net.hydromatic.optiq.tools.RuleSets.java Source code

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Here is the source code for net.hydromatic.optiq.tools.RuleSets.java

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/*
// Licensed to Julian Hyde under one or more contributor license
// agreements. See the NOTICE file distributed with this work for
// additional information regarding copyright ownership.
//
// Julian Hyde 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 net.hydromatic.optiq.tools;

import org.eigenbase.relopt.RelOptRule;

import com.google.common.collect.ImmutableList;

import java.util.Collection;
import java.util.Iterator;

/**
 * Utilities for creating and composing rule sets.
 *
 * @see net.hydromatic.optiq.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(Collection<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;

        public ListRuleSet(ImmutableList<RelOptRule> rules) {
            this.rules = rules;
        }

        @Override
        public int hashCode() {
            return rules.hashCode();
        }

        @Override
        public boolean equals(Object obj) {
            return obj == this || obj instanceof ListRuleSet && rules.equals(((ListRuleSet) obj).rules);
        }

        public Iterator<RelOptRule> iterator() {
            return rules.iterator();
        }
    }
}

// End RuleSets.java