MarianMTModel.from_pretrained('Helsinki-NLP/opus-marian-en-de') (#3908)

Co-Authored-By: Stefan Schweter <stefan@schweter.it>

src/transformers/__init__.py

@@ -44,6 +44,7 @@ from .configuration_electra import ELECTRA_PRETRAINED_CONFIG_ARCHIVE_MAP, Electr
 from .configuration_encoder_decoder import EncoderDecoderConfig
 from .configuration_flaubert import FLAUBERT_PRETRAINED_CONFIG_ARCHIVE_MAP, FlaubertConfig
 from .configuration_gpt2 import GPT2_PRETRAINED_CONFIG_ARCHIVE_MAP, GPT2Config
+from .configuration_marian import MarianConfig
 from .configuration_mmbt import MMBTConfig
 from .configuration_openai import OPENAI_GPT_PRETRAINED_CONFIG_ARCHIVE_MAP, OpenAIGPTConfig
 from .configuration_roberta import ROBERTA_PRETRAINED_CONFIG_ARCHIVE_MAP, RobertaConfig
@@ -241,6 +242,8 @@ if is_torch_available():
         BartForConditionalGeneration,
         BART_PRETRAINED_MODEL_ARCHIVE_MAP,
     )
+    from .modeling_marian import MarianMTModel
+    from .tokenization_marian import MarianSentencePieceTokenizer
     from .modeling_roberta import (
         RobertaForMaskedLM,
         RobertaModel,

src/transformers/configuration_bart.py

@@ -65,6 +65,9 @@ class BartConfig(PretrainedConfig):
         normalize_before=False,
         add_final_layer_norm=False,
         scale_embedding=False,
+        normalize_embedding=True,
+        static_position_embeddings=False,
+        add_bias_logits=False,
         **common_kwargs
     ):
         r"""
@@ -73,6 +76,8 @@ class BartConfig(PretrainedConfig):
                 config = BartConfig.from_pretrained('bart-large')
                 model = BartModel(config)
         """
+        if "hidden_size" in common_kwargs:
+            raise ValueError("hidden size is called d_model")
         super().__init__(
             num_labels=num_labels,
             pad_token_id=pad_token_id,
@@ -94,12 +99,17 @@ class BartConfig(PretrainedConfig):
         self.max_position_embeddings = max_position_embeddings
         self.init_std = init_std  # Normal(0, this parameter)
         self.activation_function = activation_function
-        self.scale_embedding = scale_embedding  # scale factor will be sqrt(d_model) if True
 
-        # True for mbart, False otherwise
+        # Params introduced for Mbart
+        self.scale_embedding = scale_embedding  # scale factor will be sqrt(d_model) if True
+        self.normalize_embedding = normalize_embedding  # True for mbart, False otherwise
         self.normalize_before = normalize_before  # combo of fairseq's encoder_ and decoder_normalize_before
         self.add_final_layer_norm = add_final_layer_norm
 
+        # Params introduced for Marian
+        self.add_bias_logits = add_bias_logits
+        self.static_position_embeddings = static_position_embeddings
+
         # 3 Types of Dropout
         self.attention_dropout = attention_dropout
         self.activation_dropout = activation_dropout

src/transformers/configuration_marian.py

@@ -0,0 +1,26 @@
+# coding=utf-8
+# Copyright 2020 The OPUS-NMT Team, Marian team, and The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+""" Marian model configuration """
+
+from .configuration_bart import BartConfig
+
+
+PRETRAINED_CONFIG_ARCHIVE_MAP = {
+    "marian-en-de": "https://s3.amazonaws.com/models.huggingface.co/bert/Helsinki-NLP/opus-mt-en-de/config.json",
+}
+
+
+class MarianConfig(BartConfig):
+    pretrained_config_archive_map = PRETRAINED_CONFIG_ARCHIVE_MAP

