/*
* 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.lucene.util;
import java.util.Arrays;
import java.util.Comparator;
/**
* Methods for manipulating arrays.
*
* @lucene.internal
*/
public final class ArrayUtil {
/** Maximum length for an array (Integer.MAX_VALUE - RamUsageEstimator.NUM_BYTES_ARRAY_HEADER). */
public static final int MAX_ARRAY_LENGTH = Integer.MAX_VALUE - RamUsageEstimator.NUM_BYTES_ARRAY_HEADER;
private ArrayUtil() {} // no instance
/*
Begin Apache Harmony code
Revision taken on Friday, June 12. https://svn.apache.org/repos/asf/harmony/enhanced/classlib/archive/java6/modules/luni/src/main/java/java/lang/Integer.java
*/
/**
* Parses a char array into an int.
* @param chars the character array
* @param offset The offset into the array
* @param len The length
* @return the int
* @throws NumberFormatException if it can't parse
*/
public static int parseInt(char[] chars, int offset, int len) throws NumberFormatException {
return parseInt(chars, offset, len, 10);
}
/**
* Parses the string argument as if it was an int value and returns the
* result. Throws NumberFormatException if the string does not represent an
* int quantity. The second argument specifies the radix to use when parsing
* the value.
*
* @param chars a string representation of an int quantity.
* @param radix the base to use for conversion.
* @return int the value represented by the argument
* @throws NumberFormatException if the argument could not be parsed as an int quantity.
*/
public static int parseInt(char[] chars, int offset, int len, int radix)
throws NumberFormatException {
if (chars == null || radix < Character.MIN_RADIX
|| radix > Character.MAX_RADIX) {
throw new NumberFormatException();
}
int i = 0;
if (len == 0) {
throw new NumberFormatException("chars length is 0");
}
boolean negative = chars[offset + i] == '-';
if (negative && ++i == len) {
throw new NumberFormatException("can't convert to an int");
}
if (negative == true){
offset++;
len--;
}
return parse(chars, offset, len, radix, negative);
}
private static int parse(char[] chars, int offset, int len, int radix,
boolean negative) throws NumberFormatException {
int max = Integer.MIN_VALUE / radix;
int result = 0;
for (int i = 0; i < len; i++){
int digit = Character.digit(chars[i + offset], radix);
if (digit == -1) {
throw new NumberFormatException("Unable to parse");
}
if (max > result) {
throw new NumberFormatException("Unable to parse");
}
int next = result * radix - digit;
if (next > result) {
throw new NumberFormatException("Unable to parse");
}
result = next;
}
/*while (offset < len) {
}*/
if (!negative) {
result = -result;
if (result < 0) {
throw new NumberFormatException("Unable to parse");
}
}
return result;
}
/*
END APACHE HARMONY CODE
*/
/** Returns an array size >= minTargetSize, generally
* over-allocating exponentially to achieve amortized
* linear-time cost as the array grows.
*
* NOTE: this was originally borrowed from Python 2.4.2
* listobject.c sources (attribution in LICENSE.txt), but
* has now been substantially changed based on
* discussions from java-dev thread with subject "Dynamic
* array reallocation algorithms", started on Jan 12
* 2010.
*
* @param minTargetSize Minimum required value to be returned.
* @param bytesPerElement Bytes used by each element of
* the array. See constants in {@link RamUsageEstimator}.
