add verify_attributes driver code

src/prolog/machine/attributed_variables.rs

@@ -0,0 +1,24 @@
+pub static VERIFY_ATTRS: &str = "
+iterate([Var-Value|Bindings]) :-
+    '$get_attr_list'(Var, Ls),
+    call_verify_attributes(Ls, Var, Value),
+    iterate(Bindings),
+    '$restore_p_from_sfcp'.
+iterate([]).
+
+call_verify_attributes(Attrs, _, _) :-
+    var(Attrs), !.
+call_verify_attributes([Attr|Attrs], Var, Value) :-
+    '$module_of'(M, Attr), % write the owning module Attr to M.
+    catch(M:verify_attribute(Var, Value, Goals), error(existence_error(procedure, _), _), true),
+    call_verify_attribute_goals(Goals),
+    call_verify_attributes(Attrs, Var, Value).
+
+call_verify_attribute_goals(Goals) :-
+    var(Goals), throw(error(instantiation_error, call_verify_attribute_goals/1)).
+call_verify_attribute_goals([Goal|Goals]) :-
+    call(Goal),
+    call_verify_attribute_goals(Goals).
+call_verify_attribute_goals([]).
+";
+