src/transformers/convert_marian_to_pytorch.py

@@ -0,0 +1,397 @@
+import argparse
+import json
+import os
+import shutil
+import warnings
+from pathlib import Path
+from typing import Dict, List, Union
+from zipfile import ZipFile
+
+import numpy as np
+import torch
+from tqdm import tqdm
+
+from transformers import MarianConfig, MarianMTModel, MarianSentencePieceTokenizer
+
+
+def remove_prefix(text: str, prefix: str):
+    if text.startswith(prefix):
+        return text[len(prefix) :]
+    return text  # or whatever
+
+
+def convert_encoder_layer(opus_dict, layer_prefix: str, converter: dict):
+    sd = {}
+    for k in opus_dict:
+        if not k.startswith(layer_prefix):
+            continue
+        stripped = remove_prefix(k, layer_prefix)
+        v = opus_dict[k].T  # besides embeddings, everything must be transposed.
+        sd[converter[stripped]] = torch.tensor(v).squeeze()
+    return sd
+
+
+def load_layers_(layer_lst: torch.nn.ModuleList, opus_state: dict, converter, is_decoder=False):
+    for i, layer in enumerate(layer_lst):
+        layer_tag = f"decoder_l{i + 1}_" if is_decoder else f"encoder_l{i + 1}_"
+        sd = convert_encoder_layer(opus_state, layer_tag, converter)
+        layer.load_state_dict(sd, strict=True)
+
+
+def add_emb_entries(wemb, final_bias, n_special_tokens=1):
+    vsize, d_model = wemb.shape
+    embs_to_add = np.zeros((n_special_tokens, d_model))
+    new_embs = np.concatenate([wemb, embs_to_add])
+    bias_to_add = np.zeros((n_special_tokens, 1))
+    new_bias = np.concatenate((final_bias, bias_to_add), axis=1)
+    return new_embs, new_bias
+
+
+def _cast_yaml_str(v):
+    bool_dct = {"true": True, "false": False}
+    if not isinstance(v, str):
+        return v
+    elif v in bool_dct:
+        return bool_dct[v]
+    try:
+        return int(v)
+    except (TypeError, ValueError):
+        return v
+
+
+def cast_marian_config(raw_cfg: Dict[str, str]) -> Dict:
+    return {k: _cast_yaml_str(v) for k, v in raw_cfg.items()}
+
+
+CONFIG_KEY = "special:model.yml"
+
+
+def load_config_from_state_dict(opus_dict):
+    import yaml
+
+    cfg_str = "".join([chr(x) for x in opus_dict[CONFIG_KEY]])
+    yaml_cfg = yaml.load(cfg_str[:-1], Loader=yaml.BaseLoader)
+    return cast_marian_config(yaml_cfg)
+
+
+def find_model_file(dest_dir):  # this one better
+    model_files = list(Path(dest_dir).glob("*.npz"))
+    assert len(model_files) == 1, model_files
+    model_file = model_files[0]
+    return model_file
+
+
+def parse_readmes(repo_path):
+    results = {}
+    for p in Path(repo_path).ls():
+        n_dash = p.name.count("-")
+        if n_dash == 0:
+            continue
+        else:
+            lns = list(open(p / "README.md").readlines())
+            results[p.name] = _parse_readme(lns)
+    return results
+
+
+def download_all_sentencepiece_models(repo_path="Opus-MT-train/models"):
+    """Requires 300GB"""
+    save_dir = Path("marian_ckpt")
+    if not Path(repo_path).exists():
+        raise ValueError("You must run: git clone git@github.com:Helsinki-NLP/Opus-MT-train.git")
+    results: dict = parse_readmes(repo_path)
+    for k, v in tqdm(list(results.items())):
+        if os.path.exists(save_dir / k):
+            print(f"already have path {k}")
+            continue
+        if "SentencePiece" not in v["pre-processing"]:
+            continue
+        download_and_unzip(v["download"], save_dir / k)
+
+
+def _parse_readme(lns):
+    """Get link and metadata from opus model card equivalent."""
+    subres = {}
+    for ln in [x.strip() for x in lns]:
+        if not ln.startswith("*"):
+            continue
+        ln = ln[1:].strip()
+
+        for k in ["download", "dataset", "models", "model", "pre-processing"]:
+            if ln.startswith(k):
+                break
+        else:
+            continue
+        if k in ["dataset", "model", "pre-processing"]:
+            splat = ln.split(":")
+            _, v = splat
+            subres[k] = v
+        elif k == "download":
+            v = ln.split("(")[-1][:-1]
+            subres[k] = v
+    return subres
+
+
+def write_metadata(dest_dir: Path):
+    dname = dest_dir.name.split("-")
+    dct = dict(target_lang=dname[-1], source_lang="-".join(dname[:-1]))
+    save_json(dct, dest_dir / "tokenizer_config.json")
+
+
+def add_to_vocab_(vocab: Dict[str, int], special_tokens: List[str]):
+    start = max(vocab.values()) + 1
+    added = 0
+    for tok in special_tokens:
+        if tok in vocab:
+            continue
+        vocab[tok] = start + added
+        added += 1
+    return added
+
+
+def add_special_tokens_to_vocab(model_dir: Path) -> None:
+    vocab = load_yaml(model_dir / "opus.spm32k-spm32k.vocab.yml")
+    vocab = {k: int(v) for k, v in vocab.items()}
+    num_added = add_to_vocab_(vocab, ["<pad>"])
