Language.h

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// Language.h: Rcpp R/C++ interface class library -- language objects (calls)
//
// Copyright (C) 2010 - 2025 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_Language_h
#define Rcpp_Language_h
 
namespace Rcpp{

    RCPP_API_CLASS(Language_Impl),
        public DottedPairProxyPolicy< Language_Impl<StoragePolicy> > ,
        public DottedPairImpl< Language_Impl<StoragePolicy> >
    {
    public:
 
        typedef typename DottedPairProxyPolicy<Language_Impl>::DottedPairProxy Proxy;
        typedef typename DottedPairProxyPolicy<Language_Impl>::const_DottedPairProxy const_Proxy;
 
        RCPP_GENERATE_CTOR_ASSIGN(Language_Impl)
 
        Language_Impl(){}

        Language_Impl(SEXP x){
            Storage::set__( r_cast<LANGSXP>(x) );
        }

        explicit Language_Impl( const std::string& symbol ){
            Storage::set__( Rf_lang1( Rf_install(symbol.c_str()) ) );
        }

        explicit Language_Impl( const Symbol& symbol ){
            Storage::set__( Rf_lang1( symbol ) );
        }

        explicit Language_Impl( const Function& function) {
            Storage::set__( Rf_lang1( function ) );
        }

        template <typename... T>
        Language_Impl(const std::string& symbol, const T&... t) {
            Storage::set__(langlist(Rf_install(symbol.c_str()), t...) );
        }
 
        template <typename... T>
        Language_Impl(const Function& function, const T&... t) {
            Storage::set__(langlist(function, t...));
        }

        void setSymbol( const std::string& symbol){
            setSymbol( Symbol( symbol ) );
        }

        void setSymbol( const Symbol& symbol ){
            SEXP x = Storage::get__();
            SETCAR( x, symbol );
            SET_TAG(x, R_NilValue);
        }

        void setFunction( const Function& function){
            SEXP x = Storage::get__();
            SETCAR( x, function );
            SET_TAG(x, R_NilValue); /* probably not necessary */
        }

        SEXP eval() const {
            return Rcpp_fast_eval( Storage::get__(), R_GlobalEnv );
        }

        SEXP eval(SEXP env) const {
            return Rcpp_fast_eval( Storage::get__(), env );
        }
 
        SEXP fast_eval() const {
            return internal::Rcpp_eval_impl( Storage::get__(), R_GlobalEnv);
        }
        SEXP fast_eval(SEXP env ) const {
            return internal::Rcpp_eval_impl( Storage::get__(), env);
        }
 
        void update(SEXP x) {
            if (TYPEOF(x) != LANGSXP) {
                Storage::set__(r_cast<LANGSXP>(x));
            }
            SET_TAG( x, R_NilValue );
        }
 
    };
 
    typedef Language_Impl<PreserveStorage> Language;
 
    template <typename RESULT_TYPE=SEXP>
    class fixed_call {
    public:
        typedef RESULT_TYPE result_type;
 
        fixed_call( Language call_ ) : call(call_){}
        fixed_call( Function fun ) : call(fun){}
 
        RESULT_TYPE operator()(){
            return as<RESULT_TYPE>( call.eval() );
        }
 
    private:
        Language call;
    };
 
    template <typename T, typename RESULT_TYPE = SEXP>
        class unary_call : public std::function<RESULT_TYPE(T)> {
    public:
        unary_call( Language call_ ) : call(call_), proxy(call_,1) {}
        unary_call( Language call_, R_xlen_t index ) : call(call_), proxy(call_,index){}
        unary_call( Function fun ) : call( fun, R_NilValue), proxy(call,1) {}
 
        RESULT_TYPE operator()( const T& object ){
            proxy = object;
            return as<RESULT_TYPE>( call.eval() );
        }
 
    private:
        Language call;
        Language::Proxy proxy;
    };
 
    template <typename T1, typename T2, typename RESULT_TYPE = SEXP>
        class binary_call : public std::function<RESULT_TYPE(T1,T2)> {
    public:
        binary_call( Language call_ ) : call(call_), proxy1(call_,1), proxy2(call_,2) {}
        binary_call( Language call_, R_xlen_t index1, R_xlen_t index2 ) : call(call_), proxy1(call_,index1), proxy2(call_,index2){}
        binary_call( Function fun) : call(fun, R_NilValue, R_NilValue), proxy1(call,1), proxy2(call,2){}
 
        RESULT_TYPE operator()( const T1& o1, const T2& o2 ){
            proxy1 = o1;
            proxy2 = o2;
            return as<RESULT_TYPE>( call.eval() );
        }
 
    private:
        Language call;
        Language::Proxy proxy1;
        Language::Proxy proxy2;
    };
 
} // namespace Rcpp
 
#endif