com.jongsoft.lang.Value Maven / Gradle / Ivy
/*
* The MIT License
*
* Copyright 2016-2019 Jong Soft.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.jongsoft.lang;
import java.io.Serializable;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* The Value interface represents a simple wrapped value. This interface can contain exactly one entity inside, or None in case of an empty
* value.
*
* @param the type of object being wrapped
* @since 0.0.1
*/
public interface Value extends Streamable, Serializable {
/**
* Validate that all elements match the predicate provided.
* This can be useful to quickly look over the elements to verify that they all meet a pre-specified criteria.
*
* Example:
* {@code // result will be true
* List("a", "b").all(x -> x.length() == 1);
* }
*
* @param predicate the predicate to test with
* @return true if all elements match the predicate, otherwise false
*
* @see #none(Predicate)
* @see #exists(Predicate)
* @throws NullPointerException in case the {@link Predicate} is null
*/
default boolean all(Predicate predicate) {
Objects.requireNonNull(predicate, "Predicate provided cannot be null");
return !exists(predicate.negate());
}
/**
* Validate if the value contains the provided item.
*
* @param element an element of type T, can be null
* @return true, if the element is contained within
*/
default boolean contains(T element) {
return exists(e -> Objects.equals(e, element));
}
/**
* Validate if an element is contained that matches the provided predicate.
*
* @param predicate the predicate to validate with
* @return true, if any element is contained within that matches the predicate
* @throws NullPointerException in case the {@link Predicate} is null
*/
default boolean exists(Predicate predicate) {
Objects.requireNonNull(predicate, "Predicate provided cannot be null");
for (T entity : this) {
if (predicate.test(entity)) {
return true;
}
}
return false;
}
/**
* Return the contents {@code T} of the wrapped value.
*
* This can throw a {@link NoSuchElementException} if no value is present.
*
* @return returns the object wrapped in this value
* @throws NoSuchElementException if no element is present
*/
T get();
/**
* Is this instance single-valued or not.
*
* @return {@code true} if single-valued, otherwise {@code false}
*/
boolean isSingleValued();
/**
* Validate that none of the elements match the {@code predicate} provided.
*
* @param predicate the predicate to test with
* @return true if none of the elements match, otherwise false
*
* @see #all(Predicate)
* @see #exists(Predicate)
* @throws NullPointerException in case the {@link Predicate} is null
*/
default boolean none(Predicate predicate) {
return !exists(predicate);
}
/**
* Create a stream of the value.
*
* @return the stream containing the value
*/
@Override
default Stream stream() {
return StreamSupport.stream(spliterator(), false);
}
}