moved ExtensionRegistry to extensions module

Author: manfred-kaiser

sifter/commands/require.py

@@ -5,8 +5,7 @@
 )
 
 from sifter.grammar.command import Command
-import sifter.grammar
-import sifter.handler
+from sifter.extensions import ExtensionRegistry
 from sifter.validators.stringlist import StringList
 from sifter.grammar.state import EvaluationState
 from sifter.grammar.actions import Actions
@@ -21,7 +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 sifter.handler.ExtensionRegistry.get('extension', ext_name):
+            if not ExtensionRegistry.get('extension', ext_name):
                 raise RuntimeError(
                     "Required extension '%s' not supported"
                     % ext_name

sifter/comparator.py

@@ -7,7 +7,7 @@
     Union
 )
 
-import sifter.handler
+from sifter.extensions import ExtensionRegistry
 
 if TYPE_CHECKING:
     from sifter.grammar.tag import Tag
@@ -31,7 +31,7 @@ def get_match_fn(
         match_type = 'IS'
 
     # TODO: support wildcard matching in comparator names (RFC 4790)
-    cmp_handler = sifter.handler.ExtensionRegistry.get('comparator', comparator)
+    cmp_handler = ExtensionRegistry.get('comparator', comparator)
     if not cmp_handler:
         raise RuntimeError("Comparator not supported: %s" % comparator)
 

sifter/extension.py

@@ -0,0 +1,56 @@
+from typing import (
+    TYPE_CHECKING,
+    Dict,
+    Text,
+    Optional,
+    Union,
+    Type
+)
+import pkg_resources
+
+if TYPE_CHECKING:
+    from sifter.grammar.rule import Rule
+    from sifter.grammar.comparator import Comparator
+
+
+class ExtensionRegistry():
+
+    _HANDLERS_MAP: Dict[Text, Dict[Text, Union[bool, Type['Comparator'], Type['Rule']]]] = {}
+    DEFAULT_EXTENSION = [
+        'regex',
+        'comparator-i;ascii-casemap',
+        'comparator-i;octet',
+        'fileinto',
+    ]
+
+    def __init__(self) -> None:
+        for extension_name in self.DEFAULT_EXTENSION:
+            self.register_extension(extension_name)
+
+        for entry_point in pkg_resources.iter_entry_points('sifter_extensions'):
+            self.register_handler(entry_point.load())
+
+    @classmethod
+    def register_extension(cls, extension_name):
+        cls.register('extension', extension_name, True)
+
+    @classmethod
+    def register_handler(cls, ext_cls):
+        cls.register(ext_cls.handler_type(), ext_cls.handler_id(), ext_cls)
+
+    @classmethod
+    def register(
+        cls,
+        handler_type: Optional[Text],
+        handler_id: Optional[Text],
+        value: Union[bool, Type['Comparator'], Type['Rule']]
+    ) -> None:
+        cls._HANDLERS_MAP.setdefault(handler_type, {})[handler_id] = value
+
+    @classmethod
+    def unregister(cls, handler_type: Text, handler_id: Text) -> Optional[Union[bool, Type['Comparator'], Type['Rule']]]:
+        return cls._HANDLERS_MAP.get(handler_type, {}).pop(handler_id, None)
+
+    @classmethod
+    def get(cls, handler_type: Text, handler_id: Text) -> Optional[Union[bool, Type['Comparator'], Type['Rule']]]:
+        return cls._HANDLERS_MAP.get(handler_type, {}).get(handler_id, None)

sifter/extensions/__init__.py

@@ -13,13 +13,11 @@
 
 import ply.yacc  # type: ignore
 
-import sifter.grammar
 from sifter.grammar.tag import Tag
 from sifter.grammar.command_list import CommandList
 from sifter.grammar.string import String
-import sifter.handler
 from sifter.grammar.lexer import SieveLexer
-from sifter.handler import ExtensionRegistry
+from sifter.extensions import ExtensionRegistry
 
 if TYPE_CHECKING:
     from py.yacc import LRParser, YaccProduction  # type: ignore
@@ -79,7 +77,7 @@ def p_command(self, p: 'YaccProduction') -> None:
         block = None
         if p[3] != ';':
             block = p[3]
-        handler = sifter.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 +134,7 @@ def p_test(self, p: 'YaccProduction') -> None:
         """test : IDENTIFIER arguments"""
         # print("TEST:", p[1], p[2])
         tests = p[2].get('tests')
-        handler = sifter.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/grammar/grammar.py

@@ -12,7 +12,6 @@
 from sifter.grammar.tag import Tag
 from sifter.grammar.validator import Validator
 import sifter.grammar
-import sifter.handler
 import sifter.utils
 
 if TYPE_CHECKING:

sifter/grammar/rule.py

@@ -12,8 +12,7 @@
 from sifter.grammar.rule import RuleSyntaxError
 from sifter.grammar import tag
 from sifter.validators.stringlist import StringList
-import sifter.handler
-import sifter.validators
+from sifter.extensions import ExtensionRegistry
 
 if TYPE_CHECKING:
     from sifter.grammar.tag import Tag as TagGrammar
@@ -98,7 +97,7 @@ def validate(
                         "'%s' comparator is unknown/unsupported"
                         % arg_list[starting_index + 1]
                     )
-                if not sifter.handler.ExtensionRegistry.get(
+                if not ExtensionRegistry.get(
                     'comparator',
                     val[0],
                 ):

sifter/handler.py

@@ -2,7 +2,7 @@
 
 import pytest
 
-import sifter.handler
+from sifter.extensions import ExtensionRegistry
 import sifter.comparator
 from sifter.grammar.comparator import Comparator
 
@@ -11,6 +11,6 @@ def test_mock_comparator() -> None:
     class MockComparator(Comparator):
         COMPARATOR_ID = 'i;vnd-mock'
 
-    sifter.handler.ExtensionRegistry.register_handler(MockComparator)
+    ExtensionRegistry.register_handler(MockComparator)
     with pytest.raises(RuntimeError):
         sifter.comparator.get_match_fn('i;vnd-mock', 'IS')

sifter/validators/tag.py

@@ -2,7 +2,7 @@
 
 import pytest
 
-from sifter.handler import ExtensionRegistry
+from sifter.extensions import ExtensionRegistry
 from sifter.grammar.state import EvaluationState