content: /*
   * 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.collect.ImmutableList;
  
  import java.util.List;
  import java.util.Set;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  /** 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) {
        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);
      }
    }
  }
  