Add argument with extra info to callback

src/toplevel.pl

@@ -205,20 +205,20 @@ instruction_match(Term, VarList) :-
        submit_query_and_print_results(Term, VarList)
     ).
 
-%% run_query(+QueryChars, +Callback_1, +Options)
+%% run_query(+QueryChars, +Callback_2, +Options)
 %
-% Runs a query from a string of chars, calling `Callback_1` on each leaf answer.
+% Runs a query from a string of chars, calling `Callback_2` on each leaf answer.
 % See `run_query_goal/4` for details.
-run_query(QueryChars, Callback_1, Options) :-
+run_query(QueryChars, Callback_2, Options) :-
     read_term_from_chars(QueryChars, QueryGoal, [variable_names(VarNames)]),
-    run_query_goal(QueryGoal, VarNames, Callback_1, Options).
+    run_query_goal(QueryGoal, VarNames, Callback_2, Options).
 
-%% run_query_goal(+QueryGoal, +VarNames, +Callback_1, +Options)
+%% run_query_goal(+QueryGoal, +VarNames, +Callback_2, +Options)
 %
-% Run a query from a goal, calling `Callback_1 on each leaf answer.
+% Run a query from a goal, calling `Callback_2` on each leaf answer.
 % `VarNames` needs to have the same format as the one from the `variable_names(-VarNames)`
 % option in `read_term/3`. That is, a list of terms of the form `Name=Var`, where `Name`
-% is an atom and `Var` is a variable. The possible arguments to `Callback_1` are:
+% is an atom and `Var` is a variable. The possible first arguments to `Callback_2` are:
 %
 % - `final(false)`
 % - `final(exception(Exception))`, where `Exception` is the exception thrown
@@ -237,9 +237,11 @@ run_query(QueryChars, Callback_1, Options) :-
 % The variants with principal functor `final/1` mean that there will be no more leaf answers,
 % and the ones with `pending/1` mean that there will be more leaf answers.
 %
+% The second argument is a list with extra information that can be activated with options.
+%
 % `Option` is a list of options. There are none currently, but in the future support for
 % inference limits and timeouts may be implemented.
-run_query_goal(QueryGoal, VarNames, Callback_1, _) :-
+run_query_goal(QueryGoal, VarNames, Callback_2, _) :-
     % The b value in the WAM basically represents which choicepoint we are at.
     % By recording it before and after we can then compare the values to know
     % if we are still inside the query or not.
@@ -256,11 +258,11 @@ run_query_goal(QueryGoal, VarNames, Callback_1, _) :-
     ),
     (   Excepted == true ->
         !,
-        call(Callback_1, final(exception(Exception)))
+        call(Callback_2, final(exception(Exception)), [])
     ;   (   VarNames == [], ResGoals == [] ->
             (   Pending == true ->
-                call(Callback_1, pending(true))
-            ;   call(Callback_1, final(true))
+                call(Callback_2, pending(true), [])
+            ;   call(Callback_2, final(true), [])
             )
         ;   copy_term([Vars1, ResVars], [Vars1, ResVars], ResGoals),
             term_variables(ResGoals, ResGoalVars),
@@ -272,16 +274,16 @@ run_query_goal(QueryGoal, VarNames, Callback_1, _) :-
             term_variables(Vars3, Vars4), % deduplicate vars of Vars1 but preserve their order.
             charsio:extend_var_list(Vars4, VarNames, NewVarNames1, fabricated),
             (   Pending == true ->
-                call(Callback_1, pending(leaf_answer(Bindings, ResGoals, NewVarNames1)))
-            ;   call(Callback_1, final(leaf_answer(Bindings, ResGoals, NewVarNames1)))
+                call(Callback_2, pending(leaf_answer(Bindings, ResGoals, NewVarNames1)), [])
+            ;   call(Callback_2, final(leaf_answer(Bindings, ResGoals, NewVarNames1)), [])
             )
         )
     ).
-run_query_goal(_, _, Callback_1, _) :-
+run_query_goal(_, _, Callback_2, _) :-
     % If the whole query failed or we didn't cut in the previous definition of
     % run_query_goal/4 (which means  we are still in the query but it has failed)
     % then we get here so we have a (tail) false.
-    call(Callback_1, final(false)).
+    call(Callback_2, final(false), []).
 
 submit_query_and_print_results(QueryTerm, VarNames) :-
     bb_put('$answer_count', 0),
@@ -304,12 +306,12 @@ increment_answer_count :-
     Count is Count0 + 1,
     bb_put('$answer_count', Count).
 
-toplevel_query_callback(pending(LeafAnswer)) :-
+toplevel_query_callback(pending(LeafAnswer), _) :-
     handle_first_answer,
     increment_answer_count,
     write_leaf_answer(LeafAnswer, []),
     read_input(LeafAnswer).
-toplevel_query_callback(final(LeafAnswer)) :-
+toplevel_query_callback(final(LeafAnswer), _) :-
     (   exception(Exception) = LeafAnswer ->
         print_exception(Exception)
     ;   handle_first_answer,