// ****************************************************************************
// ^FILE: options.h - option parsing classes
//
// ^DESCRIPTION:
//    This file defines classes used to parse command-line options.
//    Options may be parsed from an array of strings, or from any structure
//    for which a corresponding option-iterator exists.
//
// ^HISTORY:
//    03/06/92  Brad Appleton   <bradapp@enteract.com>   Created
//
//    03/23/93	Brad Appleton	<bradapp@enteract.com>
//    - Added OptIstreamIter class
//
//    03/08/94	Brad Appleton	<bradapp@enteract.com>
//    - Added Options::reset() member function
//
//    07/31/97	Brad Appleton	<bradapp@enteract.com>
//    - Added PARSE_POS control flag and POSITIONAL return value
// ^^**************************************************************************

#ifndef _options_h
#define _options_h

#include <iostream>

// Abstract class to iterate through options/arguments
//
class OptIter {
public:
   OptIter(void) {}
   virtual ~OptIter(void);

      // curr() returns the current item in the iterator without
      // advancing on to the next item. If we are at the end of items
      // then NULL is returned.
   virtual const char *
   curr(void) = 0;

      // next() advances to the next item.
   virtual void
   next(void) = 0;

      // operator() returns the current item in the iterator and then
      // advances on to the next item. If we are at the end of items
      // then NULL is returned.
   virtual const char *
   operator()(void);
} ;

// Abstract class for a rewindable OptIter
//
class OptIterRwd : public OptIter {
public:
   OptIterRwd(void);

   virtual ~OptIterRwd(void);

   virtual const char *
   curr(void) = 0;

   virtual void
   next(void) = 0;

   virtual const char *
   operator()(void) = 0;

      // rewind() resets the "current-element" to the first one in the "list"
   virtual void
   rewind(void) = 0;
} ;

// Class to iterate through an array of tokens. The array may be terminated
// by NULL or a count containing the number of tokens may be given.
//
class OptArgvIter : public OptIterRwd {
private:
   int            ndx;   // index of current arg
   int            ac;    // arg count
   const char * const * av;  // arg vector

public:
   OptArgvIter(const char * const argv[])
      : av(argv), ac(-1), ndx(0) {}

   OptArgvIter(int argc, const char * const argv[])
      : av(argv), ac(argc), ndx(0) {}

   virtual
   ~OptArgvIter(void);

   virtual const char *
   curr(void);

   virtual void
   next(void);

   virtual const char *
   operator()(void);

   virtual void
   rewind(void);

      // index returns the current index to use for argv[]
   int index(void)  { return  ndx; }
} ;


// Class to iterate through a string containing delimiter-separated tokens
//
class OptStrTokIter : public OptIterRwd {
private:
   unsigned     len;        // length of token-string
   const char * str;        // the token-string
   const char * seps;       // delimiter-set (separator-characters)
   const char * cur;        // current token
   char       * tokstr;     // our copy of the token-string

   static const char * default_delims;  // default delimiters = whitespace

public:
   OptStrTokIter(const char * tokens, const char * delimiters =0);

   virtual
   ~OptStrTokIter(void);

   virtual const char *
   curr(void);

   virtual void
   next(void);

   virtual const char *
   operator()(void);

   virtual void
   rewind(void);

      // delimiters() with NO arguments returns the current set of delimiters,
      // If an argument is given then it is used as the new set of delimiters.
   const char *
   delimiters(void)  { return  seps; }

   void
   delimiters(const char * delims) {
      seps = (delims) ? delims : default_delims ;
   }
} ;


   // OptIstreamIter is a class for iterating over arguments that come
   // from an input stream. Each line of the input stream is considered
   // to be a set of white-space separated tokens. If the the first
   // non-white character on a line is '#' ('!' for VMS systems) then
   // the line is considered a comment and is ignored.
   //
   // *Note:: If a line is more than 1022 characters in length then we
   // treat it as if it were several lines of length 1022 or less.
   //
   // *Note:: The string tokens returned by this iterator are pointers
   //         to temporary buffers which may not necessarily stick around
   //         for too long after the call to curr() or operator(), hence
   //         if you need the string value to persist - you will need to
   //         make a copy.
   //
class OptIstreamIter : public OptIter {
private:
	std::istream & is ;
   OptStrTokIter * tok_iter ;

   void
   fill(void);

public:
   static const unsigned  MAX_LINE_LEN ;

   OptIstreamIter(std::istream & input);

   virtual
   ~OptIstreamIter(void);

   virtual const char *
   curr(void);

   virtual void
   next(void);

   virtual const char *
   operator()(void);
} ;


