# Copyright (c) OpenMMLab. All rights reserved.
import torch

from mmpretrain.registry import MODELS
from .base_head import BaseHead


@MODELS.register_module()
class SwAVHead(BaseHead):
    """Head for SwAV.

    Args:
        loss (dict): Config dict for module of loss functions.
    """

    def __init__(self, loss: dict) -> None:
        super().__init__()
        self.loss_module = MODELS.build(loss)

    def loss(self, pred: torch.Tensor) -> torch.Tensor:
        """Forward function of SwAV head.

        Args:
            pred (torch.Tensor): NxC input features.

        Returns:
            torch.Tensor: The SwAV loss.
        """
        loss = self.loss_module(pred)

        return loss