[libcalamares] Provide some convenience functions for extracting configuration data

src/libcalamares/utils/CalamaresUtils.cpp

@@ -326,5 +326,35 @@ crash()
     *a = 1;
 }
 
+bool
+getBool( const QVariantMap& map, const QString& key, bool d )
+{
+    bool result = d;
+    if ( map.contains( key ) )
+    {
+        auto v = map.value( key );
+        if ( v.type() == QVariant::Bool )
+            result = v.toBool();
+    }
+
+    return result;
+}
+
+QVariantMap
+getSubMap( const QVariantMap& map, const QString& key, bool& success )
+{
+    success = false;
+
+    if ( map.contains( key ) )
+    {
+        auto v = map.value( key );
+        if ( v.type() == QVariant::Map )
+        {
+            success = true;
+            return v.toMap();
+        }
+    }
+    return QVariantMap();
+}
 
 }

src/libcalamares/utils/CalamaresUtils.h

@@ -97,6 +97,22 @@ namespace CalamaresUtils
      * @brief crash makes Calamares crash immediately.
      */
     DLLEXPORT void crash();
+
+    /**
+     * Get a bool value from a mapping with a given key; returns the default
+     * if no value is stored in the map.
+     */
+    DLLEXPORT bool getBool( const QVariantMap& map, const QString& key, bool d );
+
+    /**
+     * Returns a sub-map (i.e. a nested map) from the given mapping with the
+     * given key. @p success is set to true if the @p key exists
+     * in @p map and converts to a map, false otherwise.
+     *
+     * Returns an empty map if there is no such key or it is not a map-value.
+     * (e.g. if @p success is false).
+     */
+    DLLEXPORT QVariantMap getSubMap( const QVariantMap& map, const QString& key, bool& success );
 }
 
 #endif // CALAMARESUTILS_H