ParameterDeque.py

class ParameterDeque(nn.Module):
    def __init__(self) -> None:
        super(ParameterDeque, self).__init__()
        self.left = 0
        self.right = 0 # Points at the first non-existing element

    def _convert_idx(self, idx):
        """Get the absolute index for the list of modules"""
        idx = operator.index(idx)
        if not (-len(self) <= idx < len(self)):
            raise IndexError('index {} is out of range'.format(idx))
        if idx < 0:
            idx += len(self)
        idx += self.left
        return str(idx)

    def __getitem__(self, idx):
        return self._parameters[self._convert_idx(idx)]

    def __setitem__(self, idx: int, param):
        self._parameters[self._convert_idx(idx)] = param

    def append(self, param):
        self._parameters[str(self.right)] = param
        self.right += 1

    def __len__(self) -> int:
        return self.right - self.left

    def __iter__(self):
        return (self._parameters[i] for i in range(self.left, self.right))

    def __delitem__(self, idx):
        sidx = self._convert_idx(idx)
        if sidx == str(self.left):
            self._parameters[sidx] = None
            self.left += 1
        elif sidx == str(self.right-1):
            self.right -= 1
        else:
            raise IndexError('Can only delete from front and back.')