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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.commons.math.util;
/**
* Provides a standard interface for double arrays. Allows different
* array implementations to support various storage mechanisms
* such as automatic expansion, contraction, and array "rolling".
*
* @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $
*/
public interface DoubleArray {
/**
* Returns the number of elements currently in the array. Please note
* that this may be different from the length of the internal storage array.
*
* @return number of elements
*/
int getNumElements();
/**
* Returns the element at the specified index. Note that if an
* out of bounds index is supplied a ArrayIndexOutOfBoundsException
* will be thrown.
*
* @param index index to fetch a value from
* @return value stored at the specified index
* @throws ArrayIndexOutOfBoundsException if <code>index</code> is less than
* zero or is greater than <code>getNumElements() - 1</code>.
*/
double getElement(int index);
/**
* Sets the element at the specified index. If the specified index is greater than
* <code>getNumElements() - 1</code>, the <code>numElements</code> property
* is increased to <code>index +1</code> and additional storage is allocated
* (if necessary) for the new element and all (uninitialized) elements
* between the new element and the previous end of the array).
*
* @param index index to store a value in
* @param value value to store at the specified index
* @throws ArrayIndexOutOfBoundsException if <code>index</code> is less than
* zero.
*/
void setElement(int index, double value);
/**
* Adds an element to the end of this expandable array
*
* @param value to be added to end of array
*/
void addElement(double value);
/**
* <p>
* Adds an element to the end of the array and removes the first
* element in the array. Returns the discarded first element.
* The effect is similar to a push operation in a FIFO queue.
* </p>
* <p>
* Example: If the array contains the elements 1, 2, 3, 4 (in that order)
* and addElementRolling(5) is invoked, the result is an array containing
* the entries 2, 3, 4, 5 and the value returned is 1.
* </p>
*
* @param value the value to be added to the array
* @return the value which has been discarded or "pushed" out of the array
* by this rolling insert
*/
double addElementRolling(double value);
/**
* Returns a double[] array containing the elements of this
* <code>DoubleArray</code>. If the underlying implementation is
* array-based, this method should always return a copy, rather than a
* reference to the underlying array so that changes made to the returned
* array have no effect on the <code>DoubleArray.</code>
*
* @return all elements added to the array
*/
double[] getElements();
/**
* Clear the double array
*/
void clear();
}
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