lambda/detail/lambda_functors.hpp

0001 // Boost Lambda Library -  lambda_functors.hpp -------------------------------
0002
0003 // Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
0004 //
0005 // Distributed under the Boost Software License, Version 1.0. (See
0006 // accompanying file LICENSE_1_0.txt or copy at
0007 // http://www.boost.org/LICENSE_1_0.txt)
0008 //
0009 // For more information, see http://www.boost.org
0010
0011 // ------------------------------------------------
0012
0013 #ifndef BOOST_LAMBDA_LAMBDA_FUNCTORS_HPP
0014 #define BOOST_LAMBDA_LAMBDA_FUNCTORS_HPP
0015
0016 #include <boost/config.hpp>
0017 #include <boost/detail/workaround.hpp>
0018 #include <boost/utility/result_of.hpp>
0019
0020 #if BOOST_WORKAROUND(BOOST_MSVC, == 1310)
0021
0022 #include <boost/mpl/or.hpp>
0023 #include <boost/utility/enable_if.hpp>
0024 #include <boost/type_traits/is_array.hpp>
0025
0026 #define BOOST_LAMBDA_DISABLE_IF_ARRAY1(A1, R1)\
0027   typename lazy_disable_if<is_array<A1>, typename R1 >::type
0028 #define BOOST_LAMBDA_DISABLE_IF_ARRAY2(A1, A2, R1, R2) \
0029   typename lazy_disable_if<mpl::or_<is_array<A1>, is_array<A2> >, typename R1, R2 >::type
0030 #define BOOST_LAMBDA_DISABLE_IF_ARRAY3(A1, A2, A3, R1, R2, R3) \
0031   typename lazy_disable_if<mpl::or_<is_array<A1>, is_array<A2>, is_array<A3> >, typename R1, R2, R3 >::type
0032
0033 #else
0034
0035 #define BOOST_LAMBDA_DISABLE_IF_ARRAY1(A1, R1) typename R1::type
0036 #define BOOST_LAMBDA_DISABLE_IF_ARRAY2(A1, A2, R1, R2) typename R1, R2::type
0037 #define BOOST_LAMBDA_DISABLE_IF_ARRAY3(A1, A2, A3, R1, R2, R3) typename R1, R2, R3::type
0038
0039 #endif
0040
0041 namespace boost {
0042 namespace lambda {
0043
0044 // -- lambda_functor --------------------------------------------
0045 // --------------------------------------------------------------
0046
0047 //inline const null_type const_null_type() { return null_type(); }
0048
0049 namespace detail {
0050 namespace {
0051
0052   static const null_type constant_null_type = null_type();
0053
0054 } // unnamed
0055 } // detail
0056
0057 class unused {};
0058
0059 #define cnull_type() detail::constant_null_type
0060
0061 // -- free variables types --------------------------------------------------
0062
0063   // helper to work around the case where the nullary return type deduction
0064   // is always performed, even though the functor is not nullary
0065 namespace detail {
0066   template<int N, class Tuple> struct get_element_or_null_type {
0067     typedef typename
0068       detail::tuple_element_as_reference<N, Tuple>::type type;
0069   };
0070   template<int N> struct get_element_or_null_type<N, null_type> {
0071     typedef null_type type;
0072   };
0073 }
0074
0075 template <int I> struct placeholder;
0076
0077 template<> struct placeholder<FIRST> {
0078
0079   template<class SigArgs> struct sig {
0080     typedef typename detail::get_element_or_null_type<0, SigArgs>::type type;
0081   };
0082
0083   template<class RET, CALL_TEMPLATE_ARGS>
0084   RET call(CALL_FORMAL_ARGS) const {
0085     BOOST_STATIC_ASSERT(boost::is_reference<RET>::value);
0086     CALL_USE_ARGS; // does nothing, prevents warnings for unused args
0087     return a;
0088   }
0089 };
0090
0091 template<> struct placeholder<SECOND> {
0092
0093   template<class SigArgs> struct sig {
0094     typedef typename detail::get_element_or_null_type<1, SigArgs>::type type;
0095   };
0096
0097   template<class RET, CALL_TEMPLATE_ARGS>
0098   RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return b; }
0099 };
0100
0101 template<> struct placeholder<THIRD> {
0102
0103   template<class SigArgs> struct sig {
0104     typedef typename detail::get_element_or_null_type<2, SigArgs>::type type;
0105   };
0106
0107   template<class RET, CALL_TEMPLATE_ARGS>
0108   RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return c; }
0109 };
0110
0111 template<> struct placeholder<EXCEPTION> {
0112
0113   template<class SigArgs> struct sig {
0114     typedef typename detail::get_element_or_null_type<3, SigArgs>::type type;
0115   };
0116
0117   template<class RET, CALL_TEMPLATE_ARGS>
0118   RET call(CALL_FORMAL_ARGS) const { CALL_USE_ARGS; return env; }
0119 };
0120
0121 typedef const lambda_functor<placeholder<FIRST> >  placeholder1_type;
0122 typedef const lambda_functor<placeholder<SECOND> > placeholder2_type;
0123 typedef const lambda_functor<placeholder<THIRD> >  placeholder3_type;
0124
0125
0126 ///////////////////////////////////////////////////////////////////////////////
0127
0128
0129 // free variables are lambda_functors. This is to allow uniform handling with
0130 // other lambda_functors.
