string_proxy.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// string_proxy.h: Rcpp R/C++ interface class library --
//
// Copyright (C) 2010 - 2018 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__vector__string_proxy_h
#define Rcpp__vector__string_proxy_h
 
namespace Rcpp{
namespace internal{
 
        template<int RTYPE, template <class> class StoragePolicy>
        class string_proxy {
        public:
 
                typedef typename ::Rcpp::Vector<RTYPE, StoragePolicy> VECTOR ;
                typedef const char* iterator ;
                typedef const char& reference ;
 
                string_proxy() : parent(0), index(-1){};
 
                string_proxy( VECTOR& v, R_xlen_t index_ ) : parent(&v), index(index_){}
 
                string_proxy( const string_proxy& other ) :
                        parent(other.parent), index(other.index)
                {} ;
 
                string_proxy& operator=( const string_proxy<RTYPE, StoragePolicy>& other) {
                    set( other.get() ) ;
                    return *this ;
                }
 
                template <template <class> class StoragePolicy2>
                string_proxy& operator=( const string_proxy<RTYPE, StoragePolicy2>& other) {
                    set( other.get() ) ;
                    return *this ;
                }
 
                template <template <class> class StoragePolicy2>
                string_proxy& operator=( const const_string_proxy<RTYPE, StoragePolicy2>& other) ;
 
                string_proxy& operator=( const String& s) ;
 
                template <typename T>
                string_proxy& operator=(const std::basic_string<T>& rhs){
                        set( rhs ) ;
                        return *this ;
                }
 
                string_proxy& operator=(const char* rhs){
                        set( Rf_mkChar( rhs ) ) ;
                        return *this ;
                }
 
                string_proxy& operator=(const wchar_t* rhs){
                        set( internal::make_charsexp( rhs ) ) ;
                        return *this ;
                }
 
 
                string_proxy& operator=(SEXP rhs){
                        // TODO: check this is a CHARSXP
                        set( rhs ) ;
                        return *this ;
                }
 
                void import( const string_proxy& other){
                        parent = other.parent ;
                        index  = other.index ;
                }
 
        template <typename T>
        string_proxy& operator+=(const T& rhs) ;
 
                operator SEXP() const {
                        return get() ;
                }
 
                 operator /* const */ char*() const {
                         return const_cast<char*>( CHAR(get()) );
                 }
 
                 // operator std::wstring() const {
                 //     const char* st = CHAR(get()) ;
                 //     return std::wstring( st, st+strlen(st) ) ;
                 // }
 
                template <int RT>
                friend std::ostream& operator<<(std::ostream& os, const string_proxy<RT>& proxy);
 
                template <int RT>
                friend std::string operator+( const std::string& x, const string_proxy<RT>& proxy);
 
                void swap( string_proxy& other ){
                        Shield<SEXP> tmp( STRING_ELT(*parent, index)) ;
                        SET_STRING_ELT( *parent, index, STRING_ELT( *(other.parent), other.index) ) ;
                        SET_STRING_ELT( *(other.parent), other.index, tmp ) ;
                }
 
                VECTOR* parent;
                R_xlen_t index ;
                inline void move( R_xlen_t n ){ index += n ;}
 
                inline SEXP get() const {
                        return STRING_ELT( *parent, index ) ;
                }
                template <typename T>
                inline void set( const T& x ){
                        set( internal::make_charsexp(x) ) ;
                }
                inline void set(SEXP x){
                        SET_STRING_ELT( *parent, index, x ) ;
                }
 
                inline iterator begin() const { return CHAR( STRING_ELT( *parent, index ) ) ; }
                inline iterator end() const { return begin() + size() ; }
                inline R_xlen_t size() const { return strlen( begin() ) ; }
                inline bool empty() const { return *begin() == '\0' ; }
                inline reference operator[]( R_xlen_t n ){ return *( begin() + n ) ; }
 
                template <typename UnaryOperator>
                void transform( UnaryOperator op ){
                        buffer = begin() ;
                        std::transform( buffer.begin(), buffer.end(), buffer.begin(), op ) ;
                        set( buffer ) ;
                }
 
                template <typename OutputIterator, typename UnaryOperator>
                void apply( OutputIterator target, UnaryOperator op){
                        std::transform( begin(), end(), target, op ) ;
                }
 
                template <typename UnaryOperator>
                void apply( UnaryOperator op){
                        std::for_each( begin(), end(), op );
                }
 
                bool operator==( const char* other) const {
                        return strcmp( begin(), other ) == 0 ;
                }
                bool operator!=( const char* other) const {
                        return strcmp( begin(), other ) != 0 ;
                }
 
                template<template <class> class SP>
                bool operator==( const string_proxy<STRSXP, SP>& other) const {
                        return strcmp( begin(), other.begin() ) == 0 ;
                }
 
                template<template <class> class SP>
                bool operator!=( const string_proxy<STRSXP,SP>& other) const {
                        return strcmp( begin(), other.begin() ) != 0 ;
                }
 
        bool operator==( SEXP other ) const {
            return get() == other;
        }
 
        bool operator!=( SEXP other ) const {
            return get() != other;
        }
 
        private:
                static std::string buffer ;
 
        } ;
 
        template <int RT>
        bool operator<( const string_proxy<RT>& lhs, const string_proxy<RT>& rhs) {
                return strcmp(
                        const_cast<char *>(lhs.begin() ),
                        const_cast<char *>(rhs.begin())
                        ) < 0 ;
        }
 
        template <int RT>
        bool operator>( const string_proxy<RT>& lhs, const string_proxy<RT>& rhs) {
                return strcmp(
                        const_cast<char *>(lhs.begin() ),
                        const_cast<char *>(rhs.begin())
                        ) > 0 ;
        }
 
        template <int RT>
        bool operator>=( const string_proxy<RT>& lhs, const string_proxy<RT>& rhs) {
                return strcmp(
                        const_cast<char *>(lhs.begin() ),
                        const_cast<char *>(rhs.begin())
                        ) >= 0 ;
        }
 
        template <int RT>
        bool operator<=( const string_proxy<RT>& lhs, const string_proxy<RT>& rhs) {
                return strcmp(
                        const_cast<char *>(lhs.begin() ),
                        const_cast<char *>(rhs.begin())
                        ) <= 0 ;
        }
 
        template<int RTYPE, template <class> class StoragePolicy> std::string string_proxy<RTYPE, StoragePolicy>::buffer ;
 
        inline std::ostream& operator<<(std::ostream& os, const string_proxy<STRSXP>& proxy) {
            os << static_cast<const char*>(proxy) ;
            return os;
        }
 
        inline std::string operator+( const std::string& x, const string_proxy<STRSXP>& y ){
                return x + static_cast<const char*>(y) ;
        }
 
}
}
 
#endif