Source code for libai.layers.activation

# coding=utf-8
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#     http://www.apache.org/licenses/LICENSE-2.0
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from enum import Enum
from typing import Optional

import oneflow as flow
from oneflow import nn


class Activation(str, Enum):
    SquaredReLU = "squared_relu"
    GeLU = "gelu"
    LeakyReLU = "leaky_relu"
    ReLU = "relu"
    Tanh = "tanh"


# For unit testing / parity comparisons, probably not the fastest way
class SquaredReLU(nn.Module):
    def __init__(self) -> None:
        super().__init__()

    def forward(self, x: flow.Tensor) -> flow.Tensor:
        x_ = flow._C.relu(x)
        return x_ * x_


class Passthrough(nn.Module):
    def __init__(self) -> None:
        super().__init__()

    def forward(self, x: flow.Tensor) -> flow.Tensor:
        return x


def build_activation(activation: Optional[Activation]):
    """
    Fetching activation layers by name, e.g.,
    ``build_activation("gelu")`` returns ``nn.GELU()`` module.
    """
    if not activation:
        return Passthrough()

    return {
        Activation.ReLU: nn.ReLU,
        Activation.GeLU: nn.GELU,
        Activation.LeakyReLU: nn.LeakyReLU,
        Activation.SquaredReLU: SquaredReLU,
        Activation.Tanh: nn.Tanh,
    }[activation]()