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.tools;
  
  import org.apache.calcite.plan.RelOptRule;
  
  import com.google.common.collect.ImmutableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.Iterator;
  
  /**
   * Utilities for creating and composing rule sets.
   *
   * @see org.apache.calcite.tools.RuleSet
   */
  public class RuleSets {
    private RuleSets() {
    }
  
    /** Creates a rule set with a given array of rules. */
    public static RuleSet ofList(RelOptRule... rules) {
      return new ListRuleSet(ImmutableList.copyOf(rules));
    }
  
    /** Creates a rule set with a given collection of rules. */
    public static RuleSet ofList(Iterable<? extends RelOptRule> rules) {
      return new ListRuleSet(ImmutableList.copyOf(rules));
    }
  
    /** Rule set that consists of a list of rules. */
    private static class ListRuleSet implements RuleSet {
      private final ImmutableList<RelOptRule> rules;
  
      ListRuleSet(ImmutableList<RelOptRule> rules) {
        this.rules = rules;
      }
  
      @Override public int hashCode() {
        return rules.hashCode();
      }
  
      @Override public boolean equals(@Nullable Object obj) {
        return obj == this
            || obj instanceof ListRuleSet
            && rules.equals(((ListRuleSet) obj).rules);
      }
  
      @Override public Iterator<RelOptRule> iterator() {
        return rules.iterator();
      }
    }
  }
  