ArgList.hpp

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/*CXXR $Id: ArgList.hpp 1348 2013-02-25 17:49:03Z arr $
 *CXXR
 *CXXR This file is part of CXXR, a project to refactor the R interpreter
 *CXXR into C++.  It may consist in whole or in part of program code and
 *CXXR documentation taken from the R project itself, incorporated into
 *CXXR CXXR (and possibly MODIFIED) under the terms of the GNU General Public
 *CXXR Licence.
 *CXXR 
 *CXXR CXXR is Copyright (C) 2008-13 Andrew R. Runnalls, subject to such other
 *CXXR copyrights and copyright restrictions as may be stated below.
 *CXXR 
 *CXXR CXXR is not part of the R project, and bugs and other issues should
 *CXXR not be reported via r-bugs or other R project channels; instead refer
 *CXXR to the CXXR website.
 *CXXR */

/*
 *  R : A Computer Language for Statistical Data Analysis
 *
 *  This program 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 2.1 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, a copy is available at
 *  http://www.r-project.org/Licenses/
 */

#ifndef ARGLIST_HPP
#define ARGLIST_HPP 1

#include "CXXR/GCStackRoot.hpp"
#include "CXXR/PairList.h"
#include "CXXR/Symbol.h"

namespace CXXR {
    class DottedArgs;

    class ArgList {
    public:
        enum Status {
            RAW,       
            PROMISED,  
            EVALUATED  
        };

        ArgList(const PairList* args, Status status)
            : m_orig_list(args),
              m_list(PairList::cons(0, const_cast<PairList*>(args))),
              m_status(status)
        {}

        void evaluate(Environment* env, bool allow_missing = false);

        std::pair<bool, RObject*> firstArg(Environment* env);

        const PairList* list() const
        {
            return m_list->tail();
        }

        void merge(const ConsCell* extraargs);

        Status status() const
        {
            return m_status;
        }

        void stripTags();

        inline static const Symbol* tag2Symbol(const RObject* tag)
        {
            return ((!tag || tag->sexptype() == SYMSXP)
                    ? static_cast<const Symbol*>(tag)
                    : coerceTag(tag));
        }

        void wrapInPromises(Environment* env);
    private:
        const PairList* const m_orig_list;  // Pointer to the argument
          // list supplied to the constructor. 
        GCStackRoot<PairList> m_list;  // The current argument list,
          // preceded by a dummy element to simplify coding.  The
          // class code should never modify the PairList supplied as
          // an argument to the constructor, even though the
          // constructor casts const away when it initialises this
          // data member.
        GCStackRoot<> m_first_arg;  // If the first argument needed to
          // be evaluated in a call to firstArg(), this is a pointer
          // to the resulting value, and m_first_arg_env points to the
          // Environment in which evaluation took place.  Both
          // pointers are reset to null once the first argument has
          // been processed in a subsequent call to evaluate() or
          // wrapInPromises(). 
        GCStackRoot<Environment> m_first_arg_env;
        Status m_status;

        // Not implemented.  Declared private to suppress
        // compiler-generated versions:
        ArgList(const ArgList&);
        ArgList& operator=(const ArgList&);

        // Coerce a tag that is not already a Symbol into Symbol form:
        static const Symbol* coerceTag(const RObject* tag);
    };
}

#endif  // ARGLIST_HPP