com.google.common.primitives.Floats Maven / Gradle / Ivy
/*
* 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 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.Nullable;
/**
* Static utility methods pertaining to {@code float} primitives, that are not
* already found in either {@link Float} or {@link Arrays}.
*
* See the Guava User Guide article on
* primitive utilities.
*
* @author Kevin Bourrillion
* @since 1.0
*/
@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.
*
* @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.
*
*
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(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 nonempty 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#min(float, float)}.
*
* @param array a nonempty 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;
}
/**
* 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"}.
*
*
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]}.
*
*
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
* Lexicographical order article at Wikipedia
* @since 2.0
*/
public static Comparator lexicographicalComparator() {
return LexicographicalComparator.INSTANCE;
}
private enum LexicographicalComparator implements Comparator {
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 = Floats.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}.
*
* 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 float[] toArray(Collection 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}.
*
* 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.
*
*
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 asList(float... backingArray) {
if (backingArray.length == 0) {
return Collections.emptyList();
}
return new FloatArrayAsList(backingArray);
}
@GwtCompatible
private static class FloatArrayAsList extends AbstractList
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 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(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 '-'} ('\u002D') is recognized
* as the minus sign.
*
* 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.
*
*
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
*/
@GwtIncompatible("regular expressions")
@Nullable
@Beta
public static Float tryParse(String string) {
if (Doubles.FLOATING_POINT_PATTERN.matcher(string).matches()) {
// TODO(user): 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;
}
}