File size: 11,299 Bytes
29a229f
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
from inspect import isfunction
from typing import Callable, Optional

import torch
from einops import rearrange
from einops.layers.torch import Rearrange
from torch import nn

from .t_cond_mlp import (
    AdaptiveLayerNorm1D,
    FrequencyEmbedder,
    normalization_layer,
)
# from .vit import Attention, FeedForward


def exists(val):
    return val is not None


def default(val, d):
    if exists(val):
        return val
    return d() if isfunction(d) else d


class PreNorm(nn.Module):
    def __init__(self, dim: int, fn: Callable, norm: str = "layer", norm_cond_dim: int = -1):
        super().__init__()
        self.norm = normalization_layer(norm, dim, norm_cond_dim)
        self.fn = fn

    def forward(self, x: torch.Tensor, *args, **kwargs):
        if isinstance(self.norm, AdaptiveLayerNorm1D):
            return self.fn(self.norm(x, *args), **kwargs)
        else:
            return self.fn(self.norm(x), **kwargs)


class FeedForward(nn.Module):
    def __init__(self, dim, hidden_dim, dropout=0.0):
        super().__init__()
        self.net = nn.Sequential(
            nn.Linear(dim, hidden_dim),
            nn.GELU(),
            nn.Dropout(dropout),
            nn.Linear(hidden_dim, dim),
            nn.Dropout(dropout),
        )

    def forward(self, x):
        return self.net(x)


class Attention(nn.Module):
    def __init__(self, dim, heads=8, dim_head=64, dropout=0.0):
        super().__init__()
        inner_dim = dim_head * heads
        project_out = not (heads == 1 and dim_head == dim)

        self.heads = heads
        self.scale = dim_head**-0.5

        self.attend = nn.Softmax(dim=-1)
        self.dropout = nn.Dropout(dropout)

        self.to_qkv = nn.Linear(dim, inner_dim * 3, bias=False)

        self.to_out = (
            nn.Sequential(nn.Linear(inner_dim, dim), nn.Dropout(dropout))
            if project_out
            else nn.Identity()
        )

    def forward(self, x):
        qkv = self.to_qkv(x).chunk(3, dim=-1)
        q, k, v = map(lambda t: rearrange(t, "b n (h d) -> b h n d", h=self.heads), qkv)

        dots = torch.matmul(q, k.transpose(-1, -2)) * self.scale

        attn = self.attend(dots)
        attn = self.dropout(attn)

        out = torch.matmul(attn, v)
        out = rearrange(out, "b h n d -> b n (h d)")
        return self.to_out(out)


class CrossAttention(nn.Module):
    def __init__(self, dim, context_dim=None, heads=8, dim_head=64, dropout=0.0):
        super().__init__()
        inner_dim = dim_head * heads
        project_out = not (heads == 1 and dim_head == dim)

        self.heads = heads
        self.scale = dim_head**-0.5

        self.attend = nn.Softmax(dim=-1)
        self.dropout = nn.Dropout(dropout)

        context_dim = default(context_dim, dim)
        self.to_kv = nn.Linear(context_dim, inner_dim * 2, bias=False)
        self.to_q = nn.Linear(dim, inner_dim, bias=False)

        self.to_out = (
            nn.Sequential(nn.Linear(inner_dim, dim), nn.Dropout(dropout))
            if project_out
            else nn.Identity()
        )

    def forward(self, x, context=None):
        context = default(context, x)
        k, v = self.to_kv(context).chunk(2, dim=-1)
        q = self.to_q(x)
        q, k, v = map(lambda t: rearrange(t, "b n (h d) -> b h n d", h=self.heads), [q, k, v])

        dots = torch.matmul(q, k.transpose(-1, -2)) * self.scale

        attn = self.attend(dots)
        attn = self.dropout(attn)

        out = torch.matmul(attn, v)
        out = rearrange(out, "b h n d -> b n (h d)")
        return self.to_out(out)


