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/*
 * 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 static java.lang.Double.NEGATIVE_INFINITY;
import static java.lang.Double.POSITIVE_INFINITY;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Converter;
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 java.util.Spliterator;
import java.util.Spliterators;
import java.util.regex.Pattern;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;

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

See the Guava User Guide article on primitive utilities. * * @author Kevin Bourrillion * @since 1.0 */ @GwtCompatible(emulated = true) public final class Doubles { private Doubles() {} /** * The number of bytes required to represent a primitive {@code double} value. * *

Java 8 users: use {@link Double#BYTES} instead. * * @since 10.0 */ public static final int BYTES = Double.SIZE / Byte.SIZE; /** * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Double) * value).hashCode()}. * *

Java 8 users: use {@link Double#hashCode(double)} instead. * * @param value a primitive {@code double} value * @return a hash code for the value */ public static int hashCode(double value) { return ((Double) value).hashCode(); // TODO(kevinb): do it this way when we can (GWT problem): // long bits = Double.doubleToLongBits(value); // return (int) (bits ^ (bits >>> 32)); } /** * Compares the two specified {@code double} values. The sign of the value returned is the same as * that of ((Double) a).{@linkplain Double#compareTo compareTo}(b). As with that * method, {@code NaN} is treated as greater than all other values, and {@code 0.0 > -0.0}. * *

Note: this method simply delegates to the JDK method {@link Double#compare}. It is * provided for consistency with the other primitive types, whose compare methods were not added * to the JDK until JDK 7. * * @param a the first {@code double} to compare * @param b the second {@code double} to compare * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is * greater than {@code b}; or zero if they are equal */ public static int compare(double a, double b) { return Double.compare(a, b); } /** * Returns {@code true} if {@code value} represents a real number. This is equivalent to, but not * necessarily implemented as, {@code !(Double.isInfinite(value) || Double.isNaN(value))}. * *

Java 8 users: use {@link Double#isFinite(double)} instead. * * @since 10.0 */ public static boolean isFinite(double value) { return NEGATIVE_INFINITY < value && value < POSITIVE_INFINITY; } /** * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. Note * that this always returns {@code false} when {@code target} is {@code NaN}. * * @param array an array of {@code double} values, possibly empty * @param target a primitive {@code double} value * @return {@code true} if {@code array[i] == target} for some value of {@code i} */ public static boolean contains(double[] array, double target) { for (double 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 * that this always returns {@code -1} when {@code target} is {@code NaN}. * * @param array an array of {@code double} values, possibly empty * @param target a primitive {@code double} 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(double[] array, double target) { return indexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int indexOf(double[] array, double 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}. * *

Note that this always returns {@code -1} when {@code target} contains {@code NaN}. * * @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(double[] array, double[] 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}. Note * that this always returns {@code -1} when {@code target} is {@code NaN}. * * @param array an array of {@code double} values, possibly empty * @param target a primitive {@code double} 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(double[] array, double target) { return lastIndexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int lastIndexOf(double[] array, double target, int start, int end) { for (int i = end - 1; i >= start; i--) { if (array[i] == target) { return i; } } return -1; } /** * Returns the least value present in {@code array}, using the same rules of comparison as {@link * Math#min(double, double)}. * * @param array a nonempty array of {@code double} values * @return the value present in {@code array} that is less than or equal to every other value in * the array * @throws IllegalArgumentException if {@code array} is empty */ public static double min(double... array) { checkArgument(array.length > 0); double min = array[0]; for (int i = 1; i < array.length; i++) { min = Math.min(min, array[i]); } return min; } /** * Returns the greatest value present in {@code array}, using the same rules of comparison as * {@link Math#max(double, double)}. * * @param array a nonempty array of {@code double} values * @return the value present in {@code array} that is greater than or equal to every other value * in the array * @throws IllegalArgumentException if {@code array} is empty */ public static double max(double... array) { checkArgument(array.length > 0); double max = array[0]; for (int i = 1; i < array.length; i++) { max = Math.max(max, array[i]); } return max; } /** * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}. * *

