Method tryEvaluateCartesian

src/backend/gsl/ExpressionParser.cpp:348–385

* Evaluate cartesian expression returning true on success and false if parsing fails * using given range */

 * using given range
 */
bool ExpressionParser::tryEvaluateCartesian(const QString& expr,
											const Range<double> range,
											int count,
											QVector<double>* xVector,
											QVector<double>* yVector,
											const QStringList& paramNames,
											const QVector<double>& paramValues) {
	DEBUG(Q_FUNC_INFO << ", v0: range = " << range.toStdString())
	const double step = range.stepSize(count);
	DEBUG(Q_FUNC_INFO << ", range = " << range.toStdString() << ", step = " << step)

	Parser parser(true);
	ParserLastErrorMessage lock(parser, m_lastErrorMessage);

	for (int i = 0; i < paramNames.size(); ++i)
		parser.assign_symbol(qPrintable(paramNames.at(i)), paramValues.at(i));

	const auto numberLocale = QLocale();
	gsl_set_error_handler_off();
	for (int i = 0; i < count; i++) {
		const double x{range.start() + step * i};
		parser.assign_symbol("x", x);

		double y = parser.parse(qPrintable(expr), qPrintable(numberLocale.name()));
		if (parser.parseErrors() > 0) // try default locale if failing
			y = parser.parse(qPrintable(expr), "en_US");
		if (parser.parseErrors() > 0)
			return false;

		if (std::isnan(y))
			WARN(Q_FUNC_INFO << ", WARNING: expression " << STDSTRING(expr) << " evaluated @ " << x << " is NAN")

		(*xVector)[i] = x;
		(*yVector)[i] = y;
	}

	return true;
}
/*
 * Evaluate cartesian expression returning true on success and false if parsing fails
 * min and max are localized strings which are parsed to support expressions like "pi + 1.5"