Use Top type to handle wildcards in queries.

Cf. #94, #95, #96.

tests/test_query.py

@@ -4,7 +4,7 @@
 from rdflib.term import BNode, Node, URIRef, Literal
 from rdflib.namespace import RDF
 
-from transformation_algebra.type import TypeOperator, Type, TypeAlias
+from transformation_algebra.type import TypeOperator, Type, TypeAlias, _
 from transformation_algebra.expr import Operator, Expr
 from transformation_algebra.lang import Language
 from transformation_algebra.graph import TransformationGraph, TA, TEST
@@ -292,6 +292,26 @@ def test_that_supertypes_are_captured(self):
         self.assertQuery(lang, graph, F(X), results={TEST.fx, TEST.fy})
         self.assertQuery(lang, graph, F(Y), results={TEST.fy})
 
+    def test_that_wildcards_are_captured(self):
+        # Test that using a wildcard in a query captures all types
+        X = TypeOperator()
+        Y = TypeOperator(supertype=X)
+        F = TypeOperator(params=2)
+        FFXYY, FYY = TypeAlias(F(F(X, Y), Y)), TypeAlias(F(Y, Y))
+        lang = Language(locals(), namespace=TEST, include_top=True)
+
+        graph = make_graph(lang, {
+            TEST.x: ~X,
+            TEST.y: ~Y,
+            TEST.ffx: ~F(F(X, Y), Y),
+            TEST.fy: ~F(Y, Y)
+        })
+
+        self.assertQuery(lang, graph, _, results={TEST.x, TEST.y, TEST.ffx,
+            TEST.fy})
+        self.assertQuery(lang, graph, F(_, _), results={TEST.ffx, TEST.fy})
+        self.assertQuery(lang, graph, F(F(_, _), _), results={TEST.ffx})
+
     def test_tree_unfold(self):
         # Test if the optional unfolding of trees happens.
         # We construct a workflow that shouldn't match with the DAG for our

transformation_algebra/graph.py

@@ -427,7 +427,8 @@ def parse_shortcuts(self, remove: bool = True) -> None:
         ns = self.language.namespace
         # TODO handle collections of types/operators
         for subj, obj in self[:ns.type:]:
-            type = self.language.parse_type(str(obj))
+            type = self.language.parse_type(str(obj)).concretize(
+                wildcard=Top)
             node = self.type_nodes[type]
             self.add((subj, TA.type, node))
 

transformation_algebra/lang.py

@@ -287,7 +287,7 @@ def backtrack():
                 else:
                     stack.append(None)
             elif token == "_":
-                stack.append(TypeVariable())
+                stack.append(TypeVariable(wildcard=True))
             elif token == "*":
                 t1 = stack.pop()
                 assert isinstance(t1, TypeInstance)