All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.google.common.primitives.Booleans Maven / Gradle / Ivy

Go to download

Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more.

There is a newer version: 33.3.0-jre
Show newest version
/*
 * Copyright (C) 2008 The Guava Authors
 *
 * 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.google.common.primitives;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.RandomAccess;
import javax.annotation.CheckForNull;

/**
 * Static utility methods pertaining to {@code boolean} primitives, that are not already found in
 * either {@link Boolean} or {@link Arrays}.
 *
 * 

See the Guava User Guide article on primitive utilities. * * @author Kevin Bourrillion * @since 1.0 */ @GwtCompatible @ElementTypesAreNonnullByDefault public final class Booleans { private Booleans() {} /** Comparators for {@code Boolean} values. */ private enum BooleanComparator implements Comparator { TRUE_FIRST(1, "Booleans.trueFirst()"), FALSE_FIRST(-1, "Booleans.falseFirst()"); private final int trueValue; private final String toString; BooleanComparator(int trueValue, String toString) { this.trueValue = trueValue; this.toString = toString; } @Override public int compare(Boolean a, Boolean b) { int aVal = a ? trueValue : 0; int bVal = b ? trueValue : 0; return bVal - aVal; } @Override public String toString() { return toString; } } /** * Returns a {@code Comparator} that sorts {@code true} before {@code false}. * *

This is particularly useful in Java 8+ in combination with {@code Comparators.comparing}, * e.g. {@code Comparators.comparing(Foo::hasBar, trueFirst())}. * * @since 21.0 */ public static Comparator trueFirst() { return BooleanComparator.TRUE_FIRST; } /** * Returns a {@code Comparator} that sorts {@code false} before {@code true}. * *

This is particularly useful in Java 8+ in combination with {@code Comparators.comparing}, * e.g. {@code Comparators.comparing(Foo::hasBar, falseFirst())}. * * @since 21.0 */ public static Comparator falseFirst() { return BooleanComparator.FALSE_FIRST; } /** * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Boolean) * value).hashCode()}. * *

Java 8 users: use {@link Boolean#hashCode(boolean)} instead. * * @param value a primitive {@code boolean} value * @return a hash code for the value */ public static int hashCode(boolean value) { return value ? 1231 : 1237; } /** * Compares the two specified {@code boolean} values in the standard way ({@code false} is * considered less than {@code true}). The sign of the value returned is the same as that of * {@code ((Boolean) a).compareTo(b)}. * *

Note for Java 7 and later: this method should be treated as deprecated; use the * equivalent {@link Boolean#compare} method instead. * * @param a the first {@code boolean} to compare * @param b the second {@code boolean} to compare * @return a positive number if only {@code a} is {@code true}, a negative number if only {@code * b} is true, or zero if {@code a == b} */ public static int compare(boolean a, boolean b) { return (a == b) ? 0 : (a ? 1 : -1); } /** * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. * *

Note: consider representing the array as a {@link java.util.BitSet} instead, * replacing {@code Booleans.contains(array, true)} with {@code !bitSet.isEmpty()} and {@code * Booleans.contains(array, false)} with {@code bitSet.nextClearBit(0) == sizeOfBitSet}. * * @param array an array of {@code boolean} values, possibly empty * @param target a primitive {@code boolean} value * @return {@code true} if {@code array[i] == target} for some value of {@code i} */ public static boolean contains(boolean[] array, boolean target) { for (boolean value : array) { if (value == target) { return true; } } return false; } /** * Returns the index of the first appearance of the value {@code target} in {@code array}. * *

Note: consider representing the array as a {@link java.util.BitSet} instead, and * using {@link java.util.BitSet#nextSetBit(int)} or {@link java.util.BitSet#nextClearBit(int)}. * * @param array an array of {@code boolean} values, possibly empty * @param target a primitive {@code boolean} value * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no * such index exists. */ public static int indexOf(boolean[] array, boolean target) { return indexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int indexOf(boolean[] array, boolean target, int start, int end) { for (int i = start; i < end; i++) { if (array[i] == target) { return i; } } return -1; } /** * Returns the start position of the first occurrence of the specified {@code target} within * {@code array}, or {@code -1} if there is no such occurrence. * *

