Add NativeFileDialogs to LÖVE filesystem API (https://github.com/mlabbe/nativefiledialog)

Dialog.cpp

enum DialogType
{
	DIALOG_SAVE,
	DIALOG_OPEN,
	DIALOG_FOLDER,
	DIALOG_MULTIPLE;
	DIALOG_MAX_ENUM
};

#import <nfd.h>

void Filesystem::showDialog(DialogType type, const char *filter, const char *dir, std::vector<std::string> &items)
{
	nfdresult_t status;

	if (type == DIALOG_MULTIPLE)
	{
		nfdpathset_t files = nullptr;

		status = NFD_OpenDialogMultiple(filter, initial, &files);

		if (status != NFD_ERROR && files != nullptr)
		{
			size_t count = NFD_PathSet_GetCount(files);
	 		for (size_t i = 0; i < count; ++i)
			{
				items.push_back(NFD_PathSet_GetPath(files, i));
			        allowMountingForPath(items.back())
			}

			NFD_PathSet_Free(set);
		}
	}
	else
	{
		nfdchar_t* file = nullptr;

		switch (type)
		{
			case DIALOG_FOLDER:
				status = NFD_PickFolder(dir, &file);
			case DIALOG_SAVE:
				status = NFD_SaveDialog(filter, dir, &file);
			case DIALOG_OPEN:
				status = NFD_OpenDialog(filter, dir, &file);
			default:
				throw love::Exception("Invalid dialog type");
		}

		if (status != NFD_ERROR && file != nullptr)
		{
			items.push_back(file);
			allowMountingForPath(file);
		}
	}

	if (status == NFD_ERROR)
		throw love::Exception(NFD_GetError());
}

bool Filesystem::getConstant(const char *in, DialogType &out)
{
	return dialogTypes.find(in, out);
}

bool Filesystem::getConstant(DialogType in, const char *&out)
{
	return dialogTypes.find(in, out);
}

std::vector<std::string> Filesystem::getConstants(DialogType)
{
	return dialogTypes.getNames();
}

StringMap<Filesystem::DialogType, Filesystem::DIALOG_MAX_ENUM>::Entry Filesystem::dialogTypeEntries[] =
{
	{ "save",     DIALOG_SAVE     },
	{ "open",     DIALOG_OPEN     },
	{ "folder",   DIALOG_FOLDER   },
	{ "multiple", DIALOG_MULTIPLE }
};

StringMap<Filesystem::DialogType, Filesystem::DIALOG_MAX_ENUM> Filesystem::dialogTypes(Filesystem::dialogTypeEntries, sizeof(Filesystem::dialogTypeEntries));

Note that both the initial and filter arguments are optional.

"folder" dialogs ignore the filter argument altogether.

"multiple" is the only type of dialog that pushes more than one entry to the returned vector. The others return the single path of the file/folder