+    print(f"added {num_added} tokens to vocab")
+    save_json(vocab, model_dir / "vocab.json")
+    write_metadata(model_dir)
+
+
+def save_tokenizer(self, save_directory):
+    dest = Path(save_directory)
+    src_path = Path(self.init_kwargs["source_spm"])
+
+    for dest_name in {"source.spm", "target.spm", "tokenizer_config.json"}:
+        shutil.copyfile(src_path.parent / dest_name, dest / dest_name)
+    save_json(self.encoder, dest / "vocab.json")
+
+
+def check_equal(marian_cfg, k1, k2):
+    v1, v2 = marian_cfg[k1], marian_cfg[k2]
+    assert v1 == v2, f"hparams {k1},{k2} differ: {v1} != {v2}"
+
+
+def check_marian_cfg_assumptions(marian_cfg):
+    assumed_settings = {
+        "tied-embeddings-all": True,
+        "layer-normalization": False,
+        "right-left": False,
+        "transformer-ffn-depth": 2,
+        "transformer-aan-depth": 2,
+        "transformer-no-projection": False,
+        "transformer-postprocess-emb": "d",
+        "transformer-postprocess": "dan",  # Dropout, add, normalize
+        "transformer-preprocess": "",
+        "type": "transformer",
+        "ulr-dim-emb": 0,
+        "dec-cell-base-depth": 2,
+        "dec-cell-high-depth": 1,
+        "transformer-aan-nogate": False,
+    }
+    for k, v in assumed_settings.items():
+        actual = marian_cfg[k]
+        assert actual == v, f"Unexpected config value for {k} expected {v} got {actual}"
+    check_equal(marian_cfg, "transformer-ffn-activation", "transformer-aan-activation")
+    check_equal(marian_cfg, "transformer-ffn-depth", "transformer-aan-depth")
+    check_equal(marian_cfg, "transformer-dim-ffn", "transformer-dim-aan")
+
+
+BIAS_KEY = "decoder_ff_logit_out_b"
+BART_CONVERTER = {  # for each encoder and decoder layer
+    "self_Wq": "self_attn.q_proj.weight",
+    "self_Wk": "self_attn.k_proj.weight",
+    "self_Wv": "self_attn.v_proj.weight",
+    "self_Wo": "self_attn.out_proj.weight",
+    "self_bq": "self_attn.q_proj.bias",
+    "self_bk": "self_attn.k_proj.bias",
+    "self_bv": "self_attn.v_proj.bias",
+    "self_bo": "self_attn.out_proj.bias",
+    "self_Wo_ln_scale": "self_attn_layer_norm.weight",
+    "self_Wo_ln_bias": "self_attn_layer_norm.bias",
+    "ffn_W1": "fc1.weight",
+    "ffn_b1": "fc1.bias",
+    "ffn_W2": "fc2.weight",
+    "ffn_b2": "fc2.bias",
+    "ffn_ffn_ln_scale": "final_layer_norm.weight",
+    "ffn_ffn_ln_bias": "final_layer_norm.bias",
+    # Decoder Cross Attention
+    "context_Wk": "encoder_attn.k_proj.weight",
+    "context_Wo": "encoder_attn.out_proj.weight",
+    "context_Wq": "encoder_attn.q_proj.weight",
+    "context_Wv": "encoder_attn.v_proj.weight",
+    "context_bk": "encoder_attn.k_proj.bias",
+    "context_bo": "encoder_attn.out_proj.bias",
+    "context_bq": "encoder_attn.q_proj.bias",
+    "context_bv": "encoder_attn.v_proj.bias",
+    "context_Wo_ln_scale": "encoder_attn_layer_norm.weight",
+    "context_Wo_ln_bias": "encoder_attn_layer_norm.bias",
+}
+
+
+class OpusState:
+    def __init__(self, source_dir):
+        npz_path = find_model_file(source_dir)
+        self.state_dict = np.load(npz_path)
+        cfg = load_config_from_state_dict(self.state_dict)
+        assert cfg["dim-vocabs"][0] == cfg["dim-vocabs"][1]
+        assert "Wpos" not in self.state_dict
+        self.state_dict = dict(self.state_dict)
+        self.wemb, self.final_bias = add_emb_entries(self.state_dict["Wemb"], self.state_dict[BIAS_KEY], 1)
+        self.pad_token_id = self.wemb.shape[0] - 1
+        cfg["vocab_size"] = self.pad_token_id + 1
+        # self.state_dict['Wemb'].sha
+        self.state_keys = list(self.state_dict.keys())
+        if "Wtype" in self.state_dict:
+            raise ValueError("found Wtype key")
+        self._check_layer_entries()
+        self.source_dir = source_dir
+        self.cfg = cfg
+        hidden_size, intermediate_shape = self.state_dict["encoder_l1_ffn_W1"].shape
+        assert hidden_size == cfg["dim-emb"] == 512
+
+        # Process decoder.yml
+        decoder_yml = cast_marian_config(load_yaml(source_dir / "decoder.yml"))
+        # TODO: what are normalize and word-penalty?
+        check_marian_cfg_assumptions(cfg)
+        self.hf_config = MarianConfig(
+            vocab_size=cfg["vocab_size"],
+            decoder_layers=cfg["dec-depth"],
+            encoder_layers=cfg["enc-depth"],
+            decoder_attention_heads=cfg["transformer-heads"],
+            encoder_attention_heads=cfg["transformer-heads"],
+            decoder_ffn_dim=cfg["transformer-dim-ffn"],
+            encoder_ffn_dim=cfg["transformer-dim-ffn"],
+            d_model=cfg["dim-emb"],
+            activation_function=cfg["transformer-aan-activation"],
+            pad_token_id=self.pad_token_id,
+            eos_token_id=0,
+            bos_token_id=0,
+            max_position_embeddings=cfg["dim-emb"],