If {@code value} is within the range {@code [min..max]}, {@code value} is returned * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code * value} is greater than {@code max}, {@code max} is returned. * * @param value the {@code double} value to constrain * @param min the lower bound (inclusive) of the range to constrain {@code value} to * @param max the upper bound (inclusive) of the range to constrain {@code value} to * @throws IllegalArgumentException if {@code min > max} * @since 21.0 */ @Beta public static double constrainToRange(double value, double min, double max) { checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max); return Math.min(Math.max(value, min), max); } /** * Returns the values from each provided array combined into a single array. For example, {@code * concat(new double[] {a, b}, new double[] {}, new double[] {c}} returns the array {@code {a, b, * c}}. * * @param arrays zero or more {@code double} arrays * @return a single array containing all the values from the source arrays, in order */ public static double[] concat(double[]... arrays) { int length = 0; for (double[] array : arrays) { length += array.length; } double[] result = new double[length]; int pos = 0; for (double[] array : arrays) { System.arraycopy(array, 0, result, pos, array.length); pos += array.length; } return result; } private static final class DoubleConverter extends Converter implements Serializable { static final DoubleConverter INSTANCE = new DoubleConverter(); @Override protected Double doForward(String value) { return Double.valueOf(value); } @Override protected String doBackward(Double value) { return value.toString(); } @Override public String toString() { return "Doubles.stringConverter()"; } private Object readResolve() { return INSTANCE; } private static final long serialVersionUID = 1; } /** * Returns a serializable converter object that converts between strings and doubles using {@link * Double#valueOf} and {@link Double#toString()}. * * @since 16.0 */ @Beta public static Converter stringConverter() { return DoubleConverter.INSTANCE; } /** * 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 double[] ensureCapacity(double[] 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 double} values, converted to strings as * specified by {@link Double#toString(double)}, and separated by {@code separator}. For example, * {@code join("-", 1.0, 2.0, 3.0)} returns the string {@code "1.0-2.0-3.0"}. * *

Note that {@link Double#toString(double)} formats {@code double} differently in GWT * sometimes. In the previous example, it returns the string {@code "1-2-3"}. * * @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 double} values, possibly empty */ public static String join(String separator, double... 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 * 12); 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 double} arrays lexicographically. That is, it * compares, using {@link #compare(double, double)}), 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 [] < [1.0] < [1.0, 2.0] < [2.0]}. * *

The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays * support only identity equality), but it is consistent with {@link Arrays#equals(double[], * double[])}. * * @since 2.0 */ public static Comparator lexicographicalComparator() { return LexicographicalComparator.INSTANCE; } private enum LexicographicalComparator implements Comparator { INSTANCE; @Override public int compare(double[] left, double[] right) { int minLength = Math.min(left.length, right.length); for (int i = 0; i < minLength; i++) { int result = Double.compare(left[i], right[i]); if (result != 0) { return result; } } return left.length - right.length; } @Override public String toString() { return "Doubles.lexicographicalComparator()"; } } /** * Sorts the elements of {@code array} in descending order. * *

Note that this method uses the total order imposed by {@link Double#compare}, which treats * all NaN values as equal and 0.0 as greater than -0.0. * * @since 23.1 */ public static void sortDescending(double[] array) { checkNotNull(array); sortDescending(array, 0, array.length); } /** * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} * exclusive in descending order. * *

Note that this method uses the total order imposed by {@link Double#compare}, which treats * all NaN values as equal and 0.0 as greater than -0.0. * * @since 23.1 */ public static void sortDescending(double[] array, int fromIndex, int toIndex) { checkNotNull(array); checkPositionIndexes(fromIndex, toIndex, array.length); Arrays.sort(array, fromIndex, toIndex); reverse(array, fromIndex, toIndex); } /** * Reverses the elements of {@code array}. This is equivalent to {@code * Collections.reverse(Doubles.asList(array))}, but is likely to be more efficient. * * @since 23.1 */ public static void reverse(double[] 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(Doubles.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(double[] array, int fromIndex, int toIndex) { checkNotNull(array); checkPositionIndexes(fromIndex, toIndex, array.length); for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { double tmp = array[i]; array[i] = array[j]; array[j] = tmp; } } /** * Returns an array containing each value of {@code collection}, converted to a {@code double} * value in the manner of {@link Number#doubleValue}. * *

Elements are copied from the argument collection as if by {@code collection.toArray()}. * Calling this method is as thread-safe as calling that method. * * @param collection a collection of {@code Number} instances * @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 * @since 1.0 (parameter was {@code Collection} before 12.0) */ public static double[] toArray(Collection collection) { if (collection instanceof DoubleArrayAsList) { return ((DoubleArrayAsList) collection).toDoubleArray(); } Object[] boxedArray = collection.toArray(); int len = boxedArray.length; double[] array = new double[len]; for (int i = 0; i < len; i++) { // checkNotNull for GWT (do not optimize) array[i] = ((Number) checkNotNull(boxedArray[i])).doubleValue(); } 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}. * *