class Transformer(nn.Module):
    def __init__(
        self,
        dim: int,
        depth: int,
        heads: int,
        dim_head: int,
        mlp_dim: int,
        dropout: float = 0.0,
        norm: str = "layer",
        norm_cond_dim: int = -1,
    ):
        super().__init__()
        self.layers = nn.ModuleList([])
        for _ in range(depth):
            sa = Attention(dim, heads=heads, dim_head=dim_head, dropout=dropout)
            ff = FeedForward(dim, mlp_dim, dropout=dropout)
            self.layers.append(
                nn.ModuleList(
                    [
                        PreNorm(dim, sa, norm=norm, norm_cond_dim=norm_cond_dim),
                        PreNorm(dim, ff, norm=norm, norm_cond_dim=norm_cond_dim),
                    ]
                )
            )

    def forward(self, x: torch.Tensor, *args):
        for attn, ff in self.layers:
            x = attn(x, *args) + x
            x = ff(x, *args) + x
        return x


class TransformerCrossAttn(nn.Module):
    def __init__(
        self,
        dim: int,
        depth: int,
        heads: int,
        dim_head: int,
        mlp_dim: int,
        dropout: float = 0.0,
        norm: str = "layer",
        norm_cond_dim: int = -1,
        context_dim: Optional[int] = None,
    ):
        super().__init__()
        self.layers = nn.ModuleList([])
        for _ in range(depth):
            sa = Attention(dim, heads=heads, dim_head=dim_head, dropout=dropout)
            ca = CrossAttention(
                dim, context_dim=context_dim, heads=heads, dim_head=dim_head, dropout=dropout
            )
            ff = FeedForward(dim, mlp_dim, dropout=dropout)
            self.layers.append(
                nn.ModuleList(
                    [
                        PreNorm(dim, sa, norm=norm, norm_cond_dim=norm_cond_dim),
                        PreNorm(dim, ca, norm=norm, norm_cond_dim=norm_cond_dim),
                        PreNorm(dim, ff, norm=norm, norm_cond_dim=norm_cond_dim),
                    ]
                )
            )

    def forward(self, x: torch.Tensor, *args, context=None, context_list=None):
        if context_list is None:
            context_list = [context] * len(self.layers)
        if len(context_list) != len(self.layers):
            raise ValueError(f"len(context_list) != len(self.layers) ({len(context_list)} != {len(self.layers)})")

        for i, (self_attn, cross_attn, ff) in enumerate(self.layers):
            x = self_attn(x, *args) + x
            x = cross_attn(x, *args, context=context_list[i]) + x
            x = ff(x, *args) + x
        return x


class DropTokenDropout(nn.Module):
    def __init__(self, p: float = 0.1):
        super().__init__()
        if p < 0 or p > 1:
            raise ValueError(
                "dropout probability has to be between 0 and 1, " "but got {}".format(p)
            )
        self.p = p

    def forward(self, x: torch.Tensor):
        # x: (batch_size, seq_len, dim)
        if self.training and self.p > 0:
            zero_mask = torch.full_like(x[0, :, 0], self.p).bernoulli().bool()
            # TODO: permutation idx for each batch using torch.argsort
            if zero_mask.any():
                x = x[:, ~zero_mask, :]
        return x


class ZeroTokenDropout(nn.Module):
    def __init__(self, p: float = 0.1):
        super().__init__()
        if p < 0 or p > 1:
            raise ValueError(
                "dropout probability has to be between 0 and 1, " "but got {}".format(p)
            )
        self.p = p

    def forward(self, x: torch.Tensor):
        # x: (batch_size, seq_len, dim)
        if self.training and self.p > 0:
            zero_mask = torch.full_like(x[:, :, 0], self.p).bernoulli().bool()
            # Zero-out the masked tokens
            x[zero_mask, :] = 0
        return x


