ChainSearch: configure the core of the chained search mechanism

...based on a monadic tree expansion: we define a single step,
which takes the current filter configuration and builds the next
filter configuration, based on a stored chain of configuration functions

The actual exhausting depth-first results just by the greedy application pattern,
and uses the stack embedded in the "Explorer" layer of TreeExplorer

src/lib/iter-chain-search.hpp

@@ -42,6 +42,7 @@
 
 #include "lib/error.hpp"
 #include "lib/iter-tree-explorer.hpp"
+#include "lib/meta/util.hpp"
 
 //#include <type_traits>
 //#include <utility>
@@ -57,6 +58,8 @@ namespace iter {
   using std::forward;
   using std::string;
   
+  using lib::meta::disable_if;
+  
   
   namespace { // type construction helpers...
     
@@ -91,7 +94,7 @@ namespace iter {
       {
         using Filter = decltype( buildSearchFilter (std::declval<SRC>()) );
         
-        using StepFunctor = typename iter_explorer::_BoundFunctor<Filter(Filter const&), Filter>::Functor;
+        using StepFunctor = typename iter_explorer::_BoundFunctor<Filter(Filter const&), Filter const&>::Functor;
         
         using Pipeline = decltype( buildExplorer (std::declval<SRC>(), std::declval<StepFunctor>()) );
       };
@@ -117,6 +120,7 @@ namespace iter {
       using _Trait = _IterChainSetup<SRC>;
       using _Base  = typename _Trait::Pipeline;
       
+      using Value  = typename _Base::value_type;
       using Filter = typename _Trait::Filter;
       using Step   = typename _Trait::StepFunctor;
       
@@ -141,18 +145,53 @@ namespace iter {
       
       
       
-      /** */
+      /** configure additional chained search condition.
-      IterChainSearch&&
+       * @param a functor `Filter const& -> filter`, which takes a current filter configuration,
-      search (string target)
+       *        returning a copy from this configuration, possibly configured differently.
+       * @note the given functor, lambda or function reference will be wrapped and adapted
+       *       to conform to the required function signature. When using a generic lambda,
+       *       the argument type `Filter const&` is assumed
+       * @remarks the additional chained search condition given here will be applied _after_
+       *       matching all other conditions already in the filter chain. Each such condition
+       *       is used to _filter_ the underlying source iterator, i.e. pull it until finding
+       *       and element to match the condition. Basically these conditions are _not_ used in
+       *       conjunction, but rather one after another. But since each such step in the chain
+       *       is defined by a functor, which gets the previous filter configuration as argument,
+       *       it is _possible_ to build a step which _extends_ or sharpens the preceding condition.
+       */
+      template<typename FUN>
+                                          disable_if<is_convertible<FUN, Value>,
+      IterChainSearch&&                             >
+      search (FUN&& configureSearchStep)
         {
-          TODO ("configure additional chained search condition");
+          stepChain_.emplace_back (Step{forward<FUN> (configureSearchStep)});
           return move(*this);
         }
       
+      /** attach additional direct search for a given value.
+       *  After successfully searching for all the conditions currently in the filter chain,
+       *  the underlying iterator will finally be pulled until matching the given target value.
+       */
+      IterChainSearch&&
+      search (Value target)
+        {
+          search ([=](Filter filter)      // note: filter taken by value
+                    {
+                      filter.setNewFilter ([target](Value const& currVal) { return currVal == target; });
+                      return filter;   // return copy of the original state with changed filter
+                    });
+          return move(*this);
+        }
+      
+      /** drop all search condition frames.
+       * @remark the filter chain becomes empty,
+       *         passing through the unaltered
+       *         source sequence
+       */
       IterChainSearch&&
       clearFilter()
         {
-          UNIMPLEMENTED ("drop all search condition frames");
+          stepChain_.clear();
           return move(*this);
         }
       
@@ -160,8 +199,11 @@ namespace iter {
       Filter
       configureFilterChain (Filter const& currentFilterState)
         {
-          uint depth = this->depth();
+          uint depth = currentFilterState.depth();
-          return Filter{}; /////TODO empty filter means recursion end
+          if (depth < stepChain_.size())
+            return stepChain_[depth](currentFilterState); // augmented copy
+          else
+            return Filter{};     // empty filter indicates recursion end
         }
     };
   

tests/library/iter-chain-search-test.cpp

@@ -111,14 +111,11 @@ namespace test{
 ///////////////////////////////////////////////////TODO WIP
           using Searcher = decltype(search);
           SHOW_TYPE (Searcher);
-          SHOW_TYPE (Searcher::DebugPipeline);
           SHOW_TYPE (Searcher::value_type);
           SHOW_TYPE (Searcher::pointer);
           
