/*
 * Copyright (c) 1995, 1996 Gunther Schadow.  All rights reserved.
 *
 * 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 PG_DELIMITERS_H_
#define PG_DELIMITERS_H_

#include <pg_config.h>

#pragma interface

#include <PGObject.h>

/*
 * There are (currently six) levels of delimiters for segments,
 * fields, repeated fields, components and sub-components. Anything can
 * be delimited by a \r since this is the end of the segment. A field
 * can be delimited by \r and |, a repeated field by \r, |, and ~ and so
 * on. Thus we handle delimiters as a set (actualy a string), ordered
 * from the lowest level (-5) of delimiter to the highest (0). Where
 * the highest level corresponds to the segment and the lowest to the
 * sub-component.
 * On request, we return the string from the actual level onwards.
 *
 * ASTM knows only 4 delimiters, but I don't know yet, how they relate
 * to HL7:
 *
 *	NAME				DEFAULT		HL7?
 *	"field delimiter"		`|'		field
 *	"repeat field delimiter"	`\'		repeat? escape?
 *	"component delimiter"		`^'		component
 *	"escape delimiter"		`&'		escape? subcomponent?
 *
 * Anyway, we use the same delimiter ordering as in HL7, just don't read
 * and write all of them. If a undefined delimiter is used, it's a problem
 * that we can't fix here anyway (except to complain).
 */
  
class Delimiters : public PGObject
{
 private:
  /*
   * The actual delimiters are to be set upon beginning of a message and
   * are valid until the message is read completely. Afterwards it should
   * be reloaded with the defaults. 
   */

  /*             Function               Default Level Position  */
  char _esc;  /* Escape character        ('\\')   -      3      */
  char _scm;  /* Sub-Component separator ('&')   -5      4      */
  char _cmp;  /* Component separator     ('^')   -4      1      */
  char _rep;  /* Repetition separator    ('~')   -3      2      */
  char _fld;  /* Field separator         ('|')   -2      5      */
  char _seg;  /* Segment separator       ('\r')  -1      -      */
  char __eos; /* = 0 end of string                0 */

 public:
  enum levels
    {
      invalid  = 1,
      toplevel = 0,
      msglevel = 0, /* messages are not ended by delimiters */
      seglevel = -1,
      fldlevel = -2,
      replevel = -3,
      cmplevel = -4,
      scmlevel = -5,
      lowlevel = -5,
      esclevel = -6,
      botlevel = -6,
    };

  typedef enum levels level_t;

  enum defaults
    {
      seg_def = 0x0D,
      fld_def = '|',
      cmp_def = '^',
      scm_def = '&',
      rep_def = '~',
      esc_def = 0134,
    };
  
  Delimiters();
  Delimiters(char fld, char rep, char cmp, char scm, char esc);

  void reset();
  void unset();
  bool ispresent() const;
  bool commit();
  
  /*     setseg(char d) is not allowed in HL7 */
  void setfld(char d);
  void setrep(char d);
  void setcmp(char d);
  void setscm(char d);
  void setesc(char d);

  char getseg() const;
  char getfld() const;
  char getrep() const;
  char getcmp() const;
  char getscm() const;
  char getesc() const;
  
  result input(istream&);
  void   output(ostream&) const;

  level_t levelof(char d) const;

/* getdel(...) -- calculate the delimiter characters for a level
 *
 * Unfortunately this function is way outdated. The level mechanism
 * is not as generally applicable as it was originally intended.
 *
 * ARGUMENT 2		RETURN VALUE			STRING
 * -------------------- ------------------------------- -----------
 * esclevel		all delimiters including ESC	"\&^~|<CR>"
 * botlevel(*)		 "      "         "       "	"\&^~|<CR>"
 * (not supplied)      	all delimiters except ESC	"&^~|<CR>"
 * lowlevel(*)		 "      "         "    "	"&^~|<CR>"
 * scmlevel		 "      "         "    "	"&^~|<CR>"
 * cmplevel		depending on stream level:  0	"^~|<CR>"
 *    " 		    "     "     "     "  : -1	"&^~|<CR>"
 * replevel		starting from REP		"~|<CR>"
 * fldlevel		starting from FLD		"|<CR>"
 * seglevel		starting from SEG		"<CR>"
 * msglevel(*)		empty string			""
 * toplevel(*)		empty string			""
 *
 * NOTE: (*) do not use this!
 *
 * This is certainly not very intelligent, and has to be cleaned up
 * sometimes! FIXME!
 */

  const char *getdel(level_t level, level_t offset) const;

  inline friend const char *getdel(const ios& io, level_t offset = lowlevel);
};

#ifndef OUTLINE
# include "Delimiters.icc"
#endif

#endif /* !PG_DELIMITERS_H_ */