add support for starlette framework

nominatim/server/starlette/server.py

@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Server implementation using the starlette webserver framework.
+"""
+from pathlib import Path
+
+from starlette.applications import Starlette
+from starlette.routing import Route
+from starlette.exceptions import HTTPException
+from starlette.responses import Response
+
+from nominatim.api import NominatimAPIAsync
+from nominatim.apicmd.status import StatusResult
+import nominatim.result_formatter.v1 as formatting
+
+CONTENT_TYPE = {
+  'text': 'text/plain; charset=utf-8',
+  'xml': 'text/xml; charset=utf-8'
+}
+
+FORMATTERS = {
+    StatusResult: formatting.create(StatusResult)
+}
+
+
+def parse_format(request, rtype, default):
+    fmt = request.query_params.get('format', default=default)
+    fmtter = FORMATTERS[rtype]
+
+    if not fmtter.supports_format(fmt):
+        raise HTTPException(400, detail="Parameter 'format' must be one of: " +
+                                        ', '.join(fmtter.list_formats()))
+
+    request.state.format = fmt
+    request.state.formatter = fmtter
+
+
+def format_response(request, result):
+    fmt = request.state.format
+    return Response(request.state.formatter.format(result, fmt),
+                    media_type=CONTENT_TYPE.get(fmt, 'application/json'))
+
+
+async def on_status(request):
+    parse_format(request, StatusResult, 'text')
+    result = await request.app.state.API.status()
+    return format_response(request, result)
+
+
+V1_ROUTES = [
+    Route('/status', endpoint=on_status)
+]
+
+def get_application(project_dir: Path) -> Starlette:
+    app = Starlette(debug=True, routes=V1_ROUTES)
+
+    app.state.API = NominatimAPIAsync(project_dir)
+
+    return app