From 604ffbf73c123715f6bfe2e426e23f3f87596618 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Mon, 3 Sep 2018 01:52:07 +0200
Subject: [PATCH] TreeExplorer: fix a bug and finish the feature

we did an unnecessary copy of the argument, which was uncovered
by the test case manipulating the state core.


Whew.
Now we have a beautiful new overengineered solution
---
 src/lib/iter-tree-explorer.hpp            | 12 +++---
 tests/library/iter-tree-explorer-test.cpp | 27 +++++++-----
 wiki/thinkPad.ichthyo.mm                  | 50 ++++++++++++++---------
 3 files changed, 54 insertions(+), 35 deletions(-)

diff --git a/src/lib/iter-tree-explorer.hpp b/src/lib/iter-tree-explorer.hpp
index eaad1db79..07d9c9a75 100644
--- a/src/lib/iter-tree-explorer.hpp
+++ b/src/lib/iter-tree-explorer.hpp
@@ -988,7 +988,7 @@ namespace lib {
             remouldFilter (forward<COND> (conjunctiveClause)
                           ,[](auto first, auto chain)
                              {
-                               return [=](auto val)
+                               return [=](auto& val)
                                          {
                                            return first(val)
                                               and chain(val);
@@ -1004,7 +1004,7 @@ namespace lib {
             remouldFilter (forward<COND> (conjunctiveClause)
                           ,[](auto first, auto chain)
                              {
-                               return [=](auto val)
+                               return [=](auto& val)
                                          {
                                            return first(val)
                                               and not chain(val);
@@ -1020,7 +1020,7 @@ namespace lib {
             remouldFilter (forward<COND> (disjunctiveClause)
                           ,[](auto first, auto chain)
                              {
-                               return [=](auto val)
+                               return [=](auto& val)
                                          {
                                            return first(val)
                                                or chain(val);
@@ -1036,7 +1036,7 @@ namespace lib {
             remouldFilter (forward<COND> (disjunctiveClause)
                           ,[](auto first, auto chain)
                              {
-                               return [=](auto val)
+                               return [=](auto& val)
                                          {
                                            return first(val)
                                                or not chain(val);
@@ -1052,7 +1052,7 @@ namespace lib {
             remouldFilter (dummy
                           ,[](auto currentFilter, auto)
                              {
-                               return [=](auto val)
+                               return [=](auto& val)
                                          {
                                            return not currentFilter(val);
                                          };
@@ -1067,7 +1067,7 @@ namespace lib {
             remouldFilter (forward<COND> (entirelyDifferentPredicate)
                           ,[](auto, auto chain)
                              {
-                               return [=](auto val)
+                               return [=](auto& val)
                                          {
                                            return chain(val);
                                          };
diff --git a/tests/library/iter-tree-explorer-test.cpp b/tests/library/iter-tree-explorer-test.cpp
index 48f4b951b..601cf5f3c 100644
--- a/tests/library/iter-tree-explorer-test.cpp
+++ b/tests/library/iter-tree-explorer-test.cpp
@@ -848,7 +848,7 @@ namespace test{
       
       
       
-      /** @test the filter layer can be re-configured on the fly */
+      /** @test a special filter layer which can be re-configured on the fly */
       void
       verify_FilterChanges()
         {
@@ -869,7 +869,7 @@ namespace test{
           CHECK (16 == *seq);
           
           seq.andFilter (takeTrd);
-          CHECK (12 == *seq);
+          CHECK (12 == *seq);   //  is divisible (by 2 AND by 3)
           
           seq.flipFilter();
           CHECK (11 == *seq);   // not divisible (by 2 AND by 3)
@@ -884,22 +884,29 @@ namespace test{
           seq.orNotFilter (takeEve);
           CHECK ( 6 == *seq);
           ++seq;
-          CHECK ( 5 == *seq);
+          CHECK ( 5 == *seq);   // disjunctive condition actually weakens the filter
           ++seq;
           CHECK ( 3 == *seq);
           
