1 // Boost Lambda Library - lambda_functors.hpp ------------------------------- 2 3 // Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi) 4 // 5 // Distributed under the Boost Software License, Version 1.0. (See 6 // accompanying file LICENSE_1_0.txt or copy at 7 // http://www.boost.org/LICENSE_1_0.txt) 8 // 9 // For more information, see http://www.boost.org 10 11 // ------------------------------------------------ 12 13 #ifndef BOOST_LAMBDA_LAMBDA_FUNCTORS_HPP 14 #define BOOST_LAMBDA_LAMBDA_FUNCTORS_HPP 15 16 #include <boost/config.hpp> 17 #include <boost/detail/workaround.hpp> 18 #include <boost/utility/result_of.hpp> 19 20 #if BOOST_WORKAROUND(BOOST_MSVC, == 1310) 21 22 #include <boost/mpl/or.hpp> 23 #include <boost/utility/enable_if.hpp> 24 #include <boost/type_traits/is_array.hpp> 25 26 #define BOOST_LAMBDA_DISABLE_IF_ARRAY1(A1, R1)\ 27 typename lazy_disable_if<is_array<A1>, typename R1 >::type 28 #define BOOST_LAMBDA_DISABLE_IF_ARRAY2(A1, A2, R1, R2) \ 29 typename lazy_disable_if<mpl::or_<is_array<A1>, is_array<A2> >, typename R1, R2 >::type 30 #define BOOST_LAMBDA_DISABLE_IF_ARRAY3(A1, A2, A3, R1, R2, R3) \ 31 typename lazy_disable_if<mpl::or_<is_array<A1>, is_array<A2>, is_array<A3> >, typename R1, R2, R3 >::type 32 33 #else 34 35 #define BOOST_LAMBDA_DISABLE_IF_ARRAY1(A1, R1) typename R1::type 36 #define BOOST_LAMBDA_DISABLE_IF_ARRAY2(A1, A2, R1, R2) typename R1, R2::type 37 #define BOOST_LAMBDA_DISABLE_IF_ARRAY3(A1, A2, A3, R1, R2, R3) typename R1, R2, R3::type 38 39 #endif 40 41 namespace boost { 42 namespace lambda { 43 44 // -- lambda_functor -------------------------------------------- 45 // -------------------------------------------------------------- 46 47 //inline const null_type const_null_type() { return null_type(); } 48 49 namespace detail { 50 namespace { 51 52 static const null_type constant_null_type = null_type(); 53 54 } // unnamed 55 } // detail 56 57 class unused {}; 58 59 #define cnull_type() detail::constant_null_type 60 61 // -- free variables types -------------------------------------------------- 62 63 // helper to work around the case where the nullary return type deduction 64 // is always performed, even though the functor is not nullary 65 namespace detail { 66 template<int N, class Tuple> struct get_element_or_null_type { 67 typedef typename 68 detail::tuple_element_as_reference<N, Tuple>::type type; 69 }; 70 template<int N> struct get_element_or_null_type<N, null_type> { 71 typedef null_type type; 72 }; 73 } 74 75 template <int I> struct placeholder; 76 77 template<> struct placeholder<FIRST> { 78 79 template<class SigArgs> struct sig { 80 typedef typename detail::get_element_or_null_type<0, SigArgs>::type type; 81 }; 82 83 template<class RET, CALL_TEMPLATE_ARGS> callboost::lambda::placeholder84 RET call(CALL_FORMAL_ARGS) const { 85 BOOST_STATIC_ASSERT(boost::is_reference<RET>::value); 86 CALL_USE_ARGS; // does nothing, prevents warnings for unused args 87 return a; 88 } 89 }; 90 91 template<> struct placeholder<SECOND> { 92 93 template<class SigArgs> struct sig { 94 typedef typename detail::get_element_or_null_type<1, SigArgs>::type type; 95 }; 96 97 template<class RET, CALL_TEMPLATE_ARGS> callboost::lambda::placeholder98 RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return b; } 99 }; 100 101 template<> struct placeholder<THIRD> { 102 103 template<class SigArgs> struct sig { 104 typedef typename detail::get_element_or_null_type<2, SigArgs>::type type; 105 }; 106 107 template<class RET, CALL_TEMPLATE_ARGS> callboost::lambda::placeholder108 RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return c; } 109 }; 110 111 template<> struct placeholder<EXCEPTION> { 112 113 template<class SigArgs> struct sig { 114 typedef typename detail::get_element_or_null_type<3, SigArgs>::type type; 115 }; 116 117 template<class RET, CALL_TEMPLATE_ARGS> callboost::lambda::placeholder118 RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return env; } 119 }; 120 121 typedef const lambda_functor<placeholder<FIRST> > placeholder1_type; 122 typedef const lambda_functor<placeholder<SECOND> > placeholder2_type; 123 typedef const lambda_functor<placeholder<THIRD> > placeholder3_type; 124 125 126 /////////////////////////////////////////////////////////////////////////////// 127 128 129 // free variables are lambda_functors. This is to allow uniform handling with 130 // other lambda_functors. 