More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array, * i, i + target.length)} contains exactly the same elements as {@code target}. * * @param array the array to search for the sequence {@code target} * @param target the array to search for as a sub-sequence of {@code array} */ public static int indexOf(boolean[] array, boolean[] target) { checkNotNull(array, "array"); checkNotNull(target, "target"); if (target.length == 0) { return 0; } outer: for (int i = 0; i < array.length - target.length + 1; i++) { for (int j = 0; j < target.length; j++) { if (array[i + j] != target[j]) { continue outer; } } return i; } return -1; } /** * Returns the index of the last appearance of the value {@code target} in {@code array}. * * @param array an array of {@code boolean} values, possibly empty * @param target a primitive {@code boolean} value * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no * such index exists. */ public static int lastIndexOf(boolean[] array, boolean target) { return lastIndexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int lastIndexOf(boolean[] array, boolean target, int start, int end) { for (int i = end - 1; i >= start; i--) { if (array[i] == target) { return i; } } return -1; } /** * Returns the values from each provided array combined into a single array. For example, {@code * concat(new boolean[] {a, b}, new boolean[] {}, new boolean[] {c}} returns the array {@code {a, * b, c}}. * * @param arrays zero or more {@code boolean} arrays * @return a single array containing all the values from the source arrays, in order */ public static boolean[] concat(boolean[]... arrays) { int length = 0; for (boolean[] array : arrays) { length += array.length; } boolean[] result = new boolean[length]; int pos = 0; for (boolean[] array : arrays) { System.arraycopy(array, 0, result, pos, array.length); pos += array.length; } return result; } /** * Returns an array containing the same values as {@code array}, but guaranteed to be of a * specified minimum length. If {@code array} already has a length of at least {@code minLength}, * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is * returned, containing the values of {@code array}, and zeroes in the remaining places. * * @param array the source array * @param minLength the minimum length the returned array must guarantee * @param padding an extra amount to "grow" the array by if growth is necessary * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative * @return an array containing the values of {@code array}, with guaranteed minimum length {@code * minLength} */ public static boolean[] ensureCapacity(boolean[] array, int minLength, int padding) { checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); checkArgument(padding >= 0, "Invalid padding: %s", padding); return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; } /** * Returns a string containing the supplied {@code boolean} values separated by {@code separator}. * For example, {@code join("-", false, true, false)} returns the string {@code * "false-true-false"}. * * @param separator the text that should appear between consecutive values in the resulting string * (but not at the start or end) * @param array an array of {@code boolean} values, possibly empty */ public static String join(String separator, boolean... array) { checkNotNull(separator); if (array.length == 0) { return ""; } // For pre-sizing a builder, just get the right order of magnitude StringBuilder builder = new StringBuilder(array.length * 7); builder.append(array[0]); for (int i = 1; i < array.length; i++) { builder.append(separator).append(array[i]); } return builder.toString(); } /** * Returns a comparator that compares two {@code boolean} arrays lexicographically. That is, it * compares, using {@link #compare(boolean, boolean)}), the first pair of values that follow any * common prefix, or when one array is a prefix of the other, treats the shorter array as the * lesser. For example, {@code [] < [false] < [false, true] < [true]}. * *

The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays * support only identity equality), but it is consistent with {@link Arrays#equals(boolean[], * boolean[])}. * * @since 2.0 */ public static Comparator lexicographicalComparator() { return LexicographicalComparator.INSTANCE; } private enum LexicographicalComparator implements Comparator { INSTANCE; @Override public int compare(boolean[] left, boolean[] right) { int minLength = Math.min(left.length, right.length); for (int i = 0; i < minLength; i++) { int result = Booleans.compare(left[i], right[i]); if (result != 0) { return result; } } return left.length - right.length; } @Override public String toString() { return "Booleans.lexicographicalComparator()"; } } /** * Copies a collection of {@code Boolean} instances into a new array of primitive {@code boolean} * values. * *

Elements are copied from the argument collection as if by {@code collection.toArray()}. * Calling this method is as thread-safe as calling that method. * *

Note: consider representing the collection as a {@link java.util.BitSet} instead. * * @param collection a collection of {@code Boolean} objects * @return an array containing the same values as {@code collection}, in the same order, converted * to primitives * @throws NullPointerException if {@code collection} or any of its elements is null */ public static boolean[] toArray(Collection collection) { if (collection instanceof BooleanArrayAsList) { return ((BooleanArrayAsList) collection).toBooleanArray(); } Object[] boxedArray = collection.toArray(); int len = boxedArray.length; boolean[] array = new boolean[len]; for (int i = 0; i < len; i++) { // checkNotNull for GWT (do not optimize) array[i] = (Boolean) checkNotNull(boxedArray[i]); } return array; } /** * Returns a fixed-size list backed by the specified array, similar to {@link * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to * set a value to {@code null} will result in a {@link NullPointerException}. * *

There are at most two distinct objects in this list, {@code (Boolean) true} and {@code * (Boolean) false}. Java guarantees that those are always represented by the same objects. * *