+            scale_embedding=True,
+            normalize_embedding="n" in cfg["transformer-preprocess"],
+            static_position_embeddings=not cfg["transformer-train-position-embeddings"],
+            dropout=0.1,  # see opus-mt-train repo/transformer-dropout param.
+            # default: add_final_layer_norm=False,
+            num_beams=decoder_yml["beam-size"],
+        )
+
+    def _check_layer_entries(self):
+        self.encoder_l1 = self.sub_keys("encoder_l1")
+        self.decoder_l1 = self.sub_keys("decoder_l1")
+        self.decoder_l2 = self.sub_keys("decoder_l2")
+        if len(self.encoder_l1) != 16:
+            warnings.warn(f"Expected 16 keys for each encoder layer, got {len(self.encoder_l1)}")
+        if len(self.decoder_l1) != 26:
+            warnings.warn(f"Expected 26 keys for each decoder layer, got {len(self.decoder_l1)}")
+        if len(self.decoder_l2) != 26:
+            warnings.warn(f"Expected 26 keys for each decoder layer, got {len(self.decoder_l1)}")
+
+    @property
+    def extra_keys(self):
+        extra = []
+        for k in self.state_keys:
+            if (
+                k.startswith("encoder_l")
+                or k.startswith("decoder_l")
+                or k in [CONFIG_KEY, "Wemb", "Wpos", "decoder_ff_logit_out_b"]
+            ):
+                continue
+            else:
+                extra.append(k)
+        return extra
+
+    def sub_keys(self, layer_prefix):
+        return [remove_prefix(k, layer_prefix) for k in self.state_dict if k.startswith(layer_prefix)]
+
+    def load_marian_model(self) -> MarianMTModel:
+        state_dict, cfg = self.state_dict, self.hf_config
+
+        assert cfg.static_position_embeddings
+        model = MarianMTModel(cfg)
+
+        assert "hidden_size" not in cfg.to_dict()
+        load_layers_(
+            model.model.encoder.layers, state_dict, BART_CONVERTER,
+        )
+        load_layers_(model.model.decoder.layers, state_dict, BART_CONVERTER, is_decoder=True)
+
+        # handle tensors not associated with layers
+        wemb_tensor = torch.nn.Parameter(torch.FloatTensor(self.wemb))
+        bias_tensor = torch.nn.Parameter(torch.FloatTensor(self.final_bias))
+        model.model.shared.weight = wemb_tensor
+        model.model.encoder.embed_tokens = model.model.decoder.embed_tokens = model.model.shared
+
+        model.final_logits_bias = bias_tensor
+
+        if "Wpos" in state_dict:
+            print("Unexpected: got Wpos")
+            wpos_tensor = torch.tensor(state_dict["Wpos"])
+            model.model.encoder.embed_positions.weight = wpos_tensor
+            model.model.decoder.embed_positions.weight = wpos_tensor
+
+        if cfg.normalize_embedding:
+            assert "encoder_emb_ln_scale_pre" in state_dict
+            raise NotImplementedError("Need to convert layernorm_embedding")
+
+        assert not self.extra_keys, f"Failed to convert {self.extra_keys}"
+        assert model.model.shared.padding_idx == self.pad_token_id
+        return model
+
+
+def download_and_unzip(url, dest_dir):
+    try:
+        import wget
+    except ImportError:
+        raise ImportError("you must pip install wget")
+
+    filename = wget.download(url)
+    unzip(filename, dest_dir)
+    os.remove(filename)
+
+
+def main(source_dir, dest_dir):
+    dest_dir = Path(dest_dir)
+    dest_dir.mkdir(exist_ok=True)
+
+    add_special_tokens_to_vocab(source_dir)
+    tokenizer = MarianSentencePieceTokenizer.from_pretrained(str(source_dir))
+    save_tokenizer(tokenizer, dest_dir)
+
+    opus_state = OpusState(source_dir)
+    assert opus_state.cfg["vocab_size"] == len(tokenizer.encoder)
+    # save_json(opus_state.cfg, dest_dir / "marian_original_config.json")
+    # ^^ Save human readable marian config for debugging
+
+    model = opus_state.load_marian_model()
+    model.save_pretrained(dest_dir)
+    model.from_pretrained(dest_dir)  # sanity check
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    # Required parameters
+    parser.add_argument("--src", type=str, help="path to marian model dir", default="en-de")
+    parser.add_argument("--dest", type=str, default=None, help="Path to the output PyTorch model.")
+    args = parser.parse_args()
+
+    source_dir = Path(args.src)
+    assert source_dir.exists()
+    dest_dir = f"converted-{source_dir.name}" if args.dest is None else args.dest
+    main(source_dir, dest_dir)
+
+
+def load_yaml(path):
+    import yaml
+
+    with open(path) as f:
+        return yaml.load(f, Loader=yaml.BaseLoader)
+
+
+def save_json(content: Union[Dict, List], path: str) -> None:
+    with open(path, "w") as f:
+        json.dump(content, f)
+
+
+def unzip(zip_path: str, dest_dir: str) -> None:
+    with ZipFile(zip_path, "r") as zipObj:
+        zipObj.extractall(dest_dir)

