make code work with Spatialite 4.3

Transfer is_address_point into SQLAlchemy function, so that
json.has_key() can use the older json_extract() function.
And work around broken Distance function.

nominatim/api/reverse.py

@@ -84,12 +84,6 @@ def _locate_interpolation(table: SaFromClause) -> SaLabel:
                    else_=0).label('position')
 
 
-def _is_address_point(table: SaFromClause) -> SaColumn:
-    return sa.and_(table.c.rank_address == 30,
-                   sa.or_(table.c.housenumber != None,
-                          sa.func.JsonHasKey(table.c.name, 'addr:housename')))
-
-
 def _get_closest(*rows: Optional[SaRow]) -> Optional[SaRow]:
     return min(rows, key=lambda row: 1000 if row is None else row.distance)
 
@@ -203,7 +197,7 @@ class ReverseGeocoder:
             max_rank = min(29, self.max_rank)
             restrict.append(lambda: no_index(t.c.rank_address).between(26, max_rank))
             if self.max_rank == 30:
-                restrict.append(lambda: _is_address_point(t))
+                restrict.append(lambda: sa.func.IsAddressPoint(t))
         if self.layer_enabled(DataLayer.POI) and self.max_rank == 30:
             restrict.append(lambda: sa.and_(no_index(t.c.rank_search) == 30,
                                             t.c.class_.not_in(('place', 'building')),
@@ -227,7 +221,7 @@ class ReverseGeocoder:
         sql: SaLambdaSelect = sa.lambda_stmt(lambda: _select_from_placex(t)
                 .where(t.c.geometry.ST_DWithin(WKT_PARAM, 0.001))
                 .where(t.c.parent_place_id == parent_place_id)
-                .where(_is_address_point(t))
+                .where(sa.func.IsAddressPoint(t))
                 .where(t.c.indexed_status == 0)
                 .where(t.c.linked_place_id == None)
                 .order_by('distance')

nominatim/db/sqlalchemy_functions.py

@@ -132,6 +132,36 @@ def select_index_placex_geometry_reverse_lookupplacenode(table: str) -> 'sa.Text
                    f" AND {table}.osm_type = 'N'")
 
 
+class IsAddressPoint(sa.sql.functions.GenericFunction[bool]):
+    type = sa.Boolean()
+    name = 'IsAddressPoint'
+    inherit_cache = True
+
+    def __init__(self, table: sa.Table) -> None:
+        super().__init__(table.c.rank_address, # type: ignore[no-untyped-call]
+                         table.c.housenumber, table.c.name)
+
+
+@compiles(IsAddressPoint) # type: ignore[no-untyped-call, misc]
+def default_is_address_point(element: SaColumn,
+                             compiler: 'sa.Compiled', **kw: Any) -> str:
+    rank, hnr, name = list(element.clauses)
+    return "(%s = 30 AND (%s IS NOT NULL OR %s ? 'addr:housename'))" % (
+                compiler.process(rank, **kw),
+                compiler.process(hnr, **kw),
+                compiler.process(name, **kw))
+
+
+@compiles(IsAddressPoint, 'sqlite') # type: ignore[no-untyped-call, misc]
+def sqlite_is_address_point(element: SaColumn,
+                            compiler: 'sa.Compiled', **kw: Any) -> str:
+    rank, hnr, name = list(element.clauses)
+    return "(%s = 30 AND coalesce(%s, json_extract(%s, '$.addr:housename')) IS NOT NULL)" % (
+                compiler.process(rank, **kw),
+                compiler.process(hnr, **kw),
+                compiler.process(name, **kw))
+
+
 class CrosscheckNames(sa.sql.functions.GenericFunction[bool]):
     """ Check if in the given list of names in parameters 1 any of the names
         from the JSON array in parameter 2 are contained.
@@ -175,22 +205,6 @@ def sqlite_json_array_each(element: SaColumn, compiler: 'sa.Compiled', **kw: Any
     return "json_each(%s)" % compiler.process(element.clauses, **kw)
 
 
-class JsonHasKey(sa.sql.functions.GenericFunction[bool]):
-    """ Return elements of a json array as a set.
-    """
-    type = sa.Boolean()
-    name = 'JsonHasKey'
-    inherit_cache = True
-
-
-@compiles(JsonHasKey) # type: ignore[no-untyped-call, misc]
-def compile_json_has_key(element: SaColumn,
-                         compiler: 'sa.Compiled', **kw: Any) -> str:
-    arg1, arg2 = list(element.clauses)
-    return "%s->%s is not null" % (compiler.process(arg1, **kw),
-                                   compiler.process(arg2, **kw))
-
-
 class Greatest(sa.sql.functions.GenericFunction[Any]):
     """ Function to compute maximum of all its input parameters.
     """

nominatim/db/sqlalchemy_types.py

@@ -38,7 +38,7 @@ def _default_distance_spheroid(element: SaColumn,
 @compiles(Geometry_DistanceSpheroid, 'sqlite') # type: ignore[no-untyped-call, misc]
 def _spatialite_distance_spheroid(element: SaColumn,
                                   compiler: 'sa.Compiled', **kw: Any) -> str:
-    return "Distance(%s, true)" % compiler.process(element.clauses, **kw)
+    return "COALESCE(Distance(%s, true), 0.0)" % compiler.process(element.clauses, **kw)
 
 
 class Geometry_IsLineLike(sa.sql.expression.FunctionElement[bool]):