The returned list is serializable. * * @param backingArray the array to back the list * @return a list view of the array */ public static List asList(boolean... backingArray) { if (backingArray.length == 0) { return Collections.emptyList(); } return new BooleanArrayAsList(backingArray); } @GwtCompatible private static class BooleanArrayAsList extends AbstractList implements RandomAccess, Serializable { final boolean[] array; final int start; final int end; BooleanArrayAsList(boolean[] array) { this(array, 0, array.length); } BooleanArrayAsList(boolean[] array, int start, int end) { this.array = array; this.start = start; this.end = end; } @Override public int size() { return end - start; } @Override public boolean isEmpty() { return false; } @Override public Boolean get(int index) { checkElementIndex(index, size()); return array[start + index]; } @Override public boolean contains(@CheckForNull Object target) { // Overridden to prevent a ton of boxing return (target instanceof Boolean) && Booleans.indexOf(array, (Boolean) target, start, end) != -1; } @Override public int indexOf(@CheckForNull Object target) { // Overridden to prevent a ton of boxing if (target instanceof Boolean) { int i = Booleans.indexOf(array, (Boolean) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public int lastIndexOf(@CheckForNull Object target) { // Overridden to prevent a ton of boxing if (target instanceof Boolean) { int i = Booleans.lastIndexOf(array, (Boolean) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public Boolean set(int index, Boolean element) { checkElementIndex(index, size()); boolean oldValue = array[start + index]; // checkNotNull for GWT (do not optimize) array[start + index] = checkNotNull(element); return oldValue; } @Override public List subList(int fromIndex, int toIndex) { int size = size(); checkPositionIndexes(fromIndex, toIndex, size); if (fromIndex == toIndex) { return Collections.emptyList(); } return new BooleanArrayAsList(array, start + fromIndex, start + toIndex); } @Override public boolean equals(@CheckForNull Object object) { if (object == this) { return true; } if (object instanceof BooleanArrayAsList) { BooleanArrayAsList that = (BooleanArrayAsList) object; int size = size(); if (that.size() != size) { return false; } for (int i = 0; i < size; i++) { if (array[start + i] != that.array[that.start + i]) { return false; } } return true; } return super.equals(object); } @Override public int hashCode() { int result = 1; for (int i = start; i < end; i++) { result = 31 * result + Booleans.hashCode(array[i]); } return result; } @Override public String toString() { StringBuilder builder = new StringBuilder(size() * 7); builder.append(array[start] ? "[true" : "[false"); for (int i = start + 1; i < end; i++) { builder.append(array[i] ? ", true" : ", false"); } return builder.append(']').toString(); } boolean[] toBooleanArray() { return Arrays.copyOfRange(array, start, end); } private static final long serialVersionUID = 0; } /** * Returns the number of {@code values} that are {@code true}. * * @since 16.0 */ public static int countTrue(boolean... values) { int count = 0; for (boolean value : values) { if (value) { count++; } } return count; } /** * Reverses the elements of {@code array}. This is equivalent to {@code * Collections.reverse(Booleans.asList(array))}, but is likely to be more efficient. * * @since 23.1 */ public static void reverse(boolean[] array) { checkNotNull(array); reverse(array, 0, array.length); } /** * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} * exclusive. This is equivalent to {@code * Collections.reverse(Booleans.asList(array).subList(fromIndex, toIndex))}, but is likely to be * more efficient. * * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or * {@code toIndex > fromIndex} * @since 23.1 */ public static void reverse(boolean[] array, int fromIndex, int toIndex) { checkNotNull(array); checkPositionIndexes(fromIndex, toIndex, array.length); for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { boolean tmp = array[i]; array[i] = array[j]; array[j] = tmp; } } /** * Performs a right rotation of {@code array} of "distance" places, so that the first element is * moved to index "distance", and the element at index {@code i} ends up at index {@code (distance * + i) mod array.length}. This is equivalent to {@code Collections.rotate(Booleans.asList(array), * distance)}, but is somewhat faster. * *

The provided "distance" may be negative, which will rotate left. * * @since 32.0.0 */ public static void rotate(boolean[] array, int distance) { rotate(array, distance, 0, array.length); } /** * Performs a right rotation of {@code array} between {@code fromIndex} inclusive and {@code * toIndex} exclusive. This is equivalent to {@code * Collections.rotate(Booleans.asList(array).subList(fromIndex, toIndex), distance)}, but is * somewhat faster. * *

The provided "distance" may be negative, which will rotate left. * * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or * {@code toIndex > fromIndex} * @since 32.0.0 */ public static void rotate(boolean[] array, int distance, int fromIndex, int toIndex) { // See Ints.rotate for more details about possible algorithms here. checkNotNull(array); checkPositionIndexes(fromIndex, toIndex, array.length); if (array.length <= 1) { return; } int length = toIndex - fromIndex; // Obtain m = (-distance mod length), a non-negative value less than "length". This is how many // places left to rotate. int m = -distance % length; m = (m < 0) ? m + length : m; // The current index of what will become the first element of the rotated section. int newFirstIndex = m + fromIndex; if (newFirstIndex == fromIndex) { return; } reverse(array, fromIndex, newFirstIndex); reverse(array, newFirstIndex, toIndex); reverse(array, fromIndex, toIndex); } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy