org.chocosolver.util.objects.IntList Maven / Gradle / Ivy
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2022, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.util.objects;
import java.util.Arrays;
/**
* A specific implementation for list of integers.
* Created by cprudhom on 20/10/2015.
* Project: choco.
*/
public class IntList {
/**
* Default initial capacity.
*/
private static final int DEFAULT_CAPACITY = 10;
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* The array buffer into which the elements of the ArrayList are stored.
*/
private int[] elements;
/**
* The size of the ArrayList (the number of elements it contains).
*/
private int size;
/**
* Constructs an empty list with the initial capacity of 10
*/
public IntList() {
this(DEFAULT_CAPACITY);
}
/**
* Constructs an empty list with the specified initial capacity.
*/
public IntList(int initialCapacity) {
this.elements = new int[initialCapacity];
this.size = 0;
}
/**
* Constructs a list containing the elements of values.
*
* @param values the values that are to be placed in this list
*/
public IntList(int... values) {
this.size = values.length;
this.elements = new int[size];
System.arraycopy(values, 0, elements, 0, size);
}
private void ensureCapacity(int minCapacity) {
if (minCapacity - elements.length > 0){
int oldCapacity = elements.length;
int newCapacity = oldCapacity + (oldCapacity >> 1);
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity - MAX_ARRAY_SIZE > 0)
newCapacity = MAX_ARRAY_SIZE;
// minCapacity is usually close to size, so this is a win:
elements = Arrays.copyOf(elements, newCapacity);
}
}
/**
* Returns the number of elements in this list.
*
* @return the number of elements in this list.
*/
public int size() {
return size;
}
/**
* Returns true if this list contains no elements.
*
* @return true if this list contains no elements.
*/
public boolean isEmpty() {
return size == 0;
}
/**
* Returns the element at the specified position in this list.
*
* @param index index of the element to return
* @return the element at the specified position in this list.
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index >= size())
*/
public int get(int index) {
if (index < 0 || index >= size) {
throw new ArrayIndexOutOfBoundsException(index);
}
return getQuick(index);
}
/**
* Returns the element at the specified position in this list without doing any bounds checking.
*
* @param index index of the element to return
* @return the element at the specified position in this list.
*/
public int getQuick(int index) {
return elements[index];
}
/**
* Replaces the element at the specified position in this list with
* the specified element.
*
* @param index index of the element to replace
* @param element element to be stored at the specified position
* @return the element previously at the specified position
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index >= size())
*/
public void replace(int index, int element) {
if (index < 0 || index >= size) {
throw new ArrayIndexOutOfBoundsException(index);
}
replaceQuick(index, element);
}
/**
* Replaces the element at the specified position in this list with
* the specified element without doing any bounds checking.
*
* @param index index of the element to replace
* @param element element to be stored at the specified position
* @return the element previously at the specified position
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index >= size())
*/
public void replaceQuick(int index, int element) {
elements[index] = element;
}
/**
* Appends the specified element to the end of this list.
*
* @param element element to be appended to this list
* @return true if this list changed as a result of the call
*/
public boolean add(int element) {
ensureCapacity(size + 1);
elements[size++] = element;
return true;
}
/**
* Add the element at the specified position in this list.
*
* @param index index of the element to put
* @param element element to be stored at the specified position
*/
public boolean addAt(int index, int element) {
ensureCapacity(index);
elements[index] = element;
return true;
}
/**
* Appends the elements of the specified list to the end of this list.
*
* @param list elements to be appended to this list
* @return true if this list changed as a result of the call
*/
public boolean addAll(IntList list) {
ensureCapacity(size + list.size);
System.arraycopy(list.elements, 0, elements, size, list.size);
size += list.size;
return true;
}
/**
* Removes the first occurrence of the specified element from this list,
* if it is present. If the list does not contain the element, it is
* unchanged.
*
* @param value element to be removed from this list, if present
* @return true if this list contained the specified element
*/
public boolean remove(int value) {
boolean removed = false;
for (int index = 0; index < size && !removed; index++) {
if (value == elements[index]) {
removeAt(index);
removed = true;
}
}
return removed;
}
/**
* Removes the element at the specified position in this list.
* Shifts any subsequent elements to the left (subtracts one from their
* indices).
*
* @param index the index of the element to be removed
* @return the element that was removed from the list
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index >= size())
*/
public void removeAt(int index) {
int numMoved = size - index - 1;
if (numMoved > 0)
System.arraycopy(elements, index+1, elements, index, numMoved);
size--;
}
/**
* Removes from this list all of the elements whose index is between
* {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
* Shifts any succeeding elements to the left (reduces their index).
* This call shortens the list by {@code (toIndex - fromIndex)} elements.
* (If {@code toIndex==fromIndex}, this operation has no effect.)
*
* @throws IndexOutOfBoundsException if {@code fromIndex} or
* {@code toIndex} is out of range
* ({@code fromIndex < 0 ||
* fromIndex >= size() ||
* toIndex > size() ||
* toIndex < fromIndex})
*/
public void removeRange(int fromIndex, int toIndex) {
int numMoved = size - toIndex;
System.arraycopy(elements, toIndex, elements, fromIndex, numMoved);
size -= (toIndex-fromIndex);
}
/**
* The list will be empty after this call returns.
* But no value is removed, only the size is reset to 0.
*/
public void clear() {
size = 0;
}
/**
* Returns an array containing all of the elements in this list
* in proper sequence (from first to last element).
*
*
The returned array will be "safe" in that no references to it are
* maintained by this list. (In other words, this method must allocate
* a new array). The caller is thus free to modify the returned array.
*
* @return an array containing all of the elements in this list in
* proper sequence
*/
public int[] toArray() {
return Arrays.copyOf(elements, size);
}
}
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