// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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.
package com.google.devtools.build.lib.actions;

import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.SerializationConstant;
import javax.annotation.Nullable;

/**
 * An interface for {@code ActionLookupKey}, or at least for a {@link Label}. Only tests and
 * internal {@link Artifact}-generators should implement this interface -- otherwise, {@code
 * ActionLookupKey} and its subclasses should be the only implementation.
 */
public interface ArtifactOwner {

  @Nullable
  Label getLabel();

  /**
   * An {@link ArtifactOwner} that just returns null for its label. Only for use with resolved
   * source artifacts and tests.
   */
  @SerializationConstant
  ArtifactOwner NULL_OWNER =
      new ArtifactOwner() {
        @Override
        public Label getLabel() {
          return null;
        }

        @Override
        public String toString() {
          return "NULL_OWNER";
        }
      };
}
