class LightConvDecoderLayer(nn.Module):
"""Decoder layer block.
Args:
args (argparse.Namespace): parsed command-line arguments
no_encoder_attn (bool, optional): whether to attend to encoder outputs.
Default: ``False``
kernel_size: kernel size of the convolution
"""
def __init__(self, args, no_encoder_attn=False, kernel_size=0):
super().__init__()
self.embed_dim = args.decoder_embed_dim
self.conv_dim = args.decoder_conv_dim
if args.decoder_glu:
self.linear1 = Linear(self.embed_dim, 2 * self.conv_dim)
self.act = nn.GLU()
else:
self.linear1 = Linear(self.embed_dim, self.conv_dim)
self.act = None
if args.decoder_conv_type == "lightweight":
self.conv = LightweightConv(
self.conv_dim,
kernel_size,
padding_l=kernel_size - 1,
weight_softmax=args.weight_softmax,
num_heads=args.decoder_attention_heads,
weight_dropout=args.weight_dropout,
)
elif args.decoder_conv_type == "dynamic":
self.conv = DynamicConv(
self.conv_dim,
kernel_size,
padding_l=kernel_size - 1,
weight_softmax=args.weight_softmax,
num_heads=args.decoder_attention_heads,
weight_dropout=args.weight_dropout,
)
else:
raise NotImplementedError
self.linear2 = Linear(self.conv_dim, self.embed_dim)
self.dropout_module = FairseqDropout(
args.dropout, module_name=self.__class__.__name__
)
self.relu_dropout_module = FairseqDropout(
args.relu_dropout, module_name=self.__class__.__name__
)
self.input_dropout_module = FairseqDropout(
args.input_dropout, module_name=self.__class__.__name__
)
self.normalize_before = args.decoder_normalize_before
self.conv_layer_norm = LayerNorm(self.embed_dim)
if no_encoder_attn:
self.encoder_attn = None
self.encoder_attn_layer_norm = None
else:
self.encoder_attn = MultiheadAttention(
self.embed_dim,
args.decoder_attention_heads,
dropout=args.attention_dropout,
encoder_decoder_attention=True,
)
self.encoder_attn_layer_norm = LayerNorm(self.embed_dim)
self.fc1 = Linear(self.embed_dim, args.decoder_ffn_embed_dim)
self.fc2 = Linear(args.decoder_ffn_embed_dim, self.embed_dim)
self.final_layer_norm = LayerNorm(self.embed_dim)
self.need_attn = True
def forward(
self,
x,
encoder_out,
encoder_padding_mask,
incremental_state,
prev_conv_state=None,
prev_attn_state=None,
conv_mask=None,
conv_padding_mask=None,
):
"""
Args:
x (Tensor): input to the layer of shape `(seq_len, batch, embed_dim)`
encoder_padding_mask (ByteTensor): binary ByteTensor of shape
`(batch, src_len)` where padding elements are indicated by ``1``.
Returns:
encoded output of shape `(batch, src_len, embed_dim)`
"""
residual = x
x = self.maybe_layer_norm(self.conv_layer_norm, x, before=True)
if prev_conv_state is not None:
if incremental_state is None:
incremental_state = {}
self.conv._set_input_buffer(incremental_state, prev_conv_state)
x = self.input_dropout_module(x)
x = self.linear1(x)
if self.act is not None:
x = self.act(x)
x = self.conv(x, incremental_state=incremental_state)
x = self.linear2(x)
x = self.dropout_module(x)
x = residual + x
x = self.maybe_layer_norm(self.conv_layer_norm, x, after=True)
attn = None
if self.encoder_attn is not None:
residual = x
x = self.maybe_layer_norm(self.encoder_attn_layer_norm, x, before=True)
if prev_attn_state is not None:
if incremental_state is None:
incremental_state = {}
prev_key, prev_value = prev_attn_state
saved_state = {"prev_key": prev_key, "prev_value": prev_value}
self.encoder_attn._set_input_buffer(incremental_state, saved_state)
x, attn = self.encoder_attn(
query=x,
key=encoder_out,
value=encoder_out,
key_padding_mask=encoder_padding_mask,
incremental_state=incremental_state,
static_kv=True,
need_weights=(not self.training and self.need_attn),
)
x = self.dropout_module(x)
x = residual + x
x = self.maybe_layer_norm(self.encoder_attn_layer_norm, x, after=True)
residual = x
x = self.maybe_layer_norm(self.final_layer_norm, x, before=True)
x = F.relu(self.fc1(x))
x = self.relu_dropout_module(x)
x = self.fc2(x)
x = self.dropout_module(x)
x = residual + x
x = self.maybe_layer_norm(self.final_layer_norm, x, after=True)
return x, attn
def maybe_layer_norm(self, layer_norm, x, before=False, after=False):
assert before ^ after
if after ^ self.normalize_before:
return layer_norm(x)
else:
return x
def make_generation_fast_(self, need_attn=False, **kwargs):
self.need_attn = need_attn
def extra_repr(self):
return (
"dropout={}, relu_dropout={}, input_dropout={}, normalize_before={}".format(
self.dropout_module.p,
self.relu_dropout_module.p,
self.input_dropout_module.p,
self.normalize_before,
)
)
class DynamicConvDecoderLayer(nn.Module):
def __init__(self,
embed_dim,
conv_dim,
num_heads,
kernel_size,
weight_dropout=0.1,
dropout=0.3,
input_dropout=0.0,
weight_softmax=True,
encoder_glu=False,
normalize_before=False):
super().__init__()
self.embed_dim = embed_dim
self.conv_dim = conv_dim
if encoder_glu:
self.linear1 = Linear(self.embed_dim, 2 * self.conv_dim)
self.act = nn.GLU()
else:
self.linear1 = Linear(self.embed_dim, self.conv_dim)
self.act = None
self.conv = DynamicConv(self.conv_dim,
kernel_size,
padding_l=kernel_size - 1,
weight_softmax=weight_softmax,
num_heads=num_heads,
weight_dropout=weight_dropout)
self.linear2 = Linear(self.conv_dim, self.embed_dim)
self.dropout = dropout
self.input_dropout = input_dropout
self.normalize_before = normalize_before
self.conv_layer_norm = LayerNorm(self.embed_dim)
def forward(self,
x,
incremental_state=None,
prev_conv_state=None,
**unused):
residual = x
x = self.maybe_layer_norm(x, before=True)
if prev_conv_state is not None:
if incremental_state is None:
incremental_state = {}
self.conv._set_input_buffer(incremental_state, prev_conv_state)
x = F.dropout(x, p=self.input_dropout, training=self.training)
x = self.linear1(x)
if self.act is not None:
x = self.act(x)
x = self.conv(x, incremental_state=incremental_state)
x = self.linear2(x)
x = F.dropout(x, p=self.dropout, training=self.training)
x = residual + x
x = self.maybe_layer_norm(x, after=True)
return x, None
def maybe_layer_norm(self, x, before=False, after=False):
assert before ^ after
if after ^ self.normalize_before:
return self.conv_layer_norm(x)
else:
return x
def extra_repr(self):
return 'dropout={}, input_dropout={}, normalize_before={}'.format(
self.dropout, self.input_dropout, self.normalize_before)