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Diffstat (limited to 'boost/functional/overloaded_function.hpp')
-rw-r--r-- | boost/functional/overloaded_function.hpp | 311 |
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diff --git a/boost/functional/overloaded_function.hpp b/boost/functional/overloaded_function.hpp new file mode 100644 index 0000000000..83fe4b3849 --- /dev/null +++ b/boost/functional/overloaded_function.hpp @@ -0,0 +1,311 @@ + +// Copyright (C) 2009-2012 Lorenzo Caminiti +// Distributed under the Boost Software License, Version 1.0 +// (see accompanying file LICENSE_1_0.txt or a copy at +// http://www.boost.org/LICENSE_1_0.txt) +// Home at http://www.boost.org/libs/functional/overloaded_function + +#ifndef DOXYGEN // Doxygen documentation only. + +#if !BOOST_PP_IS_ITERATING +# ifndef BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_HPP_ +# define BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_HPP_ + +# include <boost/functional/overloaded_function/detail/base.hpp> +# include <boost/functional/overloaded_function/detail/function_type.hpp> +# include <boost/functional/overloaded_function/config.hpp> +# include <boost/typeof/typeof.hpp> +# include <boost/preprocessor/iteration/iterate.hpp> +# include <boost/preprocessor/repetition/enum.hpp> +# include <boost/preprocessor/repetition/repeat.hpp> +# include <boost/preprocessor/control/expr_iif.hpp> +# include <boost/preprocessor/control/expr_if.hpp> +# include <boost/preprocessor/comparison/greater.hpp> +# include <boost/preprocessor/comparison/less.hpp> +# include <boost/preprocessor/cat.hpp> +# include <boost/preprocessor/arithmetic/add.hpp> +# include <boost/preprocessor/arithmetic/sub.hpp> +# include <boost/preprocessor/tuple/eat.hpp> +# include <boost/preprocessor/logical/and.hpp> +# include <boost/preprocessor/logical/not.hpp> +# include <boost/preprocessor/facilities/expand.hpp> + +#define BOOST_FUNCTIONAL_f_type(z, n, unused) \ + BOOST_PP_CAT(F, n) + +#define BOOST_FUNCTIONAL_f_arg(z, n, unused) \ + BOOST_PP_CAT(f, n) + +#define BOOST_FUNCTIONAL_f_tparam(z, n, unused) \ + typename BOOST_FUNCTIONAL_f_type(z, n, ~) \ + +#define BOOST_FUNCTIONAL_f_tparam_dflt(z, n, is_tspec) \ + BOOST_FUNCTIONAL_f_tparam(z, n, ~) \ + /* overload requires at least 2 functors so F0 and F1 not optional */ \ + BOOST_PP_EXPR_IIF(BOOST_PP_AND(BOOST_PP_NOT(is_tspec), \ + BOOST_PP_GREATER(n, 1)), \ + = void \ + ) + +#define BOOST_FUNCTIONAL_f_arg_decl(z, n, unused) \ + BOOST_FUNCTIONAL_f_type(z, n, ~) /* no qualifier to deduce tparam */ \ + BOOST_FUNCTIONAL_f_arg(z, n, ~) + +#define BOOST_FUNCTIONAL_g_type(z, n, unused) \ + BOOST_PP_CAT(G, n) + +#define BOOST_FUNCTIONAL_g_arg(z, n, unused) \ + BOOST_PP_CAT(g, n) + +#define BOOST_FUNCTIONAL_g_tparam(z, n, unused) \ + typename BOOST_FUNCTIONAL_g_type(z, n, ~) + +#define BOOST_FUNCTIONAL_g_arg_decl(z, n, unused) \ + BOOST_FUNCTIONAL_g_type(z, n, ~) /* no qualifier to deduce tparam */ \ + BOOST_FUNCTIONAL_g_arg(z, n, ~) + +#define BOOST_FUNCTIONAL_base(z, n, unused) \ + ::boost::overloaded_function_detail::base< \ + BOOST_FUNCTIONAL_f_type(z, n, ~) \ + > + +#define BOOST_FUNCTIONAL_inherit(z, n, unused) \ + public BOOST_FUNCTIONAL_base(z, n, ~) + +#define BOOST_FUNCTIONAL_base_init(z, n, unused) \ + BOOST_FUNCTIONAL_base(z, n, ~)(BOOST_FUNCTIONAL_g_arg(z, n, ~)) + +#define BOOST_FUNCTIONAL_using_operator_call(z, n, unused) \ + using BOOST_FUNCTIONAL_base(z, n, ~)::operator(); + +#define BOOST_FUNCTIONAL_function_type(z, n, unused) \ + typename ::boost::overloaded_function_detail::function_type< \ + BOOST_FUNCTIONAL_f_type(z, n, ~) \ + >::type + +# define BOOST_PP_ITERATION_PARAMS_1 \ + /* at least 2 func to overload so start from 2 to MAX */ \ + /* (cannot iterate [0, MAX-2) because error on Sun) */ \ + (3, (2, BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX, \ + "boost/functional/overloaded_function.hpp")) +# include