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arg_parser.h

/*  Arg_parser - A simple argument parser written in C++
    Copyright (C) 2006 Antonio Diaz Diaz.

    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 St, Fifth Floor, Boston, MA 02110-1301 USA
*/

/*  Arg_parser reads the arguments in `argv' and creates a number of
    option codes, option arguments and non-option arguments.

    In case of error, `error()' returns a non-empty error message.

    `options' is an array of `struct Option' terminated by an element
    containing a code which is zero. A null name means a short-only
    option. A code value outside the char range means a long-only option.

    Arg_parser normally makes it appear as if all the option arguments
    were specified before all the non-option arguments for the purposes
    of parsing, even if the user of your program intermixed option and
    non-option arguments. If you want the arguments in the exact order
    the user typed them, call `Arg_parser()' with `in_order' = true.

    The argument `--' terminates all options; any following arguments are
    treated as non-option arguments, even if they begin with a hyphen.

    The syntax for optional option arguments is `-<short_option><argument>'
    (without whitespace), or `--<long_option>=<argument>'.
*/

class Arg_parser
  {
public:
  enum Has_arg { no, yes, maybe };

  struct Option
    {
    int code;                 // Short option letter or code ( code != 0 )
    const char * name;        // Long option name (maybe null)
    Has_arg has_arg;
    };

private:
  struct Record
    {
    int code;
    std::string argument;
    Record( const int c = 0 ) : code( c ) {}
    };

  std::string _error;
  std::vector< Record > data;

  bool parse_long_option( const char * const opt, const char * const arg,
                          const Option options[], int & argind ) throw();
  bool parse_short_option( const char * const opt, const char * const arg,
                           const Option options[], int & argind ) throw();

public:
  Arg_parser( const int argc, const char * const argv[],
              const Option options[], const bool in_order = false ) throw();

      // Restricted constructor. Parses a single token and argument (if any)
  Arg_parser( const char * const opt, const char * const arg,
              const Option options[] ) throw();

  const std::string & error() const throw() { return _error; }

      // The number of arguments parsed (may be different from argc)
  int arguments() const throw() { return data.size(); }

      // If code( i ) is 0, argument( i ) is a non-option.
      // Else argument( i ) is the option's argument (or empty).
  int code( const int i ) const throw()
    {
    if( i >= 0 && i < arguments() ) return data[i].code;
    else return 0;
    }

  const std::string & argument( const int i ) const throw()
    {
    if( i >= 0 && i < arguments() ) return data[i].argument;
    else return _error;
    }
  };

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