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SQL Parser and Optimizer
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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 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.hazelcast.org.apache.calcite.adapter.enumerable;

import com.hazelcast.org.apache.calcite.linq4j.tree.BlockStatement;
import com.hazelcast.org.apache.calcite.plan.DeriveMode;
import com.hazelcast.org.apache.calcite.plan.RelTraitSet;
import com.hazelcast.org.apache.calcite.rel.PhysicalNode;
import com.hazelcast.org.apache.calcite.util.Pair;

import com.hazelcast.org.checkerframework.checker.nullness.qual.Nullable;

import java.util.List;

/**
 * A relational expression of one of the
 * {@link com.hazelcast.org.apache.calcite.adapter.enumerable.EnumerableConvention} calling
 * conventions.
 */
public interface EnumerableRel
    extends PhysicalNode {

  //~ Methods ----------------------------------------------------------------

  @Override default @Nullable Pair> passThroughTraits(
      RelTraitSet required) {
    return null;
  }

  @Override default @Nullable Pair> deriveTraits(
      RelTraitSet childTraits, int childId) {
    return null;
  }

  @Override default DeriveMode getDeriveMode() {
    return DeriveMode.LEFT_FIRST;
  }

  /**
   * Creates a plan for this expression according to a calling convention.
   *
   * @param implementor Implementor
   * @param pref Preferred representation for rows in result expression
   * @return Plan for this expression according to a calling convention
   */
  Result implement(EnumerableRelImplementor implementor, Prefer pref);

  /** Preferred physical type. */
  enum Prefer {
    /** Records must be represented as arrays. */
    ARRAY,
    /** Consumer would prefer that records are represented as arrays, but can
     * accommodate records represented as objects. */
    ARRAY_NICE,
    /** Records must be represented as objects. */
    CUSTOM,
    /** Consumer would prefer that records are represented as objects, but can
     * accommodate records represented as arrays. */
    CUSTOM_NICE,
    /** Consumer has no preferred representation. */
    ANY;

    public JavaRowFormat preferCustom() {
      return prefer(JavaRowFormat.CUSTOM);
    }

    public JavaRowFormat preferArray() {
      return prefer(JavaRowFormat.ARRAY);
    }

    public JavaRowFormat prefer(JavaRowFormat format) {
      switch (this) {
      case CUSTOM:
        return JavaRowFormat.CUSTOM;
      case ARRAY:
        return JavaRowFormat.ARRAY;
      default:
        return format;
      }
    }

    public Prefer of(JavaRowFormat format) {
      switch (format) {
      case ARRAY:
        return ARRAY;
      default:
        return CUSTOM;
      }
    }
  }

  /** Result of implementing an enumerable relational expression by generating
   * Java code. */
  class Result {
    public final BlockStatement block;

    /**
     * Describes the Java type returned by this relational expression, and the
     * mapping between it and the fields of the logical row type.
     */
    public final PhysType physType;
    public final JavaRowFormat format;

    public Result(BlockStatement block, PhysType physType,
        JavaRowFormat format) {
      this.block = block;
      this.physType = physType;
      this.format = format;
    }
  }
}