relational.h

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/*
 *  GiNaC Copyright (C) 1999-2011 Johannes Gutenberg University Mainz, Germany
 *
 *  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 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef GINAC_RELATIONAL_H
#define GINAC_RELATIONAL_H

#include "basic.h"
#include "ex.h"
#include "archive.h"

namespace GiNaC {

class relational : public basic
{
    GINAC_DECLARE_REGISTERED_CLASS(relational, basic)

// types
public:
    enum operators {
        equal,
        not_equal,
        less,
        less_or_equal,
        greater,
        greater_or_equal
    };
    
    // other constructors
public:
    relational(const ex & lhs, const ex & rhs, operators oper=equal);
    
    // functions overriding virtual functions from base classes
public:
    unsigned precedence() const {return 20;}
    bool info(unsigned inf) const;
    size_t nops() const;
    ex op(size_t i) const;
    ex map(map_function & f) const;
    ex subs(const exmap & m, unsigned options = 0) const;
    ex eval(int level=0) const;

    void archive(archive_node& n) const;
    void read_archive(const archive_node& n, lst& syms);
protected:
    ex eval_ncmul(const exvector & v) const;
    bool match_same_type(const basic & other) const;
    unsigned return_type() const;
    return_type_t return_type_tinfo() const;
    unsigned calchash() const;

    // new virtual functions which can be overridden by derived classes
protected:
    void do_print(const print_context & c, unsigned level) const;
    void do_print_python_repr(const print_python_repr & c, unsigned level) const;

public:
    virtual ex lhs() const;
    virtual ex rhs() const;

    // non-virtual functions in this class
private:
    // For conversions to boolean, as would be used in an if conditional,
    // implicit conversions from bool to int have a large number of
    // undesirable side effects.  The following safe_bool type enables
    // use of relational objects in conditionals without those side effects
    struct safe_bool_helper {
        void nonnull() {};
    };

    typedef void (safe_bool_helper::*safe_bool)();
    
    safe_bool make_safe_bool(bool) const;

public:
    operator safe_bool() const;
    safe_bool operator!() const;

// member variables
    
protected:
    ex lh;
    ex rh;
    operators o;
};
GINAC_DECLARE_UNARCHIVER(relational); 

// utility functions

// inlined functions for efficiency
inline relational::safe_bool relational::operator!() const
{
    return make_safe_bool(!static_cast<bool>(*this));
}

} // namespace GiNaC

#endif // ndef GINAC_RELATIONAL_H