Ichthyostega
2467405c25
...as expected, the first attempt to walk the full access path unveils a host of problematic aspects in the design...
140 lines
3.5 KiB
C++
140 lines
3.5 KiB
C++
/*
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PARAMETER.hpp - generic parameter values
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Copyright (C)
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2008,2026 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 parameter.hpp
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** A generic typed value that can be discovered and automated.
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** The actual data type of the parameter is an opaque implementation detail,
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** yet value ranges and conversions are handled automatically. It is thus
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** both a descriptor and an opaque container. Parameter elements can be copied,
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** yet the presence of some specific parameter at a given point in the model
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** constitutes an identity -- and the parameter descriptor can be tagged
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** with that identity.
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**
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** @todo this is a draft and placeholder, as of 2026
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*/
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#ifndef LIB_PAR_PARAMETER_H
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#define LIB_PAR_PARAMETER_H
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#include "lib/par/disposition.hpp"
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#include "lib/polymorphic-value.hpp"
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#include "lib/meta/typelist-util.hpp"
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#include "lib/util.hpp"
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#include <utility>
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namespace lib {
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namespace par {
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namespace {
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static constexpr size_t BUFF_SIZ = sizeof(ParamData<double>);
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using ParameterImplAPI = Disposition;
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using CopySupportMarker = polyvalue::CopySupport<ParameterImplAPI>;
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using ParamContainer = PolymorphicValue<ParameterImplAPI, BUFF_SIZ, CopySupportMarker>;
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}
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using util::unConst;
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/**
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* Descriptor and container to hold a generic parameter.
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* The value can be fixed or supplied by an automation function.
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*/
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class Parameter
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: protected ParamContainer
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{
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public:
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template<typename VAL>
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class Builder;
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template<typename VAL>
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VAL getVal() const;
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template<typename VAL>
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void setVal (VAL&&);
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/* === Builder API === */
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template<typename VAL>
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static Builder<VAL>
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forType() { return {}; }
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template<typename VAL>
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static Builder<std::decay_t<VAL>>
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forValue (VAL&& initVal)
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{
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using PayloadType = std::decay_t<VAL>;
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return forType<PayloadType>()
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.withValue (std::forward<VAL> (initVal));
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}
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protected:
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template<class IMP, typename...ARGS>
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Parameter (IMP* typeTag, ARGS&&... args)
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: PolymorphicValue (typeTag, std::forward<ARGS>(args)...)
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{ }
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};
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template<typename VAL>
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class Parameter::Builder
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{
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static_assert (meta::isInList<VAL, BaseTypes::List>()
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,"Only some fixed base data types are supported as Parameter value type.");
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VAL initVal_{};
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public:
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Parameter
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build()
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{
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using ImplPackage = ParamData<VAL>;
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ImplPackage* typeTag{nullptr};
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Parameter resParam{typeTag, std::move (initVal_)};
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return resParam;
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}
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template<typename X>
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Builder&&
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withValue (X&& initVal)
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{
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initVal_ = std::forward<X> (initVal);
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return std::move(this);
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}
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};
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template<typename VAL>
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VAL
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Parameter::getVal() const
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{
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return unConst(this)->getPayload().extract<VAL>();
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}
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template<typename VAL>
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void
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Parameter::setVal (VAL&& changedVal)
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{
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getPayload().setVal (changedVal);
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}
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}} // namespace lib::par
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#endif /*LIB_PAR_PARAMETER_H*/
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