[enh] add surrogates

to lower fork maintenance, some objects in SearXNG can be replaced.
The configuration is done in settings.yml

searx/query.py

@@ -8,6 +8,7 @@ from searx.engines import categories, engines, engine_shortcuts
 from searx.external_bang import get_bang_definition_and_autocomplete
 from searx.search import EngineRef
 from searx.webutils import VALID_LANGUAGE_CODE
+from searx.surrogates import get_actual_object
 
 
 class QueryPartParser(ABC):
@@ -232,7 +233,7 @@ class BangParser(QueryPartParser):
                 self._add_autocomplete(first_char + engine_shortcut)
 
 
-class RawTextQuery:
+class DefaultRawTextQuery:
     """parse raw text query (the value from the html input)"""
 
     PARSER_CLASSES = [
@@ -328,3 +329,6 @@ class RawTextQuery:
                + f"autocomplete_list={self.autocomplete_list!r}\n  " \
                + f"query_parts={self.query_parts!r}\n  " \
                + f"user_query_parts={self.user_query_parts!r} >"
+
+
+RawTextQuery = get_actual_object('searx.query.RawTextQuery', DefaultRawTextQuery)

searx/search/__init__.py

@@ -19,6 +19,7 @@ from searx.network import initialize as initialize_network
 from searx.metrics import initialize as initialize_metrics, counter_inc, histogram_observe_time
 from searx.search.processors import PROCESSORS, initialize as initialize_processors
 from searx.search.checker import initialize as initialize_checker
+from searx.surrogates import get_actual_object
 
 
 logger = logger.getChild('search')
@@ -34,7 +35,7 @@ def initialize(settings_engines=None, enable_checker=False):
         initialize_checker()
 
 
-class Search:
+class BasicSearch:
     """Search information container"""
 
     __slots__ = "search_query", "result_container", "start_time", "actual_timeout"
@@ -171,7 +172,7 @@ class Search:
         return self.result_container
 
 
-class SearchWithPlugins(Search):
+class SearchWithPlugins(BasicSearch):
     """Inherit from the Search class, add calls to the plugins."""
 
     __slots__ = 'ordered_plugin_list', 'request'
@@ -201,3 +202,6 @@ class SearchWithPlugins(Search):
         self.result_container.close()
 
         return self.result_container
+
+
+Search = get_actual_object('searx.search.Search', SearchWithPlugins)

searx/settings.yml

@@ -29,6 +29,10 @@ search:
   formats:
     - html
 
+# surrogates:
+#   searx.search.Search: bidule.search.SearchWithPlugins
+#   searx.query.RawTextQuery: searx.query.DefaultRawTextQuery
+
 server:
   # If you change port, bind_address or base_url don't forget to rebuild
   # instance's enviroment (make buildenv)

searx/settings_defaults.py

@@ -135,6 +135,10 @@ SCHEMA = {
         'public_instances': SettingsValue(str, None),
         'wiki_url': SettingsValue(str, None),
     },
+    'surrogates': SettingsValue(dict, {
+        'searx.search.Search': 'searx.search.SearchWithPlugins',
+        'searx.query.RawTextQuery': 'searx.query.DefaultRawTextQuery',
+    }),
     'search': {
         'safe_search': SettingsValue((0,1,2), 0),
         'autocomplete': SettingsValue(str, ''),

searx/surrogates.py

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# lint: pylint
+"""
+Allow to replace some objects using settings.yml to lower fork maintenance.
+"""
+
+import sys
+from importlib import import_module
+from functools import wraps
+
+from searx import settings, logger
+
+logger = logger.getChild('surrogates')
+
+
+def _get_obj_by_name(name):
+    module_name, obj_name = name.rsplit('.', 1)
+    if module_name not in sys.modules:
+        module = import_module(module_name)
+    else:
+        module = sys.modules[module_name]
+    return getattr(module, obj_name, None)
+
+
+def get_actual_object(name, obj):
+    surrogate_name = settings['surrogates'].get(name)
+    actual_obj = _get_obj_by_name(surrogate_name) if surrogate_name else obj
+    logger.info('Replace "%s" with "%s"', name, surrogate_name)
+    if not callable(actual_obj):
+        raise ValueError(f"{surrogate_name} is not callable")
+
+    @wraps(obj)
+    def wrapped(*args, **kwargs):
+        return actual_obj(*args, **kwargs)
+    return wrapped

searx/webapp.py

@@ -109,7 +109,7 @@ from searx.flaskfix import patch_application
 from searx.autocomplete import search_autocomplete, backends as autocomplete_backends
 from searx.languages import language_codes as languages
 from searx.locales import LOCALE_NAMES, UI_LOCALE_CODES, RTL_LOCALES
-from searx.search import SearchWithPlugins, initialize as search_initialize
+from searx.search import Search, initialize as search_initialize
 from searx.network import stream as http_stream, set_context_network_name
 from searx.search.checker import get_result as checker_get_result
 
@@ -652,8 +652,7 @@ def search():
         search_query, raw_text_query, _, _ = get_search_query_from_webapp(
             request.preferences, request.form
         )
-        # search = Search(search_query) #  without plugins
-        search = SearchWithPlugins(search_query, request.user_plugins, request)  # pylint: disable=redefined-outer-name
+        search = Search(search_query, request.user_plugins, request)  # pylint: disable=redefined-outer-name
 
         result_container = search.search()