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