diff --git a/tests/library/iter-tree-explorer-test.cpp b/tests/library/iter-tree-explorer-test.cpp index 5f6cdc0d6..2dd2d34e4 100644 --- a/tests/library/iter-tree-explorer-test.cpp +++ b/tests/library/iter-tree-explorer-test.cpp @@ -88,11 +88,10 @@ namespace test{ * This iteration _"state core" type_ describes * a descending sequence of numbers yet to be delivered. */ - class CountDown + struct CountDown { uint p,e; - public: CountDown(uint start =0, uint end =0) : p(start) , e(end) @@ -444,14 +443,20 @@ namespace test{ * and the resulting entity is again a Lumiera Forward Iterator with suitable value type. * The transformation function is invoked only once per step and the result produced by * this invocation is placed into a holder buffer embedded within the iterator. + * @note since the implementation uses the same generic adaptor framework, + * the transformation functor may be defined with the same variations + * as described for the expand-operation above. In theory, it might + * collaborate with the embedded "state core" type, thereby possibly + * bypassing other decorators added below. + * @warning don't try this at home */ void verify_transformOperation() { - auto multiply = [](int v){ return 2*v; }; + auto multiply = [](int v){ return 2*v; }; // functional map: value -> value _Fmt embrace{"≺%s≻"}; - auto formatify = [&](auto it){ return string{embrace % *it}; }; + auto formatify = [&](auto it){ return string{embrace % *it}; }; // generic lambda: assumed to take an Iterator& auto ii = treeExplore (CountDown{7,4}) @@ -469,6 +474,8 @@ namespace test{ VERIFY_ERROR (ITER_EXHAUST, ++ii ); + + // demonstrate chaining of several transformation layers vector numz{1,-2,3,-5,8,-13}; CHECK ("≺1≻-≺-2≻-≺3≻-≺-5≻-≺8≻-≺-13≻" == materialise (treeExplore(numz) @@ -527,6 +534,28 @@ namespace test{ VERIFY_ERROR (ITER_EXHAUST, *ii ); CHECK (fact == 2*23); // exhaustion detected on source and thus no further evaluation + + + + // demonstrate a transformer accessing the source state core... + // should not be relevant in practice, but works due to the generic adapters + auto kk = treeExplore(CountDown{9,4}) + .transform([](CountDown& core) + { + uint delta = core.p - core.e; + if (delta % 2 == 0) + --core.p; // EVIL EVIL + return delta; + }); + + CHECK (5 == *kk); // the delta between 9 (start) and 4 (end) + ++kk; + CHECK (4 == *kk); // Core manipulated by SIDE-EFFECT at this point... + CHECK (4 == *kk); // ...but not yet obvious, since the result is cached + ++kk; + CHECK (2 == *kk); // Surprise -- someone ate my numberz... + ++kk; + CHECK (isnil (kk)); } diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm index 31a73b46d..13eec33ef 100644 --- a/wiki/thinkPad.ichthyo.mm +++ b/wiki/thinkPad.ichthyo.mm @@ -5092,11 +5092,16 @@ - - + + + + + + + @@ -5322,8 +5327,8 @@ - - + + @@ -5408,10 +5413,11 @@ - - - - + + + + + @@ -5463,9 +5469,11 @@ - - - + + + + + @@ -5770,23 +5778,14 @@ - - - - + + + + - - - - - - - - - @@ -5870,8 +5869,25 @@ - + + + + + + + + +

+ ...weil man den konkreten Typ der Core kennen muß +

+ + + + + + +