add base model classes to bart subclassed models (#9230)

* add base model classes to  bart subclassed models

* add doc

src/transformers/__init__.py

@@ -406,7 +406,11 @@ if is_torch_available():
         BertGenerationEncoder,
         load_tf_weights_in_bert_generation,
     )
-    from .models.blenderbot import BLENDERBOT_PRETRAINED_MODEL_ARCHIVE_LIST, BlenderbotForConditionalGeneration
+    from .models.blenderbot import (
+        BLENDERBOT_PRETRAINED_MODEL_ARCHIVE_LIST,
+        BlenderbotForConditionalGeneration,
+        BlenderbotModel,
+    )
     from .models.camembert import (
         CAMEMBERT_PRETRAINED_MODEL_ARCHIVE_LIST,
         CamembertForCausalLM,
@@ -522,7 +526,7 @@ if is_torch_available():
         LxmertXLayer,
     )
     from .models.marian import MarianMTModel
-    from .models.mbart import MBartForConditionalGeneration
+    from .models.mbart import MBartForConditionalGeneration, MBartModel
     from .models.mmbt import MMBTForClassification, MMBTModel, ModalEmbeddings
     from .models.mobilebert import (
         MOBILEBERT_PRETRAINED_MODEL_ARCHIVE_LIST,
@@ -559,7 +563,7 @@ if is_torch_available():
         OpenAIGPTPreTrainedModel,
         load_tf_weights_in_openai_gpt,
     )
-    from .models.pegasus import PegasusForConditionalGeneration
+    from .models.pegasus import PegasusForConditionalGeneration, PegasusModel
     from .models.prophetnet import (
         PROPHETNET_PRETRAINED_MODEL_ARCHIVE_LIST,
         ProphetNetDecoder,

src/transformers/models/auto/modeling_auto.py

@@ -50,7 +50,7 @@ from ..bert.modeling_bert import (
     BertModel,
 )
 from ..bert_generation.modeling_bert_generation import BertGenerationDecoder, BertGenerationEncoder
-from ..blenderbot.modeling_blenderbot import BlenderbotForConditionalGeneration
+from ..blenderbot.modeling_blenderbot import BlenderbotForConditionalGeneration, BlenderbotModel
 from ..camembert.modeling_camembert import (
     CamembertForCausalLM,
     CamembertForMaskedLM,
@@ -111,7 +111,7 @@ from ..longformer.modeling_longformer import (
 )
 from ..lxmert.modeling_lxmert import LxmertForPreTraining, LxmertForQuestionAnswering, LxmertModel
 from ..marian.modeling_marian import MarianMTModel
-from ..mbart.modeling_mbart import MBartForConditionalGeneration
+from ..mbart.modeling_mbart import MBartForConditionalGeneration, MBartModel
 from ..mobilebert.modeling_mobilebert import (
     MobileBertForMaskedLM,
     MobileBertForMultipleChoice,
@@ -132,7 +132,7 @@ from ..mpnet.modeling_mpnet import (
 )
 from ..mt5.modeling_mt5 import MT5ForConditionalGeneration, MT5Model
 from ..openai.modeling_openai import OpenAIGPTForSequenceClassification, OpenAIGPTLMHeadModel, OpenAIGPTModel
-from ..pegasus.modeling_pegasus import PegasusForConditionalGeneration
+from ..pegasus.modeling_pegasus import PegasusForConditionalGeneration, PegasusModel
 from ..prophetnet.modeling_prophetnet import ProphetNetForCausalLM, ProphetNetForConditionalGeneration, ProphetNetModel
 from ..rag.modeling_rag import (  # noqa: F401 - need to import all RagModels to be in globals() function
     RagModel,
@@ -255,6 +255,10 @@ MODEL_MAPPING = OrderedDict(
         (RetriBertConfig, RetriBertModel),
         (MT5Config, MT5Model),
         (T5Config, T5Model),
+        (PegasusConfig, PegasusModel),
+        (MarianConfig, MarianMTModel),
+        (MBartConfig, MBartModel),
+        (BlenderbotConfig, BlenderbotModel),
         (DistilBertConfig, DistilBertModel),
         (AlbertConfig, AlbertModel),
         (CamembertConfig, CamembertModel),

src/transformers/models/blenderbot/__init__.py

@@ -22,7 +22,11 @@ from .tokenization_blenderbot import BlenderbotSmallTokenizer, BlenderbotTokeniz
 
 
 if is_torch_available():
-    from .modeling_blenderbot import BLENDERBOT_PRETRAINED_MODEL_ARCHIVE_LIST, BlenderbotForConditionalGeneration
+    from .modeling_blenderbot import (
+        BLENDERBOT_PRETRAINED_MODEL_ARCHIVE_LIST,
+        BlenderbotForConditionalGeneration,
+        BlenderbotModel,
+    )
 
 if is_tf_available():
     from .modeling_tf_blenderbot import TFBlenderbotForConditionalGeneration

src/transformers/models/blenderbot/modeling_blenderbot.py

@@ -19,7 +19,7 @@
 import torch
 
 from ...file_utils import add_start_docstrings
-from ..bart.modeling_bart import BartForConditionalGeneration
+from ..bart.modeling_bart import BartForConditionalGeneration, BartModel
 from .configuration_blenderbot import BlenderbotConfig
 
 
@@ -39,7 +39,20 @@ BLENDERBOT_PRETRAINED_MODEL_ARCHIVE_LIST = ["facebook/blenderbot-3B", "facebook/
 
