A simple Qt CSS (QSS) dialect parser

The parser is written in C++14 and parses the supported dialect of QSS i.e. Qt's CSS system. This is not exactly the same as CSS3 (web standards) which is a superset of QSS. As Qt Widgets library does not expose the built-in parser, this library takes care of parsing.

Note: This library does not actually update widgets when properties are modified. This can however be done by writing appropriate wrappers on top of Qt widget classes.

Building

mkdir build
cd build
cmake ..
make

Testing

cd build
./test_qss

Example

Parse QDarkStyleSheet and extract background color of QWidget:

QApplication a(argc, argv);
...
QString styleSheetLocation = QString(":qdarkstyle/dark/style.qss");
QFile styleSheetFile(styleSheetLocation);

if (!styleSheetFile.exists())
	printf("Unable to set stylesheet, file not found\n");
else
{
	QTextStream ts(&styleSheetFile);
	styleSheetFile.open(QFile::ReadOnly | QFile::Text);
	a.setStyleSheet(ts.readAll());
}
...
qss::Document document(qApp->styleSheet());
for (auto it = document.cbegin(); it < document.cend(); it++)
{
	auto fragment = it->first;
	if (fragment.selector().toString() != "QWidget") continue;
	
	auto block = fragment.block();
	for (auto it2 = block.cbegin(); it2 != block.cend(); it2++)
	{
		auto name = it2->first;
		if (name != "background-color") continue;
		
		auto value = it2->second.first;
		qDebug() << value << "\n";
		return value;
	}
}