Merge branch 'models_type_rework_part2_try2' into 'master'

[simgrid.git] / include / xbt / Extendable.hpp

diff --git a/include/xbt/Extendable.hpp b/include/xbt/Extendable.hpp
index 37946b6..6f8e0fc 100644 (file)
--- a/include/xbt/Extendable.hpp
+++ b/include/xbt/Extendable.hpp
@@ -1,4 +1,4 @@
-/* Copyright (c) 2015-2019. The SimGrid Team.
+/* Copyright (c) 2015-2021. The SimGrid Team.
  * All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
@@ -19,12 +19,12 @@ template<class T>          class Extendable;
 
 template<class T, class U>
 class Extension {
-  static const std::size_t INVALID_ID = std::numeric_limits<std::size_t>::max();
-  std::size_t id_;
+  static constexpr std::size_t INVALID_ID = std::numeric_limits<std::size_t>::max();
+  std::size_t id_                         = INVALID_ID;
   friend class Extendable<T>;
   explicit constexpr Extension(std::size_t id) : id_(id) {}
 public:
-  explicit constexpr Extension() : id_(INVALID_ID) {}
+  explicit constexpr Extension() = default;
   std::size_t id() const { return id_; }
   bool valid() const { return id_ != INVALID_ID; }
 };
@@ -48,10 +48,14 @@ template<class T>
 class Extendable {
 private:
   static std::vector<void(*)(void*)> deleters_;
-  std::vector<void*> extensions_;
+  std::vector<void*> extensions_{std::max<decltype(deleters_.size())>(1, deleters_.size()), nullptr};
+
 public:
   static size_t extension_create(void (*deleter)(void*))
   {
+    if (deleters_.empty()) { // Save space for void* user data
+      deleters_.push_back(nullptr);
+    }
     deleters_.push_back(deleter);
     return deleters_.size() - 1;
   }
@@ -65,7 +69,7 @@ public:
   {
     return Extension<T, U>(extension_create([](void* p) { delete static_cast<U*>(p); }));
   }
-  Extendable() : extensions_(deleters_.size(), nullptr) {}
+  Extendable()                  = default;
   Extendable(const Extendable&) = delete;
   Extendable& operator=(const Extendable&) = delete;
   ~Extendable()
@@ -76,7 +80,7 @@ public:
      * an extension A, the subsystem of B might depend on the subsystem on A and
      * an extension of B might need to have the extension of A around when executing
      * its cleanup function/destructor. */
-    for (std::size_t i = extensions_.size(); i > 0; --i)
+    for (std::size_t i = extensions_.size(); i > 1; --i) // rank=0 is the spot of user's void*
       if (extensions_[i - 1] != nullptr && deleters_[i - 1] != nullptr)
         deleters_[i - 1](extensions_[i - 1]);
   }
@@ -103,8 +107,12 @@ public:
   {
     extension_set(rank.id(), value, use_dtor);
   }
-
-  // Convenience extension access when the type has a associated EXTENSION ID:
+  // void* version, for C users and nostalgics
+  void set_data(void* data){
+    extensions_[0]=data;
+  }
+  void* get_data() const { return extensions_[0]; }
+  // Convenience extension access when the type has an associated EXTENSION ID:
   template <class U> U* extension() const { return extension<U>(U::EXTENSION_ID); }
   template<class U> void extension_set(U* p) { extension_set<U>(U::EXTENSION_ID, p); }
 };