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TreeExplorer: define interaction between expand and transform-operation

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good news: it (almost) works out-of-the-box as expected.

There is only one problem: expandChildren() alters the content of the
data source, yet downstream decorators aren't aware of that fact and
continue to present cached evaluations, until the next iterate() call
is issued. Yet unfortunately this iterate already consumes the first
of the expanded children, which thus gets shadowed by the cached
outcome of parent node already consumed and expanded at that point

See the first example:

"10-8-expand-8-4-2-6-4-2"
should be 6 ^^^
This commit is contained in:
Fischlurch 2017-12-04 03:34:27 +01:00
parent 823848db37
commit 81c6136509
2 changed files with 178 additions and 16 deletions
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57
tests/library/iter-tree-explorer-test.cpp
View file

@ -324,7 +324,7 @@ namespace test{
* will try to instantiate the passed lambda by using the concrete source iterator type as argument.
*
* @note expansion functor may use side-effects and indeed return something entirely different
* than the original sequence, as long as it is iterable and yields compatible values.
* than the original sequence, as long as it is iterable and yields compatible values.
*/
void
verify_expandOperation()
@ -339,7 +339,7 @@ namespace test{
verify_treeExpandingIterator(
treeExplore(CountDown{5})
.expand([](uint j){ return NumberSequence{j-1}; }) // expand-functor: Val > Iter
);
); // NOTE: different Iterator type than the source!
// lambda with side-effect and return type different from source iter
vector<vector<uint>> childBuffer;
@ -456,7 +456,7 @@ namespace test{
auto multiply = [](int v){ return 2*v; }; // functional map: value -> value
_Fmt embrace{"≺%s≻"};
auto formatify = [&](auto it){ return string{embrace % *it}; }; // generic lambda: assumed to take an Iterator&
auto formatify = [&](auto it){ return string{embrace % *it}; }; // generic lambda: assumed to take an Iterator&
auto ii = treeExplore (CountDown{7,4})
@ -559,12 +559,59 @@ namespace test{
}
/** @test combie the recursion into children with a tail mapping operation
/** @test combine the recursion into children with a tail mapping operation.
* Wile basically this is just the layering structure of TreeExplorer put into action,
* you should note one specific twist: the iter_explorer::Expander::expandChildren() call
* is meant to be issued from ``downstream'', from the consumer side. Yet the consumer at
* that point might well see the items as processed by a transforming step layered on top.
* So what the consumer sees and thinks will be expanded need not actually be what will
* be processed by the _expand functor_. This may look like a theoretical or cosmetic
* issue -- yet in fact it is this tiny detail which is crucial to make abstraction of
* the underlying data source actually work in conjunction with elaborate searching and
* matching algorithms. Even more so, when other operations like filtering are intermingled;
* in that case it might even happen that the downstream consumer does not even see the
* items resulting from child expansion, because they are evaluated and then filtered
* away by a transformer and filter placed in between.
* @note a corollary of the aforementioned is the observation that having several expand
* layers is rather not useful in practice. Due to the nested inheritance structure
* of the assembled TreeExplorer, it is the expansion layer most on top in the chain
* who will receive the `expandChildren()` call.
*/
void
verify_combinedExpandTransform()
{
UNIMPLEMENTED("combine child expansion and result mapping");
auto ii = treeExplore(CountDown{5})
.expand([](uint j){ return CountDown{j-1}; })
.transform([](int v){ return 2*v; })
;
CHECK ("int" == meta::typeStr(*ii)); // result type is what the last transformer yields
CHECK (10 == *ii);
++ii;
CHECK (8 == *ii);
ii.expandChildren();
cout << materialise(ii) <<endl;/////////////////////////////////TODO "8-4-2-6-4-2"
// the following contrived example demonstrates
// how intermediary processing steps may interact
cout << materialise (
treeExplore(CountDown{5})
.expand([](uint j){ return CountDown{j-1}; })
.transform([](int v){ return 2*v; })
.transform([](auto& it)
{
auto elm = *it;
if (elm == 6)
{
it.expandChildren();
elm *= 10;
}
return elm;
})
.transform([](float f){ return f/2; })
) <<endl;///////////////////////////////////////////TODO "5-4-30-1-2-1"
}

