From bf74ba62929ec30310871fed816f46763f93eceb Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Thu, 6 Jun 2024 18:41:07 +0200
Subject: [PATCH] Library: sketch for a deleter trampoline

for simple allocators this can be static
---
 src/lib/several-builder.hpp | 37 +++++++++++++++++++++++++++++++++++++
 src/lib/several.hpp         | 25 ++++++++++---------------
 wiki/thinkPad.ichthyo.mm    | 25 +++++++++++++------------
 3 files changed, 60 insertions(+), 27 deletions(-)

diff --git a/src/lib/several-builder.hpp b/src/lib/several-builder.hpp
index 61867a8c2..4da1e1e12 100644
--- a/src/lib/several-builder.hpp
+++ b/src/lib/several-builder.hpp
@@ -71,6 +71,42 @@ namespace lib {
           }
       };
     
+        
+        
+    template<class I, class E>
+    struct DeleterTrampoline
+      {
+        using Allo = std::allocator<E>;
+        using AlloT = std::allocator_traits<Allo>;
+        
+        template<typename X>
+        static auto
+        adaptAllocator()
+          {
+            using XAllo = typename AlloT::template rebind_alloc<X>;
+            if constexpr (std::is_constructible_v<XAllo, Allo>)
+              return XAllo{Allo()};
+            else
+              return XAllo{};
+          }
+        
+        static void
+        destroy (ArrayBucket<I>* bucket, size_t size)
+          {
+            Allo allo{};
+            for (size_t i=0; i<size; ++i)
+              AlloT::destroy (allo, & bucket->subscript(i));
+            
+            size_t storageBytes = sizeof(ArrayBucket<I>) - sizeof(ArrayBucket<I>::storage)
+                                + size * sizeof(E);
+        
+            using BAlloT = typename AlloT::template rebind_traits<std::byte>;
+            auto bAllo = adaptAllocator<std::byte>();
+            BAlloT::deallocate (bAllo, bucket, storageBytes);
+          };
+      };
+    
+    
     using std::is_trivially_move_constructible_v;
     using std::is_trivially_destructible_v;
     using std::has_virtual_destructor_v;
@@ -125,6 +161,7 @@ namespace lib {
           >
   class SeveralBuilder
     : Several<I>
+    , util::MoveOnly
     , POL
     {
       using Col = Several<I>;
diff --git a/src/lib/several.hpp b/src/lib/several.hpp
index 96bc8bf72..7da706306 100644
--- a/src/lib/several.hpp
+++ b/src/lib/several.hpp
@@ -50,7 +50,7 @@ namespace lib {
       {
         union Manager
           {
-            typedef void (*Deleter) (void*, size_t, size_t);
+            typedef void (*Deleter) (ArrayBucket*, size_t);
             
             bool unmanaged :1;
             Deleter deleter;
@@ -89,7 +89,7 @@ namespace lib {
    */
   template<class I>
   class Several
-//  : util::MoveAssign          ////////////////////////////////////////OOO fundamental design mismatch with intended builder usage!
+    : util::MoveAssign
     {
     protected:
       using Bucket = ArrayBucket<I>*;
@@ -97,11 +97,17 @@ namespace lib {
       size_t size_{0};
       Bucket data_{nullptr};
       
+      Several() =default; ///< may only be created through SeveralBuilder
+      
     public:
      ~Several()  noexcept
         try { discardData(); }
         ERROR_LOG_AND_IGNORE (progress, "clean-up Several data")
       
+      /// Move-Assignment allowed...
+      Several (Several&&)            =default;
+      Several& operator= (Several&&) =default;
+      
       size_t
       size()  const
         {
@@ -139,19 +145,8 @@ namespace lib {
       void
       discardData()
         {
-          if (data_ and not data_->manager.unmanaged)
-            {
-              if (data_->manager.deleter)
-                {
-                  (*data_->manager.deleter) (data_, size_, data_->spread);
-                }
-              else
-                {
-                  for (size_t i=0; i<size_; ++i)
-                    operator [](i).~I();
-                  ////////////////////////////////////////////OOO really a good idea to invoke the std::allocator_traits directly here??
-                }
-            }
+          if (data_ and data_->manager.deleter)
+            (*data_->manager.deleter) (data_, size_);
         }
     };
   
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 944c67920..d0c69aaba 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -81883,8 +81883,7 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
       hei&#223;t: er kann zwar nicht wegfallen (weil sich das dann im Typ ausdr&#252;cken w&#252;rde) &#8212; aber der Pointer bleibt dann NULL und der Container f&#228;llt auf Standard-Verhalten zur&#252;ck
     </p>
   </body>
-</html>
-</richcontent>
+</html></richcontent>
 <node CREATED="1717595296327" ID="ID_312816298" MODIFIED="1717595311329" TEXT="entweder er macht Standard-Heap-Allokationen"/>
 <node CREATED="1717595311917" ID="ID_1199827778" MODIFIED="1717595477064" TEXT="oder er de-alloziert &#xfc;berhaupt nicht">
 <richcontent TYPE="NOTE"><html>
@@ -81929,8 +81928,7 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
       Wenn dieser Test <i>scheitert, </i>dann <b>mu&#223; die Allokator-Instanz erhalten bleiben<i>.</i></b>
     </p>
   </body>
-</html>
-</richcontent>
+</html></richcontent>
 <icon BUILTIN="yes"/>
 </node>
 </node>
@@ -81973,8 +81971,7 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
       In der Tat: siehe special-job-fun.hpp
     </p>
   </body>
-</html>
-</richcontent>
+</html></richcontent>
 <icon BUILTIN="idea"/>
 </node>
 </node>
@@ -82223,8 +82220,7 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
       &#160;oder es ist eine <i>selbstzerst&#246;rende </i>Heap-Allokation
     </p>
   </body>
-</html>
-</richcontent>
+</html></richcontent>
 </node>
 </node>
 </node>
@@ -82245,10 +82241,15 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
       weil der Several-Container selber nur den Spread kennt, aber keine konkrete Typ-Info mehr hat
     </p>
   </body>
-</html>
-</richcontent>
+</html></richcontent>
 <icon BUILTIN="smily_bad"/>
 </node>
+<node COLOR="#435e98" CREATED="1717691947664" ID="ID_954213667" MODIFIED="1717691981598" TEXT="Ha! ArrayBucket&lt;I&gt; ausnutzen">
+<icon BUILTIN="idea"/>
+<node CREATED="1717691983435" ID="ID_1420225271" MODIFIED="1717692005073" TEXT="das hat bereits die ganze ben&#xf6;tigte Logik">
+<font NAME="SansSerif" SIZE="10"/>
+</node>
+</node>
 </node>
 </node>
 <node CREATED="1717543083078" ID="ID_530261806" MODIFIED="1717543114805" TEXT="getMover()"/>
@@ -82258,8 +82259,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 <node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1716914864769" ID="ID_966642586" MODIFIED="1716914906125" TEXT="Builder-Operationen">
 <icon BUILTIN="pencil"/>
-<node BACKGROUND_COLOR="#f8f1cb" COLOR="#a50125" CREATED="1717634297656" ID="ID_330412196" MODIFIED="1717634315310" TEXT="Problem: Container soll move-only sein">
-<icon BUILTIN="messagebox_warning"/>
+<node COLOR="#338800" CREATED="1717634297656" ID="ID_330412196" MODIFIED="1717688579115" TEXT="Move-builder und Container per Slice ausgeben">
+<icon BUILTIN="button_ok"/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1716914869721" ID="ID_756769385" MODIFIED="1716914902541" TEXT="basis-Allokation">
 <icon BUILTIN="flag-yellow"/>