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ChainSearch: ensure to pass current state without spurious copy

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It is essential that we pass the current state of the filter
into the expand functor, where it needs to be copied (once!)
to create a child state, which can then be augmented.

This augmented state is then pushed onto a stack, to enable backtracking.


Due to the flexible adapters and the wrapping into the TreeExplorer builder,
we ended up performing several spurious copies on the current state
This commit is contained in:
Fischlurch 2018-09-07 20:44:25 +02:00
parent d923138d1c
commit c0b8b63df0
3 changed files with 118 additions and 6 deletions
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21
src/lib/iter-chain-search.hpp
View file

@ -92,11 +92,19 @@ namespace iter {
template<class SRC>
struct _IterChainSetup
{
using Filter = decltype( buildSearchFilter (std::declval<SRC>()) );
using StepFunctor = typename iter_explorer::_BoundFunctor<Filter(Filter const&), Filter const&>::Functor;
using Filter = decltype( buildSearchFilter(std::declval<SRC>()).asIterator() );
using StepFunctor = std::function<Filter(Filter const&)>;
using StepWrapper = typename iter_explorer::_BoundFunctor<Filter(Filter const&), Filter const&>::Functor;
// ^^^^^^^^^^^^^ used as argument on generic lambda
using Pipeline = decltype( buildExplorer (std::declval<SRC>(), std::declval<StepFunctor>()) );
static Pipeline
configurePipeline (SRC&& dataSource, StepFunctor step)
{
return buildExplorer(forward<SRC> (dataSource), move (step));
}
};
}//(End)type construction helpers
@ -122,7 +130,7 @@ namespace iter {
using Value = typename _Base::value_type;
using Filter = typename _Trait::Filter;
using Step = typename _Trait::StepFunctor;
using Step = typename _Trait::StepWrapper;
std::vector<Step> stepChain_;
@ -136,8 +144,8 @@ namespace iter {
template<class SEQ>
explicit
IterChainSearch (SEQ&& srcData)
: _Base{move (buildExplorer (forward<SEQ> (srcData)
,Step{[this](Filter const& curr){ return configureFilterChain(curr); }}))}
: _Base{_Trait::configurePipeline (forward<SEQ> (srcData)
,[this](Filter const& curr){ return configureFilterChain(curr); })}
{ }
// inherited default ctor and standard copy operations
@ -165,6 +173,7 @@ namespace iter {
search (FUN&& configureSearchStep)
{
stepChain_.emplace_back (Step{forward<FUN> (configureSearchStep)});
this->iterNext(); // establish invariant: expand to leaf and forward to first match
return move(*this);
}

10
src/lib/iter-tree-explorer.hpp
View file

@ -1474,6 +1474,16 @@ namespace lib {
{
return IterExploreSource<value_type> {move(*this)};
}
/** _terminal builder_ to strip the TreeExplorer and expose the built Pipeline.
* @return a »Lumiera Forward iterator« incorporating the complete pipeline logic.
*/
SRC
asIterator()
{
return SRC {move(*this)};
}
};

93
wiki/thinkPad.ichthyo.mm
View file

@ -31215,6 +31215,99 @@
<icon BUILTIN="flag-yellow"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1536340043113" ID="ID_1162927294" MODIFIED="1536340232698" TEXT="aktuellen Zustand als Argument">
<icon BUILTIN="pencil"/>
<node COLOR="#338800" CREATED="1536340051461" ID="ID_1232898317" MODIFIED="1536345629500" TEXT="Wichtig: Referenz">
<linktarget COLOR="#a9b4c1" DESTINATION="ID_1232898317" ENDARROW="Default" ENDINCLINATION="550;0;" ID="Arrow_ID_1329838760" SOURCE="ID_1977741990" STARTARROW="None" STARTINCLINATION="109;0;"/>
<icon BUILTIN="button_ok"/>
<node CREATED="1536340255596" ID="ID_1394539187" MODIFIED="1536340348029" TEXT="&#xfc;berfl&#xfc;ssige Kopie erstellt">
<icon BUILTIN="messagebox_warning"/>
<node CREATED="1536340275802" ID="ID_1689368781" MODIFIED="1536340292559" TEXT="im Aufruf des inneren (grwrappten) Funktors">
<icon BUILTIN="info"/>
</node>
<node CREATED="1536340301958" ID="ID_932937045" MODIFIED="1536340319264" TEXT="das reingegebene Argument zeigt noch (korrekt) auf die aktuelle Pipeline"/>
<node CREATED="1536340325843" ID="ID_1834736142" MODIFIED="1536340342005" TEXT="aber das eingwickelte Lambda sieht eine const&amp; auf eine Kopie"/>
</node>
<node COLOR="#338800" CREATED="1536342792784" ID="ID_363834044" MODIFIED="1536342806527" TEXT="doppeltes Wrappen unn&#xf6;tig">
<icon BUILTIN="button_ok"/>
</node>
<node COLOR="#338800" CREATED="1536342807526" ID="ID_1490056918" MODIFIED="1536342900054" TEXT="stattdessen im vector&lt;Step&gt; wrappen">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...d.h. die <i>einzelnen</i>&#160;Steps in der Pipeline direkt wrappen.
</p>
<p>
Dann ist au&#223;en herum keine Anpassung der Argumente mehr notwendig,
</p>
<p>
und man kann die Expand-Funktion direkt als std::function-Objekt durchgeben
</p>
</body>
</html>
</richcontent>
<icon BUILTIN="idea"/>
</node>
</node>
<node CREATED="1536340063062" ID="ID_1554385479" MODIFIED="1536340152896" TEXT="und zwar const&amp;">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...um den Expand-Funktor zu zwingen, eine Kopie zu machen;
</p>
<p>
es sollte die Filter-Konfiguration auf der Kopie manipuliert werden,
</p>
<p>
w&#228;hrend das Original auf dem Auswertungs-Stack liegen bleibt,
</p>
<p>
f&#252;r sp&#228;teres Backtracking...
</p>
</body>
</html>
</richcontent>
</node>
<node COLOR="#338800" CREATED="1536345349807" ID="ID_219089137" MODIFIED="1536345462776" TEXT="TreeExplorer strippen">
<icon BUILTIN="button_ok"/>
<node CREATED="1536345360133" ID="ID_23274093" MODIFIED="1536345384449" TEXT="wird immer noch au&#xdf;ern herumgewickelt">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...damit man stets weitere Builder-Funktionen auf der Pipeline aufrufen kann
</p>
</body>
</html>
</richcontent>
</node>
<node CREATED="1536345386770" ID="ID_1554908631" MODIFIED="1536345421597" TEXT="wir brauchen aber den Filter-Iterator selber">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
weil wir <i>diesen</i>&#160;manipulieren
</p>
</body>
</html>
</richcontent>
</node>
<node CREATED="1536345422997" ID="ID_1977741990" MODIFIED="1536345460034" TEXT="nur so kann man eine Referenz auf den Zustand in den Expand-Funktor geben">
<arrowlink DESTINATION="ID_1232898317" ENDARROW="Default" ENDINCLINATION="550;0;" ID="Arrow_ID_1329838760" STARTARROW="None" STARTINCLINATION="109;0;"/>
<icon BUILTIN="idea"/>
</node>
</node>
</node>
<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="button_ok"/>