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/* Icinga 2 | (c) 2012 Icinga GmbH | GPLv2+ */
#ifndef FUNCTIONWRAPPER_H
#define FUNCTIONWRAPPER_H
#include "base/i2-base.hpp"
#include "base/value.hpp"
#include <boost/function_types/function_type.hpp>
#include <boost/function_types/parameter_types.hpp>
#include <boost/function_types/result_type.hpp>
#include <boost/function_types/function_arity.hpp>
#include <vector>
namespace icinga
{
template<typename FuncType>
typename std::enable_if<
std::is_class<FuncType>::value &&
std::is_same<typename boost::function_types::result_type<decltype(&FuncType::operator())>::type, Value>::value &&
boost::function_types::function_arity<decltype(&FuncType::operator())>::value == 2,
std::function<Value (const std::vector<Value>&)>>::type
WrapFunction(FuncType function)
{
static_assert(std::is_same<typename boost::mpl::at_c<typename boost::function_types::parameter_types<decltype(&FuncType::operator())>, 1>::type, const std::vector<Value>&>::value, "Argument type must be const std::vector<Value>");
return function;
}
inline std::function<Value (const std::vector<Value>&)> WrapFunction(void (*function)(const std::vector<Value>&))
{
return [function](const std::vector<Value>& arguments) {
function(arguments);
return Empty;
};
}
template<typename Return>
std::function<Value (const std::vector<Value>&)> WrapFunction(Return (*function)(const std::vector<Value>&))
{
return [function](const std::vector<Value>& values) -> Value { return function(values); };
}
template <std::size_t... Indices>
struct indices {
using next = indices<Indices..., sizeof...(Indices)>;
};
template <std::size_t N>
struct build_indices {
using type = typename build_indices<N-1>::type::next;
};
template <>
struct build_indices<0> {
using type = indices<>;
};
template <std::size_t N>
using BuildIndices = typename build_indices<N>::type;
struct UnpackCaller
{
private:
template <typename FuncType, size_t... I>
auto Invoke(FuncType f, const std::vector<Value>& args, indices<I...>) -> decltype(f(args[I]...))
{
return f(args[I]...);
}
public:
template <typename FuncType, int Arity>
auto operator() (FuncType f, const std::vector<Value>& args) -> decltype(Invoke(f, args, BuildIndices<Arity>{}))
{
return Invoke(f, args, BuildIndices<Arity>{});
}
};
template<typename FuncType, int Arity, typename ReturnType>
struct FunctionWrapper
{
static Value Invoke(FuncType function, const std::vector<Value>& arguments)
{
return UnpackCaller().operator()<FuncType, Arity>(function, arguments);
}
};
template<typename FuncType, int Arity>
struct FunctionWrapper<FuncType, Arity, void>
{
static Value Invoke(FuncType function, const std::vector<Value>& arguments)
{
UnpackCaller().operator()<FuncType, Arity>(function, arguments);
return Empty;
}
};
template<typename FuncType>
typename std::enable_if<
std::is_function<typename std::remove_pointer<FuncType>::type>::value && !std::is_same<FuncType, Value(*)(const std::vector<Value>&)>::value,
std::function<Value (const std::vector<Value>&)>>::type
WrapFunction(FuncType function)
{
return [function](const std::vector<Value>& arguments) {
constexpr size_t arity = boost::function_types::function_arity<typename std::remove_pointer<FuncType>::type>::value;
if (arity > 0) {
if (arguments.size() < arity)
BOOST_THROW_EXCEPTION(std::invalid_argument("Too few arguments for function."));
else if (arguments.size() > arity)
BOOST_THROW_EXCEPTION(std::invalid_argument("Too many arguments for function."));
}
using ReturnType = decltype(UnpackCaller().operator()<FuncType, arity>(*static_cast<FuncType *>(nullptr), std::vector<Value>()));
return FunctionWrapper<FuncType, arity, ReturnType>::Invoke(function, arguments);
};
}
template<typename FuncType>
typename std::enable_if<
std::is_class<FuncType>::value &&
!(std::is_same<typename boost::function_types::result_type<decltype(&FuncType::operator())>::type, Value>::value &&
boost::function_types::function_arity<decltype(&FuncType::operator())>::value == 2),
std::function<Value (const std::vector<Value>&)>>::type
WrapFunction(FuncType function)
{
static_assert(!std::is_same<typename boost::mpl::at_c<typename boost::function_types::parameter_types<decltype(&FuncType::operator())>, 1>::type, const std::vector<Value>&>::value, "Argument type must be const std::vector<Value>");
using FuncTypeInvoker = decltype(&FuncType::operator());
return [function](const std::vector<Value>& arguments) {
constexpr size_t arity = boost::function_types::function_arity<FuncTypeInvoker>::value - 1;
if (arity > 0) {
if (arguments.size() < arity)
BOOST_THROW_EXCEPTION(std::invalid_argument("Too few arguments for function."));
else if (arguments.size() > arity)
BOOST_THROW_EXCEPTION(std::invalid_argument("Too many arguments for function."));
}
using ReturnType = decltype(UnpackCaller().operator()<FuncType, arity>(*static_cast<FuncType *>(nullptr), std::vector<Value>()));
return FunctionWrapper<FuncType, arity, ReturnType>::Invoke(function, arguments);
};
}
}
#endif /* FUNCTIONWRAPPER_H */
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