codingutf8 2021 the facebook inc 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 orglicenseslicense2 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 blenderbotsmall model import copy import math from typing import list optional tuple union import torch import torch utils checkpoint from torch import nn from torch nn import crossentropyloss from activations import act2fn from modelingattnmaskutils import prepare4dattentionmask prepare4dcausalattentionmask from modelingoutputs import basemodeloutput basemodeloutputwithpastandcrossattentions causallmoutputwithcrossattentions seq2seqlmoutput seq2seqmodeloutput from modelingutils import pretrainedmodel from utils import addenddocstrings addstartdocstrings addstartdocstringstomodelforward logging replacereturndocstrings from configurationblenderbotsmall import blenderbotsmallconfig logger logging getloggername configfordoc blenderbotsmallconfig blenderbotsmallpretrainedmodelarchivelist facebookblenderbotsmall90m see all blenderbotsmall models at https huggingface comodels filterblenderbotsmall copied from transformers models bart modelingbart shifttokensright def shifttokensrightinputids torch tensor padtokenid int decoderstarttokenid int shiftedinputids inputids newzerosinputids shape shiftedinputids 1 inputids 1 clone shiftedinputids 0 decoderstarttokenid if padtokenid is none raise valueerrorself model config padtokenid has to be defined replace possible 100 values in labels by padtokenid shiftedinputids maskedfillshiftedinputids 100 padtokenid return shiftedinputids copied from transformers models blenderbot modelingblenderbot blenderbotlearnedpositionalembedding with blenderbotblenderbotsmall class blenderbotsmalllearnedpositionalembeddingnn embedding def initself numembeddings int embeddingdim int super initnumembeddings embeddingdim def forwardself inputidsshape torch size pastkeyvalueslength int 0 copied from transformers models bart modelingbart bartattention with bartblenderbotsmall multiheaded attention from attention is all you need paper def init self embeddim int numheads int dropout float 0 0 isdecoder bool false bias bool true iscausal bool false config optionalblenderbotsmallconfig none super init self embeddim embeddim self numheads numheads self dropout dropout self headdim embeddim numheads self config config if self headdim numheads self embeddim raise valueerror fembeddim must be divisible by numheads got embeddim self embeddim f and numheads numheads self scaling self headdim0 5 self isdecoder isdecoder self iscausal iscausal self kproj nn linearembeddim embeddim biasbias self vproj nn linearembeddim embeddim biasbias self qproj nn linearembeddim embeddim biasbias self outproj nn linearembeddim embeddim biasbias def shapeself tensor torch tensor seqlen int bsz int return tensor viewbsz seqlen self numheads self headdim transpose1 2 contiguous def forward self hiddenstates torch tensor keyvaluestates optionaltorch tensor none pastkeyvalue optionaltupletorch tensor none attentionmask optionaltorch tensor none layerheadmask optionaltorch tensor none outputattentions bool false tupletorch tensor optionaltorch tensor optionaltupletorch tensor if keyvaluestates are provided this layer is used as a crossattention layer for the decoder get query proj get key value proj pastkeyvalue0 shape2 keyvaluestates shape1 is checking that the sequencelength of the pastkeyvalue is the same as the provided keyvaluestates to support prefix tuning reuse k v crossattentions crossattentions reuse k v selfattention selfattention if crossattention save tupletorch tensor torch tensor of all cross attention keyvaluestates further calls to crossattention layer can then reuse all crossattention keyvaluestates first if case if unidirectional selfattention decoder save tupletorch tensor torch tensor of all previous decoder keyvaluestates further calls to unidirectional selfattention can concat previous decoder keyvaluestates to current projected keyvaluestates third elif case if encoder bidirectional selfattention pastkeyvalue is always none this operation is a bit awkward but it s required to make sure that attnweights keeps its gradient in order to do so attnweights have to be reshaped twice and have to be reused in the following use the embeddim from the config stored in the class rather than hiddenstate because attnoutput can be partitioned across gpus when using tensorparallelism copied from transformers models bart modelingbart bartencoderlayer with bartblenderbotsmall bartblenderbotsmall args hiddenstates torch floattensor input to the layer of shape batch seqlen embeddim attentionmask torch floattensor attention mask of size batch 1 tgtlen srclen where padding elements are indicated by very large negative values layerheadmask torch floattensor mask for attention heads in a given layer of size encoderattentionheads outputattentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail copied from transformers models bart modelingbart bartdecoderlayer with bartblenderbotsmall bartblenderbotsmall args hiddenstates torch floattensor input to the layer of shape batch seqlen embeddim attentionmask torch floattensor attention mask of size batch 1 tgtlen srclen where padding elements are indicated by very large negative values encoderhiddenstates torch floattensor cross attention input to the layer of shape batch seqlen embeddim encoderattentionmask torch floattensor encoder attention mask of size batch 1 tgtlen srclen where padding elements are indicated by very large negative values layerheadmask torch floattensor mask for attention heads in a given layer of size encoderattentionheads crossattnlayerheadmask torch floattensor mask for crossattention heads in a given layer of size decoderattentionheads pastkeyvalue tupletorch floattensor cached past key and value projection states outputattentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail self attention decoder unidirectional selfattention cached keyvalues tuple is at positions 1 2 add present selfattn cache to positions 1 2 of presentkeyvalue tuple crossattention block crossattn cached keyvalues tuple is at positions 3 4 of presentkeyvalue tuple add crossattn to positions 3 4 of presentkeyvalue tuple fully connected blenderbotsmallgenerationexample r conversation example python from transformers import autotokenizer blenderbotsmallforconditionalgeneration mname facebookblenderbotsmall90m model blenderbotsmallforconditionalgeneration frompretrainedmname tokenizer autotokenizer frompretrainedmname utterance my friends are cool but they eat too many carbs printhuman utterance human my friends are cool but they eat too many carbs inputs tokenizerutterance returntensorspt replyids model generateinputs printbot tokenizer batchdecodereplyids skipspecialtokenstrue0 bot what kind of carbs do they eat i don t know much about carbs reply i m not sure printhuman reply human i m not sure nextutterance my friends are cool but they eat too many carbs end startwhat kind of carbs do they eat i don t know much about carbsend start i m not sure inputs tokenizernextutterance returntensorspt nextreplyids model generateinputs printbot tokenizer batchdecodenextreplyids skipspecialtokenstrue0 bot they eat a lot of carbs carbs are high in fat protein and fats class blenderbotsmallencoderblenderbotsmallpretrainedmodel def initself config blenderbotsmallconfig embedtokens optionalnn embedding none super initconfig self dropout config dropout self layerdrop config encoderlayerdrop embeddim config dmodel self paddingidx config padtokenid self maxsourcepositions config maxpositionembeddings self embedscale math sqrtembeddim if config scaleembedding else 1 0 if embedtokens is not none self embedtokens embedtokens else self embedtokens nn embeddingconfig vocabsize embeddim self paddingidx self embedpositions blenderbotsmalllearnedpositionalembedding config maxpositionembeddings embeddim self layers nn modulelistblenderbotsmallencoderlayerconfig for in rangeconfig encoderlayers self layernormembedding nn layernormembeddim self gradientcheckpointing false initialize weights and apply final processing self postinit def forward self inputidsnone attentionmasknone headmasknone inputsembedsnone outputattentionsnone outputhiddenstatesnone returndictnone r args inputids torch longtensor of shape batchsize sequencelength indices of input sequence tokens in the vocabulary padding will be ignored by default should you provide it indices can be obtained using autotokenizer see pretrainedtokenizer encode and pretrainedtokenizer call for details what are input ids glossaryinputids attentionmask torch tensor of shape batchsize sequencelength optional mask to avoid performing attention on padding token indices mask values selected in 0 1 1 for tokens that are not masked 0 for tokens that are masked what are attention masks glossaryattentionmask headmask torch tensor of shape encoderlayers encoderattentionheads optional mask to nullify selected heads of the attention modules mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked inputsembeds torch floattensor of shape batchsize sequencelength hiddensize optional optionally instead of passing inputids you can choose to directly pass an embedded representation this is useful if you want more control over how to convert inputids indices into associated vectors than the model s internal embedding lookup matrix outputattentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail outputhiddenstates bool optional whether or not to return the hidden states of all layers see hiddenstates under returned tensors for more detail returndict bool optional whether or not to return a utils modeloutput instead of a plain tuple retrieve inputids and inputsembeds expand attentionmask bsz seqlen bsz 1 tgtseqlen srcseqlen check if headmask has a correct number of layers specified if desired add layerdrop see https arxiv orgabs1909 11556 for description transformer decoder consisting of config decoderlayers layers each layer is a blenderbotsmalldecoderlayer args config blenderbotsmallconfig embedtokens nn embedding output embedding initialize weights and apply final processing outputattentions outputattentions if outputattentions is not none else self config outputattentions outputhiddenstates outputhiddenstates if outputhiddenstates is not none else self config outputhiddenstates usecache usecache if usecache is not none else self config usecache returndict returndict if returndict is not none else self config usereturndict retrieve inputids and inputsembeds if inputids is not none and inputsembeds is not none raise valueerroryou cannot specify both decoderinputids and decoderinputsembeds at the same time elif inputids is not none inputshape inputids size inputids inputids view1 inputshape1 elif inputsembeds is not none inputshape inputsembeds size 1 else raise valueerroryou have to specify either decoderinputids or decoderinputsembeds pastkeyvalueslength pastkeyvalueslength pastkeyvalues00 shape2 if pastkeyvalues is not none else 0 if inputsembeds is none inputsembeds