 //        TypeDebugger<Searcher::reference> guggi;   // --> std::__cxx11::basic_string<char> const&
           cout << "search[0]=" <<*search<<endl;
-          ++search;
-          cout << "search[1]=" <<*search<<endl;
 ///////////////////////////////////////////////////TODO WIP
           CHECK (search);
           CHECK (not isnil(search));

wiki/thinkPad.ichthyo.mm

@@ -31196,15 +31196,15 @@
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 <node CREATED="1536018276593" ID="ID_1222260775" MODIFIED="1536018287299" TEXT="prekonfigurierte Builder-Funktionen f&#xfc;r Standardf&#xe4;lle"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018364845" ID="ID_1351452920" MODIFIED="1536018457506" TEXT="Implementierung">
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018364845" ID="ID_1351452920" MODIFIED="1536329770737" TEXT="Implementierung">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="pencil"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018375244" ID="ID_1906913554" MODIFIED="1536018458786" TEXT="Kern: Explore-Mechanismus">
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018375244" ID="ID_1906913554" MODIFIED="1536329750864" TEXT="Kern: Explore-Mechanismus">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="pencil"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018644456" ID="ID_477475522" MODIFIED="1536018654007" TEXT="Signatur der Explore-Funktion festlegen">
+<node COLOR="#338800" CREATED="1536018644456" ID="ID_477475522" MODIFIED="1536329729458" TEXT="Signatur der Explore-Funktion festlegen">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="button_ok"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018705511" ID="ID_1131109871" MODIFIED="1536018800891" TEXT="greedy Tiefensuche">
+<node COLOR="#338800" CREATED="1536018705511" ID="ID_1131109871" MODIFIED="1536329731179" TEXT="greedy Tiefensuche">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="button_ok"/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018802738" ID="ID_1560348563" MODIFIED="1536018807506" TEXT="Abbruchbedingung">
 <icon BUILTIN="flag-yellow"/>
@@ -31215,9 +31215,9 @@
 <icon BUILTIN="flag-yellow"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018862802" ID="ID_1044555993" MODIFIED="1536326576841" TEXT="abgeleiteten Frame konstruieren">
+<node COLOR="#338800" CREATED="1536018862802" ID="ID_1044555993" MODIFIED="1536329736419" TEXT="abgeleiteten Frame konstruieren">
 <linktarget COLOR="#65a7b1" DESTINATION="ID_1044555993" ENDARROW="Default" ENDINCLINATION="70;92;" ID="Arrow_ID_575633930" SOURCE="ID_1532889609" STARTARROW="None" STARTINCLINATION="149;-3;"/>
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="button_ok"/>
 </node>
 </node>
 <node COLOR="#338800" CREATED="1536018406232" ID="ID_1330264339" MODIFIED="1536326484790" TEXT="Schritte als Funktoren">
@@ -31456,14 +31456,14 @@
 <icon BUILTIN="flag-yellow"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018442123" ID="ID_829730232" MODIFIED="1536018463121" TEXT="Abk&#xfc;rzung f&#xfc;r direkten Match">
+<node COLOR="#338800" CREATED="1536018442123" ID="ID_829730232" MODIFIED="1536329759111" TEXT="Abk&#xfc;rzung f&#xfc;r direkten Match">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="button_ok"/>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018985450" ID="ID_1700266521" MODIFIED="1536019004173" TEXT="Wert-Typ deduzieren">
+<node COLOR="#338800" CREATED="1536018985450" ID="ID_1700266521" MODIFIED="1536329755895" TEXT="Wert-Typ deduzieren">
 <arrowlink DESTINATION="ID_1619721301" ENDARROW="Default" ENDINCLINATION="129;0;" ID="Arrow_ID_1721152439" STARTARROW="None" STARTINCLINATION="76;-5;"/>
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="button_ok"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536019008151" ID="ID_29813547" MODIFIED="1536019026064" TEXT="equality comparision in Lambda">
+<node COLOR="#338800" CREATED="1536019008151" ID="ID_29813547" MODIFIED="1536329757422" TEXT="equality comparision in Lambda">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="button_ok"/>
 </node>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018471975" ID="ID_1115030606" MODIFIED="1536018481902" TEXT="Variante f&#xfc;r bidirektionale Suche">
@@ -31484,8 +31484,8 @@
 <icon BUILTIN="idea"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018539621" ID="ID_1857591081" MODIFIED="1536018556917" TEXT="simpleSearch()">
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018539621" ID="ID_1857591081" MODIFIED="1536329779734" TEXT="simpleSearch()">
-<icon BUILTIN="flag-yellow"/>
+<icon BUILTIN="pencil"/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536018544936" ID="ID_1750921303" MODIFIED="1536018557580" TEXT="chainedIteration()">
 <icon BUILTIN="flag-yellow"/>