/** @file relational.h
 *
 *  Interface to relations between expressions. */

#ifndef _RELATIONAL_H_
#define _RELATIONAL_H_

class relational;

#include "basic.h"

/** This class holds a relation consisting of two expressions and a logical
 *  relation between them. */
class relational : public basic
{

// types
public:
    enum operators { equal,
           not_equal,
           less,
           less_or_equal,
           greater,
           greater_or_equal
    };
    
// member functions

    // default constructor, destructor, copy constructor assignment operator and helpers
public:
    relational();
    ~relational();
    relational(relational const & other);
    relational const & operator=(relational const & other);
protected:
    void copy(relational const & other);
    void destroy(bool call_parent);

    // other constructors
public:
    relational(ex const & lhs, ex const & rhs, operators oper=equal);
    
    // functions overriding virtual functions from bases classes
public:
    basic * duplicate() const;
    void printraw(ostream & os) const;
    void print(ostream & os, unsigned upper_precedence=0) const;
    void printcsrc(ostream & os, unsigned type, unsigned upper_precedence=0) const;
    bool info(unsigned inf) const;
    int nops() const;
    ex & let_op(int const i);
    ex eval(int level=0) const;
    ex evalf(int level=0) const;
    ex simplify_ncmul(exvector const & v) const;
protected:
    int compare_same_type(basic const & other) const;
    unsigned return_type(void) const;
    unsigned return_type_tinfo(void) const;

    // new virtual functions which can be overridden by derived classes
    // none

    // non-virtual functions in this class
public:
    operator bool(void) const;
    
// member variables
    
protected:
    ex lh;
    ex rh;
    operators o;
    static unsigned precedence;
};

// global constants

extern const relational some_relational;
extern type_info const & typeid_relational;

#define ex_to_relational(X) static_cast<relational const &>(*(X).bp)

#endif // ndef _RELATIONAL_H_