0131 // -------------------------------------------------------------------
0132
0133 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
0134 #pragma warning(push)
0135 #pragma warning(disable:4512) //assignment operator could not be generated
0136 #endif
0137
0138 // -- lambda_functor NONE ------------------------------------------------
0139 template <class T>
0140 class lambda_functor : public T
0141 {
0142
0143 BOOST_STATIC_CONSTANT(int, arity_bits = get_arity<T>::value);
0144
0145 public:
0146   typedef T inherited;
0147
0148   lambda_functor() {}
0149   lambda_functor(const lambda_functor& l) : inherited(l) {}
0150
0151   lambda_functor(const T& t) : inherited(t) {}
0152
0153   template <class SigArgs> struct sig {
0154     typedef typename inherited::template
0155       sig<typename SigArgs::tail_type>::type type;
0156   };
0157
0158   // Note that this return type deduction template is instantiated, even
0159   // if the nullary
0160   // operator() is not called at all. One must make sure that it does not fail.
0161   typedef typename
0162     inherited::template sig<null_type>::type
0163       nullary_return_type;
0164
0165   // Support for boost::result_of.
0166   template <class Sig> struct result;
0167   template <class F>
0168   struct result<F()> {
0169     typedef nullary_return_type type;
0170   };
0171   template <class F, class A>
0172   struct result<F(A)> {
0173     typedef typename sig<tuple<F, A> >::type type;
0174   };
0175   template <class F, class A, class B>
0176   struct result<F(A, B)> {
0177     typedef typename sig<tuple<F, A, B> >::type type;
0178   };
0179   template <class F, class A, class B, class C>
0180   struct result<F(A, B, C)> {
0181     typedef typename sig<tuple<F, A, B, C> >::type type;
0182   };
0183
0184   nullary_return_type operator()() const {
0185     return inherited::template
0186       call<nullary_return_type>
0187         (cnull_type(), cnull_type(), cnull_type(), cnull_type());
0188   }
0189
0190   template<class A>
0191   typename inherited::template sig<tuple<A&> >::type
0192   operator()(A& a) const {
0193     return inherited::template call<
0194       typename inherited::template sig<tuple<A&> >::type
0195     >(a, cnull_type(), cnull_type(), cnull_type());
0196   }
0197
0198   template<class A>
0199   BOOST_LAMBDA_DISABLE_IF_ARRAY1(A, inherited::template sig<tuple<A const&> >)
0200   operator()(A const& a) const {
0201     return inherited::template call<
0202       typename inherited::template sig<tuple<A const&> >::type
0203     >(a, cnull_type(), cnull_type(), cnull_type());
0204   }
0205
0206   template<class A, class B>
0207   typename inherited::template sig<tuple<A&, B&> >::type
0208   operator()(A& a, B& b) const {
0209     return inherited::template call<
0210       typename inherited::template sig<tuple<A&, B&> >::type
0211     >(a, b, cnull_type(), cnull_type());
0212   }
0213
0214   template<class A, class B>
0215   BOOST_LAMBDA_DISABLE_IF_ARRAY2(A, B, inherited::template sig<tuple<A const&, B&> >)
0216   operator()(A const& a, B& b) const {
0217     return inherited::template call<
0218       typename inherited::template sig<tuple<A const&, B&> >::type
0219     >(a, b, cnull_type(), cnull_type());
0220   }
0221
0222   template<class A, class B>
0223   BOOST_LAMBDA_DISABLE_IF_ARRAY2(A, B, inherited::template sig<tuple<A&, B const&> >)
0224   operator()(A& a, B const& b) const {
0225     return inherited::template call<
0226       typename inherited::template sig<tuple<A&, B const&> >::type
0227     >(a, b, cnull_type(), cnull_type());
0228   }
0229
0230   template<class A, class B>
0231   BOOST_LAMBDA_DISABLE_IF_ARRAY2(A, B, inherited::template sig<tuple<A const&, B const&> >)
0232   operator()(A const& a, B const& b) const {
0233     return inherited::template call<
0234       typename inherited::template sig<tuple<A const&, B const&> >::type
0235     >(a, b, cnull_type(), cnull_type());
0236   }
0237
