From fb1857423eddbc7601ea44b13b2426f178050aee Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Fri, 25 Mar 2016 20:46:48 +0100
Subject: [PATCH] implement mutation start and lifecycle

the whole implementation will very much be based on
my experiences with the TestMutationTarget and TestWireTap.
Insofar it was a good idea to implement this test dummy first,
as a prototype. Basically what emerges here is a standard pattern
how to implement a tree mutator:

- the TreeMutator will be a one-way-off "throwaway" object.
- its lifecylce starts with sucking away the previous contents
- consuming the diff moves contents back in place
- thus the mutator always attaches onto a target by reference
  and needs the ability to manipulate the target
---
 src/lib/diff/test-mutation-target.hpp         | 11 +++-----
 .../diff/tree-mutator-collection-binding.hpp  | 26 ++++++++++++++-----
 src/lib/diff/tree-mutator.hpp                 |  1 +
 wiki/thinkPad.ichthyo.mm                      |  8 ++++++
 4 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/src/lib/diff/test-mutation-target.hpp b/src/lib/diff/test-mutation-target.hpp
index 004eb94f7..f715a3cf6 100644
--- a/src/lib/diff/test-mutation-target.hpp
+++ b/src/lib/diff/test-mutation-target.hpp
@@ -47,7 +47,6 @@
 
 #include "lib/error.hpp"
 #include "lib/symbol.hpp"
-#include "lib/iter-adapter-stl.hpp"
 #include "lib/diff/record.hpp"
 #include "lib/diff/tree-mutator.hpp"
 #include "lib/idi/genfunc.hpp"
@@ -227,12 +226,13 @@ namespace diff{
       
       /* === Operation / Mutation API === */
       
-      void
+      iterator
       initMutation (string mutatorID)
         {
           prev_content_.clear();
           swap (content_, prev_content_);
           log_.event ("attachMutator "+mutatorID);
+          return srcIter();
         }
       
       void
@@ -366,11 +366,8 @@ namespace diff{
         TestWireTap(Target& dummy, PAR const& chain)
           : PAR(chain)
           , target_(dummy)
-          , pos_()
-          {
-            target_.initMutation (identify(this));
-            pos_ = target_.srcIter();
-          }
+          , pos_(target_.initMutation (identify(this)))
+          { }
         
         
         
diff --git a/src/lib/diff/tree-mutator-collection-binding.hpp b/src/lib/diff/tree-mutator-collection-binding.hpp
index e84f66b4f..12c705d4a 100644
--- a/src/lib/diff/tree-mutator-collection-binding.hpp
+++ b/src/lib/diff/tree-mutator-collection-binding.hpp
@@ -59,6 +59,8 @@
     
     using lib::meta::Strip;
     using lib::diff::GenNode;
+    using lib::iter_stl::eachElm;
+    
     
     
     /** verify the installed functors or lambdas expose the expected signature */
@@ -88,13 +90,18 @@
       {
         using Coll = typename Strip<COLL>::TypeReferred;
         using Elm  = typename Coll::value_type;
-
+        
+        using iterator       = typename lib::iter_stl::_SeqT<Coll>::Range;
+        using const_iterator = typename lib::iter_stl::_SeqT<const Coll>::Range;
+        
+        
         ASSERT_VALID_SIGNATURE (MAT, bool(GenNode const& spec, Elm const& elm))
         ASSERT_VALID_SIGNATURE (CTR, Elm (GenNode const&))
         ASSERT_VALID_SIGNATURE (SEL, bool(GenNode const&))
         ASSERT_VALID_SIGNATURE (ASS, bool(Elm&, GenNode const&))
         ASSERT_VALID_SIGNATURE (MUT, bool(Elm&, TreeMutator::MutatorBuffer))
         
+        
         Coll& collection;
         
         MAT matches;
@@ -117,15 +124,15 @@
         
         Coll contentBuffer;
         
-#if false /////////////////////////////////////////////////////////////////////////////////////////////////////////////UNIMPLEMENTED :: TICKET #992
-        void
-        initMutation (string mutatorID)
+        iterator
+        initMutation ()
           {
-            prev_content_.clear();
-            swap (content_, prev_content_);
-            log_.event ("attachMutator "+mutatorID);
+            contentBuffer.clear();
+            swap (collection, contentBuffer);
+            return eachElm (contentBuffer);
           }
         
+#if false /////////////////////////////////////////////////////////////////////////////////////////////////////////////UNIMPLEMENTED :: TICKET #992
         void
         inject (GenNode&& elm, string operationID)
           {
@@ -165,12 +172,17 @@
     class ChildCollectionMutator
       : public PAR
       {
+        using Iter = typename BIN::iterator;
+        
         BIN binding_;
+        Iter pos_;
+        
         
       public:
         ChildCollectionMutator(BIN wiringClosures, PAR const& chain)
           : PAR(chain)
           , binding_(wiringClosures)
+          , pos_(binding_.initMutation())
           { }
         
         
diff --git a/src/lib/diff/tree-mutator.hpp b/src/lib/diff/tree-mutator.hpp
index 3399ea019..3b6ca52a1 100644
--- a/src/lib/diff/tree-mutator.hpp
+++ b/src/lib/diff/tree-mutator.hpp
@@ -77,6 +77,7 @@
 #include "lib/meta/trait.hpp"
 #include "lib/diff/gen-node.hpp"
 #include "lib/opaque-holder.hpp"
+#include "lib/iter-adapter-stl.hpp"
 //#include "lib/util.hpp"
 //#include "lib/format-string.hpp"
 
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 50b723978..87df08862 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -2443,6 +2443,14 @@
 <node CREATED="1458850746184" ID="ID_105803291" MODIFIED="1458850752370" TEXT="kein Mutator"/>
 </node>
 <node CREATED="1458850782747" ID="ID_1019140953" MODIFIED="1458850793430" TEXT="Umgang mit fehlendem Selector"/>
+<node CREATED="1458934854051" ID="ID_898160956" MODIFIED="1458934860213" TEXT="Binding st&#xe4;rker abschlie&#xdf;en">
+<node CREATED="1458934863225" ID="ID_843139682" MODIFIED="1458934897237" TEXT="contentBuffer k&#xf6;nnte privat sein">
+<icon BUILTIN="help"/>
+</node>
+<node CREATED="1458934878911" ID="ID_986928457" MODIFIED="1458934893132" TEXT="welche Iteratoren m&#xfc;ssen exponiert werden">
+<icon BUILTIN="help"/>
+</node>
+</node>
 </node>
 <node CREATED="1458868836883" ID="ID_717368167" MODIFIED="1458868851053" TEXT="Beobachtungen">
 <node CREATED="1458868852849" ID="ID_1641586585" MODIFIED="1458869076689" TEXT="Sonderbarer &quot;this&quot;-Typ">