
(********************************************************************)
(*                                                                  *)
(*  reference.s7i   Reference to object support library             *)
(*  Copyright (C) 1989 - 2012  Thomas Mertes                        *)
(*                                                                  *)
(*  This file is part of the Seed7 Runtime Library.                 *)
(*                                                                  *)
(*  The Seed7 Runtime 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.                                      *)
(*                                                                  *)
(*  The Seed7 Runtime 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 program; if not, write to the    *)
(*  Free Software Foundation, Inc., 51 Franklin Street,             *)
(*  Fifth Floor, Boston, MA  02110-1301, USA.                       *)
(*                                                                  *)
(********************************************************************)


(**
 *  The type ''reference'' describes a reference to any object.
 *)
const type: reference is subtype object;


IN_PARAM_IS_VALUE(reference);

const proc: (ref reference: dest) ::= (in reference: source)           is action "REF_CREATE";
const proc: destroy (ref reference: aValue)                            is action "GEN_DESTR";
const proc: (inout reference: dest) := (in reference: source)          is action "REF_CPY";
(* Deactivated since it allows 'reference' := anything which is aggainst type checking *)
(* const proc: (inout reference: dest) := (in object: source)          is action "REF_MKREF"; *)


(**
 *  Check if two references are equal.
 *  @return TRUE if both references are equal,
 *          FALSE otherwise.
 *)
const func boolean: (in reference: ref1) = (in reference: ref2)        is action "REF_EQ";


(**
 *  Check if two references are equal.
 *  @return FALSE if both references are equal,
 *          TRUE otherwise.
 *)
const func boolean: (in reference: ref1) <> (in reference: ref2)       is action "REF_NE";


(**
 *  Compare two references.
 *  @return -1, 0 or 1 if the first argument is considered to be
 *          respectively less than, equal to, or greater than the
 *          second.
 *)
const func integer: compare (in reference: ref1, in reference: ref2)   is action "REF_CMP";


(**
 *  Compute the hash value of a ''reference''.
 *  @return the hash value.
 *)
const func integer: hashCode (in reference: aReference)                is action "REF_HASHCODE";


(**
 *  Convert a ''reference'' to a [[string]].
 *  @return the [[string]] result of the conversion.
 *  @exception MEMORY_ERROR Not enough memory to represent the result.
 *)
const func string: str (ref reference: aReference)                     is action "REF_STR";


const func reference: _GENERATE_NIL                                    is action "REF_NIL";


(**
 *  Reference to no element.
 *)
const reference: NIL                                                   is _GENERATE_NIL;


const reference: (attr reference) . value                              is NIL;


(**
 *  Get the type of the referenced object.
 *  @return the type of the object referenced by ''aReference''.
 *)
const func type: getType (in reference: aReference)                    is action "REF_TYPE";


(**
 *  Set the type of the referenced object to ''aType''.
 *)
const proc: setType (in reference: aReference, in type: aType)         is action "REF_SETTYPE";


const func boolean: is_symb (in reference: aReference)                 is action "REF_ISSYMB";
const func f_param: symb (in reference: aReference)                    is action "REF_SYMB";
const func type: getValue (in reference: aReference, attr type)        is action "TYP_VALUE";
const func reference: getfunc (in expr param)                          is action "DCL_GETFUNC";
const func reference: getobj (in expr param)                           is action "DCL_GETOBJ";

const proc: TRACE_REF (in reference: aReference) is  action "REF_TRACE";

const func type: get_type (in reference: type_ref) is func
  result
    var type: aType is void;
  begin
    if type_ref <> NIL and getType(type_ref) = type then
      aType := getValue(type_ref, type);
    end if;
  end func;