*
* @lucene.internal
*/
public static int oversize(int minTargetSize, int bytesPerElement) {
if (minTargetSize < 0) {
// catch usage that accidentally overflows int
throw new IllegalArgumentException("invalid array size " + minTargetSize);
}
if (minTargetSize == 0) {
// wait until at least one element is requested
return 0;
}
if (minTargetSize > MAX_ARRAY_LENGTH) {
throw new IllegalArgumentException("requested array size " + minTargetSize + " exceeds maximum array in java (" + MAX_ARRAY_LENGTH + ")");
}
// asymptotic exponential growth by 1/8th, favors
// spending a bit more CPU to not tie up too much wasted
// RAM:
int extra = minTargetSize >> 3;
if (extra < 3) {
// for very small arrays, where constant overhead of
// realloc is presumably relatively high, we grow
// faster
extra = 3;
}
int newSize = minTargetSize + extra;
// add 7 to allow for worst case byte alignment addition below:
if (newSize+7 < 0 || newSize+7 > MAX_ARRAY_LENGTH) {
// int overflowed, or we exceeded the maximum array length
return MAX_ARRAY_LENGTH;
}
if (Constants.JRE_IS_64BIT) {
// round up to 8 byte alignment in 64bit env
switch(bytesPerElement) {
case 4:
// round up to multiple of 2
return (newSize + 1) & 0x7ffffffe;
case 2:
// round up to multiple of 4
return (newSize + 3) & 0x7ffffffc;
case 1:
// round up to multiple of 8
return (newSize + 7) & 0x7ffffff8;
case 8:
// no rounding
default:
// odd (invalid?) size
return newSize;
}
} else {
// round up to 4 byte alignment in 64bit env
switch(bytesPerElement) {
case 2:
// round up to multiple of 2
return (newSize + 1) & 0x7ffffffe;
case 1:
// round up to multiple of 4
return (newSize + 3) & 0x7ffffffc;
case 4:
case 8:
// no rounding
default:
// odd (invalid?) size
return newSize;
}
}
}
public static <T> T[] grow(T[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, RamUsageEstimator.NUM_BYTES_OBJECT_REF));
} else
return array;
}
public static short[] grow(short[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Short.BYTES));
} else
return array;
}
public static short[] grow(short[] array) {
return grow(array, 1 + array.length);
}
public static float[] grow(float[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Float.BYTES));
} else
return array;
}
public static float[] grow(float[] array) {
return grow(array, 1 + array.length);
}
public static double[] grow(double[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Double.BYTES));
} else
return array;
}
public static double[] grow(double[] array) {
return grow(array, 1 + array.length);
}
public static int[] grow(int[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Integer.BYTES));
} else
return array;
}
public static int[] grow(int[] array) {
return grow(array, 1 + array.length);
}
public static long[] grow(long[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Long.BYTES));
} else
return array;
}
public static long[] grow(long[] array) {
return grow(array, 1 + array.length);
}
public static byte[] grow(byte[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Byte.BYTES));
} else
return array;
}
public static byte[] grow(byte[] array) {
return grow(array, 1 + array.length);
}
public static char[] grow(char[] array, int minSize) {
assert minSize >= 0: "size must be positive (got " + minSize + "): likely integer overflow?";
if (array.length < minSize) {
return Arrays.copyOf(array, oversize(minSize, Character.BYTES));
} else
return array;
}
public static char[] grow(char[] array) {
return grow(array, 1 + array.length);
}
/**
* Returns hash of chars in range start (inclusive) to
* end (inclusive)
*/
public static int hashCode(char[] array, int start, int end) {
int code = 0;
for (int i = end - 1; i >= start; i--)
code = code * 31 + array[i];
return code;
}
// Since Arrays.equals doesn't implement offsets for equals
/**
* See if two array slices are the same.
*
* @param left The left array to compare
* @param offsetLeft The offset into the array. Must be positive
* @param right The right array to compare
* @param offsetRight the offset into the right array. Must be positive
* @param length The length of the section of the array to compare
* @return true if the two arrays, starting at their respective offsets, are equal
*
* @see java.util.Arrays#equals(byte[], byte[])
*/
public static boolean equals(byte[] left, int offsetLeft, byte[] right, int offsetRight, int length) {
if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
for (int i = 0; i < length; i++) {
if (left[offsetLeft + i] != right[offsetRight + i]) {
return false;
}
}
return true;
}
return false;
}
// Since Arrays.equals doesn't implement offsets for equals
/**
* See if two array slices are the same.
