1 /* Icinga 2 | (c) 2012 Icinga GmbH | GPLv2+ */
2
3 #ifndef FUNCTIONWRAPPER_H
4 #define FUNCTIONWRAPPER_H
5
6 #include "base/i2-base.hpp"
7 #include "base/value.hpp"
8 #include <boost/function_types/function_type.hpp>
9 #include <boost/function_types/parameter_types.hpp>
10 #include <boost/function_types/result_type.hpp>
11 #include <boost/function_types/function_arity.hpp>
12 #include <vector>
13
14 namespace icinga
15 {
16
17 template<typename FuncType>
18 typename std::enable_if<
19 std::is_class<FuncType>::value &&
20 std::is_same<typename boost::function_types::result_type<decltype(&FuncType::operator())>::type, Value>::value &&
21 boost::function_types::function_arity<decltype(&FuncType::operator())>::value == 2,
22 std::function<Value (const std::vector<Value>&)>>::type
WrapFunction(FuncType function)23 WrapFunction(FuncType function)
24 {
25 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>");
26 return function;
27 }
28
WrapFunction(void (* function)(const std::vector<Value> &))29 inline std::function<Value (const std::vector<Value>&)> WrapFunction(void (*function)(const std::vector<Value>&))
30 {
31 return [function](const std::vector<Value>& arguments) {
32 function(arguments);
33 return Empty;
34 };
35 }
36
37 template<typename Return>
WrapFunction(Return (* function)(const std::vector<Value> &))38 std::function<Value (const std::vector<Value>&)> WrapFunction(Return (*function)(const std::vector<Value>&))
39 {
40 return [function](const std::vector<Value>& values) -> Value { return function(values); };
41 }
42
43 template <std::size_t... Indices>
44 struct indices {
45 using next = indices<Indices..., sizeof...(Indices)>;
46 };
47
48 template <std::size_t N>
49 struct build_indices {
50 using type = typename build_indices<N-1>::type::next;
51 };
52
53 template <>
54 struct build_indices<0> {
55 using type = indices<>;
56 };
57
58 template <std::size_t N>
59 using BuildIndices = typename build_indices<N>::type;
60
61 struct UnpackCaller
62 {
63 private:
64 template <typename FuncType, size_t... I>
Invokeicinga::UnpackCaller65 auto Invoke(FuncType f, const std::vector<Value>& args, indices<I...>) -> decltype(f(args[I]...))
66 {
67 return f(args[I]...);
68 }
69
70 public:
71 template <typename FuncType, int Arity>
operator ()icinga::UnpackCaller72 auto operator() (FuncType f, const std::vector<Value>& args) -> decltype(Invoke(f, args, BuildIndices<Arity>{}))
73 {
74 return Invoke(f, args, BuildIndices<Arity>{});
75 }
76 };
77
78 template<typename FuncType, int Arity, typename ReturnType>
79 struct FunctionWrapper
80 {
Invokeicinga::FunctionWrapper81 static Value Invoke(FuncType function, const std::vector<Value>& arguments)
82 {
83 return UnpackCaller().operator()<FuncType, Arity>(function, arguments);
84 }
85 };
86
87 template<typename FuncType, int Arity>
88 struct FunctionWrapper<FuncType, Arity, void>
89 {
Invokeicinga::FunctionWrapper90 static Value Invoke(FuncType function, const std::vector<Value>& arguments)
91 {
92 UnpackCaller().operator()<FuncType, Arity>(function, arguments);
93 return Empty;
94 }
95 };
96
97 template<typename FuncType>
98 typename std::enable_if<
99 std::is_function<typename std::remove_pointer<FuncType>::type>::value && !std::is_same<FuncType, Value(*)(const std::vector<Value>&)>::value,
100 std::function<Value (const std::vector<Value>&)>>::type
WrapFunction(FuncType function)101 WrapFunction(FuncType function)
102 {
103 return [function](const std::vector<Value>& arguments) {
104 constexpr size_t arity = boost::function_types::function_arity<typename std::remove_pointer<FuncType>::type>::value;
105
106 if (arity > 0) {
107 if (arguments.size() < arity)
108 BOOST_THROW_EXCEPTION(std::invalid_argument("Too few arguments for function."));
109 else if (arguments.size() > arity)
110 BOOST_THROW_EXCEPTION(std::invalid_argument("Too many arguments for function."));
111 }
112
113 using ReturnType = decltype(UnpackCaller().operator()<FuncType, arity>(*static_cast<FuncType *>(nullptr), std::vector<Value>()));
114
115 return FunctionWrapper<FuncType, arity, ReturnType>::Invoke(function, arguments);
116 };
117 }
118
119 template<typename FuncType>
120 typename std::enable_if<
121 std::is_class<FuncType>::value &&
122 !(std::is_same<typename boost::function_types::result_type<decltype(&FuncType::operator())>::type, Value>::value &&
123 boost::function_types::function_arity<decltype(&FuncType::operator())>::value == 2),
124 std::function<Value (const std::vector<Value>&)>>::type
WrapFunction(FuncType function)125 WrapFunction(FuncType function)
126 {
127 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>");
128
129 using FuncTypeInvoker = decltype(&FuncType::operator());
130
131 return [function](const std::vector<Value>& arguments) {
132 constexpr size_t arity = boost::function_types::function_arity<FuncTypeInvoker>::value - 1;
133
134 if (arity > 0) {
135 if (arguments.size() < arity)
136 BOOST_THROW_EXCEPTION(std::invalid_argument("Too few arguments for function."));
137 else if (arguments.size() > arity)
138 BOOST_THROW_EXCEPTION(std::invalid_argument("Too many arguments for function."));
139 }
140
141 using ReturnType = decltype(UnpackCaller().operator()<FuncType, arity>(*static_cast<FuncType *>(nullptr), std::vector<Value>()));
142
143 return FunctionWrapper<FuncType, arity, ReturnType>::Invoke(function, arguments);
144 };
145 }
146
147 }
148
149 #endif /* FUNCTIONWRAPPER_H */
150