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.rel.rules;
  
  import org.apache.calcite.linq4j.Ord;
  import org.apache.calcite.plan.Convention;
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.AbstractRelNode;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.RelWriter;
  import org.apache.calcite.rel.core.JoinRelType;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.rex.RexShuttle;
  import org.apache.calcite.util.ImmutableBitSet;
  import org.apache.calcite.util.ImmutableIntList;
  import org.apache.calcite.util.ImmutableNullableList;
  
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableMap;
  import com.google.common.collect.Lists;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A MultiJoin represents a join of N inputs, whereas regular Joins
   * represent strictly binary joins.
   */
  public final class MultiJoin extends AbstractRelNode {
    //~ Instance fields --------------------------------------------------------
  
    private final List<RelNode> inputs;
    private final RexNode joinFilter;
    @SuppressWarnings("HidingField")
    private final RelDataType rowType;
    private final boolean isFullOuterJoin;
    private final List<@Nullable RexNode> outerJoinConditions;
    private final ImmutableList<JoinRelType> joinTypes;
    private final List<@Nullable ImmutableBitSet> projFields;
    public final ImmutableMap<Integer, ImmutableIntList> joinFieldRefCountsMap;
    private final @Nullable RexNode postJoinFilter;
  
    //~ Constructors -----------------------------------------------------------
  
    /**
     * Constructs a MultiJoin.
     *
     * @param cluster               cluster that join belongs to
     * @param inputs                inputs into this multi-join
     * @param joinFilter            join filter applicable to this join node
     * @param rowType               row type of the join result of this node
     * @param isFullOuterJoin       true if the join is a full outer join
     * @param outerJoinConditions   outer join condition associated with each join
     *                              input, if the input is null-generating in a
     *                              left or right outer join; null otherwise
     * @param joinTypes             the join type corresponding to each input; if
     *                              an input is null-generating in a left or right
     *                              outer join, the entry indicates the type of
     *                              outer join; otherwise, the entry is set to
     *                              INNER
     * @param projFields            fields that will be projected from each input;
     *                              if null, projection information is not
     *                              available yet so it's assumed that all fields
     *                              from the input are projected
     * @param joinFieldRefCountsMap counters of the number of times each field
     *                              is referenced in join conditions, indexed by
     *                              the input #
     * @param postJoinFilter        filter to be applied after the joins are
     */
    public MultiJoin(
        RelOptCluster cluster,
        List<RelNode> inputs,
        RexNode joinFilter,
        RelDataType rowType,
        boolean isFullOuterJoin,
        List<? extends @Nullable RexNode> outerJoinConditions,
        List<JoinRelType> joinTypes,
        List<? extends @Nullable ImmutableBitSet> projFields,
        ImmutableMap<Integer, ImmutableIntList> joinFieldRefCountsMap,
        @Nullable RexNode postJoinFilter) {
      super(cluster, cluster.traitSetOf(Convention.NONE));
      this.inputs = Lists.newArrayList(inputs);
      this.joinFilter = joinFilter;
      this.rowType = rowType;
      this.isFullOuterJoin = isFullOuterJoin;
      this.outerJoinConditions =
          ImmutableNullableList.copyOf(outerJoinConditions);
      assert outerJoinConditions.size() == inputs.size();
      this.joinTypes = ImmutableList.copyOf(joinTypes);
      this.projFields = ImmutableNullableList.copyOf(projFields);
      this.joinFieldRefCountsMap = joinFieldRefCountsMap;
      this.postJoinFilter = postJoinFilter;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void replaceInput(int ordinalInParent, RelNode p) {
      inputs.set(ordinalInParent, p);
      recomputeDigest();
    }
  
    @Override public RelNode copy(RelTraitSet traitSet, List<RelNode> inputs) {
      assert traitSet.containsIfApplicable(Convention.NONE);
      return new MultiJoin(
          getCluster(),
          inputs,
          joinFilter,
          rowType,
          isFullOuterJoin,
          outerJoinConditions,
          joinTypes,
          projFields,
          joinFieldRefCountsMap,
          postJoinFilter);
    }
  
