File size: 9,595 Bytes
12bfd03
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
# Copyright (c) 2021 Mobvoi Inc (Binbin Zhang, Di Wu)
#               2022 Xingchen Song (sxc19@mails.tsinghua.edu.cn)
#
# 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.
# Modified from ESPnet(https://github.com/espnet/espnet)
"""Encoder self-attention layer definition."""

from typing import Optional, Tuple

import torch
from torch import nn


class TransformerEncoderLayer(nn.Module):
    """Encoder layer module.

    Args:
        size (int): Input dimension.
        self_attn (torch.nn.Module): Self-attention module instance.
            `MultiHeadedAttention` or `RelPositionMultiHeadedAttention`
            instance can be used as the argument.
        feed_forward (torch.nn.Module): Feed-forward module instance.
            `PositionwiseFeedForward`, instance can be used as the argument.
        dropout_rate (float): Dropout rate.
        normalize_before (bool):
            True: use layer_norm before each sub-block.
            False: to use layer_norm after each sub-block.
    """

    def __init__(
        self,
        size: int,
        self_attn: torch.nn.Module,
        feed_forward: torch.nn.Module,
        dropout_rate: float,
        normalize_before: bool = True,
    ):
        """Construct an EncoderLayer object."""
        super().__init__()
        self.self_attn = self_attn
        self.feed_forward = feed_forward
        self.norm1 = nn.LayerNorm(size, eps=1e-5)
        self.norm2 = nn.LayerNorm(size, eps=1e-5)
        self.dropout = nn.Dropout(dropout_rate)
        self.size = size
        self.normalize_before = normalize_before

    def forward(
        self,
        x: torch.Tensor,
        mask: torch.Tensor,
        pos_emb: torch.Tensor,
        mask_pad: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        att_cache: torch.Tensor = torch.zeros((0, 0, 0, 0)),
        cnn_cache: torch.Tensor = torch.zeros((0, 0, 0, 0)),
    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]:
        """Compute encoded features.

        Args:
            x (torch.Tensor): (#batch, time, size)
            mask (torch.Tensor): Mask tensor for the input (#batch, time,time),
                (0, 0, 0) means fake mask.
            pos_emb (torch.Tensor): just for interface compatibility
                to ConformerEncoderLayer
            mask_pad (torch.Tensor): does not used in transformer layer,
                just for unified api with conformer.
            att_cache (torch.Tensor): Cache tensor of the KEY & VALUE
                (#batch=1, head, cache_t1, d_k * 2), head * d_k == size.
            cnn_cache (torch.Tensor): Convolution cache in conformer layer
                (#batch=1, size, cache_t2), not used here, it's for interface
                compatibility to ConformerEncoderLayer.
        Returns:
            torch.Tensor: Output tensor (#batch, time, size).
            torch.Tensor: Mask tensor (#batch, time, time).
            torch.Tensor: att_cache tensor,
                (#batch=1, head, cache_t1 + time, d_k * 2).
            torch.Tensor: cnn_cahce tensor (#batch=1, size, cache_t2).

        """
        residual = x
        if self.normalize_before:
            x = self.norm1(x)
        x_att, new_att_cache = self.self_attn(x, x, x, mask, pos_emb=pos_emb, cache=att_cache)
        x = residual + self.dropout(x_att)
        if not self.normalize_before:
            x = self.norm1(x)

        residual = x
        if self.normalize_before:
            x = self.norm2(x)
        x = residual + self.dropout(self.feed_forward(x))
        if not self.normalize_before:
            x = self.norm2(x)

        fake_cnn_cache = torch.zeros((0, 0, 0), dtype=x.dtype, device=x.device)
        return x, mask, new_att_cache, fake_cnn_cache


class ConformerEncoderLayer(nn.Module):
    """Encoder layer module.
    Args:
        size (int): Input dimension.
        self_attn (torch.nn.Module): Self-attention module instance.
            `MultiHeadedAttention` or `RelPositionMultiHeadedAttention`
            instance can be used as the argument.
        feed_forward (torch.nn.Module): Feed-forward module instance.
            `PositionwiseFeedForward` instance can be used as the argument.
        feed_forward_macaron (torch.nn.Module): Additional feed-forward module
             instance.
            `PositionwiseFeedForward` instance can be used as the argument.
        conv_module (torch.nn.Module): Convolution module instance.
            `ConvlutionModule` instance can be used as the argument.
        dropout_rate (float): Dropout rate.
        normalize_before (bool):
            True: use layer_norm before each sub-block.
            False: use layer_norm after each sub-block.
    """

