// 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.skyframe;

import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyFunctionException;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;

/**
 * Builder for {@link PrecomputedValue}s.
 *
 * <p>Always throws an error, because the values aren't computed inside the skyframe framework.
 */
public class PrecomputedFunction implements SkyFunction {

  @Override
  public SkyValue compute(SkyKey skyKey, Environment env) throws SkyFunctionException,
      InterruptedException {
    throw new IllegalStateException(skyKey + " not set");
  }

  @Override
  public String extractTag(SkyKey skyKey) {
    return null;
  }
}