now wakes the peers resolves bug I mention in SWI-Prolog/roadmap#40 (…

…comment)

boot/attvar.pl

@@ -30,6 +30,7 @@
 
 :- module('$attvar',
 	  [ '$wakeup'/1,		% +Wakeup list
+            unify/4,
 	    freeze/2,			% +Var, :Goal
 	    frozen/2,			% @Var, -Goal
 	    call_residue_vars/2,        % :Goal, -Vars
@@ -80,6 +81,12 @@
         '$attvar_assign'(Var,Value),
         call(Next).
 
+unify(att(Module, _AttVal, Rest), Next, Var, Value):-
+        Module:verify_attributes(Var, Value, Goals),
+        unify(Rest, Next, Var, Value),
+        goals_with_module(Goals,Module).
+unify(_, Next,Var, Value):-
+        call(Next).
 
 goals_with_module([G|Gs], M):- !,
         M:call(G),
@@ -91,7 +98,7 @@
 system:compare_to_retcode(<,-1).
 system:compare_to_retcode(==,0).
 :- meta_predicate(system:wnmt(:)).
-system:wnmt(G):-setup_call_cleanup(metaterm_options(W,0),G,metaterm_options(0,W)).
+system:wnmt(G):-setup_call_cleanup(metaterm_options(W,0),(trace,G),metaterm_options(0,W)).
 system:'$meta'('==', Var, Value, 1):-!, wnmt(Var==Value). % this one ends up calling compare/3 
 system:'$meta'('=@=', Var, Value, 1):-!, wnmt(Var=@=Value).
 system:'$meta'(copy_term, Var, Value, 1):-!, wnmt(copy_term(Var,Value)).
@@ -108,7 +115,7 @@
 system:'$meta'('$undo_unify', _, Goal, 1):- '$schedule_wakeup'(Goal).
 '$undo_unify':verify_attributes(_,_,[]).
 undo(GoalIn):- 
-        metaterm_options(W,W), T is W \/ 8, % Flag to turn on trail scanning
+        metaterm_options(W,W), T is W \/ 0x0800, % Flag to turn on trail scanning
            ( T == W 
              -> GoalIn=Goal ;
                 Goal=(metaterm_options(_,W),GoalIn)),

src/ATOMS

@@ -1015,6 +1015,7 @@ F tty			1
 F type			1
 F type_error		2
 F undefinterc		4
+F unify			4
 F unify_determined	2
 F uninstantiation_error	1
 F var			1

src/pl-attvar.c

@@ -206,10 +206,10 @@ assignAttVar(Word av, Word value, int flags ARG_LD)
              
           Discussion:  https://github.com/SWI-Prolog/roadmap/issues/40#issuecomment-173002313
     
-         ?- when(=(X,Y),X==Y), Y=A, X=A.
+         ?- on_unify(X, X==Y), Y=A, X=A.
          Yes.
 
-         ?- when(=(X,Y),X\==Y), Y=A, X=A.
+         ?- on_unify(X, X\==Y), Y=A, X=A.
          No.
     
      */
@@ -228,19 +228,17 @@ assignAttVar(Word av, Word value, int flags ARG_LD)
 
   DEBUG(MSG_WAKEUPS, Sdprintf("assignAttVar(%s)\n", vName(av)));
 
-  if ( isAttVar(*value) )
-  { if ( value > av )
-    { if (!(flags & ATT_NO_SWAP ))
-      { Word tmp = av;
-        av = value;
-        value = tmp;
-      }
-    } else if ( av == value )
-      return;
-  }
+  bool other_attvar = isAttVar(*value);
 
+  if ( av == value ) return;
+
   if( !(flags & ATT_ASSIGNONLY) )
-  {   registerWakeup(FUNCTOR_wakeup4, av, valPAttVar(*av), value PASS_LD);
+  {
+      if( other_attvar && (MATTS_DEFAULT & MATTS_PEER_WAKEUP) )
+      {   DEBUG(MSG_WAKEUPS, Sdprintf("MATTS_PEER_WAKEUP(%s)\n", vName(value)));
+          registerWakeup(FUNCTOR_unify4, value, valPAttVar(*value), av PASS_LD);
+      }
+      registerWakeup(FUNCTOR_wakeup4, av, valPAttVar(*av), value PASS_LD);
   }
 
   if ( (flags&ATT_WAKEBINDS) )
@@ -270,10 +268,10 @@ assignAttVar(Word av, Word value, int flags ARG_LD)
   {  if( (flags & ATT_ASSIGNONLY) )
 	 { DEBUG(MSG_WAKEUPS, Sdprintf("Assigning attvar with a plain VAR ref\n"));
 	    *av = makeRef(value);			/* JW: Does this happen? */ 
-	  } else
+	 } else
      { DEBUG(MSG_WAKEUPS, Sdprintf("Putting ORIGINAL attvar into plain var\n"));
-	       Trail(value, makeRef(av));
-	  }
+	    Trail(value, makeRef(av));
+	 }
   } else
     *av = *value;
 

src/pl-incl.h

@@ -2017,17 +2017,17 @@ typedef struct
 		 *	      METATERMS           	*
 		 *******************************/
 
-#define MATTS_ENABLE_VMI  	0x0100 /* Hook WAM */
-#define MATTS_ENABLE_CPREDS	0x0200 /* Hook CPREDS (WAM can miss a few)*/
-#define MATTS_SKIP_HIDDEN   0x0400 /* dont factor $meta into attvar identity */
-#define MATTS_ENABLE_UNDO  	0x0800 /* check attvars for undo hooks (perfomance checking)*/
-#define MATTS_DO_UNIFY  	0x1000 /* debugging for a moment trying to guage if damaging do_unify() 
+#define MATTS_ENABLE_VMI  	0x0010 /* Hook WAM */
+#define MATTS_ENABLE_CPREDS	0x0020 /* Hook CPREDS (WAM can miss a few)*/
+#define MATTS_SKIP_HIDDEN   0x0040 /* dont factor $meta into attvar identity */
+#define MATTS_ENABLE_UNDO  	0x0080 /* check attvars for undo hooks (perfomance checking)*/
+#define MATTS_DO_UNIFY  	0x0100 /* debugging for a moment trying to guage if damaging do_unify() 
                                     Goal, really I would like to figure out the best way to allow unification to 
                                     a between an attvar and a variable.   Instead of merly placing the entire attvar self into the variable,
                                     I want the attvar's hook to copy some attributes onto the plain variable (turning it into an attvar)
-                                    as the result of unification.
-
+                                    as the result of unification.                                    
                                  */
+#define MATTS_PEER_WAKEUP  	0x0200 /* Wakeup peer attvars */
 #define MATTS_DISABLED   	0x8000 /* disable all options (allows the options to be saved) */
 #define MATTS_DEFAULT  	    MATTS_ENABLE_VMI|MATTS_ENABLE_CPREDS|MATTS_SKIP_HIDDEN|ATT_NO_SWAP