com.hazelcast.org.apache.calcite.rel.metadata.MetadataDef Maven / Gradle / Ivy

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in com.hazelcast.com.liance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.com.hazelcast.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.hazelcast.org.apache.calcite.rel.metadata;

import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.util.Pair;

import com.hazelcast.com.google.com.hazelcast.com.on.collect.ImmutableList;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;

/**
 * Definition of metadata.
 *
 * @param  Kind of metadata
 */
public class MetadataDef {
  public final Class metadataClass;
  public final Class> handlerClass;
  public final ImmutableList methods;

  private MetadataDef(Class metadataClass,
      Class> handlerClass, Method... methods) {
    this.metadataClass = metadataClass;
    this.handlerClass = handlerClass;
    this.methods = ImmutableList.copyOf(methods);
    final Method[] handlerMethods = handlerClass.getDeclaredMethods();

    // Handler must have the same methods as Metadata, each method having
    // additional "subclass-of-RelNode, RelMetadataQuery" parameters.
    assert handlerMethods.length == methods.length;
    for (Pair pair : Pair.zip(methods, handlerMethods)) {
      final List> leftTypes =
          Arrays.asList(pair.left.getParameterTypes());
      final List> rightTypes =
          Arrays.asList(pair.right.getParameterTypes());
      assert leftTypes.size() + 2 == rightTypes.size();
      assert RelNode.class.isAssignableFrom(rightTypes.get(0));
      assert RelMetadataQuery.class == rightTypes.get(1);
      assert leftTypes.equals(rightTypes.subList(2, rightTypes.size()));
    }
  }

  /** Creates a {@link com.hazelcast.org.apache.calcite.rel.metadata.MetadataDef}. */
  public static  MetadataDef of(Class metadataClass,
      Class> handlerClass, Method... methods) {
    return new MetadataDef<>(metadataClass, handlerClass, methods);
  }
}