    /**
     * Returns a deep copy of {@link #joinFieldRefCountsMap}.
     */
    private Map<Integer, int[]> cloneJoinFieldRefCountsMap() {
      Map<Integer, int[]> clonedMap = new HashMap<>();
      for (int i = 0; i < inputs.size(); i++) {
        clonedMap.put(i, requireNonNull(joinFieldRefCountsMap.get(i)).toIntArray());
      }
      return clonedMap;
    }
  
    @Override public RelWriter explainTerms(RelWriter pw) {
      List<String> joinTypeNames = new ArrayList<>();
      List<String> outerJoinConds = new ArrayList<>();
      List<String> projFieldObjects = new ArrayList<>();
      for (int i = 0; i < inputs.size(); i++) {
        joinTypeNames.add(joinTypes.get(i).name());
        RexNode outerJoinCondition = outerJoinConditions.get(i);
        if (outerJoinCondition == null) {
          outerJoinConds.add("NULL");
        } else {
          outerJoinConds.add(outerJoinCondition.toString());
        }
        ImmutableBitSet projField = projFields.get(i);
        if (projField == null) {
          projFieldObjects.add("ALL");
        } else {
          projFieldObjects.add(projField.toString());
        }
      }
  
      super.explainTerms(pw);
      for (Ord<RelNode> ord : Ord.zip(inputs)) {
        pw.input("input#" + ord.i, ord.e);
      }
      return pw.item("joinFilter", joinFilter)
          .item("isFullOuterJoin", isFullOuterJoin)
          .item("joinTypes", joinTypeNames)
          .item("outerJoinConditions", outerJoinConds)
          .item("projFields", projFieldObjects)
          .itemIf("postJoinFilter", postJoinFilter, postJoinFilter != null);
    }
  
    @Override public RelDataType deriveRowType() {
      return rowType;
    }
  
    @Override public List<RelNode> getInputs() {
      return inputs;
    }
  
    @Override public RelNode accept(RexShuttle shuttle) {
      RexNode joinFilter = shuttle.apply(this.joinFilter);
      List<@Nullable RexNode> outerJoinConditions = shuttle.apply(this.outerJoinConditions);
      RexNode postJoinFilter = shuttle.apply(this.postJoinFilter);
  
      if (joinFilter == this.joinFilter
          && outerJoinConditions == this.outerJoinConditions
          && postJoinFilter == this.postJoinFilter) {
        return this;
      }
  
      return new MultiJoin(
          getCluster(),
          inputs,
          joinFilter,
          rowType,
          isFullOuterJoin,
          outerJoinConditions,
          joinTypes,
          projFields,
          joinFieldRefCountsMap,
          postJoinFilter);
    }
  
    /**
     * Returns join filters associated with this MultiJoin.
     */
    public RexNode getJoinFilter() {
      return joinFilter;
    }
  
    /**
     * Returns true if the MultiJoin corresponds to a full outer join.
     */
    public boolean isFullOuterJoin() {
      return isFullOuterJoin;
    }
  
    /**
     * Returns outer join conditions for null-generating inputs.
     */
    public List<@Nullable RexNode> getOuterJoinConditions() {
      return outerJoinConditions;
    }
  
    /**
     * Returns join types of each input.
     */
    public List<JoinRelType> getJoinTypes() {
      return joinTypes;
    }
  
    /**
     * Returns bitmaps representing the fields projected from each input; if an
     * entry is null, all fields are projected.
     */
    public List<@Nullable ImmutableBitSet> getProjFields() {
      return projFields;
    }
  
    /**
     * Returns the map of reference counts for each input, representing the fields
     * accessed in join conditions.
     */
    public ImmutableMap<Integer, ImmutableIntList> getJoinFieldRefCountsMap() {
      return joinFieldRefCountsMap;
    }
  
    /**
     * Returns a copy of the map of reference counts for each input, representing
     * the fields accessed in join conditions.
     */
    public Map<Integer, int[]> getCopyJoinFieldRefCountsMap() {
      return cloneJoinFieldRefCountsMap();
    }
  
    /**
     * Returns post-join filter associated with this MultiJoin.
     */
    public @Nullable RexNode getPostJoinFilter() {
      return postJoinFilter;
    }
  
    boolean containsOuter() {
      for (JoinRelType joinType : joinTypes) {
        if (joinType.isOuterJoin()) {
          return true;
        }
      }
      return false;
    }
  }
  