137
wiki/thinkPad.ichthyo.mm
View file

@ -5105,7 +5105,7 @@
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1510941463562" ID="ID_845080696" MODIFIED="1510941523082" TEXT="TreeExplorer">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1511571446467" FOLDED="true" ID="ID_1778455053" MODIFIED="1511827102192" TEXT="expand-Operation">
<node COLOR="#338800" CREATED="1511571446467" FOLDED="true" ID="ID_1778455053" MODIFIED="1512358577968" TEXT="expand-Operation">
<icon BUILTIN="button_ok"/>
<node COLOR="#338800" CREATED="1511227813712" ID="ID_1961708112" MODIFIED="1511228177906" TEXT="Fall-1">
<icon BUILTIN="button_ok"/>
@ -5327,7 +5327,7 @@
</node>
</node>
</node>
<node COLOR="#338800" CREATED="1511827103749" ID="ID_1699316886" MODIFIED="1512278362994" TEXT="transform-Operation">
<node COLOR="#338800" CREATED="1511827103749" FOLDED="true" ID="ID_1699316886" MODIFIED="1512358581381" TEXT="transform-Operation">
<icon BUILTIN="button_ok"/>
<node CREATED="1511827249561" ID="ID_794510302" MODIFIED="1511827265634" TEXT="strikt nach Dekorator-Pattern"/>
<node CREATED="1511827337686" ID="ID_1214119488" MODIFIED="1511827345695" TEXT="bestehendern TransformIter verwenden?">
@ -5394,8 +5394,7 @@
TreeExplorer per <i>slicing move</i>&#160;entfernen
</p>
</body>
</html>
</richcontent>
</html></richcontent>
</node>
<node CREATED="1512262331008" ID="ID_287760536" MODIFIED="1512262346625" TEXT="enthaltenen SrcIter dekorieren -&gt; Core"/>
<node CREATED="1512262347637" ID="ID_1683477051" MODIFIED="1512262371854" TEXT="erneut einen TreeExplorer dar&#xfc;ber adaptieren"/>
@ -5469,7 +5468,7 @@
<node CREATED="1512010371291" ID="ID_563900951" MODIFIED="1512010383805" TEXT="bietet die ExtensionPoints einer State-Core"/>
</node>
</node>
<node COLOR="#338800" CREATED="1511837027405" ID="ID_233806852" MODIFIED="1512278360077" TEXT="Argument-Detektor-Magie">
<node COLOR="#338800" CREATED="1511837027405" FOLDED="true" ID="ID_233806852" MODIFIED="1512358518711" TEXT="Argument-Detektor-Magie">
<icon BUILTIN="button_ok"/>
<node CREATED="1511837039180" ID="ID_1296099637" MODIFIED="1512278401909" TEXT="ganz analog zur expand-Operation">
<icon BUILTIN="idea"/>
@ -5673,6 +5672,7 @@
<icon BUILTIN="forward"/>
</node>
</node>
</node>
<node COLOR="#338800" CREATED="1512179383254" FOLDED="true" ID="ID_1554412479" MODIFIED="1512358439866" TEXT="mu&#xdf; value_type from Funktor gewinnen">
<icon BUILTIN="button_ok"/>
<node CREATED="1512181398331" ID="ID_1715550480" MODIFIED="1512181407142" TEXT="value_type rebinden"/>
@ -5691,7 +5691,6 @@
</node>
</node>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1511837279715" ID="ID_1694539348" MODIFIED="1511837456610" TEXT="filter-Operation">
<icon BUILTIN="hourglass"/>
<node CREATED="1511837285306" ID="ID_928417859" MODIFIED="1511837293629" TEXT="der Vollst&#xe4;ndigkeit halber">
@ -5706,12 +5705,109 @@
<node CREATED="1511837345226" ID="ID_991593174" MODIFIED="1511837351797" TEXT="bestehende Funktor-Argument-Traits"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1512363846804" ID="ID_1346062807" MODIFIED="1512363878326" TEXT="auto-expand">
<icon BUILTIN="hourglass"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1512363286920" ID="ID_1420123769" MODIFIED="1512363305422" TEXT="Zusammenspiel">
<icon BUILTIN="flag-yellow"/>
<node BACKGROUND_COLOR="#fdfdcf" COLOR="#ff0000" CREATED="1512363297486" ID="ID_531127457" MODIFIED="1512363711955" TEXT="re-evaluate">
<linktarget COLOR="#a25a86" DESTINATION="ID_531127457" ENDARROW="Default" ENDINCLINATION="385;167;" ID="Arrow_ID_556443427" SOURCE="ID_579206895" STARTARROW="None" STARTINCLINATION="844;55;"/>