BOOST_PP_ITERATE() // Iterate over function arity. + +#undef BOOST_FUNCTIONAL_f_type +#undef BOOST_FUNCTIONAL_f_arg +#undef BOOST_FUNCTIONAL_f_tparam +#undef BOOST_FUNCTIONAL_f_arg_decl +#undef BOOST_FUNCTIONAL_f_tparam_dflt +#undef BOOST_FUNCTIONAL_g_type +#undef BOOST_FUNCTIONAL_g_arg +#undef BOOST_FUNCTIONAL_g_tparam +#undef BOOST_FUNCTIONAL_g_arg_decl +#undef BOOST_FUNCTIONAL_base +#undef BOOST_FUNCTIONAL_inherit +#undef BOOST_FUNCTIONAL_base_init +#undef BOOST_FUNCTIONAL_using_operator_call +#undef BOOST_FUNCTIONAL_function_type + +# endif // #include guard + +#elif BOOST_PP_ITERATION_DEPTH() == 1 +# define BOOST_FUNCTIONAL_overloads \ + /* iterate as OVERLOADS, OVERLOADS-1, OVERLOADS-2, ... */ \ + /* (add 2 because iteration started from 2 to MAX) */ \ + BOOST_PP_ADD(2, BOOST_PP_SUB( \ + BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX, \ + BOOST_PP_FRAME_ITERATION(1))) +# define BOOST_FUNCTIONAL_is_tspec \ + /* if template specialization */ \ + BOOST_PP_LESS(BOOST_FUNCTIONAL_overloads, \ + BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX) + +// For type-of emulation: This must be included at this pp iteration level. +# include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP() + +namespace boost { + +template< + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_f_tparam_dflt, + BOOST_FUNCTIONAL_is_tspec) +> +class overloaded_function + // Template specialization. + BOOST_PP_EXPR_IIF(BOOST_PP_EXPAND(BOOST_FUNCTIONAL_is_tspec), <) + BOOST_PP_IIF(BOOST_FUNCTIONAL_is_tspec, + BOOST_PP_ENUM + , + BOOST_PP_TUPLE_EAT(3) + )(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_f_type, ~) + BOOST_PP_EXPR_IIF(BOOST_PP_EXPAND(BOOST_FUNCTIONAL_is_tspec), >) + // Bases (overloads >= 2 so always at least 2 bases). + : BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, + BOOST_FUNCTIONAL_inherit, ~) +{ +public: + template< + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_g_tparam, ~) + > /* implicit */ inline overloaded_function( + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, + BOOST_FUNCTIONAL_g_arg_decl, ~)) + // Overloads >= 2 so always at least 2 bases to initialize. + : BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, + BOOST_FUNCTIONAL_base_init, ~) + {} + + BOOST_PP_REPEAT(BOOST_FUNCTIONAL_overloads, + BOOST_FUNCTIONAL_using_operator_call, ~) +}; + +template< + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_f_tparam, ~) +> +overloaded_function< + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_function_type, ~) +> make_overloaded_function( + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_f_arg_decl, ~) +) { + return overloaded_function< + BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, + BOOST_FUNCTIONAL_function_type, ~) + >(BOOST_PP_ENUM(BOOST_FUNCTIONAL_overloads, BOOST_FUNCTIONAL_f_arg, ~)); +} + +} // namespace + +// For type-of emulation: Register overloaded function type (for _AUTO, etc). +BOOST_TYPEOF_REGISTER_TEMPLATE(boost::overloaded_function, + BOOST_FUNCTIONAL_overloads) + +# undef BOOST_FUNCTIONAL_overloads +# undef BOOST_FUNCTIONAL_is_tspec +#endif // iteration + +// DOCUMENTATION // + +#else // DOXYGEN + +/** @file +@brief Overload distinct function pointers, function references, and +monomorphic function objects into a single function object. +*/ + +namespace boost { + +/** +@brief Function object to overload functions with distinct signatures. + +This function object aggregates together calls to functions of all the +specified function types <c>F1</c>, <c>F2</c>, etc which must have distinct +function signatures from one another. + +@Params +@Param{F<em>i</em>, +Each function type must be specified using the following syntax (which is +Boost.Function's preferred syntax): +@code + result_type (argument1_type\, argumgnet2_type\, ...) +@endcode +} +@EndParams + +In some cases, the @RefFunc{make_overloaded_function} function