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Some stellar general purpose utils.
/*
* Copyright (C) Posten Norge AS
*
* 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 no.digipost;
import java.util.Collection;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collector;
import java.util.stream.Stream;
import static java.util.Arrays.asList;
import static java.util.Arrays.stream;
import static java.util.stream.Collectors.joining;
/**
* Utilities for working with Java {@code enum}s.
*/
public final class DiggEnums {
/**
* Resolve {@code enum} constants from a string of comma separated names. The names must be exactly equal
* to the constant names of the given {@code enum} type, but may include any whitespace before and/or after
* each comma.
*
* @param enumNames the string containing the comma separated {@code enum} names.
* @param enumType the type of the {@code enum}.
* @return a stream of the resolved {@code enum} constants.
*/
public static > Stream fromCommaSeparatedNames(String enumNames, Class enumType) {
return fromCommaSeparated(enumNames, Function.identity(), enumType);
}
/**
* Resolve {@code enum} constants from a string of comma separated identifiers.
* The string may include any whitespace before and/or after each comma.
* The identifiers must be converted to {@code enum} names using a given {@link Function}.
*
* @param enumsString the string containing the comma separated {@code enum} identifiers.
* @param toEnumName the function to convert from the identifiers to {@code enum} names.
* @param enumType the type of the {@code enum}.
* @return a stream of the resolved {@code enum} constants.
*/
public static > Stream fromCommaSeparated(String enumsString, Function toEnumName, Class enumType) {
return fromEnumsString(enumsString, "\\s*,\\s*", toEnumName.andThen(e -> Enum.valueOf(enumType, e)));
}
/**
* Resolve {@code enum} constants from a string containing identifiers separated by a delimiter.
* The identifiers must be converted to {@code enum} constants using a given {@link Function}.
*
* @param enumsString the string containing the {@code enum} identifiers.
* @param delimRegex the regular expression which is applied to the {code enumString} to split it into
* separate identifiers.
* @param convertToEnum the function to convert from the identifiers to {@code enum} constants from the identifiers.
* @return a stream of the resolved {@code enum} constants.
*/
public static > Stream fromEnumsString(String enumsString, String delimRegex, Function convertToEnum) {
return fromEnumsString(enumsString, delimRegex, e -> true, convertToEnum);
}
/**
* Resolve {@code enum} constants from a string containing identifiers separated by a delimiter.
* The identifiers must be converted to {@code enum} constants using a given {@link Function}. In
* addition, this method offers a filtering mechanism to only include identifiers which satisfy a {@link Predicate}.
*
* @param enumsString the string containing the {@code enum} identifiers.
* @param delimRegex the regular expression which is applied to the {code enumString} to split it into
* separate identifiers.
* @param included predicate which is used as a filter on each identifier. Identifiers not satisfying this predicate
* will not be attempted to resolve as an {@code enum} constant.
* @param convertToEnum the function to convert from the identifiers to {@code enum} constants from the identifiers.
* @return a stream of the resolved {@code enum} constants.
*/
public static > Stream fromEnumsString(String enumsString, String delimRegex, Predicate included, Function convertToEnum) {
String trimmed = enumsString != null ? enumsString.trim() : "";
return trimmed.isEmpty() ? Stream.empty() : stream(trimmed.split(delimRegex)).filter(included).map(convertToEnum);
}
/**
* Join several {@code enum} constants to a comma separated string of their {@link Enum#name() names}.
*
* @param enums the {@code enum}s
* @return the comma separated {@code enum} names.
*/
@SafeVarargs
public static > String toCommaSeparatedNames(E ... enums) {
return toCommaSeparatedNames(asList(enums));
}
/**
* Join several {@code enum} constants to a comma separated string of their {@link Enum#name() names}.
*
* @param enums the {@code enum}s
* @return the comma separated {@code enum} names.
*/
public static > String toCommaSeparatedNames(Collection enums) {
return toNames(",", enums);
}
/**
* Join several {@code enum} constants to a string of their {@link Enum#name() names},
* separated by the given {@code delim}iter.
*
* @param delim the {@code delim}iter.
* @param enums the {@code enum}s.
* @return the {@code enum} names, separated by the {@code delim}iter.
*/
@SafeVarargs
public static > String toNames(String delim, E ... enums) {
return toNames(delim, asList(enums));
}
/**
* Join several {@code enum} constants to a string of their {@link Enum#name() names},
* separated by the given {@code delim}iter.
*
* @param delim the {@code delim}iter.
* @param enums the {@code enum}s.
* @return the {@code enum} names, separated by the {@code delim}iter.
*/
public static > String toNames(String delim, Collection enums) {
return toStringOf(Enum::name, delim, enums);
}
/**
* Join several {@code enum} constants to a string where each constant is converted to
* a string, and separated by the given {@code delim}iter.
*
* @param enumAsString the function which converts each {@code enum} constant to a string.
* @param delim the {@code delim}iter.
* @param enums the {@code enum}s.
* @return the joined string
*/
@SafeVarargs
public static > String toStringOf(Function enumAsString, String delim, E ... enums) {
return toStringOf(enumAsString, delim, asList(enums));
}
/**
* Join several {@code enum} constants to a string where each constant is converted to
* a string, and separated by the given {@code delim}iter.
*
* @param enumAsString the function which converts each {@code enum} constant to a string.
* @param delim the {@code delim}iter.
* @param enums the {@code enum}s.
* @return the joined string.
*/
public static > String toStringOf(Function enumAsString, String delim, Collection enums) {
return toStringOf(enumAsString, joining(delim), enums);
}
/**
* Join several {@code enum} constants to a string where each constant is converted to
* a string, and joined to one string using a given {@link Collector}.
*
* @param enumAsString the function which converts each {@code enum} constant to a string.
* @param joiner the {@code Collector} to join the strings.
* @param enums the {@code enum}s.
* @return the joined string.
*/
@SafeVarargs
public static > String toStringOf(Function enumAsString, Collector joiner, E ... enums) {
return toStringOf(enumAsString, joiner, asList(enums));
}
/**
* Join several {@code enum} constants to a string where each constant is converted to
* a string, and joined to one string using a given {@link Collector}.
*
* @param enumAsString the function which converts each {@code enum} constant to a string.
* @param joiner the {@code Collector} to join the strings.
* @param enums the {@code enum}s.
* @return the joined string.
*/
public static > String toStringOf(Function enumAsString, Collector joiner, Collection enums) {
return enums.stream().map(enumAsString).collect(joiner);
}
private DiggEnums() {}
}