/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * 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.facebook.buck.core.rules.platform;

import com.facebook.buck.core.exceptions.DependencyStack;
import com.facebook.buck.core.model.BuildTarget;
import com.facebook.buck.core.model.platform.Platform;
import com.facebook.buck.core.model.platform.PlatformResolver;
import java.util.concurrent.ConcurrentHashMap;

/**
 * An implementation of {@link PlatformResolver} that caches platforms created by a given delegate.
 */
public class CachingPlatformResolver implements PlatformResolver {

  private final PlatformResolver delegate;

  private final ConcurrentHashMap<BuildTarget, Platform> platformCache = new ConcurrentHashMap<>();

  public CachingPlatformResolver(PlatformResolver delegate) {
    this.delegate = delegate;
  }

  @Override
  public Platform getPlatform(BuildTarget buildTarget, DependencyStack dependencyStack) {
    return platformCache.computeIfAbsent(
        buildTarget, t -> delegate.getPlatform(t, dependencyStack));
  }
}
