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/*
* Copyright (C) 2014 The Android Open Source Project
*
* 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.android.internal.util;
/**
* A helper class that aims to provide comparable growth performance to ArrayList, but on primitive
* arrays. Common array operations are implemented for efficient use in dynamic containers.
*
* All methods in this class assume that the length of an array is equivalent to its capacity and
* NOT the number of elements in the array. The current size of the array is always passed in as a
* parameter.
*
*
*/
public final class GrowingArrayUtils {
/**
* Appends an element to the end of the array, growing the array if there is no more room.
* @param array The array to which to append the element. This must NOT be null.
* @param currentSize The number of elements in the array. Must be less than or equal to
* array.length.
* @param element The element to append.
* @return the array to which the element was appended. This may be different than the given
* array.
*/
public static T[] append(T[] array, int currentSize, T element) {
assert currentSize <= array.length;
if (currentSize + 1 > array.length) {
@SuppressWarnings("unchecked")
T[] newArray = ArrayUtils.newUnpaddedArray(
(Class) array.getClass().getComponentType(), growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, currentSize);
array = newArray;
}
array[currentSize] = element;
return array;
}
/**
* Primitive int version of {@link #append(Object[], int, Object)}.
*/
public static int[] append(int[] array, int currentSize, int element) {
assert currentSize <= array.length;
if (currentSize + 1 > array.length) {
int[] newArray = ArrayUtils.newUnpaddedIntArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, currentSize);
array = newArray;
}
array[currentSize] = element;
return array;
}
/**
* Primitive long version of {@link #append(Object[], int, Object)}.
*/
public static long[] append(long[] array, int currentSize, long element) {
assert currentSize <= array.length;
if (currentSize + 1 > array.length) {
long[] newArray = ArrayUtils.newUnpaddedLongArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, currentSize);
array = newArray;
}
array[currentSize] = element;
return array;
}
/**
* Primitive boolean version of {@link #append(Object[], int, Object)}.
*/
public static boolean[] append(boolean[] array, int currentSize, boolean element) {
assert currentSize <= array.length;
if (currentSize + 1 > array.length) {
boolean[] newArray = ArrayUtils.newUnpaddedBooleanArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, currentSize);
array = newArray;
}
array[currentSize] = element;
return array;
}
/**
* Primitive float version of {@link #append(Object[], int, Object)}.
*/
public static float[] append(float[] array, int currentSize, float element) {
assert currentSize <= array.length;
if (currentSize + 1 > array.length) {
float[] newArray = ArrayUtils.newUnpaddedFloatArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, currentSize);
array = newArray;
}
array[currentSize] = element;
return array;
}
/**
* Inserts an element into the array at the specified index, growing the array if there is no
* more room.
*
* @param array The array to which to append the element. Must NOT be null.
* @param currentSize The number of elements in the array. Must be less than or equal to
* array.length.
* @param element The element to insert.
* @return the array to which the element was appended. This may be different than the given
* array.
*/
public static T[] insert(T[] array, int currentSize, int index, T element) {
assert currentSize <= array.length;
if (currentSize + 1 <= array.length) {
System.arraycopy(array, index, array, index + 1, currentSize - index);
array[index] = element;
return array;
}
@SuppressWarnings("unchecked")
T[] newArray = ArrayUtils.newUnpaddedArray((Class)array.getClass().getComponentType(),
growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, index);
newArray[index] = element;
System.arraycopy(array, index, newArray, index + 1, array.length - index);
return newArray;
}
/**
* Primitive int version of {@link #insert(Object[], int, int, Object)}.
*/
public static int[] insert(int[] array, int currentSize, int index, int element) {
assert currentSize <= array.length;
if (currentSize + 1 <= array.length) {
System.arraycopy(array, index, array, index + 1, currentSize - index);
array[index] = element;
return array;
}
int[] newArray = ArrayUtils.newUnpaddedIntArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, index);
newArray[index] = element;
System.arraycopy(array, index, newArray, index + 1, array.length - index);
return newArray;
}
/**
* Primitive long version of {@link #insert(Object[], int, int, Object)}.
*/
public static long[] insert(long[] array, int currentSize, int index, long element) {
assert currentSize <= array.length;
if (currentSize + 1 <= array.length) {
System.arraycopy(array, index, array, index + 1, currentSize - index);
array[index] = element;
return array;
}
long[] newArray = ArrayUtils.newUnpaddedLongArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, index);
newArray[index] = element;
System.arraycopy(array, index, newArray, index + 1, array.length - index);
return newArray;
}
/**
* Primitive boolean version of {@link #insert(Object[], int, int, Object)}.
*/
public static boolean[] insert(boolean[] array, int currentSize, int index, boolean element) {
assert currentSize <= array.length;
if (currentSize + 1 <= array.length) {
System.arraycopy(array, index, array, index + 1, currentSize - index);
array[index] = element;
return array;
}
boolean[] newArray = ArrayUtils.newUnpaddedBooleanArray(growSize(currentSize));
System.arraycopy(array, 0, newArray, 0, index);
newArray[index] = element;
System.arraycopy(array, index, newArray, index + 1, array.length - index);
return newArray;
}
/**
* Given the current size of an array, returns an ideal size to which the array should grow.
* This is typically double the given size, but should not be relied upon to do so in the
* future.
*/
public static int growSize(int currentSize) {
return currentSize <= 4 ? 8 : currentSize * 2;
}
// Uninstantiable
private GrowingArrayUtils() {}
}
