Ichthyostega
6207f475eb
Building a correct processing-identification is a complex and challenging task; only some aspects can be targeted and implemented right now, as part of the »Playback Vertical Slice« * components of the ProcID * parsing the argument-spec * dispatch of detail information function to retrieve source ports
86 lines
2.4 KiB
C++
86 lines
2.4 KiB
C++
/*
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FUN-HASH-DISPATCH.hpp - enrol and dispatch prepared functors keyed by hash-ID
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Copyright (C)
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2025, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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*/
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/** @file fun-hash-dispatch.hpp
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** Service to register and dispatch opaque functions.
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** Under the hood, the implementation is a hash table holding function pointers.
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** An instance is thus always tied to one specific function signature. Yet due
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** to the implicit conversion, simple capture-less λ can be attached as well.
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**
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** The purpose for such a setup is to provide a simple per-signature backend for
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** some advanced registration scheme involving specific function patterns. The
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** hash-IDs may be tied to target properties, which sometimes allows to limit
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** the number of actual functions in the dispatcher tables and can thus be
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** superior to a classic OO interface when subclasses would be templated.
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** @see FunHashDispatch_test
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** @see proc-id.hpp "usage example"
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*/
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#ifndef LIB_SEVERAL_H
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#define LIB_SEVERAL_H
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#include "lib/error.hpp"
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#include "lib/nocopy.hpp"
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#include "lib/hash-value.h"
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#include "lib/util.hpp"
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#include <unordered_map>
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namespace lib {
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/**
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* Dispatcher-table for state-less functions with a given signature.
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* Entries are keyed by hashID and can not be changed, once entered.
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*/
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template<class SIG>
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class FunHashDispatch
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: util::MoveOnly
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{
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using DispatchTab = std::unordered_map<HashVal, SIG*>;
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DispatchTab dispatchTab_{};
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public:
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SIG*
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enrol (HashVal key, SIG* fun)
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{
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auto [entry,_] = dispatchTab_.emplace (key,fun);
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return entry->second;
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}
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bool
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contains (HashVal key) const
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{
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return util::contains (dispatchTab_, key);
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}
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/** retrieve entry, which can be invoked directly */
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SIG*
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select (HashVal key)
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{
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auto it = dispatchTab_.find (key);
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if (it == dispatchTab_.end())
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throw lumiera::error::Logic{"Expect function for given hash to be previously enrolled."};
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else
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return it->second;
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}
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};
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} // namespace lib
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#endif
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