+          // NOTE: arbitrary functors can be used/combined,
+          //       since they are adapted individually.
+          // To demonstrate this, we use a functor accessing and
+          // manipulating the state core by side effect...
           string buff{"."};
           seq.andNotFilter ([&](CountDown& core)
                               {
                                 buff += util::toString(core.p) + ".";
-                                --core.p;
-                                return core.p % 2;
+                                --core.p;                              // manipulate state core
+                                return core.p % 2;                     // return a number, not bool
                               });
-          cout << "URGS: "<<*seq<< " ..."<<buff<<endl;
-          ++seq;
-          cout << "URGS: "<<*seq<< " ..."<<buff<<endl;
-          ++seq;
-          CHECK (isnil (seq));
+          
+          CHECK ( 2 == *seq);                   // value in the core has been manipulated
+          CHECK (".3." == buff);                // the filter has been invoked once, and saw core == 3
+          
+          ++seq;                                // core == 2 is filtered by the existing other filter (== not take even)
+          CHECK (".3.1." == buff);              // the filter has been invoked again, and saw core == 1
+          CHECK (0 == seq.p);                   // ...which he manipulated, so that core == 0
+          CHECK (isnil (seq));                  // .....and thus iteration end is detected
           VERIFY_ERROR (ITER_EXHAUST, *seq );
         }
       
