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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.Float.NEGATIVE_INFINITY; import static java.lang.Float.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 javax.annotation.CheckForNull; import javax.annotation.CheckReturnValue; import javax.annotation.Nullable; /** * Static utility methods pertaining to {@code float} primitives, that are not * already found in either {@link Float} or {@link Arrays}. * * <p>See the Guava User Guide article on <a href= * "https://github.com/google/guava/wiki/PrimitivesExplained"> * primitive utilities</a>. * * @author Kevin Bourrillion * @since 1.0 */ @CheckReturnValue @GwtCompatible(emulated = true) public final class Floats { private Floats() { } /** * The number of bytes required to represent a primitive {@code float} * value. * * @since 10.0 */ public static final int BYTES = Float.SIZE / Byte.SIZE; /** * Returns a hash code for {@code value}; equal to the result of invoking * {@code ((Float) value).hashCode()}. * * @param value a primitive {@code float} value * @return a hash code for the value */ public static int hashCode(float value) { // TODO(kevinb): is there a better way, that's still gwt-safe? return ((Float) value).hashCode(); } /** * Compares the two specified {@code float} values using {@link * Float#compare(float, float)}. You may prefer to invoke that method * directly; this method exists only for consistency with the other utilities * in this package. * * <p><b>Note:</b> this method simply delegates to the JDK method {@link * Float#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 float} to compare * @param b the second {@code float} to compare * @return the result of invoking {@link Float#compare(float, float)} */ public static int compare(float a, float b) { return Float.compare(a, b); } /** * Returns {@code true} if {@code value} represents a real number. This is * equivalent to, but not necessarily implemented as, * {@code !(Float.isInfinite(value) || Float.isNaN(value))}. * * @since 10.0 */ public static boolean isFinite(float 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 float} values, possibly empty * @param target a primitive {@code float} value * @return {@code true} if {@code array[i] == target} for some value of {@code * i} */ public static boolean contains(float[] array, float target) { for (float 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 float} values, possibly empty * @param target a primitive {@code float} 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(float[] array, float target) { return indexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int indexOf(float[] array, float 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. * * <p>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}. * * <p>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(float[] array, float[] 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 float} values, possibly empty * @param target a primitive {@code float} 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(float[] array, float target) { return lastIndexOf(array, target, 0, array.length); } // TODO(kevinb): consider making this public private static int lastIndexOf(float[] array, float 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(float, float)}. * * @param array a <i>nonempty</i> array of {@code float} 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 float min(float... array) { checkArgument(array.length > 0); float 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(float, float)}. * * @param array a <i>nonempty</i> array of {@code float} 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 float max(float... array) { checkArgument(array.length > 0); float 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 float[] {a, b}, new float[] {}, new * float[] {c}} returns the array {@code {a, b, c}}. * * @param arrays zero or more {@code float} arrays * @return a single array containing all the values from the source arrays, in * order */ public static float[] concat(float[]... arrays) { int length = 0; for (float[] array : arrays) { length += array.length; } float[] result = new float[length]; int pos = 0; for (float[] array : arrays) { System.arraycopy(array, 0, result, pos, array.length); pos += array.length; } return result; } private static final class FloatConverter extends Converter<String, Float> implements Serializable { static final FloatConverter INSTANCE = new FloatConverter(); @Override protected Float doForward(String value) { return Float.valueOf(value); } @Override protected String doBackward(Float value) { return value.toString(); } @Override public String toString() { return "Floats.stringConverter()"; } private Object readResolve() { return INSTANCE; } private static final long serialVersionUID = 1; } /** * Returns a serializable converter object that converts between strings and * floats using {@link Float#valueOf} and {@link Float#toString()}. * * @since 16.0 */ @Beta public static Converter<String, Float> stringConverter() { return FloatConverter.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 float[] ensureCapacity(float[] 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 float[] copyOf(float[] original, int length) { float[] copy = new float[length]; System.arraycopy(original, 0, copy, 0, Math.min(original.length, length)); return copy; } /** * Returns a string containing the supplied {@code float} values, converted * to strings as specified by {@link Float#toString(float)}, and separated by * {@code separator}. For example, {@code join("-", 1.0f, 2.0f, 3.0f)} * returns the string {@code "1.0-2.0-3.0"}. * * <p>Note that {@link Float#toString(float)} formats {@code float} * differently in GWT. 