<icon BUILTIN="messagebox_warning"/>
<node CREATED="1512363369036" ID="ID_134602126" MODIFIED="1512363378567" TEXT="Problem Quell-&#xc4;nderung">
<icon BUILTIN="messagebox_warning"/>
<node CREATED="1512363380411" ID="ID_1008917631" MODIFIED="1512363473668" TEXT="expandChildren &#xe4;ndert aktuellen Gehalt der Quelle">
<icon BUILTIN="info"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1512363397897" ID="ID_1178182932" MODIFIED="1512363487789" TEXT="aber downstream reagiert (bisher) nur auf iterate()">
<icon BUILTIN="flag-yellow"/>
</node>
<node BACKGROUND_COLOR="#fdfdcf" COLOR="#ff0000" CREATED="1512363421797" ID="ID_1732504592" MODIFIED="1512363505534" TEXT="Folge: geCacheter Wert aus Transformer &#xfc;berdeckt">
<icon BUILTIN="broken-line"/>
</node>
</node>
<node CREATED="1512363518944" ID="ID_1189860266" MODIFIED="1512363524154" TEXT="L&#xf6;sungsidee">
<icon BUILTIN="idea"/>
<node CREATED="1512363525815" ID="ID_108313040" MODIFIED="1512363819912" TEXT="Hook, auf den alle reagieren">
<font ITALIC="true" NAME="SansSerif" SIZE="12"/>
</node>
<node CREATED="1512363586327" ID="ID_594917391" MODIFIED="1512363811942" TEXT="TreeExplorer wird Update-Manager">
<icon BUILTIN="help"/>
</node>
</node>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1511837384749" ID="ID_274979743" MODIFIED="1511837465023" TEXT="asIterSource">
<icon BUILTIN="hourglass"/>
<node CREATED="1511837396075" ID="ID_1916743569" MODIFIED="1511837401078" TEXT="abschlie&#xdf;ender Dekorator"/>
<node CREATED="1511837401738" ID="ID_289320579" MODIFIED="1511837414204" TEXT="verpackt hinter OO-Interface mit virtuellen Funktionen"/>
<node CREATED="1511837421967" ID="ID_906113750" MODIFIED="1511837433914" TEXT="automatische Heap-Storage"/>
</node>
<node CREATED="1512358595283" FOLDED="true" ID="ID_1526405052" MODIFIED="1512359008205" TEXT="piggyback?">
<icon BUILTIN="help"/>
<node CREATED="1512358616584" ID="ID_1041373923" MODIFIED="1512358662699" TEXT="&quot;k&#xf6;nnte mal praktisch sein&quot;">
<font ITALIC="true" NAME="SansSerif" SIZE="12"/>
</node>
<node CREATED="1512358626607" ID="ID_853537387" MODIFIED="1512358721321" TEXT="hab die Idee schon lange">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...da&#223; man ein Ding komplett in einen Iterator packt,
</p>
<p>
und dieser es dann auch managed
</p>
</body>
</html>
</richcontent>
<node CREATED="1512358864343" FOLDED="true" ID="ID_1251747225" MODIFIED="1512358957195">
<richcontent TYPE="NODE"><html>
<head>
</head>
<body>
<p>
ist das <font color="#9e1124">#190</font>
</p>
</body>
</html>
</richcontent>
<icon BUILTIN="button_cancel"/>
<node CREATED="1512358896258" ID="ID_62377324" MODIFIED="1512358945435" TEXT="nein das ist was anderes">
<icon BUILTIN="stop-sign"/>
</node>
<node CREATED="1512358903177" ID="ID_1427111206" MODIFIED="1512358940471" TEXT="das w&#xe4;re OpaqueHolder heute">
<icon BUILTIN="idea"/>
</node>
<node CREATED="1512358931774" ID="ID_1681797535" MODIFIED="1512358937271" TEXT="plus etwas Magie">
<icon BUILTIN="ksmiletris"/>
</node>
</node>
<node CREATED="1512358965657" ID="ID_816120367" MODIFIED="1512359005565" TEXT="trotzdem... auch IterSnapshot">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...ist partiell diese Idee.
</p>
<p>
Nur auch das auf einem etwas anderem Level,
</p>
<p>
und immer mit einem Heap-allozierten vector
</p>
</body>
</html>
</richcontent>
</node>
</node>
<node CREATED="1512358632486" ID="ID_1795551304" MODIFIED="1512358640785" TEXT="aber keine konkrete Anwendung"/>
