diff --git a/src/lib/iter-chain-search.hpp b/src/lib/iter-chain-search.hpp index 6332fa2b2..4c7e96145 100644 --- a/src/lib/iter-chain-search.hpp +++ b/src/lib/iter-chain-search.hpp @@ -33,6 +33,38 @@ ** then lead to a match. Basically we have to try all combinations of all possible local ** matches, to find a solution to satisfy the whole chain of conditions. ** + ** ## Design + ** + ** The IterChainSearch component is built as a processing pipeline, based on the + ** [Tree-Explorer framework](\ref iter-tree-explorer.hpp). This yields several benefits, yet also + ** imposes some drawbacks. Without much effort, we get a extremely flexible and configurable + ** solution, with acceptable / moderate performance. The result automatically adapts to a wide + ** array of data sources; it is possible (and even intended) to attach it on top of an already + ** existing on-demand data processing pipeline. The "source" can itself be a "state core" and + ** we may install suitable filter predicates to possibly collaborate with the internals of + ** such a state core. Yet we may also confine ourselves to pure functions and value processing. + ** + ** The obvious downside of such an approach is its complexity in terms of code to understand. + ** The collaboration between several layers in a filter pipeline can be intricate, leading to + ** chains of layered similar functions calling each other. Most of these abstractions and + ** decorations will be removed by the compiler and optimiser, typically leading to long + ** compilation times and rather large size of the generated code (which in debugging mode + ** with full type information can even become excessively huge). + ** + ** Some caveats + ** - the resulting pipeline is copyable, and it is typically moved out from a builder + ** function into the target location. So beware of _lambda captures by reference._ + ** When you capture _anything_ within the pipeline itself, like some `this` pointer, + ** you'll end up with a dangling reference for sure. However, it is just fine to + ** capture extended facilities within the scope _enclosing_ the pipeline, as long + ** as this scope remains intact during the whole usage time of the pipeline. + ** - the resulting entity, an instantiation of the IterChainSearch template, is + ** not a generic TreeExplorer (builder). Be careful when using any builder + ** functions still accessible. The only functions meant to be used in + ** builder style are the IterChainSearch::search() variations. + ** - if you copy, the embedded state is copied alongside, but not + ** any external state referred by it. + ** ** @see IterCursor_test ** @see iter-adapter.hpp ** @see [usage example](event-log.hpp) @@ -48,8 +80,6 @@ #include "lib/iter-tree-explorer.hpp" #include "lib/meta/util.hpp" -//#include -//#include #include #include #include @@ -128,6 +158,13 @@ namespace iter { /** Storage for a sequence of filter configuration functors */ std::vector stepChain_; + + + bool + needsExpansion() const + { + return _Base::depth() < stepChain_.size(); + } public: /** Build a chain-search mechanism based on the given source data sequence. @@ -153,14 +190,25 @@ namespace iter { iterNext() { _Base::__throw_if_empty(); - uint depth; - while (stepChain_.size() > (depth=_Base::depth()) // Backtracking loop: attempt to establish all conditions - and _Base::checkPoint()) // possibly trying further combinations until success: - { - _Base::expandChildren(); // create copy of current filter embedded into child level - stepChain_[depth] (_Base::accessCurrentChildIter()); // invoke step functor to reconfigure this filter... - _Base::dropExhaustedChildren(); // which thereby might become empty - } + if (not needsExpansion()) + _Base::iterNext(); + else + do + { + uint depth =_Base::depth(); + _Base::expandChildren(); // create copy of current filter embedded into child level + stepChain_[depth] (_Base::accessCurrentChildIter()); // invoke step functor to reconfigure this filter... + _Base::dropExhaustedChildren(); // which thereby might become empty + } + while (needsExpansion() // Backtracking loop: attempt to establish all conditions + and _Base::checkPoint()); // possibly trying further combinations until success: + } + + IterChainSearch& + operator++() + { + iterNext(); + return *this; } diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm index 3e5a22242..f06848cc2 100644 --- a/wiki/thinkPad.ichthyo.mm +++ b/wiki/thinkPad.ichthyo.mm @@ -31832,8 +31832,8 @@ - - + + @@ -32336,8 +32336,8 @@ - - + + @@ -32345,13 +32345,13 @@ - - + + - - + + @@ -32372,7 +32372,7 @@ - + @@ -32384,8 +32384,8 @@ - - + + @@ -32406,7 +32406,13 @@ - + + + + + + + @@ -32456,6 +32462,29 @@ + + + + + + + + + + +

+ sausage-bacon-tomato-and-sausage-spam-spam-bacon-spam-tomato-and-spam-spam-bacon-tomato-and-spam-bacon-tomato-and-spam-tomato-and-spam +

+ + + + + + + + + +