    def __init__(
        self,
        size: int,
        self_attn: torch.nn.Module,
        feed_forward: Optional[nn.Module] = None,
        feed_forward_macaron: Optional[nn.Module] = None,
        conv_module: Optional[nn.Module] = None,
        dropout_rate: float = 0.1,
        normalize_before: bool = True,
    ):
        """Construct an EncoderLayer object."""
        super().__init__()
        self.self_attn = self_attn
        self.feed_forward = feed_forward
        self.feed_forward_macaron = feed_forward_macaron
        self.conv_module = conv_module
        self.norm_ff = nn.LayerNorm(size, eps=1e-5)  # for the FNN module
        self.norm_mha = nn.LayerNorm(size, eps=1e-5)  # for the MHA module
        if feed_forward_macaron is not None:
            self.norm_ff_macaron = nn.LayerNorm(size, eps=1e-5)
            self.ff_scale = 0.5
        else:
            self.ff_scale = 1.0
        if self.conv_module is not None:
            self.norm_conv = nn.LayerNorm(size, eps=1e-5)  # for the CNN module
            self.norm_final = nn.LayerNorm(
                size, eps=1e-5)  # for the final output of the block
        self.dropout = nn.Dropout(dropout_rate)
        self.size = size
        self.normalize_before = normalize_before

    def forward(
        self,
        x: torch.Tensor,
        mask: torch.Tensor,
        pos_emb: torch.Tensor,
        mask_pad: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        att_cache: torch.Tensor = torch.zeros((0, 0, 0, 0)),
        cnn_cache: torch.Tensor = torch.zeros((0, 0, 0, 0)),
    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]:
        """Compute encoded features.

        Args:
            x (torch.Tensor): (#batch, time, size)
            mask (torch.Tensor): Mask tensor for the input (#batch, time,time),
                (0, 0, 0) means fake mask.
            pos_emb (torch.Tensor): positional encoding, must not be None
                for ConformerEncoderLayer.
            mask_pad (torch.Tensor): batch padding mask used for conv module.
                (#batch, 1,time), (0, 0, 0) means fake mask.
            att_cache (torch.Tensor): Cache tensor of the KEY & VALUE
                (#batch=1, head, cache_t1, d_k * 2), head * d_k == size.
            cnn_cache (torch.Tensor): Convolution cache in conformer layer
                (#batch=1, size, cache_t2)
        Returns:
            torch.Tensor: Output tensor (#batch, time, size).
            torch.Tensor: Mask tensor (#batch, time, time).
            torch.Tensor: att_cache tensor,
                (#batch=1, head, cache_t1 + time, d_k * 2).
            torch.Tensor: cnn_cahce tensor (#batch, size, cache_t2).
        """

        # whether to use macaron style
        if self.feed_forward_macaron is not None:
            residual = x
            if self.normalize_before:
                x = self.norm_ff_macaron(x)
            x = residual + self.ff_scale * self.dropout(
                self.feed_forward_macaron(x))
            if not self.normalize_before:
                x = self.norm_ff_macaron(x)

        # multi-headed self-attention module
        residual = x
        if self.normalize_before:
            x = self.norm_mha(x)
        x_att, new_att_cache = self.self_attn(x, x, x, mask, pos_emb,
                                              att_cache)
        x = residual + self.dropout(x_att)
        if not self.normalize_before:
            x = self.norm_mha(x)

        # convolution module
        # Fake new cnn cache here, and then change it in conv_module
        new_cnn_cache = torch.zeros((0, 0, 0), dtype=x.dtype, device=x.device)
        if self.conv_module is not None:
            residual = x
            if self.normalize_before:
                x = self.norm_conv(x)
            x, new_cnn_cache = self.conv_module(x, mask_pad, cnn_cache)
            x = residual + self.dropout(x)

            if not self.normalize_before:
                x = self.norm_conv(x)

        # feed forward module
        residual = x
        if self.normalize_before:
            x = self.norm_ff(x)

        x = residual + self.ff_scale * self.dropout(self.feed_forward(x))
        if not self.normalize_before:
            x = self.norm_ff(x)

        if self.conv_module is not None:
            x = self.norm_final(x)

        return x, mask, new_att_cache, new_cnn_cache