lib/configuration improvements

Configuration changes:
- Configuration::value return type is now [[nodiscard]]
- Configuration::value<T> is now a generic template that only works with
the exact types of the underlying std::variant
- Add Configuration::value<concept_value_t> for standard library types
compatible with the types of std::variant
- Add Configuration::shortcut<> placeholder, and QAction and
QKeySequence specializations as a convenient way to set up shortcuts
- Deprecate setShortcut
- Add Configuration::read_file convenience member that takes file path
as parameter

Format changes:
- Configuration files can now have sections, specified as [section
name]. Section names are prepended to keys. Section names cannot be
nested.
- Configuration files can now have @@include directives, causing another
file to be read as well. The included file is not treated as nested into
a section, and will overwrite values previously set.

Others:
- add some tests for libconfiguration. QAction/QKeySequence require a
QApplication be set up, so the test application may require running
xorg/wayland.

old coverage: lines: 15.6% (960 out of 6172) branches: 9.9% (1187 out of 12012)
new coverage: lines: 17.1% (1067 out of 6254) branches: 11.0% (1388 out of 12644)

1 files changed, 55 insertions, 0 deletions

diff --git a/lib/configuration/qt_specialization.cpp b/lib/configuration/qt_specialization.cpp
new file mode 100644
index 0000000..4e79492
--- /dev/null
+++ b/lib/configuration/qt_specialization.cpp
@@ -0,0 +1,55 @@
+#include "configuration.h"
+#include <stdexcept>
+
+template <>
+callable_when(unconsumed) [[nodiscard]] std::optional<QString> Configuration::value(const char *path) const
+{
+    const auto v = value<std::string>(path);
+    if(!v)
+        return std::nullopt;
+    else
+        return QString::fromStdString(v.value());
+}
+
+template <>
+callable_when(unconsumed) [[nodiscard]] std::optional<QStringList> Configuration::value(const char *path) const
+{
+    const auto v = value<std::string>(path);
+    if(!v)
+        return std::nullopt;
+    else
+        return QString::fromStdString(v.value()).split(';');
+}
+
+void setShortcut(QAction *action, const char *name)
+{
+    Configuration conf;
+
+    if(const auto shortcutText = conf.value<QString>(name)) {
+        const QString tooltip = action->toolTip();
+        action->setShortcut(QKeySequence::fromString(shortcutText.value()));
+        action->setToolTip(QString("%1 (%2)").arg(tooltip, shortcutText.value()));
+    } else {
+        throw new std::runtime_error(std::string("fixme: setShortcut found no such value for ") + name);
+    }
+}
+
+template <>
+callable_when(unconsumed) QAction &Configuration::shortcut(QAction &action, const char *name) const
+{
+    if(const auto shortcut = value<QString>(name)) {
+        const QString old_tooltip = action.toolTip();
+        action.setShortcut(QKeySequence::fromString(shortcut.value()));
+        action.setToolTip(QString("%1 (%2)").arg(old_tooltip, shortcut.value()));
+    }
+    return action;
+}
+
+template <>
+callable_when(unconsumed) QKeySequence &Configuration::shortcut(QKeySequence &sequence, const char *name) const
+{
+    if(const auto shortcut = value<QString>(name)) {
+        sequence = QKeySequence::fromString(shortcut.value());
+    }
+    return sequence;
+}