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Statistical sampling library for use in virtualdataset libraries, based on apache commons math 4
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.lang3;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
/**
* Utility library to provide helper methods for Java enums.
*
* #ThreadSafe#
*
* @since 3.0
*/
public class EnumUtils {
private static final String NULL_ELEMENTS_NOT_PERMITTED = "null elements not permitted";
private static final String CANNOT_STORE_S_S_VALUES_IN_S_BITS = "Cannot store %s %s values in %s bits";
private static final String S_DOES_NOT_SEEM_TO_BE_AN_ENUM_TYPE = "%s does not seem to be an Enum type";
private static final String ENUM_CLASS_MUST_BE_DEFINED = "EnumClass must be defined.";
/**
* This constructor is public to permit tools that require a JavaBean
* instance to operate.
*/
public EnumUtils() {
}
/**
* Gets the {@code Map} of enums by name.
*
* This method is useful when you need a map of enums by name.
*
* @param the type of the enumeration
* @param enumClass the class of the enum to query, not null
* @return the modifiable map of enum names to enums, never null
*/
public static > Map getEnumMap(final Class enumClass) {
final Map map = new LinkedHashMap<>();
for (final E e: enumClass.getEnumConstants()) {
map.put(e.name(), e);
}
return map;
}
/**
* Gets the {@code List} of enums.
*
* This method is useful when you need a list of enums rather than an array.
*
* @param the type of the enumeration
* @param enumClass the class of the enum to query, not null
* @return the modifiable list of enums, never null
*/
public static > List getEnumList(final Class enumClass) {
return new ArrayList<>(Arrays.asList(enumClass.getEnumConstants()));
}
/**
* Checks if the specified name is a valid enum for the class.
*
* This method differs from {@link Enum#valueOf} in that checks if the name is
* a valid enum without needing to catch the exception.
*
* @param the type of the enumeration
* @param enumClass the class of the enum to query, not null
* @param enumName the enum name, null returns false
* @return true if the enum name is valid, otherwise false
*/
public static > boolean isValidEnum(final Class enumClass, final String enumName) {
return getEnum(enumClass, enumName) != null;
}
/**
* Checks if the specified name is a valid enum for the class.
*
* This method differs from {@link Enum#valueOf} in that checks if the name is
* a valid enum without needing to catch the exception
* and performs case insensitive matching of the name.
*
* @param the type of the enumeration
* @param enumClass the class of the enum to query, not null
* @param enumName the enum name, null returns false
* @return true if the enum name is valid, otherwise false
* @since 3.8
*/
public static > boolean isValidEnumIgnoreCase(final Class enumClass, final String enumName) {
return getEnumIgnoreCase(enumClass, enumName) != null;
}
/**
* Gets the enum for the class, returning {@code null} if not found.
*
* This method differs from {@link Enum#valueOf} in that it does not throw an exception
* for an invalid enum name.
*
* @param the type of the enumeration
* @param enumClass the class of the enum to query, not null
* @param enumName the enum name, null returns null
* @return the enum, null if not found
*/
public static > E getEnum(final Class enumClass, final String enumName) {
if (enumName == null) {
return null;
}
try {
return Enum.valueOf(enumClass, enumName);
} catch (final IllegalArgumentException ex) {
return null;
}
}
/**
* Gets the enum for the class, returning {@code null} if not found.
*
* This method differs from {@link Enum#valueOf} in that it does not throw an exception
* for an invalid enum name and performs case insensitive matching of the name.
*
* @param the type of the enumeration
* @param enumClass the class of the enum to query, not null
* @param enumName the enum name, null returns null
* @return the enum, null if not found
* @since 3.8
*/
public static > E getEnumIgnoreCase(final Class enumClass, final String enumName) {
if (enumName == null || !enumClass.isEnum()) {
return null;
}
for (final E each : enumClass.getEnumConstants()) {
if (each.name().equalsIgnoreCase(enumName)) {
return each;
}
}
return null;
}
/**
* Creates a long bit vector representation of the given subset of an Enum.
*
* This generates a value that is usable by {@link EnumUtils#processBitVector}.
*
* Do not use this method if you have more than 64 values in your Enum, as this
* would create a value greater than a long can hold.
*
* @param enumClass the class of the enum we are working with, not {@code null}
* @param values the values we want to convert, not {@code null}, neither containing {@code null}
* @param the type of the enumeration
* @return a long whose value provides a binary representation of the given set of enum values.
* @throws NullPointerException if {@code enumClass} or {@code values} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class or has more than 64 values,
* or if any {@code values} {@code null}
* @since 3.0.1
* @see #generateBitVectors(Class, Iterable)
*/
public static > long generateBitVector(final Class enumClass, final Iterable values) {
checkBitVectorable(enumClass);
Validate.notNull(values);
long total = 0;
for (final E constant : values) {
Validate.isTrue(constant != null, NULL_ELEMENTS_NOT_PERMITTED);
total |= 1L << constant.ordinal();
}
return total;
}
/**
* Creates a bit vector representation of the given subset of an Enum using as many {@code long}s as needed.
*
* This generates a value that is usable by {@link EnumUtils#processBitVectors}.
*
* Use this method if you have more than 64 values in your Enum.
*
* @param enumClass the class of the enum we are working with, not {@code null}
* @param values the values we want to convert, not {@code null}, neither containing {@code null}
* @param the type of the enumeration
* @return a long[] whose values provide a binary representation of the given set of enum values
* with least significant digits rightmost.
