feat(async_dialect): add SQLiteDialect_libsql_async

- provides compatibility with create_async_engine and async_session

sqlalchemy_libsql/__init__.py

@@ -1,8 +1,13 @@
 from sqlalchemy.dialects import registry as _registry
 from sqlalchemy_libsql.libsql import SQLiteDialect_libsql
+from sqlalchemy_libsql.libsql_async import SQLiteDialect_libsql_async
 
 __version__ = "0.1.0-pre"
 
 _registry.register(
     "sqlite.libsql", "sqlalchemy_libsql", "SQLiteDialect_libsql"
 )
+
+_registry.register(
+    "sqlite.libsql_async", "sqlalchemy_libsql", "SQLiteDialect_libsql_async"
+)

sqlalchemy_libsql/libsql_async.py

@@ -0,0 +1,48 @@
+r"""
+.. dialect:: sqlite+libsql_async
+    :name: libsql_async
+    :dbapi: libsql_client.dbapi2
+    :connectstring: sqlite+libsql_async://your-db.your-server.com?authToken=JWT_HERE&secure=true
+    :url: https://github.com/libsql/libsql-client-py/
+
+    Note that this driver is based on the standard SQLAlchemy ``pysqlite``
+    dialect, the only change is how to connect, accepting remote URL in
+    addition to the file dialects
+
+    Disclaimer: While this dialect allows for async_engine compatibility with
+    libsql, the dbapi remains synchronous
+
+Driver
+------
+
+The ``libsql_client.dbapi2`` offers compatibility with standard library's
+``sqlite3.dbapi2``. For local files or ``:memory:``, the standard library
+connection is used. Whenever a host is provided, then the connection
+will use LibSQL network protocol via ``ws`` (WebSocket) or ``wss``
+(secure WebSocket), the decision depends on the presence of ``secure=true``
+query parameter.
+
+Connect Strings
+---------------
+
+In addition to `Pysqlite
+<https://docs.sqlalchemy.org/en/20/dialects/sqlite.html#connect-strings>`_,
+this driver accepts URL with user, password, hostname and port.
+
+These will use the LibSQL network protocol on top of WebSockets. The selection
+between ``ws://`` and ``wss://` (secure) is defined by the query/search
+parameter ``secure=true``. It defaults to  ``secure=false``.
+
+If the given URL provides a hostname, then it will default to ``uri=true``.
+
+"""  # noqa: E501
+
+from sqlalchemy_libsql.libsql import SQLiteDialect_libsql
+
+class SQLiteDialect_libsql_async(SQLiteDialect_libsql):
+    driver = "libsql"
+    # need to be set explicitly
+    supports_statement_cache = SQLiteDialect_libsql.supports_statement_cache
+    is_async = True
+
+dialect = SQLiteDialect_libsql_async