src/transformers/modeling_bart.py

@@ -18,6 +18,7 @@ import math
 import random
 from typing import Dict, List, Optional, Tuple
 
+import numpy as np
 import torch
 import torch.nn.functional as F
 from torch import Tensor, nn
@@ -125,7 +126,9 @@ class PretrainedBartModel(PreTrainedModel):
             module.weight.data.normal_(mean=0.0, std=std)
             if module.bias is not None:
                 module.bias.data.zero_()
-        if isinstance(module, nn.Embedding):
+        elif isinstance(module, SinusoidalPositionalEmbedding):
+            pass
+        elif isinstance(module, nn.Embedding):
             module.weight.data.normal_(mean=0.0, std=std)
             if module.padding_idx is not None:
                 module.weight.data[module.padding_idx].zero_()
@@ -250,10 +253,16 @@ class BartEncoder(nn.Module):
         self.max_source_positions = config.max_position_embeddings
 
         self.embed_tokens = embed_tokens
-
-        self.embed_positions = LearnedPositionalEmbedding(config.max_position_embeddings, embed_dim, self.padding_idx,)
+        if config.static_position_embeddings:
+            self.embed_positions = SinusoidalPositionalEmbedding(
+                config.max_position_embeddings, embed_dim, self.padding_idx
+            )
+        else:
+            self.embed_positions = LearnedPositionalEmbedding(
+                config.max_position_embeddings, embed_dim, self.padding_idx,
+            )
         self.layers = nn.ModuleList([EncoderLayer(config) for _ in range(config.encoder_layers)])
-        self.layernorm_embedding = LayerNorm(embed_dim)
+        self.layernorm_embedding = LayerNorm(embed_dim) if config.normalize_embedding else nn.Identity()
         # mbart has one extra layer_norm
         self.layer_norm = LayerNorm(config.d_model) if config.normalize_before else None
 
@@ -422,13 +431,18 @@ class BartDecoder(nn.Module):
         self.max_target_positions = config.max_position_embeddings
         self.embed_scale = math.sqrt(config.d_model) if config.scale_embedding else 1.0
         self.embed_tokens = embed_tokens
-        self.embed_positions = LearnedPositionalEmbedding(
-            config.max_position_embeddings, config.d_model, self.padding_idx,
-        )
+        if config.static_position_embeddings:
+            self.embed_positions = SinusoidalPositionalEmbedding(
+                config.max_position_embeddings, config.d_model, config.pad_token_id
+            )
+        else:
+            self.embed_positions = LearnedPositionalEmbedding(
+                config.max_position_embeddings, config.d_model, self.padding_idx,
+            )
         self.layers = nn.ModuleList(
             [DecoderLayer(config) for _ in range(config.decoder_layers)]
         )  # type: List[DecoderLayer]
-        self.layernorm_embedding = LayerNorm(config.d_model)
+        self.layernorm_embedding = LayerNorm(config.d_model) if config.normalize_embedding else nn.Identity()
         self.layer_norm = LayerNorm(config.d_model) if config.add_final_layer_norm else None
 
     def forward(
@@ -470,7 +484,7 @@ class BartDecoder(nn.Module):
         if use_cache:
             input_ids = input_ids[:, -1:]
             positions = positions[:, -1:]  # happens after we embed them
-            assert input_ids.ne(self.padding_idx).any()
+            # assert input_ids.ne(self.padding_idx).any()
 
