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TreeMutator: combine no-op layer with selective other diff binding

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...and complete unit test coverage.
This is complex stuff and we'd better be careful it actually works
This commit is contained in:
Fischlurch 2018-10-12 02:05:11 +02:00
parent 0d5f29446b
commit e81b0592d3
3 changed files with 119 additions and 19 deletions
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22
src/lib/diff/tree-mutator-noop-binding.hpp
View file

@ -51,14 +51,10 @@
#include "lib/error.hpp"
#include "lib/symbol.hpp"
#include "lib/diff/gen-node.hpp"
#include "lib/diff/tree-mutator.hpp"
#include "lib/format-string.hpp"
#include "lib/idi/entry-id.hpp"
#include <utility>
#include <type_traits>
namespace lib {
namespace diff{
@ -85,7 +81,7 @@ namespace diff{
bool hasSrc() override { return true; } ///< always keen to do yet more
bool injectNew (Elm) override { return true; } ///< pretend to inject a new element
bool injectNew (Elm) override { return true; } ///< pretend to inject something new
bool matchSrc (Elm) override { return true; } ///< purport suitable element is waiting
bool acceptSrc (Elm) override { return true; } ///< claim to handle any diff task
bool accept_until (Elm) override { return true; } ///< profess to forward anywhere
@ -93,7 +89,7 @@ namespace diff{
bool assignElm (Elm) override { return true; } ///< accept any assignment
bool
mutateChild (Elm, Buff buff) override ///< bluff to care for children, while just reproducing ourselves
mutateChild (Elm, Buff buff) override ///< ignore inferiors, yet reproduce yourself
{
buff.create (BlackHoleMutation());
return true;
@ -102,11 +98,21 @@ namespace diff{
/** Entry point for DSL builder */
/** Entry point for DSL builder: create a binding which consumes any diff without effect.
* @warning must be used as bottom most layer in a custom TreeMutator, since it would
* otherwise shadow and disable any binding layer below.
* @note however it is possible to add a (typically selective) binding layer on top;
* any diff verb _not handled_ by such a top layer will fall through and
* be silently ignored. Such a setup can be used to "fish" for some specific
* attributes within a diff stream.
*/
template<class PAR>
inline auto
Builder<PAR>::ignoreAllChanges()
{
static_assert (std::is_same<PAR, TreeMutator>()
,"ignoreAllChanges() must be used as bottom layer.");
return Builder<BlackHoleMutation> (BlackHoleMutation{});
}

72
tests/library/diff/diff-ignore-changes-test.cpp
View file

@ -145,15 +145,35 @@ namespace test{
virtual void
run (Arg)
{
fail_or_ignore();
fish_for_content();
}
/** @test fail or ignore, depending on toggle.
* - the TreeMutator default implementation produces a failure,
* when it actually has to handle some diff verb
* - yet a custom TreeMutator can be configured to `ignoreAllChanges()`,
* in which case it will consume any diff without effect.
* This test also demonstrates that the actual TreeMutator is built anew
* for each diff application (TreeMutator is meant to be disposable).
* Thus we may alter the behaviour of the diff binding dynamically.
* @remark the actual use case for this is the TimelineGui, which
* either forwards changes to a TimelineWidget, or silently
* ignores them when the corresponding timeline is not opened.
*/
void
fail_or_ignore()
{
struct HappyBlackHole
{
bool grumpy = true;
bool diligent = true;
void
buildMutator (TreeMutator::Handle buff)
{
if (grumpy)
if (diligent)
buff.create(
TreeMutator());
else
@ -170,12 +190,58 @@ namespace test{
VERIFY_ERROR(DIFF_CONFLICT, application.consume(reorderingDiff()) );
VERIFY_ERROR(DIFF_CONFLICT, application.consume(mutationDiff()) );
subject.grumpy = false;
subject.diligent = false;
application.consume(populationDiff());
application.consume(reorderingDiff());
application.consume(mutationDiff());
}
/** @test fish some content and ignore everything else.
* While the BlackHoleMutation binding generated by `ignoreAllChanges()`
* must be used as bottom layer of a custom TreeMutator, it is possible
* to layer a partial diff binding on top. This test demonstrates this
* with a single attribute binding, which just "fishes" any value
* mentioned in the diff for that specific attribute. Any other
* changes are silently ignored non the less...
*/
void
fish_for_content()
{
struct Scrounger
{
double loot = 0.0;
void
buildMutator (TreeMutator::Handle buff)
{
buff.create(
TreeMutator::build()
.ignoreAllChanges()
.change("γ", [&](double val) { loot = val; }));
}
};
Scrounger subject;
DiffApplicator<Scrounger> application(subject);
const auto NOTHING = 0.0;
const auto VAL_1 = ATTRIB3.data.get<double>();
const auto VAL_2 = GAMMA_PI.data.get<double>();
CHECK (subject.loot == NOTHING);
application.consume(populationDiff());
CHECK (subject.loot == VAL_1);
application.consume(reorderingDiff());
CHECK (subject.loot == VAL_1);
application.consume(mutationDiff());
CHECK (subject.loot == VAL_2);
}
};

