# Copyright 2020 Xilinx Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Module for the RemoveUnusedOperators pass"""


from ..passing import XGraphMutator

from .. import XGraph
from ..layer.xlayer import defaultXLayer, XLayer


class RemoveUnusedOps(XGraphMutator):
    """Remove unused operators"""

    def __init__(self):
        super().__init__()

    def visit(self, X: XLayer) -> XLayer:
        if len(X.bottoms) == 0 and len(X.tops) == 0:
            return None
        return super().visit(X)
