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;
  
  /**
   * A conflict rule (CR) is a pair of table sets denoted by T1 → T2, which means that if T1
   * intersects with the table under the join operator, T2 must be included in this join. With every
   * hyperedge in hypergraph, we associate a set of conflict rules.
   *
   * @see HyperEdge
   * @see ConflictDetectionHelper
   */
  public class ConflictRule {
  
    // 'from' and 'to' are bitmaps where index refer to inputs of hypergraph
    final long from;
  
    final long to;
  
    public ConflictRule(long from, long to) {
      this.from = from;
      this.to = to;
    }
  
    @Override public String toString() {
      return "Table" + LongBitmap.printBitmap(from) + " -> Table"
          + LongBitmap.printBitmap(to);
    }
  
    public ConflictRule shift(int offset) {
      return new ConflictRule(from << offset, to << offset);
    }
  }
  