added Pair_optional_adaptor (WIP)

Orthtree/include/CGAL/Orthtree.h

@@ -27,6 +27,7 @@
 #include <CGAL/intersections.h>
 #include <CGAL/squared_distance_3.h>
 #include <CGAL/span.h>
+#include <CGAL/Pair_optional_adaptor.h>
 
 #include <boost/function.hpp>
 #include <boost/iterator/iterator_facade.hpp>
@@ -526,7 +527,7 @@ public:
     \return an optional containing the property map if it exists
    */
   template <typename T>
-  std::optional<Property_map<T>>
+  Pair_optional_adaptor<Property_map<T>>
   node_property(const std::string& name) {
     auto p = m_node_properties.template get_property_if_exists<T>(name);
     if (p)

Orthtree/test/Orthtree/test_octree_custom_properties.cpp

@@ -39,15 +39,27 @@ int main(void) {
   auto prop5 = tree.add_node_property("test", int(0));
   assert(!prop5.second);
 
-  auto prop3 = tree.node_property<int>("test");
+  auto a1 = tree.node_property<int>("test");
-  assert(prop3.has_value());
+  std::pair<typename Octree::Property_map<int>, bool> p1 = tree.node_property<int>("test");
+  std::optional<typename Octree::Property_map<int>> o1 = tree.node_property<int>("test");
+  auto f = a1.first;
+  auto pf1 = p1.first;
+  auto of1 = o1.value();
+  auto fo1 = a1.value();
+  std::cout << f.size() << std::endl;
+
+  auto a2 = tree.node_property<std::string>("test");
+  std::pair<typename Octree::Property_map<std::string>, bool> p2 = tree.node_property<std::string>("test");
+  std::optional<typename Octree::Property_map<std::string>> o2 = tree.node_property<std::string>("test");
+
+  //assert(prop3.has_value());
 
   auto prop4 = tree.node_property<std::string>("test");
   assert(!prop4.has_value());
 
   // removal of properties
   num = tree.properties().size();
-  tree.remove_node_property(*prop3);
+  //tree.remove_node_property(*prop3);
   assert(tree.properties().size() == (num - 1));
 
   // Default value should be respected

STL_Extension/include/CGAL/Pair_optional_adaptor.h

@@ -0,0 +1,60 @@
+// Copyright (c) 2024 GeometryFactory Sarl (France).
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org).
+//
+// $URL$
+// $Id$
+// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
+//
+//
+// Author(s)     : Sven Oesau
+
+#ifndef CGAL_PAIR_OPTIONAL_ADAPTOR
+#define CGAL_PAIR_OPTIONAL_ADAPTOR
+
+namespace CGAL {
+
+// T is supposed to be a handle
+template<typename T>
+class Pair_optional_adaptor : public std::optional<T> {
+public:
+  Pair_optional_adaptor(std::optional<T>& obj) : std::optional<T>(obj), second(obj.has_value()), first(u.t) {
+    std::cout << "optional constructor" << std::endl;
+    if (obj.has_value())
+      u.t = *obj;
+  }
+
+  Pair_optional_adaptor(const std::nullopt_t& obj) : std::optional<T>(std::nullopt), second(false), first(u.t) {
+    std::cout << "nullopt constructor" << std::endl;
+  }
+
+  Pair_optional_adaptor(std::pair<T, bool>& p) : std::optional<T>(b ? p.first : std::nullopt), first(p.first), second(b) {
+    std::cout << "pair constructor" << std::endl;
+  }
+
+  operator std::pair<T, bool>() {
+    return std::pair<T, bool>(first, second);
+  }
+
+  operator std::optional<T>() {
+    if (second)
+      return std::optional<T>(first);
+    else return std::nullopt;
+  }
+
+  T &first;
+  bool second;
+
+private:
+  union U {
+    T t;
+    int i;
+    U() : i(0) {}
+    U(T t) : t(t) {}
+  } u;
+};
+
+} // CGAL
+
+#endif