highlight error and warning messages in output window

tools/lammps-gui/flagwarnings.cpp

@@ -0,0 +1,44 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://www.lammps.org/, Sandia National Laboratories
+   LAMMPS development team: developers@lammps.org
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#include "flagwarnings.h"
+
+#include "helpers.h"
+
+#include <QColor>
+#include <QFont>
+
+// workaround for Qt-5.12
+#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
+namespace QColorConstants {
+const QColor Red     = QColor::fromRgb(0xff, 0x00, 0x00);
+} // namespace QColorConstants
+#endif
+
+FlagWarnings::FlagWarnings(QTextDocument *parent) :
+    QSyntaxHighlighter(parent), isWarning(QStringLiteral("^(ERROR|WARNING).*$"))
+{
+    formatWarning.setForeground(QColorConstants::Red);
+    formatWarning.setFontWeight(QFont::Bold);
+}
+
+void FlagWarnings::highlightBlock(const QString &text)
+{
+    // nothing to do for empty lines
+    if (text.isEmpty()) return;
+
+    auto match = isWarning.match(text);
+    if (match.hasMatch()) {
+        setFormat(match.capturedStart(0), match.capturedLength(0), formatWarning);
+    }
+}