44
wiki/thinkPad.ichthyo.mm
View file

@ -16549,7 +16549,7 @@
</node>
<node CREATED="1539270808827" ID="ID_1352270227" MODIFIED="1539270817730" TEXT="f&#xfc;r TimelineGui">
<linktarget COLOR="#a9b4c1" DESTINATION="ID_1352270227" ENDARROW="Default" ENDINCLINATION="117;0;" ID="Arrow_ID_1672775567" SOURCE="ID_1624846094" STARTARROW="None" STARTINCLINATION="117;0;"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1539294555064" HGAP="45" ID="ID_1365984217" MODIFIED="1539299038616" TEXT="Problem: diff ignorieren" VSHIFT="23">
<node COLOR="#435e98" CREATED="1539294555064" HGAP="45" ID="ID_1365984217" MODIFIED="1539302548248" TEXT="Problem: diff ignorieren" VSHIFT="23">
<icon BUILTIN="messagebox_warning"/>
<node CREATED="1539294576338" ID="ID_485684974" MODIFIED="1539294587881" TEXT="kann das auftreten....?">
<icon BUILTIN="help"/>
@ -16579,12 +16579,14 @@
<node CREATED="1539294678444" ID="ID_934706379" MODIFIED="1539294693604" TEXT="TreeMutator scheitert per Default">
<icon BUILTIN="broken-line"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1539294698801" ID="ID_1533611583" MODIFIED="1539299026168" TEXT="also brauche ich einen /dev/null-Mutator">
<icon BUILTIN="pencil"/>
<node COLOR="#338800" CREATED="1539294698801" ID="ID_1533611583" MODIFIED="1539302545239" TEXT="also brauche ich einen /dev/null-Mutator">
<icon BUILTIN="button_ok"/>
<node COLOR="#338800" CREATED="1539294727470" ID="ID_1958316881" MODIFIED="1539299017213" TEXT="speziellen Binding-Layer fabrizieren">
<icon BUILTIN="button_ok"/>
<node CREATED="1539294807066" ID="ID_1137741867" MODIFIED="1539294809654" TEXT="wie?"/>
<node CREATED="1539294812306" ID="ID_1564927840" MODIFIED="1539294826763" TEXT="mu&#xdf; das Standard-Mapping anschauen"/>
<node CREATED="1539294812306" ID="ID_1564927840" MODIFIED="1539302566302" TEXT="mu&#xdf; das Standard-Mapping anschauen">
<font ITALIC="true" NAME="SansSerif" SIZE="12"/>
</node>
<node CREATED="1539294846845" ID="ID_1839295475" MODIFIED="1539294935855" TEXT="TreeDiffMutatorBinding">
<icon BUILTIN="info"/>
<node CREATED="1539294859537" ID="ID_637091190" MODIFIED="1539294928138" TEXT="__expect_further_elements -&gt; immer true">
@ -16600,20 +16602,46 @@
<icon BUILTIN="button_ok"/>
</node>
</node>
<node COLOR="#338800" CREATED="1539302456636" ID="ID_809868228" MODIFIED="1539302478177" TEXT="Idee: mit anderen Layern kombinieren...">
<icon BUILTIN="idea"/>
</node>
<node COLOR="#435e98" CREATED="1539302481080" ID="ID_126724611" MODIFIED="1539302542052" TEXT="static_assertion">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...damit es nicht versehentlich &#252;ber einen anderen Layer gelegt wird,
</p>
<p>
welchen es dann &#252;berdecken und au&#223;er Gefecht setzen w&#252;rde.
</p>
<p>
</p>
<p>
Habe verifiziert, da&#223; diese Assertion tats&#228;chlich greift
</p>
</body>
</html>
</richcontent>
<icon BUILTIN="button_ok"/>
</node>
</node>
<node COLOR="#338800" CREATED="1539294743739" ID="ID_1596076772" MODIFIED="1539294758145" TEXT="Builder().ignoreAll()">
<icon BUILTIN="button_ok"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1539294760464" ID="ID_1376112641" MODIFIED="1539294792408" TEXT="DiffIgnoreChanges_test">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1539294760464" ID="ID_1376112641" MODIFIED="1539302371782" TEXT="DiffIgnoreChanges_test">
<icon BUILTIN="button_ok"/>
<node COLOR="#338800" CREATED="1539298953819" ID="ID_1706428916" MODIFIED="1539298972769" TEXT="leerer TreeMutator produziert Fehler">
<icon BUILTIN="button_ok"/>
</node>
<node COLOR="#338800" CREATED="1539298974312" ID="ID_986781359" MODIFIED="1539298992271" TEXT="BlackHoleMutation fri&#xdf;t alles">
<icon BUILTIN="button_ok"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1539298993222" ID="ID_647799125" MODIFIED="1539299007509" TEXT="Kombinieren mit speziellem Overlay">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1539298993222" ID="ID_647799125" MODIFIED="1539302373522" TEXT="Kombinieren mit speziellem Overlay">
<icon BUILTIN="button_ok"/>
</node>
</node>
</node>