src/main/java/com/google/devtools/build/lib/skyframe/serialization/DeserializationContext.java


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// Copyright 2018 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.serialization;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.protobuf.CodedInputStream;
import java.io.IOException;

/** Stateful class for providing additional context to a single deserialization "session". */
// TODO(bazel-team): This class is just a shell, fill in.
public class DeserializationContext {

  private final ObjectCodecRegistry registry;
  private final ImmutableMap<Class<?>, Object> dependencies;

  public DeserializationContext(
      ObjectCodecRegistry registry, ImmutableMap<Class<?>, Object> dependencies) {
    this.registry = registry;
    this.dependencies = dependencies;
  }

  public DeserializationContext(ImmutableMap<Class<?>, Object> dependencies) {
    this(AutoRegistry.get(), dependencies);
  }

  // TODO(shahan): consider making codedIn a member of this class.
  @SuppressWarnings({"TypeParameterUnusedInFormals", "unchecked"})
  public <T> T deserialize(CodedInputStream codedIn) throws IOException, SerializationException {
    int tag = codedIn.readSInt32();
    if (tag == 0) {
      return null;
    }
    return (T) registry.getCodecDescriptorByTag(tag).deserialize(this, codedIn);
  }

  @SuppressWarnings("unchecked")
  public <T> T getDependency(Class<T> type) {
    Preconditions.checkNotNull(type);
    return (T) dependencies.get(type);
  }
}