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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.math3.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".
*/
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);
/**
* Adds elements to the end of this expandable array
*
* @param values to be added to end of array
*/
void addElements(double[] values);
/**
* 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>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.
*
* @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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