chore: import upstream snapshot with attribution

2026-07-13 13:24:13 +08:00
commit 1037506f2e
6050 changed files with 1731598 additions and 0 deletions
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+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import torch.nn as nn
+
+from .learned_positional_embedding import LearnedPositionalEmbedding
+from .sinusoidal_positional_embedding import SinusoidalPositionalEmbedding
+
+
+def PositionalEmbedding(
+    num_embeddings: int,
+    embedding_dim: int,
+    padding_idx: int,
+    learned: bool = False,
+):
+    if learned:
+        # if padding_idx is specified then offset the embedding ids by
+        # this index and adjust num_embeddings appropriately
+        # TODO: The right place for this offset would be inside
+        # LearnedPositionalEmbedding. Move this there for a cleaner implementation.
+        if padding_idx is not None:
+            num_embeddings = num_embeddings + padding_idx + 1
+        m = LearnedPositionalEmbedding(num_embeddings, embedding_dim, padding_idx)
+        nn.init.normal_(m.weight, mean=0, std=embedding_dim ** -0.5)
+        if padding_idx is not None:
+            nn.init.constant_(m.weight[padding_idx], 0)
+    else:
+        m = SinusoidalPositionalEmbedding(
+            embedding_dim,
+            padding_idx,
+            init_size=num_embeddings + padding_idx + 1,
+        )
+    return m