// Now we are ready to define a class to declare and parse command-options
//
//
// CLASS
// =====
// Options  -- parse command-line options
//
// SYNOPSIS
// ========
//   #include <options.h>
//
//   Options opts(cmdname, optv);
//   char cmdname[], *optv[];
//
// DESCRIPTION
// ===========
// The Options constructor expects a command-name (usually argv[0]) and
// a pointer to an array of strings.  The last element in this array MUST
// be NULL. Each non-NULL string in the array must have the following format:
//
//   The 1st character must be the option-name ('c' for a -c option).
//
//   The 2nd character must be one of '|', '?', ':', '*', or '+'.
//      '|' -- indicates that the option takes NO argument;
//      '?' -- indicates that the option takes an OPTIONAL argument;
//      ':' -- indicates that the option takes a REQUIRED argument;
//      '*' -- indicates that the option takes 0 or more arguments;
//      '+' -- indicates that the option takes 1 or more arguments;
//
//   The remainder of the string must be the long-option name.
//
//   If desired, the long-option name may be followed by one or more
//   spaces and then by the name of the option value. This name will
//   be used when printing usage messages. If the option-value-name
//   is not given then the string "<value>" will be used in usage
//   messages.
//
//   One may use a space to indicate that a particular option does not
//   have a corresponding long-option.  For example, "c: " (or "c:")
//   means the -c option takes a value & has NO corresponding long-option.
//
//   To specify a long-option that has no corresponding single-character
//   option is a bit trickier: Options::operator() still needs an "option-
//   character" to return when that option is matched. One may use a whitespace
//   character or a non-printable character as the single-character option
//   in such a case. (hence " |hello" would only match "--hello").
//
//   EXCEPTIONS TO THE ABOVE:
//   ------------------------ 
//   If the 1st character of the string is '-', then the rest of the
//   string must correspond to the above format, and the option is
//   considered to be a hidden-option. This means it will be parsed
//   when actually matching options from the command-line, but will
//   NOT show-up if a usage message is printed using the usage() member
//   function. Such an example might be "-h|hidden". If you want to
//   use any "dummy" options (options that are not parsed, but that
//   to show up in the usage message), you can specify them along with
//   any positional parameters to the usage() member function.
//
//   If the 2nd character of the string is '\0' then it is assumed
//   that there is no corresponding long-option and that the option
//   takes no argument (hence "f", and "f| " are equivalent).
//
//   Examples:
//      const char * optv[] = {
//          "c:count   <number>",
//          "s?str     <string>",
//          "x",
//          " |hello",
//          "g+groups  <newsgroup>",
//          NULL
//      } ;
//
//      optv[] now corresponds to the following:
//
//            usage: cmdname [-c|--count <number>] [-s|--str [<string>]]
//                           [-x] [--hello] [-g|--groups <newsgroup> ...]
//
// Long-option names are matched case-insensitive and only a unique prefix
// of the name needs to be specified.
//
// Option-name characters are case-sensitive!
//
// CAVEAT
// ======
// Because of the way in which multi-valued options and options with optional
// values are handled, it is NOT possible to supply a value to an option in
// a separate argument (different argv[] element) if the value is OPTIONAL
// and begins with a '-'. What this means is that if an option "-s" takes an
// optional value value and you wish to supply a value of "-foo" then you must
// specify this on the command-line as "-s-foo" instead of "-s -foo" because
// "-s -foo" will be considered to be two separate sets of options.
//
// A multi-valued option is terminated by another option or by the end-of
// options. The following are all equivalent (if "-l" is a multi-valued
// option and "-x" is an option that takes no value):
//
//    cmdname -x -l item1 item2 item3 -- arg1 arg2 arg3
//    cmdname -x -litem1 -litem2 -litem3 -- arg1 arg2 arg3
//    cmdname -l item1 item2 item3 -x arg1 arg2 arg3
//
//
// EXAMPLE
// =======
//    #include <options.h>
//
//    static const char * optv[] = {
//       "H|help",
//       "c:count   <number>",
//       "s?str     <string>",
//       "x",
//       " |hello",
//       "g+groups  <newsgroup>",
//       NULL
//    } ;
//
//    main(int argc, char * argv[]) {
//       int  optchar;
//       const char * optarg;
//       const char * str = "default_string";
//       int  count = 0, xflag = 0, hello = 0;
//       int  errors = 0, ngroups = 0;
//    
//       Options  opts(*argv, optv);
//       OptArgvIter  iter(--argc, ++argv);
//    
//       while( optchar = opts(iter, optarg) ) {
//          switch (optchar) {
//          case 'H' :
//             opts.usage(cout, "files ...");
//             exit(0);
//             break;
//          case 'g' :
//             ++ngroups; break;  // the groupname is in "optarg"
//          case 's' :
//             str = optarg; break;
//          case 'x' :
//             ++xflag; break;
//          case ' ' :
//             ++hello; break;
//          case 'c' :
//             if (optarg == NULL)  ++errors;
//             else  count = (int) atol(optarg);
//             break;
//          default :  ++errors; break;
//          } //switch
//       }
//    
//       if (errors || (iter.index() == argc)) {
//          if (! errors) {
//             cerr << opts.name() << ": no filenames given." << endl ;
//          }
//          opts.usage(cerr, "files ...");
//          exit(1);
//       }
//    
//       cout << "xflag=" << ((xflag) ? "ON"  : "OFF") << endl
//            << "hello=" << ((hello) ? "YES" : "NO") << endl
//            << "count=" << count << endl
//            << "str=\"" << ((str) ? str : "No value given!") << "\"" << endl
//            << "ngroups=" << ngroups << endl ;
//    
//       if (iter.index() < argc) {
//          cout << "files=" ;
//          for (int i = iter.index() ; i < argc ; i++) {
//             cout << "\"" << argv[i] << "\" " ;
//          }
//          cout << endl ;
//       }
//    }
//
class Options {
private:
   unsigned       explicit_end : 1;  // were we terminated because of "--"?
   unsigned       optctrls : 7;  // control settings (a set of OptCtrl masks)
   const char  * const * optvec; // vector of option-specifications (last=NULL)
   const char   * nextchar;      // next option-character to process
   const char   * listopt;       // last list-option we matched
   const char   * cmdname;       // name of the command

