pig/src/main/java/org/apache/calcite/adapter/pig/PigRelFactories.java

/*
 * 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 org.apache.calcite.adapter.pig;

import org.apache.calcite.plan.Context;
import org.apache.calcite.plan.Contexts;
import org.apache.calcite.plan.RelOptCluster;
import org.apache.calcite.plan.RelOptTable;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.AggregateCall;
import org.apache.calcite.rel.core.CorrelationId;
import org.apache.calcite.rel.core.JoinRelType;
import org.apache.calcite.rel.core.RelFactories;
import org.apache.calcite.rel.hint.RelHint;
import org.apache.calcite.rex.RexNode;
import org.apache.calcite.util.ImmutableBitSet;
import org.apache.calcite.util.Util;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;

import java.util.List;
import java.util.Set;

/** Implementations of factories in {@link RelFactories}
 * for the Pig adapter. */
public class PigRelFactories {

  public static final Context ALL_PIG_REL_FACTORIES =
      Contexts.of(PigTableScanFactory.INSTANCE,
          PigFilterFactory.INSTANCE,
          PigAggregateFactory.INSTANCE,
          PigJoinFactory.INSTANCE);

  // prevent instantiation
  private PigRelFactories() {
  }

  /**
   * Implementation of
   * {@link org.apache.calcite.rel.core.RelFactories.TableScanFactory} that
   * returns a {@link PigTableScan}.
   */
  public static class PigTableScanFactory implements RelFactories.TableScanFactory {

    public static final PigTableScanFactory INSTANCE = new PigTableScanFactory();

    @Override public RelNode createScan(RelOptTable.ToRelContext toRelContext,
        RelOptTable table) {
      final RelOptCluster cluster = toRelContext.getCluster();
      return new PigTableScan(cluster, cluster.traitSetOf(PigRel.CONVENTION), table);
    }
  }

  /**
   * Implementation of
   * {@link org.apache.calcite.rel.core.RelFactories.FilterFactory} that
   * returns a {@link PigFilter}.
   */
  public static class PigFilterFactory implements RelFactories.FilterFactory {

    public static final PigFilterFactory INSTANCE = new PigFilterFactory();

    @Override public RelNode createFilter(RelNode input, RexNode condition,
        Set<CorrelationId> variablesSet) {
      Preconditions.checkArgument(variablesSet.isEmpty(),
          "PigFilter does not allow variables");
      final RelTraitSet traitSet =
          input.getTraitSet().replace(PigRel.CONVENTION);
      return new PigFilter(input.getCluster(), traitSet, input, condition);
    }
  }

  /**
   * Implementation of
   * {@link org.apache.calcite.rel.core.RelFactories.AggregateFactory} that
   * returns a {@link PigAggregate}.
   */
  public static class PigAggregateFactory implements RelFactories.AggregateFactory {

    public static final PigAggregateFactory INSTANCE = new PigAggregateFactory();

    @Override public RelNode createAggregate(RelNode input,
        List<RelHint> hints,
        ImmutableBitSet groupSet, ImmutableList<ImmutableBitSet> groupSets,
        List<AggregateCall> aggCalls) {
      Util.discard(hints);
      return new PigAggregate(input.getCluster(), input.getTraitSet(), input,
          groupSet, groupSets, aggCalls);
    }
  }

  /**
   * Implementation of
   * {@link org.apache.calcite.rel.core.RelFactories.JoinFactory} that
   * returns a {@link PigJoin}.
   */
  public static class PigJoinFactory implements RelFactories.JoinFactory {

    public static final PigJoinFactory INSTANCE = new PigJoinFactory();

    @Override public RelNode createJoin(RelNode left, RelNode right, List<RelHint> hints,
        RexNode condition, Set<CorrelationId> variablesSet, JoinRelType joinType,
        boolean semiJoinDone) {
      Util.discard(hints);
      Util.discard(variablesSet);
      Util.discard(semiJoinDone);
      return new PigJoin(left.getCluster(), left.getTraitSet(), left, right, condition, joinType);
    }
  }
}