         x = self.embed_tokens(input_ids) * self.embed_scale
         x += positions
@@ -859,6 +873,22 @@ class BartForConditionalGeneration(PretrainedBartModel):
         super().__init__(config)
         base_model = BartModel(config)
         self.model = base_model
+        self.register_buffer("final_logits_bias", torch.zeros((1, self.model.shared.num_embeddings)))
+
+    def resize_token_embeddings(self, new_num_tokens: int) -> nn.Embedding:
+        old_num_tokens = self.model.shared.num_embeddings
+        new_embeddings = super().resize_token_embeddings(new_num_tokens)
+        self.model.shared = new_embeddings
+        self._resize_final_logits_bias(new_num_tokens, old_num_tokens)
+        return new_embeddings
+
+    def _resize_final_logits_bias(self, new_num_tokens: int, old_num_tokens: int) -> None:
+        if new_num_tokens <= old_num_tokens:
+            new_bias = self.final_logits_bias[:, :new_num_tokens]
+        else:
+            extra_bias = torch.zeros((1, new_num_tokens - old_num_tokens))
+            new_bias = torch.cat([self.final_logits_bias, extra_bias], dim=1)
+        self.register_buffer("final_logits_bias", new_bias)
 
     @add_start_docstrings_to_callable(BART_INPUTS_DOCSTRING)
     def forward(
@@ -923,8 +953,8 @@ class BartForConditionalGeneration(PretrainedBartModel):
             decoder_cached_states=decoder_cached_states,
             use_cache=use_cache,
         )
-        lm_logits = F.linear(outputs[0], self.model.shared.weight)
-        outputs = (lm_logits,) + outputs[1:]  # Add hidden states and attention if they are here
+        lm_logits = F.linear(outputs[0], self.model.shared.weight, bias=self.final_logits_bias)
+        outputs = (lm_logits,) + outputs[1:]  # Add cache, hidden states and attention if they are here
         if lm_labels is not None:
             loss_fct = nn.CrossEntropyLoss()
             # TODO(SS): do we need to ignore pad tokens in lm_labels?
@@ -957,6 +987,18 @@ class BartForConditionalGeneration(PretrainedBartModel):
             self._force_token_ids_generation(scores, self.config.eos_token_id)
         return scores
 
+    def _force_token_ids_generation(self, scores, token_ids) -> None:
+        """force one of token_ids to be generated by setting prob of all other tokens to 0"""
+        if isinstance(token_ids, int):
+            token_ids = [token_ids]
+        all_but_token_ids_mask = torch.tensor(
+            [x for x in range(self.config.vocab_size) if x not in token_ids],
+            dtype=torch.long,
+            device=next(self.parameters()).device,
+        )
+        assert len(scores.shape) == 2, "scores should be of rank 2 with shape: [batch_size, vocab_size]"
+        scores[:, all_but_token_ids_mask] = -float("inf")
+
     @staticmethod
     def _reorder_cache(past, beam_idx):
         ((enc_out, enc_mask), decoder_cached_states) = past
@@ -1061,3 +1103,39 @@ class BartForSequenceClassification(PretrainedBartModel):
             outputs = (loss,) + outputs
 
         return outputs
+
+
+class SinusoidalPositionalEmbedding(nn.Embedding):
+    """This module produces sinusoidal positional embeddings of any length."""
+
+    def __init__(self, num_positions, embedding_dim, padding_idx=None):
+        super().__init__(num_positions, embedding_dim)
+        if embedding_dim % 2 != 0:
+            raise NotImplementedError(f"odd embedding_dim {embedding_dim} not supported")
+        self.weight = self._init_weight(self.weight)
+
+    @staticmethod
+    def _init_weight(out: nn.Parameter):
+        """Identical to the XLM create_sinusoidal_embeddings except features are not interleaved.
+            The cos features are in the 2nd half of the vector. [dim // 2:]
+        """
+        n_pos, dim = out.shape
+        position_enc = np.array(
+            [[pos / np.power(10000, 2 * (j // 2) / dim) for j in range(dim)] for pos in range(n_pos)]
+        )
+        out[:, 0 : dim // 2] = torch.FloatTensor(np.sin(position_enc[:, 0::2]))  # This line breaks for odd n_pos
+        out[:, dim // 2 :] = torch.FloatTensor(np.cos(position_enc[:, 1::2]))
+        out.detach_()
+        out.requires_grad = False
+        return out
+
+    @torch.no_grad()
+    def forward(self, input_ids, use_cache=False):
+        """Input is expected to be of size [bsz x seqlen]."""
+        bsz, seq_len = input_ids.shape[:2]
+        if use_cache:
+            positions = input_ids.data.new(1, 1).fill_(seq_len - 1)  # called before slicing
+        else:
+            # starts at 0, ends at 1-seq_len
+            positions = torch.arange(seq_len, dtype=torch.long, device=self.weight.device)
+        return super().forward(positions)

