Give the json path the class its own type carries

docs/object-model.md

@@ -113,7 +113,7 @@ hierarchies — `Box` (`TBox`, `STBox`, `TPCBox`), `Collection`
 tstz/geo/… leaves) and `Value` — and `objectModel.algebra` records which
 companion a temporal family yields.
 
-`Value` holds the base values themselves: `Text`, `Jsonb`, `Geo` over
+`Value` holds the base values themselves: `Text`, `Jsonb`, `JsonPath`, `Geo` over
 `Geometry` and `Geography` (both a `GSERIALIZED`, parented exactly as
 `TGeo` parents `TGeometry` and `TGeography`), `Cbuffer`, `Npoint`,
 `Nsegment`, `Pose`, `PoseChain`, `Pcpoint`, `Pcpatch` and `Raquet`. A
@@ -123,8 +123,9 @@ a `uint64`, need no class and the ten by-reference base types do.
 `DriftGate::test_every_byreference_base_type_has_a_value_class` derives
 that set from the two predicates and fails until each has a class, so a
 base type MEOS adds reaches the model with no edit to the file.
-`Nsegment` and `Raquet` are the two MeosTypes no membership predicate
-admits; the model states them, and the same gate states that it does.
+`Nsegment`, `Raquet` and `JsonPath` are the MeosTypes no membership
+predicate admits; the model states them, and the same gate states that it
+does.
 
 `Box` is covered the same way, from the `type_bboxtype` column of
 `MEOS_RELTYPE_CATALOG`: it names the box each type stores, so its

meta/object-model.json

@@ -593,6 +593,16 @@
           "conditional": "JSON",
           "doc": "PostgreSQL jsonb, the base type of TJsonb and JsonbSet."
         },
+        "JsonPath": {
+          "kind": "leaf",
+          "parent": "Value",
+          "prefixes": [
+            "jsonpath"
+          ],
+          "temptype": "T_JSONPATH",
+          "conditional": "JSON",
+          "doc": "A path into a jsonb value. A MeosType no membership predicate admits, as Nsegment and Raquet are; the nine signatures naming it are what need it."
+        },
         "Geo": {
           "kind": "abstract",
           "parent": "Value",

tests/test_object_model.py

@@ -599,7 +599,8 @@ def test_every_byreference_base_type_has_a_value_class(self):
         self.assertEqual(needed - set(seen), set(),
                          "a base type MEOS passes by reference has no Value "
                          "class, so every method naming it stays untypable")
-        self.assertEqual(set(seen) - needed, {"T_NSEGMENT", "T_RAQUET"},
+        self.assertEqual(set(seen) - needed,
+                         {"T_NSEGMENT", "T_RAQUET", "T_JSONPATH"},
                          "the Value classes MEOS admits without making them "
                          "base types moved; each is a MeosType a signature "
                          "names, and this states which")