* @throws NullPointerException if {@code enumClass} or {@code values} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class, or if any {@code values} {@code null}
* @since 3.2
*/
public static > long[] generateBitVectors(final Class enumClass, final Iterable values) {
asEnum(enumClass);
Validate.notNull(values);
final EnumSet condensed = EnumSet.noneOf(enumClass);
for (final E constant : values) {
Validate.isTrue(constant != null, NULL_ELEMENTS_NOT_PERMITTED);
condensed.add(constant);
}
final long[] result = new long[(enumClass.getEnumConstants().length - 1) / Long.SIZE + 1];
for (final E value : condensed) {
result[value.ordinal() / Long.SIZE] |= 1L << (value.ordinal() % Long.SIZE);
}
ArrayUtils.reverse(result);
return result;
}
/**
* Creates a long bit vector representation of the given array of Enum values.
*
* This generates a value that is usable by {@link EnumUtils#processBitVector}.
*
* Do not use this method if you have more than 64 values in your Enum, as this
* would create a value greater than a long can hold.
*
* @param enumClass the class of the enum we are working with, not {@code null}
* @param values the values we want to convert, not {@code null}
* @param the type of the enumeration
* @return a long whose value provides a binary representation of the given set of enum values.
* @throws NullPointerException if {@code enumClass} or {@code values} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class or has more than 64 values
* @since 3.0.1
* @see #generateBitVectors(Class, Iterable)
*/
@SafeVarargs
public static > long generateBitVector(final Class enumClass, final E... values) {
Validate.noNullElements(values);
return generateBitVector(enumClass, Arrays.asList(values));
}
/**
* Creates a bit vector representation of the given subset of an Enum using as many {@code long}s as needed.
*
* This generates a value that is usable by {@link EnumUtils#processBitVectors}.
*
* Use this method if you have more than 64 values in your Enum.
*
* @param enumClass the class of the enum we are working with, not {@code null}
* @param values the values we want to convert, not {@code null}, neither containing {@code null}
* @param the type of the enumeration
* @return a long[] whose values provide a binary representation of the given set of enum values
* with least significant digits rightmost.
* @throws NullPointerException if {@code enumClass} or {@code values} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class, or if any {@code values} {@code null}
* @since 3.2
*/
@SafeVarargs
public static > long[] generateBitVectors(final Class enumClass, final E... values) {
asEnum(enumClass);
Validate.noNullElements(values);
final EnumSet condensed = EnumSet.noneOf(enumClass);
Collections.addAll(condensed, values);
final long[] result = new long[(enumClass.getEnumConstants().length - 1) / Long.SIZE + 1];
for (final E value : condensed) {
result[value.ordinal() / Long.SIZE] |= 1L << (value.ordinal() % Long.SIZE);
}
ArrayUtils.reverse(result);
return result;
}
/**
* Convert a long value created by {@link EnumUtils#generateBitVector} into the set of
* enum values that it represents.
*
* If you store this value, beware any changes to the enum that would affect ordinal values.
* @param enumClass the class of the enum we are working with, not {@code null}
* @param value the long value representation of a set of enum values
* @param the type of the enumeration
* @return a set of enum values
* @throws NullPointerException if {@code enumClass} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class or has more than 64 values
* @since 3.0.1
*/
public static > EnumSet processBitVector(final Class enumClass, final long value) {
checkBitVectorable(enumClass).getEnumConstants();
return processBitVectors(enumClass, value);
}
/**
* Convert a {@code long[]} created by {@link EnumUtils#generateBitVectors} into the set of
* enum values that it represents.
*
* If you store this value, beware any changes to the enum that would affect ordinal values.
* @param enumClass the class of the enum we are working with, not {@code null}
* @param values the long[] bearing the representation of a set of enum values, least significant digits rightmost, not {@code null}
* @param the type of the enumeration
* @return a set of enum values
* @throws NullPointerException if {@code enumClass} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class
* @since 3.2
*/
public static > EnumSet processBitVectors(final Class enumClass, final long... values) {
final EnumSet results = EnumSet.noneOf(asEnum(enumClass));
final long[] lvalues = ArrayUtils.clone(Validate.notNull(values));
ArrayUtils.reverse(lvalues);
for (final E constant : enumClass.getEnumConstants()) {
final int block = constant.ordinal() / Long.SIZE;
if (block < lvalues.length && (lvalues[block] & 1L << (constant.ordinal() % Long.SIZE)) != 0) {
results.add(constant);
}
}
return results;
}
/**
* Validate that {@code enumClass} is compatible with representation in a {@code long}.
* @param the type of the enumeration
* @param enumClass to check
* @return {@code enumClass}
* @throws NullPointerException if {@code enumClass} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class or has more than 64 values
* @since 3.0.1
*/
private static > Class checkBitVectorable(final Class enumClass) {
final E[] constants = asEnum(enumClass).getEnumConstants();
Validate.isTrue(constants.length <= Long.SIZE, CANNOT_STORE_S_S_VALUES_IN_S_BITS,
Integer.valueOf(constants.length), enumClass.getSimpleName(), Integer.valueOf(Long.SIZE));
return enumClass;
}
/**
* Validate {@code enumClass}.
* @param the type of the enumeration
* @param enumClass to check
* @return {@code enumClass}
* @throws NullPointerException if {@code enumClass} is {@code null}
* @throws IllegalArgumentException if {@code enumClass} is not an enum class
* @since 3.2
*/
private static > Class asEnum(final Class enumClass) {
Validate.notNull(enumClass, ENUM_CLASS_MUST_BE_DEFINED);
Validate.isTrue(enumClass.isEnum(), S_DOES_NOT_SEEM_TO_BE_AN_ENUM_TYPE, enumClass);
return enumClass;
}
}