src/transformers/modeling_marian.py

@@ -0,0 +1,35 @@
+# coding=utf-8
+# Copyright 2020 Marian Team Authors and The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""PyTorch MarianMTModel model, ported from the Marian C++ repo."""
+
+
+from transformers.modeling_bart import BartForConditionalGeneration
+
+
+PRETRAINED_MODEL_ARCHIVE_MAP = {
+    "opus-mt-en-de": "https://s3.amazonaws.com/models.huggingface.co/bert/Helsinki-NLP/opus-mt-en-de/pytorch_model.bin",
+}
+
+
+class MarianMTModel(BartForConditionalGeneration):
+    """Pytorch version of marian-nmt's transformer.h (c++). Designed for the OPUS-NMT translation checkpoints.
+    Model API is identical to BartForConditionalGeneration"""
+
+    pretrained_model_archive_map = PRETRAINED_MODEL_ARCHIVE_MAP
+
+    def prepare_scores_for_generation(self, scores, cur_len, max_length):
+        if cur_len == max_length - 1 and self.config.eos_token_id is not None:
+            self._force_token_ids_generation(scores, self.config.eos_token_id)
+        return scores

src/transformers/modeling_utils.py

@@ -1530,18 +1530,6 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin):
 
         return decoded
 
-    # force one of token_ids to be generated by setting prob of all other tokens to 0.
-    def _force_token_ids_generation(self, scores, token_ids) -> None:
-        if isinstance(token_ids, int):
-            token_ids = [token_ids]
-        all_but_token_ids_mask = torch.tensor(
-            [x for x in range(self.config.vocab_size) if x not in token_ids],
-            dtype=torch.long,
-            device=next(self.parameters()).device,
-        )
-        assert len(scores.shape) == 2, "scores should be of rank 2 with shape: [batch_size, vocab_size]"
-        scores[:, all_but_token_ids_mask] = -float("inf")
-
     @staticmethod
     def _reorder_cache(past: Tuple, beam_idx: Tensor) -> Tuple[Tensor]:
         return tuple(layer_past.index_select(1, beam_idx) for layer_past in past)

