added methods for gettting commands, tests, ... from extension registry

Author: manfred-kaiser

sifter/commands/require.py

@@ -20,7 +20,7 @@ class CommandRequire(Command):
     def evaluate(self, message: Message, state: EvaluationState) -> Optional[Actions]:
         ext_name_list = self.positional_args[0]
         for ext_name in ext_name_list:  # type: ignore
-            if not ExtensionRegistry.get('extension', ext_name):
+            if not ExtensionRegistry.has_extension(ext_name):
                 raise RuntimeError(
                     "Required extension '%s' not supported"
                     % ext_name

sifter/comparator.py

@@ -31,7 +31,7 @@ def get_match_fn(
         match_type = 'IS'
 
     # TODO: support wildcard matching in comparator names (RFC 4790)
-    cmp_handler = ExtensionRegistry.get('comparator', comparator)
+    cmp_handler = ExtensionRegistry.get_comparator(comparator)
     if not cmp_handler:
         raise RuntimeError("Comparator not supported: %s" % comparator)
 

sifter/extensions/__init__.py

@@ -9,9 +9,13 @@
 )
 import pkg_resources
 
+
+from sifter.grammar.comparator import Comparator
+from sifter.grammar.rule import Rule
+from sifter.grammar.command import Command
+from sifter.grammar.test import Test
 if TYPE_CHECKING:
-    from sifter.grammar.rule import Rule
-    from sifter.grammar.comparator import Comparator
+    from sifter.grammar.tag import Tag
 
 
 class ExtensionRegistry():
@@ -39,6 +43,33 @@ def register_extension(cls, extension_name: Text) -> None:
     def register_handler(cls, ext_cls: Union[Type['Comparator'], Type['Rule']]) -> None:
         cls.register(ext_cls.handler_type(), ext_cls.handler_id(), ext_cls)
 
+    @classmethod
+    def get_comparator(cls, comparator: Union[Text, 'Tag']) -> Type['Comparator']:
+        handler = cls.get('comparator', comparator)
+        if not isinstance(handler, type) or not issubclass(handler, Comparator):
+            raise ValueError('Wrong Comparator Type!')
+        return handler
+
+    @classmethod
+    def get_command(cls, commandname: Text) -> Type['Command']:
+        handler = cls.get('command', commandname)
+        if not isinstance(handler, type) or not issubclass(handler, Command):
+            raise ValueError('Wrong Command Type!')
+        return handler
+
+    @classmethod
+    def get_test(cls, testname: Text) -> Type['Test']:
+        handler = cls.get('test', testname)
+        if not isinstance(handler, type) or not issubclass(handler, Test):
+            raise ValueError('Wrong Test Type!')
+        return handler
+
+    @classmethod
+    def has_extension(cls, ext_name: Text) -> bool:
+        if cls.get('extension', ext_name):
+            return True
+        return False
+
     @classmethod
     def register(
         cls,

sifter/grammar/grammar.py

@@ -79,7 +79,7 @@ def p_command(self, p: 'YaccProduction') -> None:
         block = None
         if p[3] != ';':
             block = p[3]
-        handler = ExtensionRegistry.get('command', p[1])
+        handler = ExtensionRegistry.get_command(p[1])
         if handler is None:
             print("No handler registered for command '%s' on line %d" % (p[1], p.lineno(1)))
             raise SyntaxError
@@ -136,7 +136,7 @@ def p_test(self, p: 'YaccProduction') -> None:
         """test : IDENTIFIER arguments"""
         # print("TEST:", p[1], p[2])
         tests = p[2].get('tests')
-        handler = ExtensionRegistry.get('test', p[1])
+        handler = ExtensionRegistry.get_test(p[1])
         if handler is None:
             print("No handler registered for test '%s' on line %d" % (p[1], p.lineno(1)))
             raise SyntaxError

sifter/validators/tag.py

@@ -97,10 +97,7 @@ def validate(
                         "'%s' comparator is unknown/unsupported"
                         % arg_list[starting_index + 1]
                     )
-                if not ExtensionRegistry.get(
-                    'comparator',
-                    val[0],
-                ):
+                if not ExtensionRegistry.get_comparator(val[0]):
                     raise RuleSyntaxError(
                         "'%s' comparator is unknown/unsupported"
                         % val[0]