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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.geometry.core;
18  
19  /** Interface representing a point in a mathematical space.
20   *
21   * <p>Implementations of this interface are sufficient to define a
22   * space since they define both the structure of the points making up
23   * the space and the operations permitted on them. The only mathematical
24   * requirement at this level is that the represented space have a defined
25   * distance metric, meaning an operation that can compute the distance
26   * between two points (ie, the space must be a metric space).
27   * </p>
28   *
29   * <p>This interface uses self-referencing generic parameters to ensure
30   * that implementations are only used with instances of their own type.
31   * This removes the need for casting inside of methods in order to access
32   * implementation-specific data, such as coordinate values.
33   * </p>
34   *
35   * @see <a href="https://en.wikipedia.org/wiki/Metric_space">Metric space</a>
36   *
37   * @param <P> Point implementation type
38   */
39  public interface Point<P extends Point<P>> extends Spatial {
40  
41      /** Compute the distance between this point and another point.
42       * @param p second point
43       * @return the distance between this point and p
44       */
45      double distance(P p);
46  }