com.google.common.graph.ElementOrder Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of wildfly-client-all

This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 35.0.0.Beta1

Show newest version

/*
 * Copyright (C) 2016 The Guava Authors
 *
 * Licensed 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 com.google.common.graph;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.common.annotations.Beta;
import com.google.common.base.MoreObjects;
import com.google.common.base.MoreObjects.ToStringHelper;
import com.google.common.base.Objects;
import com.google.common.collect.Maps;
import com.google.common.collect.Ordering;
import com.google.errorprone.annotations.Immutable;
import java.util.Comparator;
import java.util.Map;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;

/**
 * Used to represent the order of elements in a data structure that supports different options for
 * iteration order guarantees.
 *
 * Example usage:
 *
 * 
{@code
 * MutableGraph graph =
 *     GraphBuilder.directed().nodeOrder(ElementOrder.natural()).build();
 * }
 *
 * @author Joshua O'Madadhain
 * @since 20.0
 */
@Beta
@Immutable
public final class ElementOrder {
  private final Type type;

  @SuppressWarnings("Immutable") // Hopefully the comparator provided is immutable!
  @NullableDecl
  private final Comparator comparator;

  /**
   * The type of ordering that this object specifies.
   *
   * 
   *   UNORDERED: no order is guaranteed.
   *   
INSERTION: insertion ordering is guaranteed.
   *   
SORTED: ordering according to a supplied comparator is guaranteed.
   * 
   */
  public enum Type {
    UNORDERED,
    INSERTION,
    SORTED
  }

  private ElementOrder(Type type, @NullableDecl Comparator comparator) {
    this.type = checkNotNull(type);
    this.comparator = comparator;
    checkState((type == Type.SORTED) == (comparator != null));
  }

  /** Returns an instance which specifies that no ordering is guaranteed. */
  public static  ElementOrder unordered() {
    return new ElementOrder(Type.UNORDERED, null);
  }

  /** Returns an instance which specifies that insertion ordering is guaranteed. */
  public static  ElementOrder insertion() {
    return new ElementOrder(Type.INSERTION, null);
  }

  /**
   * Returns an instance which specifies that the natural ordering of the elements is guaranteed.
   */
  public static > ElementOrder natural() {
    return new ElementOrder(Type.SORTED, Ordering.natural());
  }

  /**
   * Returns an instance which specifies that the ordering of the elements is guaranteed to be
   * determined by {@code comparator}.
   */
  public static  ElementOrder sorted(Comparator comparator) {
    return new ElementOrder(Type.SORTED, comparator);
  }

  /** Returns the type of ordering used. */
  public Type type() {
    return type;
  }

  /**
   * Returns the {@link Comparator} used.
   *
   * @throws UnsupportedOperationException if comparator is not defined
   */
  public Comparator comparator() {
    if (comparator != null) {
      return comparator;
    }
    throw new UnsupportedOperationException("This ordering does not define a comparator.");
  }

  @Override
  public boolean equals(@NullableDecl Object obj) {
    if (obj == this) {
      return true;
    }
    if (!(obj instanceof ElementOrder)) {
      return false;
    }

    ElementOrder other = (ElementOrder) obj;
    return (type == other.type) && Objects.equal(comparator, other.comparator);
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(type, comparator);
  }

  @Override
  public String toString() {
    ToStringHelper helper = MoreObjects.toStringHelper(this).add("type", type);
    if (comparator != null) {
      helper.add("comparator", comparator);
    }
    return helper.toString();
  }

  /** Returns an empty mutable map whose keys will respect this {@link ElementOrder}. */
   Map createMap(int expectedSize) {
    switch (type) {
      case UNORDERED:
        return Maps.newHashMapWithExpectedSize(expectedSize);
      case INSERTION:
        return Maps.newLinkedHashMapWithExpectedSize(expectedSize);
      case SORTED:
        return Maps.newTreeMap(comparator());
      default:
        throw new AssertionError();
    }
  }

  @SuppressWarnings("unchecked")
   ElementOrder cast() {
    return (ElementOrder) this;
  }
}