* 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.
package org.apache.calcite.rel.core;

import org.apache.calcite.plan.RelOptUtil;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rex.RexBuilder;
import org.apache.calcite.rex.RexNode;
import org.apache.calcite.rex.RexUtil;
import org.apache.calcite.runtime.FlatLists;
import org.apache.calcite.util.ImmutableBitSet;
import org.apache.calcite.util.ImmutableIntList;
import org.apache.calcite.util.mapping.IntPair;

import com.google.common.collect.ImmutableList;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

/** An analyzed join condition.
 * <p>It is useful for the many algorithms that care whether a join has an
 * equi-join condition.
 * <p>You can create one using {@link #of}, or call
 * {@link Join#analyzeCondition()}; many kinds of join cache their
 * join info, especially those that are equi-joins.</p>
 * @see Join#analyzeCondition() */
public class JoinInfo {
  public final ImmutableIntList leftKeys;
  public final ImmutableIntList rightKeys;
  public final ImmutableList<RexNode> nonEquiConditions;

  /** Creates a JoinInfo. */
  protected JoinInfo(ImmutableIntList leftKeys, ImmutableIntList rightKeys,
      ImmutableList<RexNode> nonEquiConditions) {
    this.leftKeys = Objects.requireNonNull(leftKeys);
    this.rightKeys = Objects.requireNonNull(rightKeys);
    this.nonEquiConditions = Objects.requireNonNull(nonEquiConditions);
    assert leftKeys.size() == rightKeys.size();

  /** Creates a {@code JoinInfo} by analyzing a condition. */
  public static JoinInfo of(RelNode left, RelNode right, RexNode condition) {
    final List<Integer> leftKeys = new ArrayList<>();
    final List<Integer> rightKeys = new ArrayList<>();
    final List<Boolean> filterNulls = new ArrayList<>();
    final List<RexNode> nonEquiList = new ArrayList<>();
    RelOptUtil.splitJoinCondition(left, right, condition, leftKeys, rightKeys,
        filterNulls, nonEquiList);
    return new JoinInfo(ImmutableIntList.copyOf(leftKeys),
        ImmutableIntList.copyOf(rightKeys), ImmutableList.copyOf(nonEquiList));

  /** Creates an equi-join. */
  public static JoinInfo of(ImmutableIntList leftKeys,
      ImmutableIntList rightKeys) {
    return new JoinInfo(leftKeys, rightKeys, ImmutableList.of());

  /** Returns whether this is an equi-join. */
  public boolean isEqui() {
    return nonEquiConditions.isEmpty();

  /** Returns a list of (left, right) key ordinals. */
  public List<IntPair> pairs() {
    return IntPair.zip(leftKeys, rightKeys);

  public ImmutableBitSet leftSet() {
    return ImmutableBitSet.of(leftKeys);

  public ImmutableBitSet rightSet() {
    return ImmutableBitSet.of(rightKeys);

  @Deprecated // to be removed before 2.0
  public RexNode getRemaining(RexBuilder rexBuilder) {
    return RexUtil.composeConjunction(rexBuilder, nonEquiConditions);

  public RexNode getEquiCondition(RelNode left, RelNode right,
      RexBuilder rexBuilder) {
    return RelOptUtil.createEquiJoinCondition(left, leftKeys, right, rightKeys,

  public List<ImmutableIntList> keys() {
    return FlatLists.of(leftKeys, rightKeys);