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| import flax.linen as nn | |
| import jax | |
| from transformers import BartConfig | |
| from transformers.models.bart.modeling_flax_bart import ( | |
| FlaxBartDecoder, | |
| FlaxBartEncoder, | |
| FlaxBartForConditionalGeneration, | |
| FlaxBartForConditionalGenerationModule, | |
| FlaxBartModule, | |
| ) | |
| class CustomFlaxBartModule(FlaxBartModule): | |
| def setup(self): | |
| # we keep shared to easily load pre-trained weights | |
| self.shared = nn.Embed( | |
| self.config.vocab_size, | |
| self.config.d_model, | |
| embedding_init=jax.nn.initializers.normal(self.config.init_std), | |
| ) | |
| # a separate embedding is used for the decoder | |
| self.decoder_embed = nn.Embed( | |
| self.config.image_vocab_size + 1, | |
| self.config.d_model, | |
| embedding_init=jax.nn.initializers.normal(self.config.init_std), | |
| ) | |
| self.encoder = FlaxBartEncoder( | |
| self.config, dtype=self.dtype, embed_tokens=self.shared | |
| ) | |
| # the decoder has a different config | |
| # TODO: should not be needed once we have custom config/module | |
| decoder_config = BartConfig(self.config.to_dict()) | |
| decoder_config.max_position_embeddings = ( | |
| self.config.image_length + 1 # image tokens + BOS | |
| ) | |
| decoder_config.vocab_size = self.config.image_vocab_size + 1 | |
| self.decoder = FlaxBartDecoder( | |
| decoder_config, dtype=self.dtype, embed_tokens=self.decoder_embed | |
| ) | |
| class CustomFlaxBartForConditionalGenerationModule( | |
| FlaxBartForConditionalGenerationModule | |
| ): | |
| def setup(self): | |
| # set default config | |
| self.config.normalize_text = getattr(self.config, "normalize_text", False) | |
| self.config.image_length = getattr(self.config, "image_length", 256) | |
| self.config.image_vocab_size = getattr(self.config, "image_vocab_size", 16384) | |
| self.model = CustomFlaxBartModule(config=self.config, dtype=self.dtype) | |
| self.lm_head = nn.Dense( | |
| self.config.image_vocab_size + 1, # encoded image token space + 1 for bos | |
| use_bias=False, | |
| kernel_init=jax.nn.initializers.normal(self.config.init_std), | |
| ) | |
| self.final_logits_bias = self.param( | |
| "final_logits_bias", self.bias_init, (1, self.config.image_vocab_size + 1) | |
| ) | |
| class CustomFlaxBartForConditionalGeneration(FlaxBartForConditionalGeneration): | |
| module_class = CustomFlaxBartForConditionalGenerationModule | |