StringTransformer.h

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// clone.h: Rcpp R/C++ interface class library -- clone RObject's
//
// Copyright (C) 2010 - 2022 Dirk Eddelbuettel and Romain Francois
//
// This file is part of Rcpp.
//
// Rcpp is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// Rcpp is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.
 
#ifndef Rcpp__StringTransformer_h
#define Rcpp__StringTransformer_h
 
#include <RcppCommon.h>
 
namespace Rcpp{
 
        template <typename UnaryOperator>
#if __cplusplus < 201103L
            class StringTransformer : public std::unary_function<const char*, const char*> {
#else
        class StringTransformer : public std::function<const char*(const char*)> {
#endif
                public:
                StringTransformer( const UnaryOperator& op_ ): op(op_), buffer(){}
                ~StringTransformer(){}
 
                const char* operator()(const char* input ) {
                        buffer = input;
                        std::transform( buffer.begin(), buffer.end(), buffer.begin(), op );
                        return buffer.c_str();
                }
 
        private:
                const UnaryOperator& op;
                std::string buffer;
        };
 
        template <typename UnaryOperator>
        StringTransformer<UnaryOperator> make_string_transformer( const UnaryOperator& fun){
                return StringTransformer<UnaryOperator>( fun );
        }
 
}
 
#endif