src/transformers/tokenization_marian.py

@@ -0,0 +1,160 @@
+import json
+import warnings
+from typing import Dict, List, Optional, Union
+
+import sentencepiece
+
+from .file_utils import S3_BUCKET_PREFIX
+from .tokenization_utils import BatchEncoding, PreTrainedTokenizer
+
+
+vocab_files_names = {
+    "source_spm": "source.spm",
+    "target_spm": "target.spm",
+    "vocab": "vocab.json",
+    "tokenizer_config_file": "tokenizer_config.json",
+}
+MODEL_NAMES = ("opus-mt-en-de",)
+PRETRAINED_VOCAB_FILES_MAP = {
+    k: {m: f"{S3_BUCKET_PREFIX}/Helsinki-NLP/{m}/{fname}" for m in MODEL_NAMES}
+    for k, fname in vocab_files_names.items()
+}
+# Example URL https://s3.amazonaws.com/models.huggingface.co/bert/Helsinki-NLP/opus-mt-en-de/vocab.json
+
+
+class MarianSentencePieceTokenizer(PreTrainedTokenizer):
+    vocab_files_names = vocab_files_names
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = {m: 512 for m in MODEL_NAMES}
+    model_input_names = ["attention_mask"]  # actually attention_mask, decoder_attention_mask
+
+    def __init__(
+        self,
+        vocab=None,
+        source_spm=None,
+        target_spm=None,
+        source_lang=None,
+        target_lang=None,
+        unk_token="<unk>",
+        eos_token="</s>",
+        pad_token="<pad>",
+        max_len=512,
+    ):
+
+        super().__init__(
+            # bos_token=bos_token,
+            max_len=max_len,
+            eos_token=eos_token,
+            unk_token=unk_token,
+            pad_token=pad_token,
+        )
+        self.encoder = load_json(vocab)
+        assert self.pad_token in self.encoder
+        self.decoder = {v: k for k, v in self.encoder.items()}
+
+        self.source_lang = source_lang
+        self.target_lang = target_lang
+
+        # load SentencePiece model for pre-processing
+        self.paths = {}
+
+        self.spm_source = sentencepiece.SentencePieceProcessor()
+        self.spm_source.Load(source_spm)
+
+        self.spm_target = sentencepiece.SentencePieceProcessor()
+        self.spm_target.Load(target_spm)
+
+        # Note(SS): splitter would require lots of book-keeping.
+        # self.sentence_splitter = MosesSentenceSplitter(source_lang)
+        try:
+            from mosestokenizer import MosesPunctuationNormalizer
+
+            self.punc_normalizer = MosesPunctuationNormalizer(source_lang)
+        except ImportError:
+            warnings.warn("Recommended: pip install mosestokenizer")
+            self.punc_normalizer = lambda x: x
+
+    def _convert_token_to_id(self, token):
+        return self.encoder[token]
+
+    def _tokenize(self, text: str, src=True) -> List[str]:
+        spm = self.spm_source if src else self.spm_target
+        return spm.EncodeAsPieces(text)
+
+    def _convert_id_to_token(self, index: int) -> str:
+        """Converts an index (integer) in a token (str) using the encoder."""
+        return self.decoder.get(index, self.unk_token)
+
+    def convert_tokens_to_string(self, tokens: List[str]) -> str:
+        """Uses target language sentencepiece model"""
+        return self.spm_target.DecodePieces(tokens)
+
+    def _append_special_tokens_and_truncate(self, tokens: str, max_length: int,) -> List[int]:
+        ids: list = self.convert_tokens_to_ids(tokens)[:max_length]
+        return ids + [self.eos_token_id]
+
+    def build_inputs_with_special_tokens(self, token_ids_0, token_ids_1=None) -> List[int]:
+        """Build model inputs from a sequence by appending eos_token_id."""
+        if token_ids_1 is None:
+            return token_ids_0 + [self.eos_token_id]
+        # We don't expect to process pairs, but leave the pair logic for API consistency
+        return token_ids_0 + token_ids_1 + [self.eos_token_id]
+
+    def decode_batch(self, token_ids, **kwargs) -> List[str]:
+        return [self.decode(ids, **kwargs) for ids in token_ids]
+
+    def prepare_translation_batch(
+        self,
+        src_texts: List[str],
+        tgt_texts: Optional[List[str]] = None,
+        max_length: Optional[int] = None,
+        pad_to_max_length: bool = True,
+        return_tensors: str = "pt",
+    ) -> BatchEncoding:
+        """
+        Arguments:
+            src_texts: list of src language texts
+            src_lang: default en_XX (english)
+            tgt_texts: list of tgt language texts
+            tgt_lang: default ro_RO (romanian)
+            max_length: (None) defer to config (1024 for mbart-large-en-ro)
+            pad_to_max_length: (bool)
+
+        Returns:
+            BatchEncoding: with keys [input_ids, attention_mask, decoder_input_ids,  decoder_attention_mask]
+            all shaped bs, seq_len. (BatchEncoding is a dict of string -> tensor or lists)
+
+        Examples:
+            from transformers import MarianS
+        """
+        model_inputs: BatchEncoding = self.batch_encode_plus(
+            src_texts,
+            add_special_tokens=True,
+            return_tensors=return_tensors,
+            max_length=max_length,
+            pad_to_max_length=pad_to_max_length,
+            src=True,
+        )
+        if tgt_texts is None:
+            return model_inputs
+
+        decoder_inputs: BatchEncoding = self.batch_encode_plus(
+            tgt_texts,
+            add_special_tokens=True,
+            return_tensors=return_tensors,
+            max_length=max_length,
+            pad_to_max_length=pad_to_max_length,
+            src=False,
+        )
+        for k, v in decoder_inputs.items():
+            model_inputs[f"decoder_{k}"] = v
+        return model_inputs
+
+    @property
+    def vocab_size(self) -> int:
+        return len(self.encoder)
+
+
+def load_json(path: str) -> Union[Dict, List]:
+    with open(path, "r") as f:
+        return json.load(f)

src/transformers/tokenization_utils.py

@@ -31,7 +31,7 @@ from tokenizers import Encoding as EncodingFast
 from tokenizers.decoders import Decoder as DecoderFast
 from tokenizers.implementations import BaseTokenizer as BaseTokenizerFast
 
-from .file_utils import cached_path, hf_bucket_url, is_remote_url, is_tf_available, is_torch_available
+from .file_utils import cached_path, hf_bucket_url, is_remote_url, is_tf_available, is_torch_available, torch_required
 
 
 if is_tf_available():
@@ -458,6 +458,12 @@ class BatchEncoding(UserDict):
             char_index = batch_or_char_index
         return self._encodings[batch_index].char_to_word(char_index)
 
+    @torch_required
+    def to(self, device: str):
+        """Send all values to device by calling v.to(device)"""
+        self.data = {k: v.to(device) for k, v in self.data.items()}
+        return self
+
 
 class SpecialTokensMixin:
     """ SpecialTokensMixin is derived by ``PreTrainedTokenizer`` and ``PreTrainedTokenizerFast`` and