*
* @param left The left array to compare
* @param offsetLeft The offset into the array. Must be positive
* @param right The right array to compare
* @param offsetRight the offset into the right array. Must be positive
* @param length The length of the section of the array to compare
* @return true if the two arrays, starting at their respective offsets, are equal
*
* @see java.util.Arrays#equals(char[], char[])
*/
public static boolean equals(int[] left, int offsetLeft, int[] right, int offsetRight, int length) {
if ((offsetLeft + length <= left.length) && (offsetRight + length <= right.length)) {
for (int i = 0; i < length; i++) {
if (left[offsetLeft + i] != right[offsetRight + i]) {
return false;
}
}
return true;
}
return false;
}
/** Swap values stored in slots <code>i</code> and <code>j</code> */
public static <T> void swap(T[] arr, int i, int j) {
final T tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
// intro-sorts
/**
* Sorts the given array slice using the {@link Comparator}. This method uses the intro sort
* algorithm, but falls back to insertion sort for small arrays.
* @param fromIndex start index (inclusive)
* @param toIndex end index (exclusive)
*/
public static <T> void introSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> comp) {
if (toIndex-fromIndex <= 1) return;
new ArrayIntroSorter<>(a, comp).sort(fromIndex, toIndex);
}
/**
* Sorts the given array using the {@link Comparator}. This method uses the intro sort
* algorithm, but falls back to insertion sort for small arrays.
*/
public static <T> void introSort(T[] a, Comparator<? super T> comp) {
introSort(a, 0, a.length, comp);
}
/**
* Sorts the given array slice in natural order. This method uses the intro sort
* algorithm, but falls back to insertion sort for small arrays.
* @param fromIndex start index (inclusive)
* @param toIndex end index (exclusive)
*/
public static <T extends Comparable<? super T>> void introSort(T[] a, int fromIndex, int toIndex) {
if (toIndex-fromIndex <= 1) return;
introSort(a, fromIndex, toIndex, Comparator.naturalOrder());
}
/**
* Sorts the given array in natural order. This method uses the intro sort
* algorithm, but falls back to insertion sort for small arrays.
*/
public static <T extends Comparable<? super T>> void introSort(T[] a) {
introSort(a, 0, a.length);
}
// tim sorts:
/**
* Sorts the given array slice using the {@link Comparator}. This method uses the Tim sort
* algorithm, but falls back to binary sort for small arrays.
* @param fromIndex start index (inclusive)
* @param toIndex end index (exclusive)
*/
public static <T> void timSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> comp) {
if (toIndex-fromIndex <= 1) return;
new ArrayTimSorter<>(a, comp, a.length / 64).sort(fromIndex, toIndex);
}
/**
* Sorts the given array using the {@link Comparator}. This method uses the Tim sort
* algorithm, but falls back to binary sort for small arrays.
*/
public static <T> void timSort(T[] a, Comparator<? super T> comp) {
timSort(a, 0, a.length, comp);
}
/**
* Sorts the given array slice in natural order. This method uses the Tim sort
* algorithm, but falls back to binary sort for small arrays.
* @param fromIndex start index (inclusive)
* @param toIndex end index (exclusive)
*/
public static <T extends Comparable<? super T>> void timSort(T[] a, int fromIndex, int toIndex) {
if (toIndex-fromIndex <= 1) return;
timSort(a, fromIndex, toIndex, Comparator.naturalOrder());
}
/**
* Sorts the given array in natural order. This method uses the Tim sort
* algorithm, but falls back to binary sort for small arrays.
*/
public static <T extends Comparable<? super T>> void timSort(T[] a) {
timSort(a, 0, a.length);
}
/** Reorganize {@code arr[from:to[} so that the element at offset k is at the
* same position as if {@code arr[from:to[} was sorted, and all elements on
* its left are less than or equal to it, and all elements on its right are
* greater than or equal to it.
* This runs in linear time on average and in {@code n log(n)} time in the
* worst case.*/
public static <T> void select(T[] arr, int from, int to, int k, Comparator<? super T> comparator) {
new IntroSelector() {
T pivot;
@Override
protected void swap(int i, int j) {
ArrayUtil.swap(arr, i, j);
}
@Override
protected void setPivot(int i) {
pivot = arr[i];
}
@Override
protected int comparePivot(int j) {
return comparator.compare(pivot, arr[j]);
}
}.select(from, to, k);
}
}