Partitioner Improvements and Utils on top of #3603 (#3611)

* Implements Random Access Iterator Facade for EdgeIDIterator

* Makes StaticGraph Node and Edge requirements explicit

* Cleans up Bisection Graph, Node and Edge

* Cleans up GraphView

include/util/static_graph.hpp

@@ -4,6 +4,7 @@
 #include "util/integer_range.hpp"
 #include "util/percent.hpp"
 #include "util/shared_memory_vector_wrapper.hpp"
+#include "util/static_graph_traits.hpp"
 #include "util/typedefs.hpp"
 
 #include <boost/assert.hpp>
@@ -62,6 +63,11 @@ template <typename EdgeDataT> class SortableEdgeWithData
 
 template <typename NodeT, typename EdgeT, bool UseSharedMemory = false> class FlexibleStaticGraph
 {
+    static_assert(traits::HasFirstEdgeMember<NodeT>(),
+                  "Model for compatible Node type requires .first_edge member attribute");
+    static_assert(traits::HasDataAndTargetMember<EdgeT>(),
+                  "Model for compatible Edge type requires .data and .target member attribute");
+
   public:
     using NodeIterator = static_graph_details::NodeIterator;
     using EdgeIterator = static_graph_details::EdgeIterator;
@@ -210,8 +216,8 @@ template <typename NodeT, typename EdgeT, bool UseSharedMemory = false> class Fl
         return current_iterator;
     }
 
-    const NodeArrayEntry& GetNode(const NodeID nid) const { return node_array[nid]; }
-    const EdgeArrayEntry& GetEdge(const EdgeID eid) const { return edge_array[eid]; }
+    const NodeArrayEntry &GetNode(const NodeID nid) const { return node_array[nid]; }
+    const EdgeArrayEntry &GetEdge(const EdgeID eid) const { return edge_array[eid]; }
 
   private:
     NodeIterator number_of_nodes;

include/util/static_graph_traits.hpp

@@ -0,0 +1,56 @@
+#ifndef STATIC_GRAPH_TRAITS_HPP
+#define STATIC_GRAPH_TRAITS_HPP
+
+#include <type_traits>
+
+namespace osrm
+{
+namespace util
+{
+
+namespace traits
+{
+
+// Introspection for an arbitrary .data member attribute
+template <typename T, typename = void> struct HasDataMember : std::false_type
+{
+};
+
+template <typename T>
+struct HasDataMember<T, decltype((void)(sizeof(std::declval<T>().data) > 0))> : std::true_type
+{
+};
+
+// Introspection for an arbitrary .target member attribute
+template <typename T, typename = void> struct HasTargetMember : std::false_type
+{
+};
+
+template <typename T>
+struct HasTargetMember<T, decltype((void)(sizeof(std::declval<T>().target) > 0))> : std::true_type
+{
+};
+
+// Static Graph requires edges to have a .target and .data member attribute
+template <typename Edge>
+struct HasDataAndTargetMember
+    : std::integral_constant<bool, HasDataMember<Edge>() && HasTargetMember<Edge>()>
+{
+};
+
+// Static Graph requires nodes to have a .first_edge member attribute
+template <typename T, typename = void> struct HasFirstEdgeMember : std::false_type
+{
+};
+
+template <typename T>
+struct HasFirstEdgeMember<T, decltype((void)(sizeof(std::declval<T>().first_edge) > 0))>
+    : std::true_type
+{
+};
+
+} // ns traits
+} // ns util
+} // ns osrm
+
+#endif // STATIC_GRAPH_TRAITS_HPP