0238   template<class A, class B, class C>
0239   typename inherited::template sig<tuple<A&, B&, C&> >::type
0240   operator()(A& a, B& b, C& c) const
0241   {
0242     return inherited::template call<
0243       typename inherited::template sig<tuple<A&, B&, C&> >::type
0244     >(a, b, c, cnull_type());
0245   }
0246
0247   template<class A, class B, class C>
0248   BOOST_LAMBDA_DISABLE_IF_ARRAY3(A, B, C, inherited::template sig<tuple<A const&, B const&, C const&> >)
0249   operator()(A const& a, B const& b, C const& c) const
0250   {
0251     return inherited::template call<
0252       typename inherited::template sig<tuple<A const&, B const&, C const&> >::type
0253     >(a, b, c, cnull_type());
0254   }
0255
0256   // for internal calls with env
0257   template<CALL_TEMPLATE_ARGS>
0258   typename inherited::template sig<tuple<CALL_REFERENCE_TYPES> >::type
0259   internal_call(CALL_FORMAL_ARGS) const {
0260      return inherited::template
0261        call<typename inherited::template
0262          sig<tuple<CALL_REFERENCE_TYPES> >::type>(CALL_ACTUAL_ARGS);
0263   }
0264
0265   template<class A>
0266   const lambda_functor<lambda_functor_base<
0267                   other_action<assignment_action>,
0268                   boost::tuple<lambda_functor,
0269                   typename const_copy_argument <const A>::type> > >
0270   operator=(const A& a) const {
0271     return lambda_functor_base<
0272                   other_action<assignment_action>,
0273                   boost::tuple<lambda_functor,
0274                   typename const_copy_argument <const A>::type> >
0275      (  boost::tuple<lambda_functor,
0276              typename const_copy_argument <const A>::type>(*this, a) );
0277   }
0278
0279   template<class A>
0280   const lambda_functor<lambda_functor_base<
0281                   other_action<subscript_action>,
0282                   boost::tuple<lambda_functor,
0283                         typename const_copy_argument <const A>::type> > >
0284   operator[](const A& a) const {
0285     return lambda_functor_base<
0286                   other_action<subscript_action>,
0287                   boost::tuple<lambda_functor,
0288                         typename const_copy_argument <const A>::type> >
0289      ( boost::tuple<lambda_functor,
0290              typename const_copy_argument <const A>::type>(*this, a ) );
0291   }
0292 };
0293
0294 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
0295 #pragma warning(pop)
0296 #endif
0297
0298 } // namespace lambda
0299 } // namespace boost
0300
0301 namespace boost {
0302
0303 #if !defined(BOOST_RESULT_OF_USE_DECLTYPE) || defined(BOOST_NO_CXX11_DECLTYPE)
0304
0305 template<class T>
0306 struct result_of<boost::lambda::lambda_functor<T>()>
0307 {
0308     typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type;
0309 };
0310
0311 template<class T>
0312 struct result_of<const boost::lambda::lambda_functor<T>()>
0313 {
0314     typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type;
0315 };
0316
0317 #endif
0318
0319 template<class T>
0320 struct tr1_result_of<boost::lambda::lambda_functor<T>()>
0321 {
0322     typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type;
0323 };
0324
0325 template<class T>
0326 struct tr1_result_of<const boost::lambda::lambda_functor<T>()>
0327 {
0328     typedef typename boost::lambda::lambda_functor<T>::nullary_return_type type;
0329 };
0330
0331 }
0332
0333 // is_placeholder
0334
0335 #include <boost/is_placeholder.hpp>
0336
0337 namespace boost
0338 {
0339
0340 template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::FIRST> > >
0341 {
0342     enum _vt { value = 1 };
0343 };
0344
0345 template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::SECOND> > >
0346 {
0347     enum _vt { value = 2 };
0348 };
0349
0350 template<> struct is_placeholder< lambda::lambda_functor< lambda::placeholder<lambda::THIRD> > >
0351 {
0352     enum _vt { value = 3 };
0353 };
0354
0355 } // namespace boost
0356
0357 #endif