class TransformerEncoder(nn.Module):
    def __init__(
        self,
        num_tokens: int,
        token_dim: int,
        dim: int,
        depth: int,
        heads: int,
        mlp_dim: int,
        dim_head: int = 64,
        dropout: float = 0.0,
        emb_dropout: float = 0.0,
        emb_dropout_type: str = "drop",
        emb_dropout_loc: str = "token",
        norm: str = "layer",
        norm_cond_dim: int = -1,
        token_pe_numfreq: int = -1,
    ):
        super().__init__()
        if token_pe_numfreq > 0:
            token_dim_new = token_dim * (2 * token_pe_numfreq + 1)
            self.to_token_embedding = nn.Sequential(
                Rearrange("b n d -> (b n) d", n=num_tokens, d=token_dim),
                FrequencyEmbedder(token_pe_numfreq, token_pe_numfreq - 1),
                Rearrange("(b n) d -> b n d", n=num_tokens, d=token_dim_new),
                nn.Linear(token_dim_new, dim),
            )
        else:
            self.to_token_embedding = nn.Linear(token_dim, dim)
        self.pos_embedding = nn.Parameter(torch.randn(1, num_tokens, dim))
        if emb_dropout_type == "drop":
            self.dropout = DropTokenDropout(emb_dropout)
        elif emb_dropout_type == "zero":
            self.dropout = ZeroTokenDropout(emb_dropout)
        else:
            raise ValueError(f"Unknown emb_dropout_type: {emb_dropout_type}")
        self.emb_dropout_loc = emb_dropout_loc

        self.transformer = Transformer(
            dim, depth, heads, dim_head, mlp_dim, dropout, norm=norm, norm_cond_dim=norm_cond_dim
        )

    def forward(self, inp: torch.Tensor, *args, **kwargs):
        x = inp

        if self.emb_dropout_loc == "input":
            x = self.dropout(x)
        x = self.to_token_embedding(x)

        if self.emb_dropout_loc == "token":
            x = self.dropout(x)
        b, n, _ = x.shape
        x += self.pos_embedding[:, :n]

        if self.emb_dropout_loc == "token_afterpos":
            x = self.dropout(x)
        x = self.transformer(x, *args)
        return x


class TransformerDecoder(nn.Module):
    def __init__(
        self,
        num_tokens: int,
        token_dim: int,
        dim: int,
        depth: int,
        heads: int,
        mlp_dim: int,
        dim_head: int = 64,
        dropout: float = 0.0,
        emb_dropout: float = 0.0,
        emb_dropout_type: str = 'drop',
        norm: str = "layer",
        norm_cond_dim: int = -1,
        context_dim: Optional[int] = None,
        skip_token_embedding: bool = False,
    ):
        super().__init__()
        if not skip_token_embedding:
            self.to_token_embedding = nn.Linear(token_dim, dim)
        else:
            self.to_token_embedding = nn.Identity()
            if token_dim != dim:
                raise ValueError(
                    f"token_dim ({token_dim}) != dim ({dim}) when skip_token_embedding is True"
                )

        self.pos_embedding = nn.Parameter(torch.randn(1, num_tokens, dim))
        if emb_dropout_type == "drop":
            self.dropout = DropTokenDropout(emb_dropout)
        elif emb_dropout_type == "zero":
            self.dropout = ZeroTokenDropout(emb_dropout)
        elif emb_dropout_type == "normal":
            self.dropout = nn.Dropout(emb_dropout)

        self.transformer = TransformerCrossAttn(
            dim,
            depth,
            heads,
            dim_head,
            mlp_dim,
            dropout,
            norm=norm,
            norm_cond_dim=norm_cond_dim,
            context_dim=context_dim,
        )

    def forward(self, inp: torch.Tensor, *args, context=None, context_list=None):
        x = self.to_token_embedding(inp)
        b, n, _ = x.shape

        x = self.dropout(x)
        x += self.pos_embedding[:, :n]

        x = self.transformer(x, *args, context=context, context_list=context_list)
        return x