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6a5387ec21
* add visitor pattern implementation for Poco::Dynamic::Var * add changes to Makefile and vcxproj for VarVisitor * resolve review comments Poco::Dynamic::Var --------- Co-authored-by: Alexander B <bas524@ya.ru>
100 lines
2.3 KiB
C++
100 lines
2.3 KiB
C++
#ifndef Foundation_VarVisitor_INCLUDED
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#define Foundation_VarVisitor_INCLUDED
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//
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// VarVisitor.h
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//
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// Library: Foundation
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// Package: Dynamic
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// Module: VarVisitor
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//
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// Definition of the VarVisitor class.
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//
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// Copyright (c) 2023, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#include "Poco/Dynamic/Var.h"
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#include <unordered_map>
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#include <functional>
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namespace Poco {
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namespace Details {
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struct TypeInfoHash
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{
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inline std::size_t operator()(std::type_info const& t) const { return t.hash_code(); }
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};
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struct EqualRef
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{
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template <typename T>
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bool operator()(std::reference_wrapper<T> a, std::reference_wrapper<T> b) const
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{
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return a.get() == b.get();
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}
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};
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using TypeInfoRef = std::reference_wrapper<std::type_info const>;
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using HandlerCaller = std::function<void(const Poco::Dynamic::Var&)>;
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template <typename T>
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using HandlerPointer = void (*)(const T &);
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template <typename T>
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using Handler = std::function<void(const T&)>;
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} // Details
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namespace Dynamic {
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class Foundation_API Visitor
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/// VarVisitor class.
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{
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std::unordered_map<Details::TypeInfoRef,
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Details::HandlerCaller,
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Details::TypeInfoHash,
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Details::EqualRef> _handlers;
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public:
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template <typename T>
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bool addHandler(const Details::Handler<T> &f)
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/// Add handler for specific type T which holds in Var
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/// This method is more safe, because it saves copy of handler : lambda or std::function
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/// Returns true if handler was added
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{
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auto result = _handlers.emplace(std::ref(typeid(T)),
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Details::HandlerCaller([handler = f](const Poco::Dynamic::Var& x)
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{
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handler(x.extract<T>());
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}));
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return result.second;
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}
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template <typename T>
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bool addHandler(Details::HandlerPointer<T> f)
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/// Add handler for specific type T which holds in Var
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/// This method is less safe, because it saves only copy of function pointer
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/// Returns true if handler was added
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{
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auto result = _handlers.emplace(std::ref(typeid(T)),
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Details::HandlerCaller([handlerPointer = f](const Poco::Dynamic::Var& x)
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{
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handlerPointer(x.extract<T>());
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}));
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return result.second;
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}
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bool visit(const Poco::Dynamic::Var& x) const;
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/// Find handler for holded type and if it exists call handler
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/// Returns true if hanler was found othrewise returns false
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};
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} } // namespace Poco::Dynamic
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#endif // Foundation_VarVisitor_INCLUDED
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