self embedtokensinputids self embedscale attentionmask prepare4dcausalattentionmask attentionmask inputshape inputsembeds pastkeyvalueslength expand encoder attention mask if encoderhiddenstates is not none and encoderattentionmask is not none bsz seqlen bsz 1 tgtseqlen srcseqlen encoderattentionmask prepare4dattentionmask encoderattentionmask inputsembeds dtype tgtleninputshape1 embed positions positions self embedpositionsinputshape pastkeyvalueslength blenderbotsmall applies layer norm on hiddenstates inputsembeds self layernormembeddinginputsembeds hiddenstates inputsembeds positions hiddenstates nn functional dropouthiddenstates pself dropout trainingself training if self gradientcheckpointing and self training if usecache logger warningonce usecachetrue is incompatible with gradient checkpointing setting usecachefalse usecache false decoder layers allhiddenstates if outputhiddenstates else none allselfattns if outputattentions else none allcrossattentions if outputattentions and encoderhiddenstates is not none else none nextdecodercache if usecache else none check if headmaskcrossattnheadmask has a correct number of layers specified if desired for attnmask maskname in zipheadmask crossattnheadmask headmask crossattnheadmask if attnmask is not none if attnmask size0 lenself layers raise valueerror fthe maskname should be specified for lenself layers layers but it is for f headmask size0 for idx decoderlayer in enumerateself layers add layerdrop see https arxiv orgabs1909 11556 for description if outputhiddenstates allhiddenstates hiddenstates if self training dropoutprobability torch rand if dropoutprobability self layerdrop continue pastkeyvalue pastkeyvaluesidx if pastkeyvalues is not none else none if self gradientcheckpointing and self training layeroutputs self gradientcheckpointingfunc decoderlayer call hiddenstates attentionmask encoderhiddenstates encoderattentionmask headmaskidx if headmask is not none else none crossattnheadmaskidx if crossattnheadmask is not none else none none outputattentions usecache else layeroutputs decoderlayer hiddenstates attentionmaskattentionmask encoderhiddenstatesencoderhiddenstates encoderattentionmaskencoderattentionmask layerheadmaskheadmaskidx if headmask is not none else none crossattnlayerheadmask crossattnheadmaskidx if crossattnheadmask is not none else none pastkeyvaluepastkeyvalue outputattentionsoutputattentions usecacheusecache hiddenstates layeroutputs0 if usecache nextdecodercache layeroutputs3 if outputattentions else 1 if outputattentions allselfattns layeroutputs1 if encoderhiddenstates is not none allcrossattentions layeroutputs2 add hidden states from the last decoder layer if outputhiddenstates allhiddenstates hiddenstates nextcache nextdecodercache if usecache else none if not returndict return tuple v for v in hiddenstates nextcache allhiddenstates allselfattns allcrossattentions if v is not none return basemodeloutputwithpastandcrossattentions lasthiddenstatehiddenstates pastkeyvaluesnextcache hiddenstatesallhiddenstates attentionsallselfattns crossattentionsallcrossattentions addstartdocstrings the bare blenderbotsmall model outputting raw hiddenstates without any specific head on top blenderbotsmallstartdocstring class blenderbotsmallmodelblenderbotsmallpretrainedmodel tiedweightskeys decoder embedtokens weight encoder embedtokens weight def initself config blenderbotsmallconfig super initconfig paddingidx vocabsize config padtokenid config vocabsize self shared nn embeddingvocabsize config dmodel paddingidx self encoder blenderbotsmallencoderconfig self shared self decoder blenderbotsmalldecoderconfig self shared initialize weights and apply final processing self postinit def getinputembeddingsself return self shared def setinputembeddingsself value self shared value self encoder embedtokens self shared self decoder embedtokens self shared def getencoderself return self encoder def getdecoderself return self decoder addstartdocstringstomodelforwardblenderbotsmallinputsdocstring replacereturndocstringsoutputtypeseq2seqmodeloutput configclassconfigfordoc def forward self inputids optionaltorch longtensor none attentionmask optionaltorch tensor none decoderinputids optionaltorch longtensor none decoderattentionmask optionaltorch longtensor none headmask optionaltorch tensor none decoderheadmask optionaltorch tensor none crossattnheadmask optionaltorch tensor none encoderoutputs optionaluniontuple basemodeloutput none pastkeyvalues optionallisttorch floattensor none inputsembeds optionaltorch tensor none decoderinputsembeds optionaltorch floattensor none usecache optionalbool none outputattentions optionalbool none outputhiddenstates optionalbool none returndict optionalbool none uniontupletorch floattensor seq2seqmodeloutput r returns example python from transformers import autotokenizer blenderbotsmallmodel model blenderbotsmallmodel frompretrainedfacebookblenderbotsmall90m tokenizer autotokenizer frompretrainedfacebookblenderbotsmall90m inputs tokenizerstudies have been shown that owning a dog is good for you returntensorspt decoderinputs tokenizerstudies show that returntensorspt batch size 1 outputs modelinputidsinputs inputids decoderinputidsdecoderinputs inputids lasthiddenstates outputs lasthiddenstate listlasthiddenstates shape 1 3 512 outputattentions outputattentions if outputattentions is not none else self config outputattentions outputhiddenstates outputhiddenstates if outputhiddenstates is not none else self config outputhiddenstates usecache usecache if usecache is not none else self config usecache returndict returndict if returndict is not none else self config usereturndict if encoderoutputs is none encoderoutputs self encoder inputidsinputids attentionmaskattentionmask headmaskheadmask inputsembedsinputsembeds outputattentionsoutputattentions outputhiddenstatesoutputhiddenstates returndictreturndict if the user passed a tuple for encoderoutputs we wrap it in a basemodeloutput when returndicttrue elif returndict and not isinstanceencoderoutputs basemodeloutput encoderoutputs basemodeloutput lasthiddenstateencoderoutputs0 hiddenstatesencoderoutputs1 if lenencoderoutputs 1 else none attentionsencoderoutputs2 if lenencoderoutputs 2 else none decoder outputs consists of decfeatures pastkeyvalue dechidden decattn decoderoutputs self decoder inputidsdecoderinputids attentionmaskdecoderattentionmask encoderhiddenstatesencoderoutputs0 encoderattentionmaskattentionmask headmaskdecoderheadmask crossattnheadmaskcrossattnheadmask pastkeyvaluespastkeyvalues inputsembedsdecoderinputsembeds usecacheusecache outputattentionsoutputattentions outputhiddenstatesoutputhiddenstates returndictreturndict if not returndict return decoderoutputs encoderoutputs return seq2seqmodeloutput lasthiddenstatedecoderoutputs lasthiddenstate pastkeyvaluesdecoderoutputs pastkeyvalues decoderhiddenstatesdecoderoutputs hiddenstates decoderattentionsdecoderoutputs attentions crossattentionsdecoderoutputs crossattentions encoderlasthiddenstateencoderoutputs lasthiddenstate encoderhiddenstatesencoderoutputs hiddenstates encoderattentionsencoderoutputs attentions addstartdocstrings the blenderbotsmall model with a language modeling head can be used for summarization blenderbotsmallstartdocstring class blenderbotsmallforconditionalgenerationblenderbotsmallpretrainedmodel basemodelprefix model keystoignoreonloadmissing finallogitsbias tiedweightskeys decoder embedtokens weight encoder embedtokens weight lmhead weight def initself config blenderbotsmallconfig super initconfig self model blenderbotsmallmodelconfig self registerbufferfinallogitsbias torch zeros1 self model shared numembeddings self lmhead nn linearconfig dmodel self model shared numembeddings biasfalse initialize weights and apply final processing self postinit def getencoderself return self model getencoder def getdecoderself return self model getdecoder def resizetokenembeddingsself newnumtokens int padtomultipleof optionalint none nn embedding newembeddings super resizetokenembeddingsnewnumtokens padtomultipleof self resizefinallogitsbiasnewembeddings weight shape0 return newembeddings def resizefinallogitsbiasself newnumtokens int none oldnumtokens self finallogitsbias shape1 if newnumtokens oldnumtokens newbias self finallogitsbias newnumtokens else extrabias torch zeros1 newnumtokens oldnumtokens deviceself finallogitsbias device newbias torch catself finallogitsbias extrabias dim1 self registerbufferfinallogitsbias newbias def getoutputembeddingsself return self lmhead def setoutputembeddingsself newembeddings self lmhead newembeddings addstartdocstringstomodelforwardblenderbotsmallinputsdocstring replacereturndocstringsoutputtypeseq2seqlmoutput configclassconfigfordoc addenddocstringsblenderbotsmallgenerationexample def forward self inputids optionaltorch longtensor none attentionmask optionaltorch tensor none decoderinputids optionaltorch longtensor none decoderattentionmask optionaltorch longtensor none headmask optionaltorch tensor none decoderheadmask optionaltorch tensor none crossattnheadmask optionaltorch tensor none encoderoutputs optionaluniontuple basemodeloutput none pastkeyvalues optionallisttorch floattensor none inputsembeds optionaltorch tensor none decoderinputsembeds optionaltorch floattensor none labels optionaltorch longtensor none usecache optionalbool none outputattentions optionalbool none outputhiddenstates optionalbool none returndict optionalbool none uniontupletorch floattensor seq2seqlmoutput r labels torch longtensor of shape batchsize sequencelength optional labels for computing the masked language modeling loss indices should either be in 0 config vocabsize or 100 see inputids docstring tokens with indices set to 100 are ignored masked the loss is only computed for the tokens with labels in 0 config vocabsize returns cut decoderinputids if past is used some generation methods already pass only the last input id default to old behavior keep only final id cached crossattention states don t have to be reordered they are always the same copied from transformers models bart modelingbart bartdecoderwrapper with bartblenderbotsmall this wrapper class is a helper class to correctly load pretrained checkpoints when the causal language model is used in combination with the encoderdecodermodel framework copied from transformers models bart modelingbart bartforcausallm with bartblenderbotsmall facebookbartbasefacebookblenderbotsmall90m initialize weights and apply final processing decoder outputs consists of decfeatures layerstate dechidden decattn if model is used as a decoder in encoderdecoder model the decoder attention mask is created on the fly some generation methods already pass only the last input id default to old behavior keep only final id first step decodercachedstates are empty coding utf 8 2021 the facebook inc 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 blenderbotsmall model see all blenderbotsmall models at https huggingface co models filter blenderbot_small copied from transformers models bart