From 0e2ca6ee1ce557f190075b0445044825d7e086b7 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Thu, 6 Jun 2024 21:13:50 +0200
Subject: [PATCH] =?UTF-8?q?Library:=20consider=20to=20align=20this=20with?=
 =?UTF-8?q?=20the=20=C2=BBFactory=C2=AB=20concept?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

even while at first sight only a ''deleter instance'' is required,
it seems prudent to rearrange the code in accordance to the prospective
Allocator / Object Factory concept, and rather try to incorporate
the specifics of the memory layout into this generic view, thereby
abstracting the actual allocator away.

This can be achieved by using a standard-allocator for `std::byte`
as the base allocator and treat each individual element allocator
as a specialised cross-allocator (assuming that this cross adaptation
is actually trivial in almost all cases)
---
 src/lib/several-builder.hpp | 32 ++++++++++++++++++++------------
 wiki/thinkPad.ichthyo.mm    | 12 +++++++++++-
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/lib/several-builder.hpp b/src/lib/several-builder.hpp
index 4da1e1e12..8c3309a0e 100644
--- a/src/lib/several-builder.hpp
+++ b/src/lib/several-builder.hpp
@@ -73,36 +73,44 @@ namespace lib {
     
         
         
-    template<class I, class E>
-    struct DeleterTrampoline
+    template<class I, template<typename> class ALO>
+    struct ElementFactory
+      : private ALO<std::byte>
       {
-        using Allo = std::allocator<E>;
+        using Allo = ALO<std::byte>;
         using AlloT = std::allocator_traits<Allo>;
         
+        Allo& baseAllocator() { return *this; }
+        
         template<typename X>
-        static auto
+        auto
         adaptAllocator()
           {
             using XAllo = typename AlloT::template rebind_alloc<X>;
             if constexpr (std::is_constructible_v<XAllo, Allo>)
-              return XAllo{Allo()};
+              return XAllo{baseAllocator()};
             else
               return XAllo{};
           }
         
-        static void
+        ElementFactory (Allo allo = Allo{})
+          : Allo{std::move (allo)}
+          { }
+        
+        template<class E>
+        void
         destroy (ArrayBucket<I>* bucket, size_t size)
           {
-            Allo allo{};
+            REQUIRE (bucket);
+            using ElmAlloT = typename AlloT::template rebind_traits<E>;
+            auto elmAllo = adaptAllocator<E>();
             for (size_t i=0; i<size; ++i)
-              AlloT::destroy (allo, & bucket->subscript(i));
+              ElmAlloT::destroy (elmAllo, & bucket->subscript(i));
             
             size_t storageBytes = sizeof(ArrayBucket<I>) - sizeof(ArrayBucket<I>::storage)
-                                + size * sizeof(E);
+                                + size * bucket->spread;
         
-            using BAlloT = typename AlloT::template rebind_traits<std::byte>;
-            auto bAllo = adaptAllocator<std::byte>();
-            BAlloT::deallocate (bAllo, bucket, storageBytes);
+            AlloT::deallocate (baseAllocator(), bucket, storageBytes);
           };
       };
     
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index d0c69aaba..6d8fab0e4 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -81975,6 +81975,11 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <icon BUILTIN="idea"/>
 </node>
 </node>
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1717710799094" ID="ID_310099304" MODIFIED="1717710881440" TEXT="ObjectFactory">
+<linktarget COLOR="#867587" DESTINATION="ID_310099304" ENDARROW="Default" ENDINCLINATION="-927;146;" ID="Arrow_ID_1881268863" SOURCE="ID_342640598" STARTARROW="None" STARTINCLINATION="-107;-6;"/>
+<icon BUILTIN="flag-yellow"/>
+<node CREATED="1717710834678" ID="ID_16117383" MODIFIED="1717710852024" TEXT="eine Variation der generischen StdFactory"/>
+</node>
 </node>
 </node>
 </node>
@@ -82231,7 +82236,7 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <node CREATED="1717632444817" ID="ID_362040312" MODIFIED="1717632448869" TEXT="Speicher freigeben"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1717632477490" ID="ID_83921320" MODIFIED="1717632530750" TEXT="beide Aufgaben m&#xfc;ssen in das Trampolin">
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1717632477490" ID="ID_83921320" MODIFIED="1717710899555" TEXT="beide Aufgaben m&#xfc;ssen in das Trampolin">
 <icon BUILTIN="flag-yellow"/>
 <node CREATED="1717632816553" ID="ID_719956571" MODIFIED="1717632856947" TEXT="geht leider nicht anders...">
 <richcontent TYPE="NOTE"><html>
@@ -82251,6 +82256,11 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 </node>
 </node>
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1717710755310" ID="ID_342640598" MODIFIED="1717710895137" TEXT="sinnvollerweise mit einer Allocator-Factory hinterlegen">
+<arrowlink COLOR="#867587" DESTINATION="ID_310099304" ENDARROW="Default" ENDINCLINATION="-927;146;" ID="Arrow_ID_1881268863" STARTARROW="None" STARTINCLINATION="-107;-6;"/>
+<icon BUILTIN="flag-yellow"/>
+<node CREATED="1717710901355" ID="ID_718524980" MODIFIED="1717710916991" TEXT="das Meiste ist n&#xe4;mlich generische boilerplate"/>
+</node>
 </node>
 <node CREATED="1717543083078" ID="ID_530261806" MODIFIED="1717543114805" TEXT="getMover()"/>
 </node>