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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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.rapiddweller.common.collection;

import com.rapiddweller.common.ArrayUtil;

/**
 * Implements a generic ring buffer.


 * Created: 25.11.2017 23:34:53
 *
 * @param  the type of object to be buffered
 * @author Volker Bergmann
 * @since 1.0.12
 */
public class RingBuffer {

  /**
   * The Buffer.
   */
  protected final E[] buffer;
  private int cursor;
  private int size;

  /**
   * Instantiates a new Ring buffer.
   *
   * @param componentClass the component class
   * @param capacity       the capacity
   */
  public RingBuffer(Class componentClass, int capacity) {
    this.buffer = ArrayUtil.newInstance(componentClass, capacity);
    this.cursor = 0;
    this.size = 0;
  }

  /**
   * Gets capacity.
   *
   * @return the capacity
   */
  public int getCapacity() {
    return buffer.length;
  }

  /**
   * Size int.
   *
   * @return the int
   */
  public int size() {
    return size;
  }

  /**
   * Is filled boolean.
   *
   * @return the boolean
   */
  public boolean isFilled() {
    return (size == buffer.length);
  }

  /**
   * Contains boolean.
   *
   * @param object the object
   * @return the boolean
   */
  public boolean contains(E object) {
    for (Object o : buffer) {
      if (o != null && o.equals(object)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Add e.
   *
   * @param object the object
   * @return the e
   */
  public E add(E object) {
    E oldComponent = buffer[cursor];
    buffer[cursor++] = object;
    if (cursor == buffer.length) {
      cursor = 0;
    }
    if (size < buffer.length) {
      size++;
    }
    return oldComponent;
  }

  /**
   * Get e.
   *
   * @param index the index
   * @return the e
   */
  public E get(int index) {
    if (index > size - 1) {
      return null;
    }
    int offset = cursor - index - 1;
    if (offset < 0) {
      offset += buffer.length;
    }
    return buffer[offset];
  }

}