131 // ------------------------------------------------------------------- 132 133 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) 134 #pragma warning(push) 135 #pragma warning(disable:4512) //assignment operator could not be generated 136 #endif 137 138 // -- lambda_functor NONE ------------------------------------------------ 139 template <class T> 140 class lambda_functor : public T 141 { 142 143 BOOST_STATIC_CONSTANT(int, arity_bits = get_arity<T>::value); 144 145 public: 146 typedef T inherited; 147 lambda_functor()148 lambda_functor() {} lambda_functor(const lambda_functor & l)149 lambda_functor(const lambda_functor& l) : inherited(l) {} 150 lambda_functor(const T & t)151 lambda_functor(const T& t) : inherited(t) {} 152 153 template <class SigArgs> struct sig { 154 typedef typename inherited::template 155 sig<typename SigArgs::tail_type>::type type; 156 }; 157 158 // Note that this return type deduction template is instantiated, even 159 // if the nullary 160 // operator() is not called at all. One must make sure that it does not fail. 161 typedef typename 162 inherited::template sig<null_type>::type 163 nullary_return_type; 164 165 // Support for boost::result_of. 166 template <class Sig> struct result; 167 template <class F> 168 struct result<F()> { 169 typedef nullary_return_type type; 170 }; 171 template <class F, class A> 172 struct result<F(A)> { 173 typedef typename sig<tuple<F, A> >::type type; 174 }; 175 template <class F, class A, class B> 176 struct result<F(A, B)> { 177 typedef typename sig<tuple<F, A, B> >::type type; 178 }; 179 template <class F, class A, class B, class C> 180 struct result<F(A, B, C)> { 181 typedef typename sig<tuple<F, A, B, C> >::type type; 182 }; 183 operator ()() const184 nullary_return_type operator()() const { 185 return inherited::template 186 call<nullary_return_type> 187 (cnull_type(), cnull_type(), cnull_type(), cnull_type()); 188 } 189 190 template<class A> 191 typename inherited::template sig<tuple<A&> >::type operator ()(A & a) const192 operator()(A& a) const { 193 return inherited::template call< 194 typename inherited::template sig<tuple<A&> >::type 195 >(a, cnull_type(), cnull_type(), cnull_type()); 196 } 197 198 template<class A> BOOST_LAMBDA_DISABLE_IF_ARRAY1(A,inherited::template sig<tuple<A const &>>)199 BOOST_LAMBDA_DISABLE_IF_ARRAY1(A, inherited::template sig<tuple<A const&> >) 200 operator()(A const& a) const { 201 return inherited::template call< 202 typename inherited::template sig<tuple<A const&> >::type 203 >(a, cnull_type(), cnull_type(), cnull_type()); 204 } 205 206 template<class A, class B> 207 typename inherited::template sig<tuple<A&, B&> >::type operator ()(A & a,B & b) const208 operator()(A& a, B& b) const { 209 return inherited::template call< 210 typename inherited::template sig<tuple<A&, B&> >::type 211 >(a, b, cnull_type(), cnull_type()); 212 } 213 214 template<class A, class B> BOOST_LAMBDA_DISABLE_IF_ARRAY2(A,B,inherited::template sig<tuple<A const &,B &>>)215 BOOST_LAMBDA_DISABLE_IF_ARRAY2(A, B, inherited::template sig<tuple<A const&, B&> >) 216 operator()(A const& a, B& b) const { 217 return inherited::template call< 218 typename inherited::template sig<tuple<A const&, B&> >::type 219 >(a, b, cnull_type(), cnull_type()); 220 } 221 222 template<class A, class B> BOOST_LAMBDA_DISABLE_IF_ARRAY2(A,B,inherited::template sig<tuple<A &,B const &>>)223 BOOST_LAMBDA_DISABLE_IF_ARRAY2(A, B, inherited::template sig<tuple<A&, B const&> >) 224 operator()(A& a, B const& b) const { 225 return inherited::template call< 226 typename inherited::template sig<tuple<A&, B const&> >::type 227 >(a, b, cnull_type(), cnull_type()); 228 } 229 230 template<class A, class