/*
**      SWISH++
**      conf_var.h
**
**      Copyright (C) 1998  Paul J. Lucas
**
**      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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef conf_var_H
#define conf_var_H

// standard
#include <iostream>
#include <map>
#include <string>

// local
#include "less.h"

//*****************************************************************************
//
// SYNOPSIS
//
        class conf_var
//
// DESCRIPTION
//
//      A conf_var is the abstract base class for all configuration file
//      variables.  It parses a given line and, based on the variable name,
//      which is the first word on the line, dispatches to an appropriate
//      instance of a derived class to parse the rest of the line.
//
//*****************************************************************************
{
public:
    static void             parse_file( char const *file_name );
    char const*             name() const { return name_; }
    static void             register_var( char const *name );
protected:
    conf_var( char const *var_name );
    virtual ~conf_var();

    virtual void            parse_value( char *line ) = 0;
    //                      Derived classes must define this to parse a line
    //                      and set their value.

    void                    parse_const_value( char const *line );
    //                      This is a convenience function that can be called
    //                      to parse a line where the line is const.  This is
    //                      used by operator=().

    virtual void            reset() = 0;
    //                      Reset value to default.

    static void             reset_all();
    //                      Reset all configuration variables to defaults.

    static std::ostream&    error  ( std::ostream& = std::cerr );
    static std::ostream&    warning( std::ostream& = std::cerr );
private:
    //
    // Note that the declaration of std::map has a default "Compare" template
    // parameter of "less< key_type >" and, since we've included less.h above
    // that defines "less< char const* >", C-style string comparisons work
    // properly.
    //
    typedef std::map< char const*, conf_var* > map_type;

    char const              *const name_;
    static int              current_config_file_line_no_;

    static void             init_mod_vars(); // generated by init_vars-sh
    static map_type&        map_ref();
    static std::ostream&    msg( std::ostream&, char const *label );
    static void             parse_line( char *line, int line_no );
};

////////// Inlines ////////////////////////////////////////////////////////////

inline std::ostream& conf_var::error( std::ostream &o ) {
    return msg( o, "error" );
}
inline std::ostream& conf_var::warning( std::ostream &o ) {
    return msg( o, "warning" );
}

//
// We define this macro for convenience since operator=() is not inherited.
//
#define CONF_VAR_ASSIGN_OPS(T)              \
    T& operator=( std::string const &s ) {  \
        parse_const_value( s.c_str() );     \
        return *this;                       \
    }                                       \
    T& operator=( char const *s ) {         \
        parse_const_value( s );             \
        return *this;                       \
    }

//
// This template declaration allows specializations for T later.
//
template< class T > class conf;

#endif  /* conf_var_H */
/* vim:set et sw=4 ts=4: */