Refactor code and add German negation

negate/__init__.py

@@ -1,6 +1,5 @@
 from .negate import Negator
-from .tokens import Token
+from .utils.tokens import Token
 
 # Don't expose the following submodules.
 del globals()["negate"]
-del globals()["tokens"]

negate/base.py

@@ -0,0 +1,63 @@
+"""Base negator."""
+
+from abc import ABC, abstractmethod
+from typing import Any, Dict, List, Optional
+
+
+class BaseNegator(ABC):
+    """Base negator.
+
+    Specific negators for different languages must inherit from this class.
+    """
+
+    @abstractmethod
+    def __init__(
+        self,
+        use_transformers: Optional[bool] = None,
+        use_gpu: Optional[bool] = None,
+        fail_on_unsupported: Optional[bool] = None,
+        log_level: Optional[int] = None,
+        **kwargs,
+    ):
+        """Instanciate a :obj:`Negator`.
+
+        Args:
+            use_transformers (:obj:`Optional[bool]`, defaults to :obj:`False`):
+                Whether to use a Transformer model for POS tagging and
+                dependency parsing.
+            use_gpu (:obj:`Optional[bool]`, defaults to :obj:`False`):
+                Whether to use the GPU, if available. This parameter is ignored
+                when :param:`use_transformers` is set to :obj:`False`.
+            fail_on_unsupported (:obj:`Optional[bool]`, defaults to :obj:`False`):
+                Whether to fail upon non-supported sentences. If set to
+                :obj:`False`, a warning will be printed, and the sentence will
+                try to be negated in a best-effort fashion.
+            log_level (:obj:`Optional[int]`, defaults to ``logging.INFO``):
+                The level of the logger.
+
+        Raises:
+            :obj:`RuntimeError`: If the sentence is not supported and
+            :arg:`fail_on_unsupported` is set to :obj:`True`.
+        """
+        pass
+
+    @abstractmethod
+    def negate_sentence(
+        self,
+        sentence: str,
+        **kwargs: Dict[str, Any],
+    ) -> List[str]:
+        """Negate a sentence.
+
+        Affirmative sentences will be turned into negative ones and vice versa.
+
+        Args:
+            sentence (:obj:`str`):
+                The sentence to negate.
+            **kwargs (:obj:`Dict[str, Any]`):
+                Additional parameters to pass to the concrete language negator.
+
+        Returns:
+            :obj:`List[str]`: The negated sentence(s).
+        """
+        pass