src/FbTk/SelectArg.hh (raw)
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// SelectArg.hh for FbTk // Copyright (c) 2010 Fluxbox Team (fluxgen at fluxbox dot org) // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the "Software"), // to deal in the Software without restriction, including without limitation // the rights to use, copy, modify, merge, publish, distribute, sublicense, // and/or sell copies of the Software, and to permit persons to whom the // Software is furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // DEALINGS IN THE SOFTWARE. #ifndef FBTK_STLUTIL_SELECT_ARG_HH #define FBTK_STLUTIL_SELECT_ARG_HH #include "STLUtil.hh" namespace FbTk { namespace STLUtil { /** * Selects a single argument from a maximum set of three arguments at compile time. * For example: * \begincode * SelectArg<0>()( 10, 20, "hello" ); // returns first argument ( 10 ) * SelectArg<1>()( 10, "hello", 30 ); // returns second argument ( "hello" ) * SelectArg<2>()( 10, "hello", 30 ); // returns third argument ( 30 ) * \endcode * * The selection of argument 1 and 2 can return the last argument if the * arguments are less or equal to two. For instance: * \begincode * SelectArg<1>()(10); // returns 10 * SelectArg<2>()(10, 20); // returns 20 * SelectArg<2>()(10); // returns 10 * \endcode */ template < int N > struct SelectArg { template <typename Type1, typename Type2> typename IfThenElse<N==0, Type1, Type2>::ResultType& operator ()(Type1& a, Type2& b){ return IfThenElse<N==0, Type1, Type2>()(a, b); } template <typename Type1, typename Type2, typename Type3> typename IfThenElse<N==0, Type1, typename IfThenElse<N==1, Type2, Type3>::ResultType>::ResultType& operator () (Type1& a, Type2& b, Type3& c) { return IfThenElse<N==0, Type1, typename IfThenElse<N==1, Type2, Type3>::ResultType>() (a, IfThenElse<N==1, Type2, Type3>() (b, c) ); } template < typename Type1 > Type1 operator() (Type1 a) { return a; } }; } // end namespace STLUtil } // end namespace FbTk #endif // FBTK_STLUTIL_SELECT_ARG_HH |