B> BOOST_LAMBDA_DISABLE_IF_ARRAY2(A,B,inherited::template sig<tuple<A const &,B const &>>)231 BOOST_LAMBDA_DISABLE_IF_ARRAY2(A, B, inherited::template sig<tuple<A const&, B const&> >) 232 operator()(A const& a, B const& b) const { 233 return inherited::template call< 234 typename inherited::template sig<tuple<A const&, B const&> >::type 235 >(a, b, cnull_type(), cnull_type()); 236 } 237 238 template<class A, class B, class C> 239 typename inherited::template sig<tuple<A&, B&, C&> >::type operator ()(A & a,B & b,C & c) const240 operator()(A& a, B& b, C& c) const 241 { 242 return inherited::template call< 243 typename inherited::template sig<tuple<A&, B&, C&> >::type 244 >(a, b, c, cnull_type()); 245 } 246 247 template<class A, class B, class C> BOOST_LAMBDA_DISABLE_IF_ARRAY3(A,B,C,inherited::template sig<tuple<A const &,B const &,C const &>>)248 BOOST_LAMBDA_DISABLE_IF_ARRAY3(A, B, C, inherited::template sig<tuple<A const&, B const&, C const&> >) 249 operator()(A const& a, B const& b, C const& c) const 250 { 251 return inherited::template call< 252 typename inherited::template sig<tuple<A const&, B const&, C const&> >::type 253 >(a, b, c, cnull_type()); 254 } 255 256 // for internal calls with env 257 template<CALL_TEMPLATE_ARGS> 258 typename inherited::template sig<tuple<CALL_REFERENCE_TYPES> >::type internal_call(CALL_FORMAL_ARGS) const259 internal_call(CALL_FORMAL_ARGS) const { 260 return inherited::template 261 call<typename inherited::template 262 sig<tuple<CALL_REFERENCE_TYPES> >::type>(CALL_ACTUAL_ARGS); 263 } 264 265 template<class A> 266 const lambda_functor<lambda_functor_base< 267 other_action<assignment_action>, 268 boost::tuple<lambda_functor, 269 typename const_copy_argument <const A>::type> > > operator =(const A & a) const270 operator=(const A& a) const { 271 return lambda_functor_base< 272 other_action<assignment_action>, 273 boost::tuple<lambda_functor, 274 typename const_copy_argument <const A>::type> > 275 ( boost::tuple<lambda_functor, 276 typename const_copy_argument <const A>::type>(*this, a) ); 277 } 278 279 template<class A> 280 const lambda_functor<lambda_functor_base< 281 other_action<subscript_action>, 282 boost::tuple<lambda_functor, 283 typename const_copy_argument <const A>::type> > > operator [](const A & a) const284 operator[](const A& a) const { 285 return lambda_functor_base< 286 other_action<subscript_action>, 287 boost::tuple<lambda_functor, 288 typename const_copy_argument <const A>::type> > 289 ( boost::tuple<lambda_functor, 290 typename const_copy_argument <const A>::type>(*this, a ) ); 291 } 292 }; 293 294 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) 295 #pragma warning(pop) 296 #endif 297 298 } // namespace lambda 299 } // namespace boost 300 301 namespace boost { 302 303 #if !defined(BOOST_RESULT_OF_USE_DECLTYPE) || defined(BOOST_NO_CXX11_DECLTYPE) 304 305 template<class T> 306 struct result_of<boost::lambda::lambda_functor<T>()> 307 { 308 typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type; 309 }; 310 311 template<class T> 312 struct result_of<const boost::lambda::lambda_functor<T>()> 313 { 314 typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type; 315 }; 316 317 #endif 318 319 template<class T> 320 struct tr1_result_of<boost::lambda::lambda_functor<T>()> 321 { 322 typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type; 323 }; 324 325 template<class T> 326 struct tr1_result_of<const boost::lambda::lambda_functor<T>()> 327 { 328 typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type; 329 }; 330 331 } 332 333 // is_placeholder 334 335 #include <boost/is_placeholder.hpp> 336 337 namespace boost 338 { 339 340 template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::FIRST> > > 341 { 342 enum _vt { value = 1 }; 343 }; 344 345 template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::SECOND> > > 346 { 347 enum _vt { value = 2 }; 348 }; 349 350 template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::THIRD> > > 351 { 352 enum _vt { value = 3 }; 353 }; 354 355 } // namespace boost 356 357 #endif 358