[MPL] add overloaded operator functions.

MaterialLib/MPL/Component.cpp

@@ -31,9 +31,21 @@ Component::Component(std::string const& component_name,
 
 Property const& Component::property(PropertyType const& p) const
 {
+    Property const* const property = properties_[p].get();
+    if (property == nullptr)
+    {
+        OGS_FATAL("Trying to access undefined property '{:s}' of {:s}",
+                  property_enum_to_string[p], description());
+    }
+
     return *properties_[p];
 }
 
+Property const& Component::operator[](PropertyType const& p) const
+{
+    return property(p);
+}
+
 bool Component::hasProperty(PropertyType const& p) const
 {
     return properties_[p] != nullptr;

MaterialLib/MPL/Component.h

@@ -34,6 +34,9 @@ public:
 
     /// A get-function for retrieving a certain property.
     Property const& property(PropertyType const& /*p*/) const;
+
+    Property const& operator[](PropertyType const& p) const;
+
     bool hasProperty(PropertyType const& p) const;
 
     template <typename T>

MaterialLib/MPL/Medium.cpp

@@ -61,6 +61,11 @@ Property const& Medium::property(PropertyType const& p) const
     return *properties_[p];
 }
 
+Property const& Medium::operator[](PropertyType const& p) const
+{
+    return property(p);
+}
+
 bool Medium::hasProperty(PropertyType const& p) const
 {
     return properties_[p] != nullptr;

MaterialLib/MPL/Medium.h

@@ -45,6 +45,9 @@ public:
     /// A get-function for a property. The argument refers to the name of the
     /// property.
     Property const& property(PropertyType const& p) const;
+
+    Property const& operator[](PropertyType const& p) const;
+
     bool hasProperty(PropertyType const& p) const;
 
     /// A simple get-function for retrieving the number of phases the medium

MaterialLib/MPL/Phase.cpp

@@ -60,6 +60,11 @@ Property const& Phase::property(PropertyType const& p) const
     return *properties_[p];
 }
 
+Property const& Phase::operator[](PropertyType const& p) const
+{
+    return property(p);
+}
+
 bool Phase::hasProperty(PropertyType const& p) const
 {
     return properties_[p] != nullptr;

MaterialLib/MPL/Phase.h

@@ -46,6 +46,9 @@ public:
     /// A get-function for a property. The argument refers to the name of the
     /// property.
     Property const& property(PropertyType const& p) const;
+
+    Property const& operator[](PropertyType const& p) const;
+
     bool hasProperty(PropertyType const& p) const;
 
     /// A get-function for retrieving the number of components in this phase.