modeling_bart shift_tokens_right shift input ids one token to the right replace possible 100 values in labels by pad_token_id copied from transformers models blenderbot modeling_blenderbot blenderbotlearnedpositionalembedding with blenderbot blenderbotsmall this module learns positional embeddings up to a fixed maximum size input_ids_shape is expected to be bsz x seqlen copied from transformers models bart modeling_bart bartattention with bart blenderbotsmall multi headed attention from attention is all you need paper input shape batch x time x channel if key_value_states are provided this layer is used as a cross attention layer for the decoder get query proj get key value proj past_key_value 0 shape 2 key_value_states shape 1 is checking that the sequence_length of the past_key_value is the same as the provided key_value_states to support prefix tuning reuse k v cross_attentions cross_attentions reuse k v self_attention self_attention if cross_attention save tuple torch tensor torch tensor of all cross attention key value_states further calls to cross_attention layer can then reuse all cross attention key value_states first if case if uni directional self attention decoder save tuple torch tensor torch tensor of all previous decoder key value_states further calls to uni directional self attention can concat previous decoder key value_states to current projected key value_states third elif case if encoder bi directional self attention past_key_value is always none this operation is a bit awkward but it s required to make sure that attn_weights keeps its gradient in order to do so attn_weights have to be reshaped twice and have to be reused in the following use the embed_dim from the config stored in the class rather than hidden_state because attn_output can be partitioned across gpus when using tensor parallelism copied from transformers models bart modeling_bart bartencoderlayer with bart blenderbotsmall bart blenderbot_small args hidden_states torch floattensor input to the layer of shape batch seq_len embed_dim attention_mask torch floattensor attention mask of size batch 1 tgt_len src_len where padding elements are indicated by very large negative values layer_head_mask torch floattensor mask for attention heads in a given layer of size encoder_attention_heads output_attentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail copied from transformers models bart modeling_bart bartdecoderlayer with bart blenderbotsmall bart blenderbot_small args hidden_states torch floattensor input to the layer of shape batch seq_len embed_dim attention_mask torch floattensor attention mask of size batch 1 tgt_len src_len where padding elements are indicated by very large negative values encoder_hidden_states torch floattensor cross attention input to the layer of shape batch seq_len embed_dim encoder_attention_mask torch floattensor encoder attention mask of size batch 1 tgt_len src_len where padding elements are indicated by very large negative values layer_head_mask torch floattensor mask for attention heads in a given layer of size encoder_attention_heads cross_attn_layer_head_mask torch floattensor mask for cross attention heads in a given layer of size decoder_attention_heads past_key_value tuple torch floattensor cached past key and value projection states output_attentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail self attention decoder uni directional self attention cached key values tuple is at positions 1 2 add present self attn cache to positions 1 2 of present_key_value tuple cross attention block cross_attn cached key values tuple is at positions 3 4 of present_key_value tuple add cross attn to positions 3 4 of present_key_value tuple fully connected this model inherits from pretrainedmodel check the superclass documentation for the generic methods the library implements for all its model such as downloading or saving resizing the input embeddings pruning heads etc this model is also a pytorch torch nn module https pytorch org docs stable nn html torch nn module subclass use it as a regular pytorch module and refer to the pytorch documentation for all matter related to general usage and behavior parameters config blenderbotsmallconfig model configuration class with all the parameters of the model initializing with a config file does not load the weights associated with the model only the configuration check out the pretrainedmodel from_pretrained method to load the model weights conversation example python from transformers import autotokenizer blenderbotsmallforconditionalgeneration mname facebook blenderbot_small 90m model blenderbotsmallforconditionalgeneration from_pretrained mname tokenizer autotokenizer from_pretrained mname utterance my friends are cool but they eat too many carbs print human utterance human my friends are cool but they eat too many carbs inputs tokenizer utterance return_tensors pt reply_ids model generate inputs print bot tokenizer batch_decode reply_ids skip_special_tokens true 0 bot what kind of carbs do they eat i don t know much about carbs reply i m not sure print human reply human i m not sure next_utterance my friends are cool but they eat too many carbs __end__ __start__what kind of carbs do they eat i don t know much about carbs__end__ __start__ i m not sure inputs tokenizer next_utterance return_tensors pt next_reply_ids model generate inputs print bot tokenizer batch_decode next_reply_ids skip_special_tokens true 0 bot they eat a lot of carbs carbs are high in fat protein and fats args input_ids torch longtensor of shape batch_size sequence_length indices of input sequence tokens in the vocabulary padding will be ignored by default should you provide it indices can be obtained using autotokenizer see pretrainedtokenizer encode and pretrainedtokenizer __call__ for details what are input ids glossary input ids attention_mask torch tensor of shape batch_size sequence_length optional mask to avoid performing attention on padding token indices mask values selected in 0 1 1 for tokens that are not masked 0 for tokens that are masked what are attention masks glossary attention mask decoder_input_ids torch longtensor of shape batch_size target_sequence_length optional indices of decoder input sequence tokens in the vocabulary indices can be obtained using autotokenizer see pretrainedtokenizer encode and pretrainedtokenizer __call__ for details what are decoder input ids glossary decoder input ids blenderbotsmall uses the bos_token_id as the starting token for decoder_input_ids generation if past_key_values is used optionally only the last decoder_input_ids have to be input see past_key_values decoder_attention_mask torch longtensor of shape batch_size target_sequence_length optional default behavior generate a tensor that ignores pad tokens in decoder_input_ids causal mask will also be used by default head_mask torch tensor of shape encoder_layers encoder_attention_heads optional mask to nullify selected heads of the attention modules in the encoder mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked decoder_head_mask torch tensor of shape decoder_layers decoder_attention_heads optional mask to nullify selected heads of the attention modules in the decoder mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked cross_attn_head_mask torch tensor of shape decoder_layers decoder_attention_heads optional mask to nullify selected heads of the cross attention modules in the decoder mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked encoder_outputs tuple tuple torch floattensor optional tuple consists of last_hidden_state optional hidden_states optional attentions last_hidden_state of shape batch_size sequence_length hidden_size optional is a sequence of hidden states at the output of the last layer of the encoder used in the cross attention of the decoder past_key_values tuple tuple torch floattensor optional returned when use_cache true is passed or when config use_cache true tuple of tuple torch floattensor of length config n_layers with each tuple having 2 tensors of shape batch_size num_heads sequence_length embed_size_per_head and 2 additional tensors of shape batch_size num_heads encoder_sequence_length embed_size_per_head contains pre computed hidden states key and values in the self attention blocks and in the cross attention blocks that can be used see past_key_values input to speed up sequential decoding if past_key_values are used the user can optionally input only the last decoder_input_ids those that don t have their past key value states given to this model of shape batch_size 1 instead of all decoder_input_ids of shape batch_size sequence_length inputs_embeds torch floattensor of shape batch_size sequence_length hidden_size optional optionally instead of passing input_ids you can choose to directly pass an embedded representation this is useful if you want more control over how to convert input_ids indices into associated vectors than the model s internal embedding lookup matrix decoder_inputs_embeds torch floattensor of shape batch_size target_sequence_length hidden_size optional optionally instead of passing decoder_input_ids you can choose to directly pass an embedded representation if past_key_values is used optionally only the last decoder_inputs_embeds have to be input see past_key_values this is useful if you want more control over how to convert decoder_input_ids indices into associated vectors than the model s internal embedding lookup matrix if decoder_input_ids and decoder_inputs_embeds are both unset decoder_inputs_embeds takes the value of inputs_embeds use_cache bool optional if set to true past_key_values key value states are returned and can be used to speed up decoding see past_key_values output_attentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail output_hidden_states bool optional whether or not to return the hidden states of all layers see hidden_states under returned tensors for more detail return_dict bool optional whether or not to return a utils modeloutput instead of a plain tuple transformer encoder consisting of config encoder_layers self attention layers each layer is a blenderbotsmallencoderlayer args config blenderbotsmallconfig embed_tokens nn embedding output embedding initialize weights and apply final processing args input_ids torch longtensor of shape batch_size sequence_length indices of input sequence tokens in the vocabulary padding will be ignored by default should you provide it indices can be obtained using autotokenizer see pretrainedtokenizer encode and pretrainedtokenizer __call__ for details what are input ids glossary input ids attention_mask torch tensor of shape batch_size sequence_length optional mask to avoid performing attention on padding token indices mask values selected in 0 1 1 for tokens that are not masked 0 for tokens that are masked what are attention masks glossary attention mask head_mask torch tensor of shape encoder_layers encoder_attention_heads optional mask to nullify selected heads of the attention modules mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked inputs_embeds torch floattensor of shape batch_size sequence_length hidden_size optional optionally instead of passing input_ids you can choose to directly pass an embedded representation this is useful if you want more control over how to convert input_ids indices into associated vectors than the model s internal embedding lookup matrix output_attentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail output_hidden_states bool optional whether or not to return the hidden states of all layers see hidden_states under returned tensors for more detail return_dict bool optional whether or not to return a utils modeloutput instead of a plain tuple retrieve input_ids and inputs_embeds expand attention_mask bsz seq_len bsz 1 tgt_seq_len src_seq_len check if head_mask has a correct number of layers specified if desired add layerdrop see https arxiv org abs 1909 11556 for description skip the layer transformer decoder consisting of config decoder_layers layers each layer is a blenderbotsmalldecoderlayer args config blenderbotsmallconfig embed_tokens nn embedding output embedding initialize weights and apply final processing args input_ids torch longtensor of shape batch_size sequence_length indices of input sequence tokens in the vocabulary padding will be ignored by default should you provide it indices can be obtained using autotokenizer see pretrainedtokenizer encode and pretrainedtokenizer __call__ for details what are input ids glossary input ids attention_mask torch tensor of shape batch_size sequence_length optional mask to avoid performing attention on padding token indices mask values selected in 0 1 1 for tokens that are not masked 0 for tokens that are masked what are attention masks glossary attention mask encoder_hidden_states torch floattensor of shape batch_size encoder_sequence_length hidden_size optional sequence of hidden states at the output of the last layer of the encoder used in the cross attention of the decoder encoder_attention_mask torch longtensor of shape batch_size encoder_sequence_length optional mask to avoid performing cross attention on padding tokens indices of encoder input_ids mask values selected in 0 1 1 for tokens that are not masked 0 for tokens that are masked what are attention masks glossary attention mask head_mask torch tensor of shape decoder_layers decoder_attention_heads optional mask to nullify selected heads of the attention modules mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked cross_attn_head_mask torch tensor of shape decoder_layers decoder_attention_heads optional mask to nullify selected heads of the cross attention modules in the decoder to avoid performing cross attention on hidden heads mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked past_key_values tuple tuple torch floattensor optional returned when use_cache true is passed or when config use_cache true tuple of tuple torch floattensor of length config n_layers with each tuple having 2 tensors of shape batch_size num_heads sequence_length embed_size_per_head and 2 additional tensors of shape batch_size num_heads encoder_sequence_length embed_size_per_head contains pre computed hidden states key and values in the self attention blocks and in the cross attention blocks that can be used see past_key_values input to speed up sequential decoding if past_key_values are used the user can optionally input only the last decoder_input_ids those that don t have their past key value states given to this model of shape batch_size 1 instead of all decoder_input_ids of shape batch_size sequence_length inputs_embeds torch floattensor of shape batch_size sequence_length hidden_size optional optionally instead of passing input_ids you can choose to directly pass an embedded representation this is useful if you want more control over how to convert input_ids indices into associated vectors than the model s internal embedding lookup matrix output_attentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail output_hidden_states bool optional whether or not to return the hidden states of all layers see hidden_states under returned tensors for more detail return_dict bool optional whether or not to return a utils modeloutput instead of a plain tuple retrieve input_ids and inputs_embeds past_key_values_length expand encoder attention mask bsz seq_len bsz 1 tgt_seq_len src_seq_len embed positions blenderbotsmall applies layer norm on hidden_states decoder layers check if head_mask cross_attn_head_mask has a correct number of layers specified if desired add layerdrop see https arxiv org abs 1909 11556 for description add hidden states from the last decoder layer initialize weights and apply final processing returns example python from transformers import autotokenizer blenderbotsmallmodel model blenderbotsmallmodel from_pretrained facebook blenderbot_small 90m tokenizer autotokenizer from_pretrained facebook blenderbot_small 90m inputs tokenizer studies have been shown that owning a dog is good for you return_tensors pt decoder_inputs tokenizer studies show that return_tensors pt batch size 1 outputs model input_ids inputs input_ids decoder_input_ids decoder_inputs input_ids last_hidden_states outputs last_hidden_state list last_hidden_states shape 1 3 512 if the user passed a tuple for encoder_outputs we wrap it in a basemodeloutput when return_dict true decoder outputs consists of dec_features past_key_value dec_hidden dec_attn initialize weights and apply final processing labels torch longtensor of shape batch_size sequence_length optional labels for computing the masked language modeling loss indices should either be in 0 config vocab_size or 100 see input_ids docstring tokens with indices set to 100 are ignored masked the loss is only computed for the tokens with labels in 0 config vocab_size returns cut decoder_input_ids if past is used some generation methods already pass only the last input id default to old behavior keep only final id encoder_outputs is defined input_ids not needed change this to avoid caching presumably for debugging cached cross_attention states don t have to be reordered they are always the same copied from transformers models bart modeling_bart bartdecoderwrapper with bart blenderbotsmall this wrapper class is a helper class to correctly load pretrained checkpoints when the causal language model is used in combination with the encoderdecodermodel framework copied from transformers models bart modeling_bart bartforcausallm with bart blenderbotsmall facebook bart base facebook blenderbot_small 90m initialize weights and apply final processing args input_ids torch longtensor of shape batch_size sequence_length indices of input sequence tokens in the vocabulary padding will be ignored by default should you provide it indices can be obtained using autotokenizer see pretrainedtokenizer encode and pretrainedtokenizer __call__ for details what are input ids glossary input ids attention_mask torch tensor of shape batch_size sequence_length optional mask to avoid performing attention on padding token indices mask values selected in 0 1 1 for tokens that are not masked 0 for tokens that are masked what are attention masks glossary attention mask encoder_hidden_states torch floattensor of shape batch_size sequence_length hidden_size optional sequence of hidden states at the output of the last layer of the encoder used in the cross attention if the model is configured as a decoder encoder_attention_mask torch floattensor of shape batch_size sequence_length optional mask to avoid performing attention on the padding token indices of the encoder input this mask is used in the cross attention if the model is configured as a decoder mask values selected in 0 1 head_mask torch tensor of shape decoder_layers decoder_attention_heads optional mask to nullify selected heads of the attention modules mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked cross_attn_head_mask torch tensor of shape decoder_layers decoder_attention_heads optional mask to nullify selected heads of the cross attention modules mask values selected in 0 1 1 indicates the head is not masked 0 indicates the head is masked past_key_values tuple tuple torch floattensor optional returned when use_cache true is passed or when config use_cache true tuple of tuple torch floattensor of length config n_layers with each tuple having 2 tensors of shape batch_size num_heads sequence_length embed_size_per_head and 2 additional tensors of shape batch_size num_heads encoder_sequence_length embed_size_per_head the two additional tensors are only required when the model is used as a decoder in a sequence to sequence model contains pre computed hidden states key and values in the self attention blocks and in the cross attention blocks that can be used see past_key_values input to speed up sequential decoding if past_key_values are used the user can optionally input only the last decoder_input_ids those that don t have their past key value states given to this model of shape batch_size 1 instead of all decoder_input_ids of shape batch_size sequence_length labels torch longtensor of shape batch_size sequence_length optional labels for computing the masked language modeling loss indices should either be in 0 config vocab_size or 100 see input_ids docstring tokens with indices set to 100 are ignored masked the loss is only computed for the tokens with labels in 0 config vocab_size use_cache bool optional if set to true past_key_values key value states are returned and can be used to speed up decoding see past_key_values 1 for tokens that are not masked 0 for tokens that are masked output_attentions bool optional whether or not to return the attentions tensors of all attention layers see attentions under returned tensors for more detail output_hidden_states bool optional whether or not to return the hidden states of all layers see hidden_states under returned tensors for more detail return_dict bool optional whether or not to return a utils modeloutput instead of a plain tuple returns example python from transformers import autotokenizer blenderbotsmallforcausallm tokenizer autotokenizer from_pretrained facebook blenderbot_small 90m model blenderbotsmallforcausallm from_pretrained facebook blenderbot_small 90m add_cross_attention false assert model config is_decoder f model __class__ has to be configured as a decoder inputs tokenizer hello my dog is cute return_tensors pt outputs model inputs logits outputs logits expected_shape 1 inputs input_ids shape 1 model config vocab_size list logits shape expected_shape true decoder outputs consists of dec_features layer_state dec_hidden dec_attn if model is used as a decoder in encoder decoder model the decoder attention mask is created on the fly some generation methods already pass only the last input id default to old behavior keep only final id first step decoder_cached_states are empty encoder_outputs is defined input_ids not needed
import copy
import math
from typing import List, Optional, Tuple, Union