template can be +useful to construct an overloaded function object without explicitly +specifying the function types. + +At least two distinct function types must be specified (because there is +nothing to overload between one or zero functions). +The maximum number of functions to overload is given by the +@RefMacro{BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX} +configuration macro. +The maximum number of function parameters for each of the specified function +types is given by the +@RefMacro{BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX} +configuration macro. + +@See @RefSect{tutorial, Tutorial} section, @RefFunc{make_overloaded_function}, +@RefMacro{BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX}, +@RefMacro{BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX}, +Boost.Function. +*/ +template<typename F1, typename F2, ...> +class overloaded_function { +public: + /** + @brief Construct the overloaded function object. + + Any function pointer, function reference, and monomorphic function object + that can be converted to a <c>boost::function</c> function object can be + specified as parameter. + + @Note Unfortunately, it is not possible to support polymorphic function + objects (as explained <a + href="http://lists.boost.org/Archives/boost/2012/03/191744.php">here</a>). + */ + overloaded_function(const boost::function<F1>&, + const boost::function<F2>&, ...); + + /** + @brief Call operator matching the signature of the function type specified + as 1st template parameter. + + This will in turn invoke the call operator of the 1st function passed to + the constructor. + */ + typename boost::function_traits<F1>::result_type operator()( + typename boost::function_traits<F1>::arg1_type, + typename boost::function_traits<F1>::arg2_type, + ...) const; + + /** + @brief Call operator matching the signature of the function type specified + as 2nd template parameter. + + This will in turn invoke the call operator of the 2nd function passed to + the constructor. + + @Note Similar call operators are present for all specified function types + <c>F1</c>, <c>F2</c>, etc (even if not exhaustively listed by this + documentation). + */ + typename boost::function_traits<F2>::result_type operator()( + typename boost::function_traits<F2>::arg1_type, + typename boost::function_traits<F2>::arg2_type, + ...) const; +}; + +/** +@brief Make an overloaded function object without explicitly specifying the +function types. + +This function template creates and returns an @RefClass{overloaded_function} +object that overloads all the specified functions <c>f1</c>, <c>f2</c>, etc. + +The function types are internally determined from the template parameter types +so they do not need to be explicitly specified. +Therefore, this function template usually has a more concise syntax when +compared with @RefClass{overloaded_function}. +This is especially useful when the explicit type of the returned +@RefClass{overloaded_function} object does not need to be known (e.g., when +used with Boost.Typeof's <c>BOOST_AUTO</c>, C++11 <c>auto</c>, or when the +overloaded function object is handled using a function template parameter, see +the @RefSect{tutorial, Tutorial} section). + +The maximum number of functions to overload is given by the +@RefMacro{BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX} +configuration macro. + +@Note In this documentation, <c>__function_type__</c> is a placeholder for a +symbol that is specific to the implementation of this library. + +@See @RefSect{tutorial, Tutorial} section, @RefClass{overloaded_function}, +@RefMacro{BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX}. +*/ +template<typename F1, typename F2, ...> +overloaded_function< + __function_type__<F1>, __function_type__<F2>, ... +> make_overloaded_function(F1 f1, F2 f2, ...); + +} // namespace + +#endif // DOXYGEN + |