 
 @add_start_docstrings(
-    "The BART Model with a language modeling head. Can be used for summarization.", BLENDER_START_DOCSTRING
+    "The bare BlenderBot Model transformer outputting raw hidden-states without any specific head on top.",
+    BLENDER_START_DOCSTRING,
+)
+class BlenderbotModel(BartModel):
+    r"""
+    This class overrides :class:`~transformers.BartModel`. Please check the superclass for the appropriate
+    documentation alongside usage examples.
+    """
+
+    config_class = BlenderbotConfig
+
+
+@add_start_docstrings(
+    "The BlenderBot Model with a language modeling head. Can be used for summarization.", BLENDER_START_DOCSTRING
 )
 class BlenderbotForConditionalGeneration(BartForConditionalGeneration):
     """

src/transformers/models/mbart/__init__.py

@@ -27,7 +27,7 @@ if is_tokenizers_available():
     from .tokenization_mbart_fast import MBartTokenizerFast
 
 if is_torch_available():
-    from .modeling_mbart import MBartForConditionalGeneration
+    from .modeling_mbart import MBartForConditionalGeneration, MBartModel
 
 if is_tf_available():
     from .modeling_tf_mbart import TFMBartForConditionalGeneration

src/transformers/models/mbart/modeling_mbart.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ..bart.modeling_bart import BartForConditionalGeneration
+from ..bart.modeling_bart import BartForConditionalGeneration, BartModel
 from .configuration_mbart import MBartConfig
 
 
@@ -26,6 +26,23 @@ MBART_PRETRAINED_MODEL_ARCHIVE_LIST = [
 ]
 
 
+class MBartModel(BartModel):
+    r"""
+    This class overrides :class:`~transformers.BartModel`. Please check the superclass for the appropriate
+    documentation alongside usage examples.
+    """
+
+    config_class = MBartConfig
+    _keys_to_ignore_on_load_missing = [
+        "encoder.embed_positions.weight",
+        "decoder.embed_positions.weight",
+    ]
+    _keys_to_ignore_on_save = [
+        "encoder.embed_positions.weight",
+        "decoder.embed_positions.weight",
+    ]
+
+
 class MBartForConditionalGeneration(BartForConditionalGeneration):
     r"""
     This class overrides :class:`~transformers.BartForConditionalGeneration`. Please check the superclass for the

src/transformers/models/pegasus/__init__.py

@@ -27,7 +27,7 @@ if is_tokenizers_available():
     from .tokenization_pegasus_fast import PegasusTokenizerFast
 
 if is_torch_available():
-    from .modeling_pegasus import PegasusForConditionalGeneration
+    from .modeling_pegasus import PegasusForConditionalGeneration, PegasusModel
 
 if is_tf_available():
     from .modeling_tf_pegasus import TFPegasusForConditionalGeneration

src/transformers/models/pegasus/modeling_pegasus.py

@@ -16,10 +16,34 @@
 
 
 from ...file_utils import add_start_docstrings
-from ..bart.modeling_bart import BART_START_DOCSTRING, BartForConditionalGeneration
+from ..bart.modeling_bart import BART_START_DOCSTRING, BartForConditionalGeneration, BartModel
 from .configuration_pegasus import PegasusConfig
 
 
+@add_start_docstrings(
+    "The bare Pegasus Model transformer outputting raw hidden-states without any specific head on top.",
+    BART_START_DOCSTRING,
+)
+class PegasusModel(BartModel):
+    r"""
+    This class overrides :class:`~transformers.BartModel`. Please check the superclass for the appropriate
+    documentation alongside usage examples.
+    """
+
+    config_class = PegasusConfig
+    _keys_to_ignore_on_load_missing = [
+        r"final_logits_bias",
+        r"encoder\.version",
+        r"decoder\.version",
+        "encoder.embed_positions",
+        "decoder.embed_positions",
+    ]
+    _keys_to_ignore_on_save = [
+        "encoder.embed_positions.weight",
+        "decoder.embed_positions.weight",
+    ]
+
+
 @add_start_docstrings("The Pegasus Model for summarization ", BART_START_DOCSTRING)
 class PegasusForConditionalGeneration(BartForConditionalGeneration):
     r"""

src/transformers/utils/dummy_pt_objects.py

@@ -600,6 +600,15 @@ class BlenderbotForConditionalGeneration:
         requires_pytorch(self)
 
 
+class BlenderbotModel:
+    def __init__(self, *args, **kwargs):
+        requires_pytorch(self)
+
+    @classmethod
+    def from_pretrained(self, *args, **kwargs):
+        requires_pytorch(self)
+
+
 CAMEMBERT_PRETRAINED_MODEL_ARCHIVE_LIST = None
 
 
@@ -1297,6 +1306,15 @@ class MBartForConditionalGeneration:
         requires_pytorch(self)
 
 
+class MBartModel:
+    def __init__(self, *args, **kwargs):
+        requires_pytorch(self)
+
+    @classmethod
+    def from_pretrained(self, *args, **kwargs):
+        requires_pytorch(self)
+
+
 class MMBTForClassification:
     def __init__(self, *args, **kwargs):
         requires_pytorch(self)
@@ -1560,6 +1578,15 @@ class PegasusForConditionalGeneration:
         requires_pytorch(self)
 
 
+class PegasusModel:
+    def __init__(self, *args, **kwargs):
+        requires_pytorch(self)
+
+    @classmethod
+    def from_pretrained(self, *args, **kwargs):
+        requires_pytorch(self)
+
+
 PROPHETNET_PRETRAINED_MODEL_ARCHIVE_LIST = None