import torch
import torch.utils.checkpoint
from torch import nn
from torch.nn import CrossEntropyLoss

from ...activations import ACT2FN
from ...modeling_attn_mask_utils import _prepare_4d_attention_mask, _prepare_4d_causal_attention_mask
from ...modeling_outputs import (
    BaseModelOutput,
    BaseModelOutputWithPastAndCrossAttentions,
    CausalLMOutputWithCrossAttentions,
    Seq2SeqLMOutput,
    Seq2SeqModelOutput,
)
from ...modeling_utils import PreTrainedModel
from ...utils import (
    add_end_docstrings,
    add_start_docstrings,
    add_start_docstrings_to_model_forward,
    logging,
    replace_return_docstrings,
)
from .configuration_blenderbot_small import BlenderbotSmallConfig


logger = logging.get_logger(__name__)

_CONFIG_FOR_DOC = "BlenderbotSmallConfig"


BLENDERBOT_SMALL_PRETRAINED_MODEL_ARCHIVE_LIST = [
    "facebook/blenderbot_small-90M",
    
]



def shift_tokens_right(input_ids: torch.Tensor, pad_token_id: int, decoder_start_token_id: int):
    
    shifted_input_ids = input_ids.new_zeros(input_ids.shape)
    shifted_input_ids[:, 1:] = input_ids[:, :-1].clone()
    shifted_input_ids[:, 0] = decoder_start_token_id

    if pad_token_id is None:
        raise ValueError("self.model.config.pad_token_id has to be defined.")
    
    shifted_input_ids.masked_fill_(shifted_input_ids == -100, pad_token_id)

    return shifted_input_ids



class BlenderbotSmallLearnedPositionalEmbedding(nn.Embedding):
    

    def __init__(self, num_embeddings: int, embedding_dim: int):
        super().__init__(num_embeddings, embedding_dim)

    def forward(self, input_ids_shape: torch.Size, past_key_values_length: int = 0):
        
        bsz, seq_len = input_ids_shape[:2]
        positions = torch.arange(
            past_key_values_length, past_key_values_length + seq_len, dtype=torch.long, device=self.weight.device
        )
        return super().forward(positions)



class BlenderbotSmallAttention(nn.Module):
    

    def __init__(
        self,
        embed_dim: int,
        num_heads: int,
        dropout: float = 0.0,
        is_decoder: bool = False,
        bias: bool = True,
        is_causal: bool = False,
        config: Optional[BlenderbotSmallConfig] = None,
    ):
        super().__init__()
        self.embed_dim = embed_dim
        self.num_heads = num_heads
        self.dropout = dropout
        self.head_dim = embed_dim // num_heads
        self.config = config

        if (self.head_dim * num_heads) != self.embed_dim:
            raise ValueError(
                f"embed_dim must be divisible by num_heads (got `embed_dim`: {self.embed_dim}"
                f" and `num_heads`: {num_heads})."
            )
        self.scaling = self.head_dim**-0.5
        self.is_decoder = is_decoder
        self.is_causal = is_causal

        self.k_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
        self.v_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
        self.q_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
        self.out_proj = nn.Linear(embed_dim, embed_dim, bias=bias)

    def _shape(self, tensor: torch.Tensor, seq_len: int, bsz: int):
        return tensor.view(bsz, seq_len, self.num_heads, self.head_dim).transpose(1, 2).contiguous()

    def forward(
        self,
        hidden_states: torch.Tensor,
        key_value_states: Optional[torch.Tensor] = None,
        past_key_value: Optional[Tuple[torch.Tensor]] = None,
        attention_mask: Optional[torch.Tensor] = None,
        layer_head_mask: Optional[torch.Tensor] = None,
        output_attentions: bool = False,
    ) -> Tuple[torch.Tensor, Optional[torch.Tensor], Optional[Tuple[torch.Tensor]]]:
        

        
        
        is_cross_attention = key_value_states is not None

        bsz, tgt_len, _ = hidden_states.size()

        
        query_states = self.q_proj(hidden_states) * self.scaling
        
        
        
        
        if (
            is_cross_attention
            and past_key_value is not None
            and past_key_value[0].shape[2] == key_value_states.shape[1]
        ):
            
            key_states = past_key_value[0]
            value_states = past_key_value[1]
        elif is_cross_attention:
            
            key_states = self._shape(self.k_proj(key_value_states), -1, bsz)
            value_states = self._shape(self.v_proj(key_value_states), -1, bsz)
        elif past_key_value is not None:
            
            key_states = self._shape(self.k_proj(hidden_states), -1, bsz)
            value_states = self._shape(self.v_proj(hidden_states), -1, bsz)
            key_states = torch.cat([past_key_value[0], key_states], dim=2)
            value_states = torch.cat([past_key_value[1], value_states], dim=2)
        else:
            
            key_states = self._shape(self.k_proj(hidden_states), -1, bsz)
            value_states = self._shape(self.v_proj(hidden_states), -1, bsz)

        if self.is_decoder:
            
            
            
            
            
            
            
            past_key_value = (key_states, value_states)

        proj_shape = (bsz * self.num_heads, -1, self.head_dim)
        query_states = self._shape(query_states, tgt_len, bsz).view(*proj_shape)
        key_states = key_states.reshape(*proj_shape)
        value_states = value_states.reshape(*proj_shape)

        src_len = key_states.size(1)
        attn_weights = torch.bmm(query_states, key_states.transpose(1, 2))

        if attn_weights.size() != (bsz * self.num_heads, tgt_len, src_len):
            raise ValueError(
                f"Attention weights should be of size {(bsz * self.num_heads, tgt_len, src_len)}, but is"
                f" {attn_weights.size()}"
            )

        if attention_mask is not None:
            if attention_mask.size() != (bsz, 1, tgt_len, src_len):
                raise ValueError(
                    f"Attention mask should be of size {(bsz, 1, tgt_len, src_len)}, but is {attention_mask.size()}"
                )
            attn_weights = attn_weights.view(bsz, self.num_heads, tgt_len, src_len) + attention_mask
            attn_weights = attn_weights.view(bsz * self.num_heads, tgt_len, src_len)

        attn_weights = nn.functional.softmax(attn_weights, dim=-1)

        if layer_head_mask is not None:
            if layer_head_mask.size() != (self.num_heads,):
                raise ValueError(
                    f"Head mask for a single layer should be of size {(self.num_heads,)}, but is"
                    f" {layer_head_mask.size()}"
                )
            attn_weights = layer_head_mask.view(1, -1, 1, 1) * attn_weights.view(bsz, self.num_heads, tgt_len, src_len)
            attn_weights = attn_weights.view(bsz * self.num_heads, tgt_len, src_len)

        if output_attentions:
            
            
            
            
            attn_weights_reshaped = attn_weights.view(bsz, self.num_heads, tgt_len, src_len)
            attn_weights = attn_weights_reshaped.view(bsz * self.num_heads, tgt_len, src_len)
        else:
            attn_weights_reshaped = None

        attn_probs = nn.functional.dropout(attn_weights, p=self.dropout, training=self.training)

        attn_output = torch.bmm(attn_probs, value_states)

        if attn_output.size() != (bsz * self.num_heads, tgt_len, self.head_dim):
            raise ValueError(
                f"`attn_output` should be of size {(bsz * self.num_heads, tgt_len, self.head_dim)}, but is"
                f" {attn_output.size()}"
            )

        attn_output = attn_output.view(bsz, self.num_heads, tgt_len, self.head_dim)
        attn_output = attn_output.transpose(1, 2)

        
        
        attn_output = attn_output.reshape(bsz, tgt_len, self.embed_dim)

        attn_output = self.out_proj(attn_output)

        return attn_output, attn_weights_reshaped, past_key_value



class BlenderbotSmallEncoderLayer(nn.Module):
    def __init__(self, config: BlenderbotSmallConfig):
        super().__init__()
        self.embed_dim = config.d_model
        attn_type = "flash_attention_2" if getattr(config, "_flash_attn_2_enabled", False) else "default"

        self.self_attn = BLENDERBOT_SMALL_ATTENTION_CLASSES[attn_type](
            embed_dim=self.embed_dim,
            num_heads=config.encoder_attention_heads,
            dropout=config.attention_dropout,
            config=config,
        )
        self.self_attn_layer_norm = nn.LayerNorm(self.embed_dim)
        self.dropout = config.dropout
        self.activation_fn = ACT2FN[config.activation_function]
        self.activation_dropout = config.activation_dropout
        self.fc1 = nn.Linear(self.embed_dim, config.encoder_ffn_dim)
        self.fc2 = nn.Linear(config.encoder_ffn_dim, self.embed_dim)
        self.final_layer_norm = nn.LayerNorm(self.embed_dim)

    def forward(
        self,
        hidden_states: torch.FloatTensor,
        attention_mask: torch.FloatTensor,
        layer_head_mask: torch.FloatTensor,
        output_attentions: Optional[bool] = False,
    ) -> Tuple[torch.FloatTensor, Optional[torch.FloatTensor]]:
        
        residual = hidden_states
        hidden_states, attn_weights, _ = self.self_attn(
            hidden_states=hidden_states,
            attention_mask=attention_mask,
            layer_head_mask=layer_head_mask,
            output_attentions=output_attentions,
        )
        hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)
        hidden_states = residual + hidden_states
        hidden_states = self.self_attn_layer_norm(hidden_states)

        residual = hidden_states
        hidden_states = self.activation_fn(self.fc1(hidden_states))
        hidden_states = nn.functional.dropout(hidden_states, p=self.activation_dropout, training=self.training)
        hidden_states = self.fc2(hidden_states)
        hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)
        hidden_states = residual + hidden_states
        hidden_states = self.final_layer_norm(hidden_states)

        if hidden_states.dtype == torch.float16 and (
            torch.isinf(hidden_states).any() or torch.isnan(hidden_states).any()
        ):
            clamp_value = torch.finfo(hidden_states.dtype).max - 1000
            hidden_states = torch.clamp(hidden_states, min=-clamp_value, max=clamp_value)

        outputs = (hidden_states,)

