org.apache.calcite.rel.core.CorrelationId.java Source code

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Here is the source code for org.apache.calcite.rel.core.CorrelationId.java

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/*
 * 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.core;

import com.google.common.collect.ImmutableSet;

import java.util.Set;

/**
 * Describes the necessary parameters for an implementation in order to
 * identify and set dynamic variables
 */
public class CorrelationId implements Cloneable, Comparable<CorrelationId> {
    /**
     * Prefix to the name of correlating variables.
     */
    public static final String CORREL_PREFIX = "$cor";

    private final int id;
    private final String name;

    /**
     * Creates a correlation identifier.
     */
    private CorrelationId(int id, String name) {
        this.id = id;
        this.name = name;
    }

    /**
     * Creates a correlation identifier.
     * This is a type-safe wrapper over int.
     *
     * @param id     Identifier
     */
    public CorrelationId(int id) {
        this(id, CORREL_PREFIX + id);
    }

    /**
     * Creates a correlation identifier from a name.
     *
     * @param name     variable name
     */
    public CorrelationId(String name) {
        this(Integer.parseInt(name.substring(CORREL_PREFIX.length())), name);
        assert name.startsWith(CORREL_PREFIX) : "Correlation name should start with " + CORREL_PREFIX
                + " actual name is " + name;
    }

    /**
     * Returns the identifier.
     *
     * @return identifier
     */
    public int getId() {
        return id;
    }

    /**
     * Returns the preferred name of the variable.
     *
     * @return name
     */
    public String getName() {
        return name;
    }

    public String toString() {
        return name;
    }

    public int compareTo(CorrelationId other) {
        return id - other.id;
    }

    @Override
    public int hashCode() {
        return id;
    }

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

    /** Converts a set of correlation ids to a set of names. */
    public static ImmutableSet<CorrelationId> setOf(Set<String> set) {
        if (set.isEmpty()) {
            return ImmutableSet.of();
        }
        final ImmutableSet.Builder<CorrelationId> builder = ImmutableSet.builder();
        for (String s : set) {
            builder.add(new CorrelationId(s));
        }
        return builder.build();
    }

    /** Converts a set of names to a set of correlation ids. */
    public static Set<String> names(Set<CorrelationId> set) {
        if (set.isEmpty()) {
            return ImmutableSet.of();
        }
        final ImmutableSet.Builder<String> builder = ImmutableSet.builder();
        for (CorrelationId s : set) {
            builder.add(s.name);
        }
        return builder.build();
    }
}

// End CorrelationId.java