   void
   check_syntax(void) const;

   const char *
   match_opt(char opt, int ignore_case =0) const;

   const char *
   match_longopt(const char * opt, int  len, int & ambiguous) const;

   int
   parse_opt(OptIter & iter, const char * & optarg);

   int
   parse_longopt(OptIter & iter, const char * & optarg);

public:
   enum OptCtrl {
      DEFAULT    = 0x00,  // Default setting
      ANYCASE    = 0x01,  // Ignore case when matching short-options
      QUIET      = 0x02,  // Dont print error messages
      PLUS       = 0x04,  // Allow "+" as a long-option prefix
      SHORT_ONLY = 0x08,  // Dont accept long-options
      LONG_ONLY  = 0x10,  // Dont accept short-options
                            // (also allows "-" as a long-option prefix).
      NOGUESSING = 0x20,  // Normally, when we see a short (long) option
                            // on the command line that doesnt match any
                            // known short (long) options, then we try to
                            // "guess" by seeing if it will match any known
                            // long (short) option. Setting this mask prevents
                            // this "guessing" from occurring.
      PARSE_POS = 0x40    // By default, Options will not present positional
                            // command-line arguments to the user and will
                            // instead stop parsing when the first positonal
                            // argument has been encountered. If this flag
                            // is given, Options will present positional
                            // arguments to the user with a return code of
                            // POSITIONAL; ENDOPTS will be returned only
                            // when the end of the argument list is reached.
   } ;

      // Error return values for operator()
      //
   enum OptRC {
      ENDOPTS    =  0,
      BADCHAR    = -1,
      BADKWD     = -2,
      AMBIGUOUS  = -3,
      POSITIONAL = -4
   } ;

   Options(const char * name, const char * const optv[]);

   virtual
   ~Options(void);

      // name() returns the command name
   const char *
   name(void) const { return  cmdname; }

      // ctrls() (with no arguments) returns the existing control settings
   unsigned
   ctrls(void) const { return  optctrls; }

      // ctrls() (with 1 argument) sets new control settings
   void
   ctrls(unsigned newctrls) { optctrls = newctrls; }

      // reset for another pass to parse for options
   void
   reset(void) { nextchar = listopt = NULL; }
  
      // usage() prints options usage (followed by any positional arguments
      // listed in the parameter "positionals") on the given outstream
   void
	   usage(std::ostream & os, const char * positionals) const ;

      // operator() iterates through the arguments as necessary (using the
      // given iterator) and returns the character value of the option
      // (or long-option) that it matched. If the option has a value
      // then the value given may be found in optarg (otherwise optarg
      // will be NULL).
      //
      // 0 is returned upon end-of-options. At this point, "iter" may
      // be used to process any remaining positional parameters. If the
      // PARSE_POS control-flag is set then 0 is returned only when all
      // arguments in "iter" have been exhausted.
      //
      // If an invalid option is found then BADCHAR is returned and *optarg
      // is the unrecognized option character.
      //
      // If an invalid long-option is found then BADKWD is returned and optarg
      // points to the bad long-option.
      //
      // If an ambiguous long-option is found then AMBIGUOUS is returned and
      // optarg points to the ambiguous long-option.
      //
      // If the PARSE_POS control-flag is set then POSITIONAL is returned
      // when a positional argument is encountered and optarg points to
      // the positonal argument (and "iter" is advanced to the next argument
      // in the iterator).
      //
      // Unless Options::QUIET is used, missing option-arguments and
      // invalid options (and the like) will automatically cause error
      // messages to be issued to cerr.
   int
   operator()(OptIter & iter, const char * & optarg) ;

      // Call this member function after operator() has returned 0
      // if you want to know whether or not options were explicitly
      // terminated because "--" appeared on the command-line.
      //
   int
   explicit_endopts() const { return  explicit_end; }
} ;

#endif /* _options_h */