        if output_attentions:
            outputs += (attn_weights,)

        return outputs


BLENDERBOT_SMALL_ATTENTION_CLASSES = {"default": BlenderbotSmallAttention}



class BlenderbotSmallDecoderLayer(nn.Module):
    def __init__(self, config: BlenderbotSmallConfig):
        super().__init__()
        self.embed_dim = config.d_model

        attn_type = "flash_attention_2" if getattr(config, "_flash_attn_2_enabled", False) else "default"
        self.self_attn = BLENDERBOT_SMALL_ATTENTION_CLASSES[attn_type](
            embed_dim=self.embed_dim,
            num_heads=config.decoder_attention_heads,
            dropout=config.attention_dropout,
            is_decoder=True,
            is_causal=True,
            config=config,
        )
        self.dropout = config.dropout
        self.activation_fn = ACT2FN[config.activation_function]
        self.activation_dropout = config.activation_dropout

        self.self_attn_layer_norm = nn.LayerNorm(self.embed_dim)
        self.encoder_attn = BLENDERBOT_SMALL_ATTENTION_CLASSES[attn_type](
            self.embed_dim,
            config.decoder_attention_heads,
            dropout=config.attention_dropout,
            is_decoder=True,
            config=config,
        )
        self.encoder_attn_layer_norm = nn.LayerNorm(self.embed_dim)
        self.fc1 = nn.Linear(self.embed_dim, config.decoder_ffn_dim)
        self.fc2 = nn.Linear(config.decoder_ffn_dim, self.embed_dim)
        self.final_layer_norm = nn.LayerNorm(self.embed_dim)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: Optional[torch.Tensor] = None,
        encoder_hidden_states: Optional[torch.Tensor] = None,
        encoder_attention_mask: Optional[torch.Tensor] = None,
        layer_head_mask: Optional[torch.Tensor] = None,
        cross_attn_layer_head_mask: Optional[torch.Tensor] = None,
        past_key_value: Optional[Tuple[torch.Tensor]] = None,
        output_attentions: Optional[bool] = False,
        use_cache: Optional[bool] = True,
    ) -> Tuple[torch.FloatTensor, Optional[Tuple[torch.FloatTensor, torch.FloatTensor]]]:
        
        residual = hidden_states

        
        
        self_attn_past_key_value = past_key_value[:2] if past_key_value is not None else None
        
        hidden_states, self_attn_weights, present_key_value = self.self_attn(
            hidden_states=hidden_states,
            past_key_value=self_attn_past_key_value,
            attention_mask=attention_mask,
            layer_head_mask=layer_head_mask,
            output_attentions=output_attentions,
        )
        hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)
        hidden_states = residual + hidden_states
        hidden_states = self.self_attn_layer_norm(hidden_states)

        
        cross_attn_present_key_value = None
        cross_attn_weights = None
        if encoder_hidden_states is not None:
            residual = hidden_states

            
            cross_attn_past_key_value = past_key_value[-2:] if past_key_value is not None else None
            hidden_states, cross_attn_weights, cross_attn_present_key_value = self.encoder_attn(
                hidden_states=hidden_states,
                key_value_states=encoder_hidden_states,
                attention_mask=encoder_attention_mask,
                layer_head_mask=cross_attn_layer_head_mask,
                past_key_value=cross_attn_past_key_value,
                output_attentions=output_attentions,
            )
            hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)
            hidden_states = residual + hidden_states
            hidden_states = self.encoder_attn_layer_norm(hidden_states)

            
            present_key_value = present_key_value + cross_attn_present_key_value

        
        residual = hidden_states
        hidden_states = self.activation_fn(self.fc1(hidden_states))
        hidden_states = nn.functional.dropout(hidden_states, p=self.activation_dropout, training=self.training)
        hidden_states = self.fc2(hidden_states)
        hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)
        hidden_states = residual + hidden_states
        hidden_states = self.final_layer_norm(hidden_states)

        outputs = (hidden_states,)

        if output_attentions:
            outputs += (self_attn_weights, cross_attn_weights)

        if use_cache:
            outputs += (present_key_value,)

        return outputs


class BlenderbotSmallPreTrainedModel(PreTrainedModel):
    config_class = BlenderbotSmallConfig
    base_model_prefix = "model"
    supports_gradient_checkpointing = True

    def _init_weights(self, module):
        std = self.config.init_std
        if isinstance(module, nn.Linear):
            module.weight.data.normal_(mean=0.0, std=std)
            if module.bias is not None:
                module.bias.data.zero_()
        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_()

    @property
    def dummy_inputs(self):
        pad_token = self.config.pad_token_id
        input_ids = torch.tensor([[0, 6, 10, 4, 2], [0, 8, 12, 2, pad_token]], device=self.device)
        dummy_inputs = {
            "attention_mask": input_ids.ne(pad_token),
            "input_ids": input_ids,
            "decoder_input_ids": input_ids,
        }
        return dummy_inputs


BLENDERBOT_SMALL_START_DOCSTRING = r

BLENDERBOT_SMALL_GENERATION_EXAMPLE = r

BLENDERBOT_SMALL_INPUTS_DOCSTRING = r


class BlenderbotSmallEncoder(BlenderbotSmallPreTrainedModel):
    

    def __init__(self, config: BlenderbotSmallConfig, embed_tokens: Optional[nn.Embedding] = None):
        super().__init__(config)

        self.dropout = config.dropout
        self.layerdrop = config.encoder_layerdrop

        embed_dim = config.d_model
        self.padding_idx = config.pad_token_id
        self.max_source_positions = config.max_position_embeddings
        self.embed_scale = math.sqrt(embed_dim) if config.scale_embedding else 1.0

        if embed_tokens is not None:
            self.embed_tokens = embed_tokens
        else:
            self.embed_tokens = nn.Embedding(config.vocab_size, embed_dim, self.padding_idx)

        self.embed_positions = BlenderbotSmallLearnedPositionalEmbedding(
            config.max_position_embeddings,
            embed_dim,
        )
        self.layers = nn.ModuleList([BlenderbotSmallEncoderLayer(config) for _ in range(config.encoder_layers)])
        self.layernorm_embedding = nn.LayerNorm(embed_dim)

        self.gradient_checkpointing = False
        
        self.post_init()

    def forward(
        self,
        input_ids=None,
        attention_mask=None,
        head_mask=None,
        inputs_embeds=None,
        output_attentions=None,
        output_hidden_states=None,
        return_dict=None,
    ):
        r
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        
        if input_ids is not None and inputs_embeds is not None:
            raise ValueError("You cannot specify both input_ids and inputs_embeds at the same time")
        elif input_ids is not None:
            self.warn_if_padding_and_no_attention_mask(input_ids, attention_mask)
            input_shape = input_ids.size()
            input_ids = input_ids.view(-1, input_shape[-1])
        elif inputs_embeds is not None:
            input_shape = inputs_embeds.size()[:-1]
        else:
            raise ValueError("You have to specify either input_ids or inputs_embeds")

        if inputs_embeds is None:
            inputs_embeds = self.embed_tokens(input_ids) * self.embed_scale

        embed_pos = self.embed_positions(input_shape)

        hidden_states = inputs_embeds + embed_pos
        hidden_states = self.layernorm_embedding(hidden_states)
        hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)

        
        if attention_mask is not None:
            
            attention_mask = _prepare_4d_attention_mask(attention_mask, inputs_embeds.dtype)

        encoder_states = () if output_hidden_states else None
        all_attentions = () if output_attentions else None

        
        if head_mask is not None:
            if head_mask.size()[0] != len(self.layers):
                raise ValueError(
                    f"The head_mask should be specified for {len(self.layers)} layers, but it is for"
                    f" {head_mask.size()[0]}."
                )
        for idx, encoder_layer in enumerate(self.layers):
            if output_hidden_states:
                encoder_states = encoder_states + (hidden_states,)
            
            to_drop = False
            if self.training:
                dropout_probability = torch.rand([])
                if dropout_probability < self.layerdrop:  
                    to_drop = True

            if to_drop:
                layer_outputs = (None, None)
            else:
                if self.gradient_checkpointing and self.training:
                    layer_outputs = self._gradient_checkpointing_func(
                        encoder_layer.__call__,
                        hidden_states,
                        attention_mask,
                        (head_mask[idx] if head_mask is not None else None),
                        output_attentions,
                    )
                else:
                    layer_outputs = encoder_layer(
                        hidden_states,
                        attention_mask,
                        layer_head_mask=(head_mask[idx] if head_mask is not None else None),
                        output_attentions=output_attentions,
                    )

                hidden_states = layer_outputs[0]

            if output_attentions:
                all_attentions = all_attentions + (layer_outputs[1],)

        if output_hidden_states:
            encoder_states = encoder_states + (hidden_states,)

        if not return_dict:
            return tuple(v for v in [hidden_states, encoder_states, all_attentions] if v is not None)
        return BaseModelOutput(
            last_hidden_state=hidden_states, hidden_states=encoder_states, attentions=all_attentions
        )


class BlenderbotSmallDecoder(BlenderbotSmallPreTrainedModel):
    

    def __init__(self, config: BlenderbotSmallConfig, embed_tokens: Optional[nn.Embedding] = None):
        super().__init__(config)
        self.dropout = config.dropout
        self.layerdrop = config.decoder_layerdrop
        self.padding_idx = config.pad_token_id
        self.max_target_positions = config.max_position_embeddings
        self.embed_scale = math.sqrt(config.d_model) if config.scale_embedding else 1.0