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 float} values, possibly empty */ public static String join(String separator, float... 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 float} arrays * lexicographically. That is, it compares, using {@link * #compare(float, float)}), 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 [] < [1.0f] < [1.0f, 2.0f] * < [2.0f]}. * * <p>The returned comparator is inconsistent with {@link * Object#equals(Object)} (since arrays support only identity equality), but * it is consistent with {@link Arrays#equals(float[], float[])}. * * @see <a href="http://en.wikipedia.org/wiki/Lexicographical_order"> * Lexicographical order article at Wikipedia</a> * @since 2.0 */ public static Comparator<float[]> lexicographicalComparator() { return LexicographicalComparator.INSTANCE; } private enum LexicographicalComparator implements Comparator<float[]> { INSTANCE; @Override public int compare(float[] left, float[] right) { int minLength = Math.min(left.length, right.length); for (int i = 0; i < minLength; i++) { int result = Float.compare(left[i], right[i]); if (result != 0) { return result; } } return left.length - right.length; } } /** * Returns an array containing each value of {@code collection}, converted to * a {@code float} value in the manner of {@link Number#floatValue}. * * <p>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<Float>} before 12.0) */ public static float[] toArray(Collection<? extends Number> collection) { if (collection instanceof FloatArrayAsList) { return ((FloatArrayAsList) collection).toFloatArray(); } Object[] boxedArray = collection.toArray(); int len = boxedArray.length; float[] array = new float[len]; for (int i = 0; i < len; i++) { // checkNotNull for GWT (do not optimize) array[i] = ((Number) checkNotNull(boxedArray[i])).floatValue(); } 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}. * * <p>The returned list maintains the values, but not the identities, of * {@code Float} 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. * * <p>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<Float> asList(float... backingArray) { if (backingArray.length == 0) { return Collections.emptyList(); } return new FloatArrayAsList(backingArray); } @GwtCompatible private static class FloatArrayAsList extends AbstractList<Float> implements RandomAccess, Serializable { final float[] array; final int start; final int end; FloatArrayAsList(float[] array) { this(array, 0, array.length); } FloatArrayAsList(float[] 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 Float get(int index) { checkElementIndex(index, size()); return array[start + index]; } @Override public boolean contains(Object target) { // Overridden to prevent a ton of boxing return (target instanceof Float) && Floats.indexOf(array, (Float) target, start, end) != -1; } @Override public int indexOf(Object target) { // Overridden to prevent a ton of boxing if (target instanceof Float) { int i = Floats.indexOf(array, (Float) 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 Float) { int i = Floats.lastIndexOf(array, (Float) target, start, end); if (i >= 0) { return i - start; } } return -1; } @Override public Float set(int index, Float element) { checkElementIndex(index, size()); float oldValue = array[start + index]; // checkNotNull for GWT (do not optimize) array[start + index] = checkNotNull(element); return oldValue; } @Override public List<Float> subList(int fromIndex, int toIndex) { int size = size(); checkPositionIndexes(fromIndex, toIndex, size); if (fromIndex == toIndex) { return Collections.emptyList(); } return new FloatArrayAsList(array, start + fromIndex, start + toIndex); } @Override public boolean equals(@Nullable Object object) { if (object == this) { return true; } if (object instanceof FloatArrayAsList) { FloatArrayAsList that = (FloatArrayAsList) 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 + Floats.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(); } float[] toFloatArray() { // Arrays.copyOfRange() is not available under GWT int size = size(); float[] result = new float[size]; System.arraycopy(array, start, result, 0, size); return result; } private static final long serialVersionUID = 0; } /** * Parses the specified string as a single-precision floating point value. * The ASCII character {@code '-'} (<code>'\u002D'</code>) is recognized * as the minus sign. * * <p>Unlike {@link Float#parseFloat(String)}, this method returns * {@code null} instead of throwing an exception if parsing fails. * Valid inputs are exactly those accepted by {@link Float#valueOf(String)}, * except that leading and trailing whitespace is not permitted. * * <p>This implementation is likely to be faster than {@code * Float.parseFloat} if many failures are expected. * * @param string the string representation of a {@code float} 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 float} value * @since 14.0 */ @Beta @Nullable @CheckForNull @GwtIncompatible("regular expressions") public static Float tryParse(String string) { if (Doubles.FLOATING_POINT_PATTERN.matcher(string).matches()) { // TODO(lowasser): could be potentially optimized, but only with // extensive testing try { return Float.parseFloat(string); } catch (NumberFormatException e) { // Float.parseFloat has changed specs several times, so fall through // gracefully } } return null; } }