(next_filename);
 	}
-	return filename_stem;
 }
 
 namespace std {
@@ -212,9 +205,54 @@ std::string filesystem_error::what() const {
 	}
 }
 
-std::string path_to_string(const path& p) {
+path path::extension() const {
+	const auto t = filename().native();
+	const auto index = t.find_last_of(u'.');
+	if( index == t.npos ) {
+		return { };
+	} else {
+		return t.substr(index);
+	}
+}
+
+path path::filename() const {
+	const auto index = _s.find_last_of(preferred_separator);
+	if( index == _s.npos ) {
+		return _s;
+	} else {
+		return _s.substr(index + 1);
+	}
+}
+
+path path::stem() const {
+	const auto t = filename().native();
+	const auto index = t.find_last_of(u'.');
+	if( index == t.npos ) {
+		return t;
+	} else {
+		return t.substr(0, index);
+	}
+}
+
+std::string path::string() const {
 	std::wstring_convert<std::codecvt_utf8_utf16<path::value_type>, path::value_type> conv;
-	return conv.to_bytes(p);
+	return conv.to_bytes(native());
+}
+
+path& path::replace_extension(const path& replacement) {
+	const auto t = extension().native();
+	_s.erase(_s.size() - t.size());
+	if( !replacement._s.empty() ) {
+		if( replacement._s.front() != u'.' ) {
+			_s += u'.';
+		}
+		_s += replacement._s;
+	}
+	return *this;
+}
+
+bool operator>(const path& lhs, const path& rhs) {
+	return lhs.native() > rhs.native();
 }
 
 directory_iterator::directory_iterator(

firmware/application/file.hpp

@@ -64,14 +64,107 @@ private:
 	uint32_t err;
 };
 
-using path = std::u16string;
+struct path {
+	using string_type = std::u16string;
+	using value_type = string_type::value_type;
+
+	static constexpr value_type preferred_separator = u'/';
+
+	path(
+	) : _s { }
+	{
+	}
+
+	path(
+		const path& p
+	) : _s { p._s }
+	{
+	}
+
+	path(
+		path&& p
+	) : _s { std::move(p._s) }
+	{
+	}
+
+	template<class Source>
+	path(
+		const Source& source
+	) : path { std::begin(source), std::end(source) }
+	{
+	}
+
+	template<class InputIt>
+	path(
+		InputIt first,
+		InputIt last
+	) : _s { first, last }
+	{
+	}
+
+	path(
+		const char16_t* const s
+	) : _s { s }
+	{
+	}
+
+	path(
+		const TCHAR* const s
+	) : _s { reinterpret_cast<const std::filesystem::path::value_type*>(s) }
+	{
+	}
+
+	path& operator=(const path& p) {
+		_s = p._s;
+		return *this;
+	}
+
+	path& operator=(path&& p) {
+		_s = std::move(p._s);
+		return *this;
+	}
+
+	path extension() const;
+	path filename() const;
+	path stem() const;
+
+	bool empty() const {
+		return _s.empty();
+	}
+
+	const value_type* c_str() const {
+		return native().c_str();
+	}
+
+	const string_type& native() const {
+		return _s;
+	}
+
+	std::string string() const;
+
+	path& operator+=(const path& p) {
+		_s += p._s;
+		return *this;
+	}
+
+	path& operator+=(const string_type& str) {
+		_s += str;
+		return *this;
+	}
+
+	path& replace_extension(const path& replacement = path());
+
+private:
+	string_type _s;
+};
+
+bool operator>(const path& lhs, const path& rhs);
+
 using file_status = BYTE;
 
 static_assert(sizeof(path::value_type) == 2, "sizeof(std::filesystem::path::value_type) != 2");
 static_assert(sizeof(path::value_type) == sizeof(TCHAR), "FatFs TCHAR size != std::filesystem::path::value_type");
 
-std::string path_to_string(const path& p);
-
 struct space_info {
 	static_assert(sizeof(std::uintmax_t) >= 8, "std::uintmax_t too small (<uint64_t)");
 
@@ -85,7 +178,7 @@ struct directory_entry : public FILINFO {
 		return fattrib;
 	}
 
-	const std::filesystem::path path() const noexcept { return reinterpret_cast<const std::filesystem::path::value_type*>(fname); };
+	const std::filesystem::path path() const noexcept { return { fname }; };
 };
 
 class directory_iterator {
@@ -135,7 +228,7 @@ space_info space(const path& p);
 } /* namespace filesystem */
 } /* namespace std */
 
-std::filesystem::path next_filename_stem_matching_pattern(const std::filesystem::path& filename_stem_pattern);
+std::filesystem::path next_filename_stem_matching_pattern(std::filesystem::path filename_stem_pattern);
 
 class File {
 public:

firmware/application/ui_navigation.cpp

@@ -81,13 +81,13 @@ void SystemStatusView::set_title(const std::string new_value) {
 }
 
 void SystemStatusView::on_camera() {
-	const auto filename_stem = next_filename_stem_matching_pattern(u"SCR_????");
-	if( filename_stem.empty() ) {
+	auto path = next_filename_stem_matching_pattern(u"SCR_????");
+	if( path.empty() ) {
 		return;
 	}
 
 	PNGWriter png;
-	auto create_error = png.create(filename_stem + u".PNG");
+	auto create_error = png.create(path.replace_extension(u".PNG"));
 	if( create_error.is_valid() ) {
 		return;
 	}

firmware/application/ui_record_view.cpp

@@ -238,8 +238,8 @@ void RecordView::start() {
 		return;
 	}
 
-	const auto filename_stem = next_filename_stem_matching_pattern(filename_stem_pattern);
-	if( filename_stem.empty() ) {
+	auto base_path = next_filename_stem_matching_pattern(filename_stem_pattern);
+	if( base_path.empty() ) {
 		return;
 	}
 
@@ -250,9 +250,7 @@ void RecordView::start() {
 			auto p = std::make_unique<WAVFileWriter>(
 				sampling_rate
 			);
-			auto create_error = p->create(
-				filename_stem + u".WAV"
-			);
+			auto create_error = p->create(base_path.replace_extension(u".WAV"));
 			if( create_error.is_valid() ) {
 				handle_error(create_error.value());
 			} else {
@@ -263,16 +261,14 @@ void RecordView::start() {
 
 	case FileType::RawS16:
 		{
-			const auto metadata_file_error = write_metadata_file(filename_stem + u".TXT");
+			const auto metadata_file_error = write_metadata_file(base_path.replace_extension(u".TXT"));
 			if( metadata_file_error.is_valid() ) {
 				handle_error(metadata_file_error.value());
 				return;
 			}
 
 			auto p = std::make_unique<RawFileWriter>();
-			auto create_error = p->create(
-				filename_stem + u".C16"
-			);
+			auto create_error = p->create(base_path.replace_extension(u".C16"));
 			if( create_error.is_valid() ) {
 				handle_error(create_error.value());
 			} else {
@@ -286,7 +282,7 @@ void RecordView::start() {
 	};
 
 	if( writer ) {
-		text_record_filename.set(std::filesystem::path_to_string(filename_stem));
+		text_record_filename.set(base_path.replace_extension().string());
 		button_record.set_bitmap(&bitmap_stop);
 		capture_thread = std::make_unique<CaptureThread>(
 			std::move(writer),