        if embed_tokens is not None:
            self.embed_tokens = embed_tokens
        else:
            self.embed_tokens = nn.Embedding(config.vocab_size, config.d_model, self.padding_idx)

        self.embed_positions = BlenderbotSmallLearnedPositionalEmbedding(
            config.max_position_embeddings,
            config.d_model,
        )
        self.layers = nn.ModuleList([BlenderbotSmallDecoderLayer(config) for _ in range(config.decoder_layers)])
        self.layernorm_embedding = nn.LayerNorm(config.d_model)

        self.gradient_checkpointing = False
        
        self.post_init()

    def get_input_embeddings(self):
        return self.embed_tokens

    def set_input_embeddings(self, value):
        self.embed_tokens = value

    def forward(
        self,
        input_ids=None,
        attention_mask=None,
        encoder_hidden_states=None,
        encoder_attention_mask=None,
        head_mask=None,
        cross_attn_head_mask=None,
        past_key_values=None,
        inputs_embeds=None,
        use_cache=None,
        output_attentions=None,
        output_hidden_states=None,
        return_dict=None,
    ):
        r
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        use_cache = use_cache if use_cache is not None else self.config.use_cache
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        
        if input_ids is not None and inputs_embeds is not None:
            raise ValueError("You cannot specify both decoder_input_ids and decoder_inputs_embeds at the same time")
        elif input_ids is not None:
            input_shape = input_ids.size()
            input_ids = input_ids.view(-1, input_shape[-1])
        elif inputs_embeds is not None:
            input_shape = inputs_embeds.size()[:-1]
        else:
            raise ValueError("You have to specify either decoder_input_ids or decoder_inputs_embeds")

        
        past_key_values_length = past_key_values[0][0].shape[2] if past_key_values is not None else 0

        if inputs_embeds is None:
            inputs_embeds = self.embed_tokens(input_ids) * self.embed_scale

        attention_mask = _prepare_4d_causal_attention_mask(
            attention_mask, input_shape, inputs_embeds, past_key_values_length
        )

        
        if encoder_hidden_states is not None and encoder_attention_mask is not None:
            
            encoder_attention_mask = _prepare_4d_attention_mask(
                encoder_attention_mask, inputs_embeds.dtype, tgt_len=input_shape[-1]
            )

        
        positions = self.embed_positions(input_shape, past_key_values_length)

        
        inputs_embeds = self.layernorm_embedding(inputs_embeds)
        hidden_states = inputs_embeds + positions

        hidden_states = nn.functional.dropout(hidden_states, p=self.dropout, training=self.training)

        if self.gradient_checkpointing and self.training:
            if use_cache:
                logger.warning_once(
                    "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..."
                )
                use_cache = False

        
        all_hidden_states = () if output_hidden_states else None
        all_self_attns = () if output_attentions else None
        all_cross_attentions = () if (output_attentions and encoder_hidden_states is not None) else None
        next_decoder_cache = () if use_cache else None

        
        for attn_mask, mask_name in zip([head_mask, cross_attn_head_mask], ["head_mask", "cross_attn_head_mask"]):
            if attn_mask is not None:
                if attn_mask.size()[0] != len(self.layers):
                    raise ValueError(
                        f"The `{mask_name}` should be specified for {len(self.layers)} layers, but it is for"
                        f" {head_mask.size()[0]}."
                    )
        for idx, decoder_layer in enumerate(self.layers):
            
            if output_hidden_states:
                all_hidden_states += (hidden_states,)
            if self.training:
                dropout_probability = torch.rand([])
                if dropout_probability < self.layerdrop:
                    continue

            past_key_value = past_key_values[idx] if past_key_values is not None else None

            if self.gradient_checkpointing and self.training:
                layer_outputs = self._gradient_checkpointing_func(
                    decoder_layer.__call__,
                    hidden_states,
                    attention_mask,
                    encoder_hidden_states,
                    encoder_attention_mask,
                    head_mask[idx] if head_mask is not None else None,
                    cross_attn_head_mask[idx] if cross_attn_head_mask is not None else None,
                    None,
                    output_attentions,
                    use_cache,
                )
            else:
                layer_outputs = decoder_layer(
                    hidden_states,
                    attention_mask=attention_mask,
                    encoder_hidden_states=encoder_hidden_states,
                    encoder_attention_mask=encoder_attention_mask,
                    layer_head_mask=(head_mask[idx] if head_mask is not None else None),
                    cross_attn_layer_head_mask=(
                        cross_attn_head_mask[idx] if cross_attn_head_mask is not None else None
                    ),
                    past_key_value=past_key_value,
                    output_attentions=output_attentions,
                    use_cache=use_cache,
                )
            hidden_states = layer_outputs[0]

            if use_cache:
                next_decoder_cache += (layer_outputs[3 if output_attentions else 1],)

            if output_attentions:
                all_self_attns += (layer_outputs[1],)

                if encoder_hidden_states is not None:
                    all_cross_attentions += (layer_outputs[2],)

        
        if output_hidden_states:
            all_hidden_states += (hidden_states,)

        next_cache = next_decoder_cache if use_cache else None
        if not return_dict:
            return tuple(
                v
                for v in [hidden_states, next_cache, all_hidden_states, all_self_attns, all_cross_attentions]
                if v is not None
            )
        return BaseModelOutputWithPastAndCrossAttentions(
            last_hidden_state=hidden_states,
            past_key_values=next_cache,
            hidden_states=all_hidden_states,
            attentions=all_self_attns,
            cross_attentions=all_cross_attentions,
        )


@add_start_docstrings(
    "The bare BlenderbotSmall Model outputting raw hidden-states without any specific head on top.",
    BLENDERBOT_SMALL_START_DOCSTRING,
)
class BlenderbotSmallModel(BlenderbotSmallPreTrainedModel):
    _tied_weights_keys = ["decoder.embed_tokens.weight", "encoder.embed_tokens.weight"]

    def __init__(self, config: BlenderbotSmallConfig):
        super().__init__(config)

        padding_idx, vocab_size = config.pad_token_id, config.vocab_size
        self.shared = nn.Embedding(vocab_size, config.d_model, padding_idx)

        self.encoder = BlenderbotSmallEncoder(config, self.shared)
        self.decoder = BlenderbotSmallDecoder(config, self.shared)

        
        self.post_init()

    def get_input_embeddings(self):
        return self.shared

    def set_input_embeddings(self, value):
        self.shared = value
        self.encoder.embed_tokens = self.shared
        self.decoder.embed_tokens = self.shared

    def get_encoder(self):
        return self.encoder

    def get_decoder(self):
        return self.decoder

    @add_start_docstrings_to_model_forward(BLENDERBOT_SMALL_INPUTS_DOCSTRING)
    @replace_return_docstrings(output_type=Seq2SeqModelOutput, config_class=_CONFIG_FOR_DOC)
    def forward(
        self,
        input_ids: Optional[torch.LongTensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        decoder_input_ids: Optional[torch.LongTensor] = None,
        decoder_attention_mask: Optional[torch.LongTensor] = None,
        head_mask: Optional[torch.Tensor] = None,
        decoder_head_mask: Optional[torch.Tensor] = None,
        cross_attn_head_mask: Optional[torch.Tensor] = None,
        encoder_outputs: Optional[Union[Tuple, BaseModelOutput]] = None,
        past_key_values: Optional[List[torch.FloatTensor]] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        decoder_inputs_embeds: Optional[torch.FloatTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[Tuple[torch.FloatTensor], Seq2SeqModelOutput]:
        r
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        use_cache = use_cache if use_cache is not None else self.config.use_cache
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        if encoder_outputs is None:
            encoder_outputs = self.encoder(
                input_ids=input_ids,
                attention_mask=attention_mask,
                head_mask=head_mask,
                inputs_embeds=inputs_embeds,
                output_attentions=output_attentions,
                output_hidden_states=output_hidden_states,
                return_dict=return_dict,
            )
        
        elif return_dict and not isinstance(encoder_outputs, BaseModelOutput):
            encoder_outputs = BaseModelOutput(
                last_hidden_state=encoder_outputs[0],
                hidden_states=encoder_outputs[1] if len(encoder_outputs) > 1 else None,
                attentions=encoder_outputs[2] if len(encoder_outputs) > 2 else None,
            )

        
        decoder_outputs = self.decoder(
            input_ids=decoder_input_ids,
            attention_mask=decoder_attention_mask,
            encoder_hidden_states=encoder_outputs[0],
            encoder_attention_mask=attention_mask,
            head_mask=decoder_head_mask,
            cross_attn_head_mask=cross_attn_head_mask,
            past_key_values=past_key_values,
            inputs_embeds=decoder_inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        if not return_dict:
            return decoder_outputs + encoder_outputs

        return Seq2SeqModelOutput(
            last_hidden_state=decoder_outputs.last_hidden_state,
            past_key_values=decoder_outputs.past_key_values,
            decoder_hidden_states=decoder_outputs.hidden_states,
            decoder_attentions=decoder_outputs.attentions,
            cross_attentions=decoder_outputs.cross_attentions,
            encoder_last_hidden_state=encoder_outputs.last_hidden_state,
            encoder_hidden_states=encoder_outputs.hidden_states,
            encoder_attentions=encoder_outputs.attentions,
        )