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 78931d309..309294c49 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -30840,8 +30840,8 @@
 <icon BUILTIN="help"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1535893707036" ID="ID_257876647" MODIFIED="1535899964941" TEXT="Aufgabe: Filter erweiterbar machen">
-<icon BUILTIN="pencil"/>
+<node COLOR="#338800" CREATED="1535893707036" ID="ID_257876647" MODIFIED="1535932142834" TEXT="Aufgabe: Filter erweiterbar machen">
+<icon BUILTIN="button_ok"/>
 <node CREATED="1535893718194" ID="ID_872370459" MODIFIED="1535893743691" TEXT="analog zum Filter in den Itertools"/>
 <node CREATED="1535893752174" ID="ID_386073545" MODIFIED="1535893777011" TEXT="ggfs diesen dort abl&#xf6;sen">
 <richcontent TYPE="NOTE"><html>
@@ -30856,7 +30856,7 @@
 </html>
 </richcontent>
 </node>
-<node CREATED="1535903530421" ID="ID_384303362" MODIFIED="1535903535289" TEXT="Aua">
+<node COLOR="#338800" CREATED="1535903530421" ID="ID_384303362" MODIFIED="1535932193036" TEXT="Aua">
 <icon BUILTIN="smily_bad"/>
 <node CREATED="1535903536820" ID="ID_1343418651" MODIFIED="1535903541919" TEXT="das wird komplex..."/>
 <node CREATED="1535903542556" ID="ID_1721469481" MODIFIED="1535903551375" TEXT="der Filter-Layer ist hochgradig generisch"/>
@@ -30927,7 +30927,7 @@
 </richcontent>
 </node>
 </node>
-<node CREATED="1535904461720" ID="ID_317840110" MODIFIED="1535904468474" TEXT="will ich das wirklich.....?">
+<node CREATED="1535904461720" FOLDED="true" ID="ID_317840110" MODIFIED="1535932207865" TEXT="will ich das wirklich.....?">
 <node CREATED="1535904470670" ID="ID_160594644" MODIFIED="1535904516890" TEXT="nat&#xfc;rlich nicht">
 <richcontent TYPE="NOTE"><html>
   <head>
@@ -30977,7 +30977,7 @@
 </node>
 <node COLOR="#338800" CREATED="1535906261464" ID="ID_1343076549" MODIFIED="1535909947735" TEXT="Auswege">
 <icon BUILTIN="idea"/>
-<node COLOR="#338800" CREATED="1535906265911" ID="ID_442265155" MODIFIED="1535913504313" TEXT="speziellen Filter-Layer nur hierf&#xfc;r">
+<node COLOR="#338800" CREATED="1535906265911" FOLDED="true" ID="ID_442265155" MODIFIED="1535932222887" TEXT="speziellen Filter-Layer nur hierf&#xfc;r">
 <icon BUILTIN="button_ok"/>
 <node CREATED="1535906327782" ID="ID_1903350743" MODIFIED="1535906334769" TEXT="letztlich nur Code-Kosmetik"/>
 <node CREATED="1535909106704" ID="ID_1756811057" MODIFIED="1535909115714" TEXT="w&#xfc;rde aber sehr speziellen Fall markieren"/>
@@ -30995,7 +30995,7 @@
 <icon BUILTIN="idea"/>
 </node>
 </node>
-<node COLOR="#338800" CREATED="1535906283948" ID="ID_367978731" MODIFIED="1535909918916" TEXT="Chain-Filter-Bau in HIlfsfunktion">
+<node COLOR="#338800" CREATED="1535906283948" FOLDED="true" ID="ID_367978731" MODIFIED="1535932223855" TEXT="Chain-Filter-Bau in HIlfsfunktion">
 <icon BUILTIN="button_ok"/>
 <node CREATED="1535906394646" ID="ID_296637778" MODIFIED="1535906399057" TEXT="w&#xfc;nschenswert"/>
 <node CREATED="1535906399621" ID="ID_1487063274" MODIFIED="1535906407632" TEXT="nicht klar, ob &#xfc;berhaupt m&#xf6;glich"/>
@@ -31051,9 +31051,10 @@
 </node>
 </node>
 </node>
-<node BACKGROUND_COLOR="#fdfdcf" COLOR="#ff0000" CREATED="1535919506060" ID="ID_308901003" MODIFIED="1535920180860" TEXT="heterogene Pr&#xe4;dikat-Typen">
-<icon BUILTIN="broken-line"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1535919540560" ID="ID_544134703" MODIFIED="1535920188703" TEXT="geht nicht(?)">
+<node COLOR="#338800" CREATED="1535919506060" FOLDED="true" ID="ID_308901003" MODIFIED="1535932218407" TEXT="heterogene Pr&#xe4;dikat-Typen">
+<icon BUILTIN="button_ok"/>
+<node CREATED="1535919540560" ID="ID_544134703" MODIFIED="1535932049581" TEXT="geht nicht?">
+<font ITALIC="true" NAME="SansSerif" SIZE="12"/>
 <icon BUILTIN="messagebox_warning"/>
 </node>
 <node CREATED="1535919549942" ID="ID_809087906" MODIFIED="1535919754360" TEXT="das zu Beginn verwendete Filter-Pr&#xe4;dikat legt den Typ fest">
@@ -31081,15 +31082,26 @@
       Typischerweise wird dieser ja sogar beim Aufruf des getemplateteten Funtions-Operators geInlined
     </p>
   </body>
-</html>
-</richcontent>
+</html></richcontent>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1535919835337" ID="ID_984434298" MODIFIED="1535920192370" TEXT="Ausweg: doppelt wrappen?">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1535919835337" ID="ID_984434298" MODIFIED="1535932021329" TEXT="Ausweg: doppelt wrappen?">
+<icon BUILTIN="button_ok"/>
 <node CREATED="1535923167297" ID="ID_1611885187" MODIFIED="1535923219590" TEXT="Basis-Filter sieht unspezifische Form des Pr&#xe4;dikates"/>
 <node CREATED="1535923237336" ID="ID_873685254" MODIFIED="1535923251434" TEXT="im Funktor steckt eingewickelt eine spezifische Form"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1535924949587" ID="ID_283543674" MODIFIED="1535925042250" TEXT="L&#xf6;sung">
-<icon BUILTIN="pencil"/>
+<node CREATED="1535932069618" ID="ID_937611933" MODIFIED="1535932128786" TEXT="kein wirklicher overhead">
+<richcontent TYPE="NOTE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      der Aufruf vom &#228;u&#223;eren in den inneren Wrapper ist 1:1 und sollte vom Compiler wegoptimiert werden
+    </p>
+  </body>
+</html></richcontent>
+</node>
+<node COLOR="#338800" CREATED="1535924949587" ID="ID_283543674" MODIFIED="1535932018158" TEXT="L&#xf6;sung">
+<icon BUILTIN="button_ok"/>
 <node COLOR="#338800" CREATED="1535924955458" ID="ID_257130301" MODIFIED="1535927205707" TEXT="Typ des gewrappten Funktors konstruieren">
 <icon BUILTIN="button_ok"/>
 </node>
@@ -31109,13 +31121,13 @@
 </node>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1535899873112" ID="ID_1460874987" MODIFIED="1535913524436" TEXT="Unit-Test (replizieren)">
-<icon BUILTIN="pencil"/>
+<node COLOR="#338800" CREATED="1535899873112" ID="ID_1460874987" MODIFIED="1535932139639" TEXT="Unit-Test (replizieren)">
+<icon BUILTIN="button_ok"/>
 <node COLOR="#338800" CREATED="1535913527837" ID="ID_1506533000" MODIFIED="1535913542932" TEXT="anlegen">
 <icon BUILTIN="button_ok"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1535913531701" ID="ID_1093929821" MODIFIED="1535919483699" TEXT="andere F&#xe4;lle auch covern">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1535913531701" ID="ID_1093929821" MODIFIED="1535932138102" TEXT="andere F&#xe4;lle auch covern">
+<icon BUILTIN="button_ok"/>
 </node>
 </node>
 </node>