/*  $Id: if.c,v 1.6 2002/02/01 15:04:59 jan Exp $

    Part of XPCE --- The SWI-Prolog GUI toolkit

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi.psy.uva.nl/projects/xpce/
    Copyright (C): 1985-2002, University of Amsterdam

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <h/kernel.h>


static status
initialiseIf(If i, Code cond, Code if_true, Code if_false)
{ initialiseCode((Code) i);

  if ( isDefault(if_true) )  if_true  = NIL;
  if ( isDefault(if_false) ) if_false = NIL;

  assign(i, condition, cond);
  assign(i, then_branch, if_true);
  assign(i, else_branch, if_false);

  succeed;
}


static status
ExecuteIf(If i)
{ if ( executeCode(i->condition) )
  { if ( notNil(i->then_branch) )
      return executeCode(i->then_branch) ? SUCCEED : FAIL;
    succeed;
  } else
  { if ( notNil(i->else_branch) )
      return executeCode(i->else_branch) ? SUCCEED : FAIL;
    succeed;
  }
}


		 /*******************************
		 *	 CLASS DECLARATION	*
		 *******************************/

/* Type declarations */

static char *T_initialise[] =
        { "condition=code", "then=[code]*", "else=[code]*" };

/* Instance Variables */

static vardecl var_if[] =
{ IV(NAME_condition, "code", IV_BOTH,
     NAME_statement, "Condition to be tested"),
  IV(NAME_then, "code*", IV_BOTH,
     NAME_statement, "Executed if condition is true"),
  IV(NAME_else, "code*", IV_BOTH,
     NAME_statement, "Executed if condition is false")
};

/* Send Methods */

static senddecl send_if[] =
{ SM(NAME_Execute, 0, NULL, ExecuteIf,
     DEFAULT, "Test condition and branch"),
  SM(NAME_initialise, 3, T_initialise, initialiseIf,
     DEFAULT, "Create from condition, if- and else")
};

/* Get Methods */

#define get_if NULL
/*
static getdecl get_if[] =
{ 
};
*/

/* Resources */

#define rc_if NULL
/*
static classvardecl rc_if[] =
{ 
};
*/

/* Class Declaration */

static Name if_termnames[] = { NAME_condition, NAME_then, NAME_else };

ClassDecl(if_decls,
          var_if, send_if, get_if, rc_if,
          3, if_termnames,
          "$Rev$");

status
makeClassIf(Class class)
{ return declareClass(class, &if_decls);
}