<node CREATED="1512358649900" ID="ID_1625666992" MODIFIED="1512358657226" TEXT="w&#xe4;re hier billig zu haben"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1510941467586" ID="ID_381928532" MODIFIED="1510941523722" TEXT="TreeExplorer_test">
<icon BUILTIN="flag-yellow"/>
@ -5789,7 +5885,7 @@
<node COLOR="#338800" CREATED="1511835716176" ID="ID_1407397782" MODIFIED="1512276211354" TEXT="Transformer mit Seiteneffekt">
<icon BUILTIN="button_ok"/>
</node>
<node COLOR="#338800" CREATED="1511835691963" ID="ID_175353270" MODIFIED="1512276275698" TEXT="Transform: generic Lambda">
<node COLOR="#338800" CREATED="1511835691963" FOLDED="true" ID="ID_175353270" MODIFIED="1512358531485" TEXT="Transform: generic Lambda">
<icon BUILTIN="button_ok"/>
<node CREATED="1512181454244" ID="ID_23118252" MODIFIED="1512271778125" TEXT="AUA: warum wird hier ein Value als Arguement &#xfc;bergeben">
<arrowlink COLOR="#a83e54" DESTINATION="ID_215116122" ENDARROW="Default" ENDINCLINATION="351;347;" ID="Arrow_ID_891457048" STARTARROW="None" STARTINCLINATION="683;0;"/>
@ -5869,7 +5965,7 @@
<icon BUILTIN="button_ok"/>
</node>
</node>
<node CREATED="1511835901999" ID="ID_1717235881" MODIFIED="1512278299862" TEXT="Transform: Core&amp; -&gt; irgendwas">
<node COLOR="#338800" CREATED="1511835901999" ID="ID_1717235881" MODIFIED="1512358535692" TEXT="Transform: Core&amp; -&gt; irgendwas">
<icon BUILTIN="help"/>
<node CREATED="1512276512313" ID="ID_725756500" MODIFIED="1512276517860" TEXT="sollte theoretisch m&#xf6;glich sein"/>
<node CREATED="1512276524111" ID="ID_453994757" MODIFIED="1512276583587" TEXT="nicht sonderlich sinnvoll">
@ -5882,17 +5978,36 @@
...weil man den konkreten Typ der Core kennen mu&#223;
</p>
</body>
</html>
</richcontent>
</html></richcontent>
</node>
<node COLOR="#338800" CREATED="1512276518472" ID="ID_1860559214" MODIFIED="1512278316412" TEXT="per Testfall dokumentiert">
<icon BUILTIN="button_ok"/>
</node>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1510969031379" ID="ID_722056043" MODIFIED="1511227804622" TEXT="verify_combinedExpandTransform();">
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1510969031379" ID="ID_722056043" MODIFIED="1512358551383" TEXT="verify_combinedExpandTransform();">
<icon BUILTIN="pencil"/>
<node CREATED="1512363192308" ID="ID_1913090689" MODIFIED="1512363209302" TEXT="expand &#xfc;ber Transformer hinweg">
<node CREATED="1512363626338" ID="ID_1302720848" MODIFIED="1512363637547" TEXT="funktioniert out-of-the-Box">
<icon BUILTIN="ksmiletris"/>
</node>
<node CREATED="1512363638640" ID="ID_67728054" MODIFIED="1512363645997" TEXT="naja fast">
<icon BUILTIN="smiley-oh"/>
</node>
</node>
<node CREATED="1512363210130" ID="ID_480959271" MODIFIED="1512363224156" TEXT="expand aus manipulierendem Transformer">
<node CREATED="1512363649158" ID="ID_1152388495" MODIFIED="1512363655383" TEXT="ebenso">
<icon BUILTIN="ksmiletris"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1512363659085" ID="ID_1079241242" MODIFIED="1512363737038" TEXT="TODO output CHECK">
<icon BUILTIN="flag-yellow"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1512363228751" ID="ID_579206895" MODIFIED="1512363711955" TEXT="Problem: re-evaluate nach expand">
<arrowlink COLOR="#a25a86" DESTINATION="ID_531127457" ENDARROW="Default" ENDINCLINATION="385;167;" ID="Arrow_ID_556443427" STARTARROW="None" STARTINCLINATION="844;55;"/>
<icon BUILTIN="flag-yellow"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1511836579562" ID="ID_1718741335" MODIFIED="1511836583779" TEXT="verify_FilterIterator();">
<icon BUILTIN="flag-yellow"/>
</node>