/** @file symbol.h
 *
 *  Interface to GiNaC's symbolic objects. */

/*
 *  GiNaC Copyright (C) 1999-2007 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_SYMBOL_H__
#define __GINAC_SYMBOL_H__

#include <string>
#include "basic.h"
#include "ex.h"
#include "ptr.h"

namespace GiNaC {

/** Basic CAS symbol.  It has a name because it must know how to output itself.
 *  It may be assigned an expression, but this feature is only intended for
 *  programs like 'ginsh' that want to associate symbols with expressions.
 *  If you want to replace symbols by expressions in your code, you should
 *  use ex::subs() or use objects of class ex instead of class symbol in the
 *  first place. */
class symbol : public basic
{
	GINAC_DECLARE_REGISTERED_CLASS(symbol, basic)

	friend class realsymbol;

// types
	
	/** Symbols as keys to expressions - only for ginsh. */
	class assigned_ex_info : public refcounted {
	public:
		assigned_ex_info() throw();  ///< Default ctor
		bool is_assigned;            ///< True if there is an expression assigned
		ex assigned_expression;      ///< The actual expression
	};

// member functions
	
	// other constructors
public:
	explicit symbol(const std::string & initname, unsigned domain = domain::complex);
	symbol(const std::string & initname, const std::string & texname, unsigned domain = domain::complex);
	symbol(const std::string & initname, unsigned rt, unsigned rtt, unsigned domain = domain::complex);
	symbol(const std::string & initname, const std::string & texname, unsigned rt, unsigned rtt, unsigned domain = domain::complex);
	
	// functions overriding virtual functions from base classes
public:
	bool info(unsigned inf) const;
	ex eval(int level = 0) const;
	ex evalf(int level = 0) const { return *this; } // overwrites basic::evalf() for performance reasons
	ex series(const relational & s, int order, unsigned options = 0) const;
	ex subs(const exmap & m, unsigned options = 0) const { return subs_one_level(m, options); } // overwrites basic::subs() for performance reasons
	ex normal(exmap & repl, exmap & rev_lookup, int level = 0) const;
	ex to_rational(exmap & repl) const;
	ex to_polynomial(exmap & repl) const;
	unsigned return_type() const { return ret_type; }
	unsigned return_type_tinfo() const { return ret_type_tinfo; }
	ex conjugate() const;
protected:
	ex derivative(const symbol & s) const;
	bool is_equal_same_type(const basic & other) const;
	unsigned calchash() const;
	
	// non-virtual functions in this class
public:
	void assign(const ex & value);
	void unassign();
	void set_name(const std::string & n) { name = n; }
	std::string get_name() const { return name; }
	unsigned get_domain() const { return domain; }
protected:
	void do_print(const print_context & c, unsigned level) const;
	void do_print_latex(const print_latex & c, unsigned level) const;
	void do_print_tree(const print_tree & c, unsigned level) const;
	void do_print_python_repr(const print_python_repr & c, unsigned level) const;
private:
	std::string & autoname_prefix();
	std::string default_TeX_name() const;

// member variables

protected:
	ptr<assigned_ex_info> asexinfop; ///< assigned expression, only for private use by ginsh
	unsigned serial;                 ///< unique serial number for comparison
	std::string name;                ///< printname of this symbol
	std::string TeX_name;            ///< LaTeX name of this symbol
	unsigned domain;                 ///< domain of symbol, complex (default) or real
	unsigned ret_type;               ///< value returned by return_type()
	unsigned ret_type_tinfo;         ///< value returned by return_type_tinfo()
private:
	static unsigned next_serial;
};


/** Specialization of symbol to real domain */
class realsymbol : public symbol
{
	// constructors
public:
	realsymbol();
	explicit realsymbol(const std::string & initname, unsigned domain = domain::real);
	realsymbol(const std::string & initname, const std::string & texname, unsigned domain = domain::real);
	realsymbol(const std::string & initname, unsigned rt, unsigned rtt, unsigned domain = domain::real);
	realsymbol(const std::string & initname, const std::string & texname, unsigned rt, unsigned rtt, unsigned domain = domain::real);
};


// utility functions

/** Specialization of is_exactly_a<symbol>(obj) for symbol objects. */
template<> inline bool is_exactly_a<symbol>(const basic & obj)
{
	return obj.tinfo() == TINFO_symbol;
}

/** Specialization of is_exactly_a<realsymbol>(obj) for realsymbol objects. */
template<> inline bool is_exactly_a<realsymbol>(const basic & obj)
{
	return (obj.tinfo() == TINFO_symbol) && (static_cast<const symbol &>(obj).get_domain() == domain::real);
}

// wrapper functions around member functions
inline void unassign(symbol & symarg)
{ symarg.unassign(); }

} // namespace GiNaC

#endif // ndef __GINAC_SYMBOL_H__