The returned list maintains the values, but not the identities, of {@code Double} objects * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for * the returned list is unspecified. * *

The returned list may have unexpected behavior if it contains {@code NaN}, or if {@code NaN} * is used as a parameter to any of its methods. * *

Note: when possible, you should represent your data as an {@link * ImmutableDoubleArray} instead, which has an {@link ImmutableDoubleArray#asList asList} view. * * @param backingArray the array to back the list * @return a list view of the array */ public static List asList(double... backingArray) { if (backingArray.length == 0) { return Collections.emptyList(); } return new DoubleArrayAsList(backingArray); } @GwtCompatible private static class DoubleArrayAsList extends AbstractList implements RandomAccess, Serializable { final double[] array; final int start; final int end; DoubleArrayAsList(double[] array) { this(array, 0, array.length); } DoubleArrayAsList(double[] 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 Double get(int index) { checkElementIndex(index, size()); return array[start + index]; } @Override public Spliterator.OfDouble spliterator() { return Spliterators.spliterator(array, start, end, 0); } @Override public boolean contains(Object target) { // Overridden to prevent a ton of boxing return (target instanceof Double) && Doubles.indexOf(array, (Double) target, start, end) != -1; } @Override public int indexOf(Object target) { // Overridden to prevent a ton of boxing if (target instanceof Double) { int i = Doubles.indexOf(array, (Double) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public int lastIndexOf(Object target) { // Overridden to prevent a ton of boxing if (target instanceof Double) { int i = Doubles.lastIndexOf(array, (Double) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public Double set(int index, Double element) { checkElementIndex(index, size()); double 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 DoubleArrayAsList(array, start + fromIndex, start + toIndex); } @Override public boolean equals(@NullableDecl Object object) { if (object == this) { return true; } if (object instanceof DoubleArrayAsList) { DoubleArrayAsList that = (DoubleArrayAsList) 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 + Doubles.hashCode(array[i]); } return result; } @Override public String toString() { StringBuilder builder = new StringBuilder(size() * 12); builder.append('[').append(array[start]); for (int i = start + 1; i < end; i++) { builder.append(", ").append(array[i]); } return builder.append(']').toString(); } double[] toDoubleArray() { return Arrays.copyOfRange(array, start, end); } private static final long serialVersionUID = 0; } /** * This is adapted from the regex suggested by {@link Double#valueOf(String)} for prevalidating * inputs. All valid inputs must pass this regex, but it's semantically fine if not all inputs * that pass this regex are valid -- only a performance hit is incurred, not a semantics bug. */ @GwtIncompatible // regular expressions static final Pattern FLOATING_POINT_PATTERN = fpPattern(); @GwtIncompatible // regular expressions private static Pattern fpPattern() { String decimal = "(?:\\d++(?:\\.\\d*+)?|\\.\\d++)"; String completeDec = decimal + "(?:[eE][+-]?\\d++)?[fFdD]?"; String hex = "(?:\\p{XDigit}++(?:\\.\\p{XDigit}*+)?|\\.\\p{XDigit}++)"; String completeHex = "0[xX]" + hex + "[pP][+-]?\\d++[fFdD]?"; String fpPattern = "[+-]?(?:NaN|Infinity|" + completeDec + "|" + completeHex + ")"; return Pattern.compile(fpPattern); } /** * Parses the specified string as a double-precision floating point value. The ASCII character * {@code '-'} ('\u002D') is recognized as the minus sign. * *

Unlike {@link Double#parseDouble(String)}, this method returns {@code null} instead of * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link * Double#valueOf(String)}, except that leading and trailing whitespace is not permitted. * *

This implementation is likely to be faster than {@code Double.parseDouble} if many failures * are expected. * * @param string the string representation of a {@code double} value * @return the floating point value represented by {@code string}, or {@code null} if {@code * string} has a length of zero or cannot be parsed as a {@code double} value * @since 14.0 */ @Beta @NullableDecl @GwtIncompatible // regular expressions public static Double tryParse(String string) { if (FLOATING_POINT_PATTERN.matcher(string).matches()) { // TODO(lowasser): could be potentially optimized, but only with // extensive testing try { return Double.parseDouble(string); } catch (NumberFormatException e) { // Double.parseDouble has changed specs several times, so fall through // gracefully } } return null; } }





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