362 lines
8.3 KiB
C++
362 lines
8.3 KiB
C++
#ifndef FUNCTION_MAP_HH
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#define FUNCTION_MAP_HH
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#include "json_spirit/json_spirit_value.h"
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#include <type_traits>
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// Just for debugging:
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#include <iostream>
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#include <pEp/message_api.h>
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namespace js = json_spirit;
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template<class T> struct In;
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template<class T> struct Out;
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// "params" and "position" might be used to fetch additional parameters from the array.
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template<class T>
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T from_json(const js::Value& v);
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template<class T>
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js::Value to_json(const T& t);
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// helper classes to specify in- and out-parameters
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template<class T>
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struct In
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{
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typedef T c_type; // the according type in C function parameter
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enum { is_output = false };
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explicit In(const T& t) : value(t) {}
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~In();
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In(const In<T>& other) = delete;
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In(In<T>&& victim);
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In<T>& operator=(const In<T>&) = delete;
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// default implementation:
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In(const js::Value& v, const js::Array& params, unsigned position)
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: In( from_json<T>(v) )
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{
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}
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T value;
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};
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// to call functions that operate directly on the JSON data type
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template<class T>
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struct InRaw
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{
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typedef js::Value c_type; // do not unwrap JSON data type
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enum { is_output = false };
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explicit InRaw(const js::Value& t) : value(t) {}
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~InRaw() = default;
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InRaw(const InRaw<T>& other) = delete;
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InRaw(InRaw<T>&& victim);
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InRaw<T>& operator=(const InRaw<T>&) = delete;
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// default implementation:
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InRaw(const js::Value& v, const js::Array& params, unsigned position)
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: InRaw(v)
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{
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}
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js::Value value;
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};
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// helper classes to specify in- and out-parameters
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template<class T>
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struct InOut : public In<T>
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{
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typedef In<T> Base;
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enum { is_output = true };
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explicit InOut(const T& t) : Base(t) {}
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~InOut() = default;
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InOut<T>& operator=(const InOut<T>&) = delete;
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// default implementation:
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InOut(const js::Value& v, const js::Array& params, unsigned position)
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: Base( from_json<T>(v) )
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{
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}
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js::Value to_json() const
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{
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return ::to_json<T>(Base::value);
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}
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};
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template<class T>
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struct Out
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{
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typedef T* c_type; // the according type in C function parameter
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enum { is_output = true };
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explicit Out() : value{ new T{} }
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{
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if(typeid(T)==typeid(_message*))
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{
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std::cerr << "|$ Out<message*>(): this=" << *this << "\n";
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}
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}
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~Out();
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Out(const Out<T>& other) = delete;
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Out(Out<T>&& victim);
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// just to be sure they are not implicitly defined:
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Out<T>& operator=(const Out<T>& other) = delete;
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Out<T>& operator=(Out<T>&& victim) = delete;
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Out(const js::Value& v, const js::Array& params, unsigned position)
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: Out()
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{
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}
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js::Value to_json() const
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{
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return ::to_json<T>(*value);
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}
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T* value = nullptr;
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friend
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std::ostream& operator<<(std::ostream& o, const Out<T>& out)
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{
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o << (const void*)&out;
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if(&out)
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{
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o << ", value=" << (const void*)out.value;
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if(out.value)
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{
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o << ", *value=" << *(out.value);
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}
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}
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return o;
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}
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};
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template<class T>
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js::Value to_json(const Out<T>& o)
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{
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return ::to_json(*o.value);
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}
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template<class T>
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js::Value to_json(const InOut<T>& o)
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{
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return ::to_json(o.value);
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}
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// heloer class for generic calls:
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// R : return type of the called function
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// U : number of the parameter which is being extracted
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// MAX: maximum number of parameters. if U==MAX the function call is executed
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// Args... the function's parameter types
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template<class R, unsigned U, unsigned MAX, class... Args>
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class helper;
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// specialization for U==MAX: do the function call here
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template<class R, unsigned U, class... Args>
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class helper<R, U, U, Args...>
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{
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public:
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static js::Value call( const std::function<R(typename Args::c_type...)>& fn, js::Array& out_parameters, const js::Array& parameters, const Args&... args)
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{
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return to_json( fn(args.value...) );
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}
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};
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// specialization for Return type == void
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template<unsigned U, class... Args>
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class helper<void, U, U, Args...>
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{
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public:
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static js::Value call( const std::function<void(typename Args::c_type...)>& fn, js::Array& out_parameters, const js::Array& parameters, const Args&... args)
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{
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fn(args.value...);
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return js::Value{};
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}
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};
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// recursive helper class:
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// It is used with U==0 in Func<>::call() and calls itself recursively until U==MAX, where the real function calls occurs,
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// and the output parameters are collected during unwinding of the recursion
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template<class R, unsigned U, unsigned MAX, class... Args>
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class helper
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{
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public:
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typedef std::tuple<Args...> Tuple;
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typedef typename std::tuple_element<U, Tuple>::type Element; // The type of the U'th parameter
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typedef helper<R, U+1, MAX, Args...> NextHelper;
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public:
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// A2... a2 are the alredy pealed-off paremeters
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template<class... A2>
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static js::Value call( const std::function<R(typename Args::c_type...)>& fn, js::Array& out_parameters, const js::Array& parameters, const A2&... a2)
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{
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// extract the U'th element of the parameter list
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const Element element(parameters[U], parameters, U);
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const js::Value ret = NextHelper::call(fn, out_parameters, parameters, a2..., element );
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if(Element::is_output)
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{
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out_parameters.push_back( to_json(element) );
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}
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return ret;
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}
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};
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template<class T>
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struct Type2String
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{
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static js::Value get();
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};
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template<class T>
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struct Type2String<In<T>>
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{
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static js::Value get() { js::Object ret; ret.emplace_back("direction", "In"); ret.emplace_back("type", Type2String<T>::get() ); return ret; }
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};
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template<class T>
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struct Type2String<InRaw<T>>
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{
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static js::Value get() { js::Object ret; ret.emplace_back("direction", "In"); ret.emplace_back("type", Type2String<T>::get() ); return ret; }
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};
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template<class T>
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struct Type2String<Out<T>>
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{
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static js::Value get() { js::Object ret; ret.emplace_back("direction", "Out"); ret.emplace_back("type", Type2String<T>::get() ); return ret; }
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};
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template<class T>
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struct Type2String<InOut<T>>
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{
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static js::Value get() { js::Object ret; ret.emplace_back("direction", "InOut"); ret.emplace_back("type", Type2String<T>::get() ); return ret; }
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};
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template<class... Args> struct Type2Json;
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template<class T, class... Args>
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struct Type2Json<T, Args...>
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{
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static js::Array& get(js::Array& a)
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{
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a.push_back( Type2String<T>::get() );
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Type2Json<Args...>::get(a);
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return a;
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}
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};
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template<> struct Type2Json<>
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{
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static js::Array& get(js::Array& a) { return a; }
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};
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// abstract base class for all Func<...> types below
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class FuncBase
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{
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public:
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virtual ~FuncBase() = default;
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virtual bool isSeparator() const = 0;
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virtual void setJavaScriptSignature(js::Object& o) const = 0;
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virtual js::Value call(const js::Array& params) const = 0;
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};
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template<class R, class... Args>
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class Func : public FuncBase
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{
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public:
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// typedef std::tuple<Args...> arg_t;
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enum { Size = sizeof...(Args) };
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virtual ~Func() = default;
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virtual bool isSeparator() const override
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{
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return false;
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}
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Func() : fn() {}
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Func( const std::function<R(typename Args::c_type ...)>& _f )
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: fn(_f)
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{}
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std::function<R(typename Args::c_type ...)> fn;
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js::Value call(const js::Array& parameters) const override
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{
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if(parameters.size() != sizeof...(Args))
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throw std::runtime_error("Size mismatch: "
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"Array has " + std::to_string( parameters.size() ) + " element(s), "
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"but I expect " + std::to_string( sizeof...(Args) ) + " element(s)! "
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);
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// recursive template magic breaks loose:
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// recursively extract the JSON parameters, call 'fn' and collect its return value
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// and all output parameters into a tuple<> and return it as JSON array
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js::Array out_params;
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out_params.reserve( 1 + sizeof...(Args) ); // too big, but who cares?
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js::Value ret = helper<R, 0, sizeof...(Args), Args...>::call(fn, out_params, parameters);
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out_params.push_back( ret );
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return ret;
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}
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void setJavaScriptSignature(js::Object& o) const override
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{
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js::Array params;
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Type2Json<Args...>::get(params);
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o.emplace_back( "return", Type2String<R>::get() );
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o.emplace_back( "params", params );
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o.emplace_back( "separator", false );
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}
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};
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// Just a separating placeholder in the drop-down list. Does not calls anything.
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class Separator : public FuncBase
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{
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public:
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Separator() = default;
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virtual bool isSeparator() const override { return true; }
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virtual void setJavaScriptSignature(js::Object& o) const override { o.emplace_back("separator", true); }
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virtual js::Value call(const js::Array& params) const override { return js::Value{}; }
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};
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//typedef std::map< std::string, FuncBase* > FunctionMap;
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typedef std::vector< std::pair< std::string, FuncBase*> > FunctionMap;
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typedef FunctionMap::value_type FP;
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#endif // FUNCTION_MAP_HH
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