@add_start_docstrings(
    "The BlenderbotSmall Model with a language modeling head. Can be used for summarization.",
    BLENDERBOT_SMALL_START_DOCSTRING,
)
class BlenderbotSmallForConditionalGeneration(BlenderbotSmallPreTrainedModel):
    base_model_prefix = "model"
    _keys_to_ignore_on_load_missing = ["final_logits_bias"]
    _tied_weights_keys = ["decoder.embed_tokens.weight", "encoder.embed_tokens.weight", "lm_head.weight"]

    def __init__(self, config: BlenderbotSmallConfig):
        super().__init__(config)
        self.model = BlenderbotSmallModel(config)
        self.register_buffer("final_logits_bias", torch.zeros((1, self.model.shared.num_embeddings)))
        self.lm_head = nn.Linear(config.d_model, self.model.shared.num_embeddings, bias=False)

        
        self.post_init()

    def get_encoder(self):
        return self.model.get_encoder()

    def get_decoder(self):
        return self.model.get_decoder()

    def resize_token_embeddings(self, new_num_tokens: int, pad_to_multiple_of: Optional[int] = None) -> nn.Embedding:
        new_embeddings = super().resize_token_embeddings(new_num_tokens, pad_to_multiple_of)
        self._resize_final_logits_bias(new_embeddings.weight.shape[0])
        return new_embeddings

    def _resize_final_logits_bias(self, new_num_tokens: int) -> None:
        old_num_tokens = self.final_logits_bias.shape[-1]
        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), device=self.final_logits_bias.device)
            new_bias = torch.cat([self.final_logits_bias, extra_bias], dim=1)
        self.register_buffer("final_logits_bias", new_bias)

    def get_output_embeddings(self):
        return self.lm_head

    def set_output_embeddings(self, new_embeddings):
        self.lm_head = new_embeddings

    @add_start_docstrings_to_model_forward(BLENDERBOT_SMALL_INPUTS_DOCSTRING)
    @replace_return_docstrings(output_type=Seq2SeqLMOutput, config_class=_CONFIG_FOR_DOC)
    @add_end_docstrings(BLENDERBOT_SMALL_GENERATION_EXAMPLE)
    def forward(
        self,
        input_ids: Optional[torch.LongTensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        decoder_input_ids: Optional[torch.LongTensor] = None,
        decoder_attention_mask: Optional[torch.LongTensor] = None,
        head_mask: Optional[torch.Tensor] = None,
        decoder_head_mask: Optional[torch.Tensor] = None,
        cross_attn_head_mask: Optional[torch.Tensor] = None,
        encoder_outputs: Optional[Union[Tuple, BaseModelOutput]] = None,
        past_key_values: Optional[List[torch.FloatTensor]] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        decoder_inputs_embeds: Optional[torch.FloatTensor] = None,
        labels: Optional[torch.LongTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[Tuple[torch.FloatTensor], Seq2SeqLMOutput]:
        r
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        if labels is not None:
            if use_cache:
                logger.warning("The `use_cache` argument is changed to `False` since `labels` is provided.")
            use_cache = False
            if decoder_input_ids is None and decoder_inputs_embeds is None:
                decoder_input_ids = shift_tokens_right(
                    labels, self.config.pad_token_id, self.config.decoder_start_token_id
                )

        outputs = self.model(
            input_ids,
            attention_mask=attention_mask,
            decoder_input_ids=decoder_input_ids,
            encoder_outputs=encoder_outputs,
            decoder_attention_mask=decoder_attention_mask,
            head_mask=head_mask,
            decoder_head_mask=decoder_head_mask,
            cross_attn_head_mask=cross_attn_head_mask,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            decoder_inputs_embeds=decoder_inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )
        lm_logits = self.lm_head(outputs[0]) + self.final_logits_bias

        masked_lm_loss = None
        if labels is not None:
            loss_fct = CrossEntropyLoss()
            masked_lm_loss = loss_fct(lm_logits.view(-1, self.config.vocab_size), labels.view(-1))

        if not return_dict:
            output = (lm_logits,) + outputs[1:]
            return ((masked_lm_loss,) + output) if masked_lm_loss is not None else output

        return Seq2SeqLMOutput(
            loss=masked_lm_loss,
            logits=lm_logits,
            past_key_values=outputs.past_key_values,
            decoder_hidden_states=outputs.decoder_hidden_states,
            decoder_attentions=outputs.decoder_attentions,
            cross_attentions=outputs.cross_attentions,
            encoder_last_hidden_state=outputs.encoder_last_hidden_state,
            encoder_hidden_states=outputs.encoder_hidden_states,
            encoder_attentions=outputs.encoder_attentions,
        )

    def prepare_inputs_for_generation(
        self,
        decoder_input_ids,
        past_key_values=None,
        attention_mask=None,
        head_mask=None,
        decoder_head_mask=None,
        cross_attn_head_mask=None,
        use_cache=None,
        encoder_outputs=None,
        **kwargs,
    ):
        
        if past_key_values is not None:
            past_length = past_key_values[0][0].shape[2]

            
            if decoder_input_ids.shape[1] > past_length:
                remove_prefix_length = past_length
            else:
                
                remove_prefix_length = decoder_input_ids.shape[1] - 1

            decoder_input_ids = decoder_input_ids[:, remove_prefix_length:]

        return {
            "input_ids": None,  
            "encoder_outputs": encoder_outputs,
            "past_key_values": past_key_values,
            "decoder_input_ids": decoder_input_ids,
            "attention_mask": attention_mask,
            "head_mask": head_mask,
            "decoder_head_mask": decoder_head_mask,
            "cross_attn_head_mask": cross_attn_head_mask,
            "use_cache": use_cache,  
        }

    @staticmethod
    def _reorder_cache(past_key_values, beam_idx):
        reordered_past = ()
        for layer_past in past_key_values:
            
            reordered_past += (
                tuple(past_state.index_select(0, beam_idx.to(past_state.device)) for past_state in layer_past[:2])
                + layer_past[2:],
            )
        return reordered_past



class BlenderbotSmallDecoderWrapper(BlenderbotSmallPreTrainedModel):
    

    def __init__(self, config):
        super().__init__(config)
        self.decoder = BlenderbotSmallDecoder(config)

    def forward(self, *args, **kwargs):
        return self.decoder(*args, **kwargs)



class BlenderbotSmallForCausalLM(BlenderbotSmallPreTrainedModel):
    _tied_weights_keys = ["lm_head.weight"]

    def __init__(self, config):
        config = copy.deepcopy(config)
        config.is_decoder = True
        config.is_encoder_decoder = False
        super().__init__(config)
        self.model = BlenderbotSmallDecoderWrapper(config)

        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)

        
        self.post_init()

    def get_input_embeddings(self):
        return self.model.decoder.embed_tokens

    def set_input_embeddings(self, value):
        self.model.decoder.embed_tokens = value

    def get_output_embeddings(self):
        return self.lm_head

    def set_output_embeddings(self, new_embeddings):
        self.lm_head = new_embeddings

    def set_decoder(self, decoder):
        self.model.decoder = decoder

    def get_decoder(self):
        return self.model.decoder

    @replace_return_docstrings(output_type=CausalLMOutputWithCrossAttentions, config_class=_CONFIG_FOR_DOC)
    def forward(
        self,
        input_ids: torch.LongTensor = None,
        attention_mask: Optional[torch.Tensor] = None,
        encoder_hidden_states: Optional[torch.FloatTensor] = None,
        encoder_attention_mask: Optional[torch.FloatTensor] = None,
        head_mask: Optional[torch.Tensor] = None,
        cross_attn_head_mask: Optional[torch.Tensor] = None,
        past_key_values: Optional[List[torch.FloatTensor]] = None,
        inputs_embeds: Optional[torch.FloatTensor] = None,
        labels: Optional[torch.LongTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[Tuple, CausalLMOutputWithCrossAttentions]:
        r

        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        
        outputs = self.model.decoder(
            input_ids=input_ids,
            attention_mask=attention_mask,
            encoder_hidden_states=encoder_hidden_states,
            encoder_attention_mask=encoder_attention_mask,
            head_mask=head_mask,
            cross_attn_head_mask=cross_attn_head_mask,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        logits = self.lm_head(outputs[0])

        loss = None
        if labels is not None:
            labels = labels.to(logits.device)
            loss_fct = CrossEntropyLoss()
            loss = loss_fct(logits.view(-1, self.config.vocab_size), labels.view(-1))

        if not return_dict:
            output = (logits,) + outputs[1:]
            return (loss,) + output if loss is not None else output

        return CausalLMOutputWithCrossAttentions(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
            cross_attentions=outputs.cross_attentions,
        )

    def prepare_inputs_for_generation(
        self, input_ids, past_key_values=None, attention_mask=None, use_cache=None, **kwargs
    ):
        
        if attention_mask is None:
            attention_mask = input_ids.new_ones(input_ids.shape)

        if past_key_values:
            past_length = past_key_values[0][0].shape[2]

            
            if input_ids.shape[1] > past_length:
                remove_prefix_length = past_length
            else:
                
                remove_prefix_length = input_ids.shape[1] - 1

            input_ids = input_ids[:, remove_prefix_length:]
        
        return {
            "input_ids": input_ids,  
            "attention_mask": attention_mask,
            "past_key_values": past_key_values,
            "use_cache": use_cache,
        }

    @staticmethod
    def _reorder_cache(past_key_values, beam_idx):
        reordered_past = ()
        for layer_past in past_key_values:
            reordered_past += (
                tuple(past_state.index_select(0, beam_idx.to(past_state.device)) for past_state in layer_past),
            )
        return reordered_past