/*
* 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.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;
/**
* Static utility methods pertaining to {@code double} primitives, that are not
* already found in either {@link Double} or {@link Arrays}.
*
* @author Kevin Bourrillion
* @since 1.0
*/
@GwtCompatible
public final class Doubles {
private Doubles() {}
/**
* The number of bytes required to represent a primitive {@code double}
* value.
*
* @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()}.
*
* @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}.
*
* @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))}.
*
* @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 * java.util.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 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; } /** * 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) ? copyOf(array, minLength + padding) : array; } // Arrays.copyOf() requires Java 6 private static double[] copyOf(double[] original, int length) { double[] copy = new double[length]; System.arraycopy(original, 0, copy, 0, Math.min(original.length, length)); return copy; } /** * 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[])}.
*
* @see
* Lexicographical order article at Wikipedia
* @since 2.0
*/
public static Comparator 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 Double} 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 double[] toArray(Collection 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.
*
* @param backingArray the array to back the list
* @return a list view of the array
*/
public static List