Utils: Allow aspects to modify values for loading and saving

In some cases it is useful when the persistent value is not the
internally used actual value, e.g.  Having the displayed string
of a SelectionAspect instead of a numerical index makes
the settings more readable for a human.

Change-Id: I11ecb8e75ab041ace2358cc45972ce9ee965b24d
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/utils/aspects.cpp

@@ -60,6 +60,8 @@ public:
     Utils::Id m_id;
     QVariant m_value;
     QVariant m_defaultValue;
+    std::function<QVariant(const QVariant &)> m_toSettings;
+    std::function<QVariant(const QVariant &)> m_fromSettings;
 
     QString m_displayName;
     QString m_settingsKey; // Name of data in settings.
@@ -488,7 +490,8 @@ void BaseAspect::saveToMap(QVariantMap &data, const QVariant &value,
 */
 void BaseAspect::fromMap(const QVariantMap &map)
 {
-    setValue(map.value(settingsKey(), defaultValue()));
+    const QVariant val = map.value(settingsKey(), toSettingsValue(defaultValue()));
+    setValue(fromSettingsValue(val));
 }
 
 /*!
@@ -496,21 +499,45 @@ void BaseAspect::fromMap(const QVariantMap &map)
 */
 void BaseAspect::toMap(QVariantMap &map) const
 {
-    saveToMap(map, d->m_value, d->m_defaultValue, settingsKey());
+    saveToMap(map, toSettingsValue(d->m_value), toSettingsValue(d->m_defaultValue), settingsKey());
 }
 
 void BaseAspect::readSettings(const QSettings *settings)
 {
     if (settingsKey().isEmpty())
         return;
-    setValue(settings->value(settingsKey(), defaultValue()));
+    const QVariant val = settings->value(settingsKey(), toSettingsValue(defaultValue()));
+    setValue(fromSettingsValue(val));
 }
 
 void BaseAspect::writeSettings(QSettings *settings) const
 {
     if (settingsKey().isEmpty())
         return;
-    QtcSettings::setValueWithDefault(settings, settingsKey(), value(), defaultValue());
+    QtcSettings::setValueWithDefault(settings,
+                                     settingsKey(),
+                                     toSettingsValue(value()),
+                                     toSettingsValue(defaultValue()));
+}
+
+void BaseAspect::setFromSettingsTransformation(const SavedValueTransformation &transform)
+{
+    d->m_fromSettings = transform;
+}
+
+void BaseAspect::setToSettingsTransformation(const SavedValueTransformation &transform)
+{
+    d->m_toSettings = transform;
+}
+
+QVariant BaseAspect::toSettingsValue(const QVariant &val) const
+{
+    return d->m_toSettings ? d->m_toSettings(val) : val;
+}
+
+QVariant BaseAspect::fromSettingsValue(const QVariant &val) const
+{
+    return d->m_fromSettings ? d->m_fromSettings(val) : val;
 }
 
 /*!
@@ -1436,11 +1463,24 @@ void SelectionAspect::setValue(int value)
     }
 }
 
+void SelectionAspect::setStringValue(const QString &val)
+{
+    const int index = indexForDisplay(val);
+    QTC_ASSERT(index >= 0, return);
+    setValue(index);
+}
+
 void SelectionAspect::setDefaultValue(int val)
 {
     BaseAspect::setDefaultValue(val);
 }
 
+// Note: This needs to be set after all options are added.
+void SelectionAspect::setDefaultValue(const QString &val)
+{
+    BaseAspect::setDefaultValue(indexForDisplay(val));
+}
+
 QString SelectionAspect::stringValue() const
 {
     return d->m_options.at(value()).displayName;
@@ -1451,6 +1491,20 @@ void SelectionAspect::addOption(const QString &displayName, const QString &toolT
     d->m_options.append({displayName, toolTip});
 }
 
+int SelectionAspect::indexForDisplay(const QString &displayName) const
+{
+    for (int i = 0, n = d->m_options.size(); i < n; ++i) {
+        if (d->m_options.at(i).displayName == displayName)
+            return i;
+    }
+    return -1;
+}
+
+QString SelectionAspect::displayForIndex(int index) const
+{
+    return d->m_options.at(index).displayName;
+}
+
 /*!
     \class Utils::MultiSelectionAspect
     \inmodule QtCreator