net.yetamine.lang.containers.values.Box Maven / Gradle / Ivy
Show all versions of net.yetamine.lang Show documentation
/*
* Copyright 2016 Yetamine
*
* 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 net.yetamine.lang.containers.values;
import java.io.Serializable;
import java.util.Objects;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import net.yetamine.lang.containers.Pointer;
/**
* A mutable container for holding a single value.
*
* @param
* the type of the stored value
*/
public final class Box implements Serializable, Value, Pointer {
/** Serialization version: 1 */
private static final long serialVersionUID = 1L;
/** Boxed value. */
private T value;
/**
* Creates a new instance filled with {@code null}.
*/
private Box() {
// Default constructor
}
/**
* Creates a new instance filled with the initial value.
*
* @param initial
* the initial value
*/
private Box(T initial) {
value = initial;
}
/**
* Creates a new instance filled with the initial value.
*
* @param
* the type of the stored value
* @param value
* the initial value
*
* @return the new instance
*/
public static Box of(T value) {
return new Box<>(value);
}
/**
* Creates a new instance filled with {@code null}.
*
* @param
* the type of the stored value
*
* @return the new instance
*/
public static Box empty() {
return new Box<>();
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return new StringBuilder("box[").append(value).append(']').toString();
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
return ((obj instanceof Box) && Objects.equals(((Box) obj).value, value));
}
/**
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
return Objects.hashCode(value);
}
/**
* @see java.util.function.Consumer#accept(java.lang.Object)
*/
public void accept(T t) {
value = t;
}
/**
* @see net.yetamine.lang.containers.Pointer#get()
*/
public T get() {
return value;
}
/**
* Sets the element value.
*
*
* This method is an alias to {@link #accept(Object)}, just returns this
* instance.
*
* @param t
* the value to set
*
* @return this instance
*/
public Box set(T t) {
value = t;
return this;
}
/**
* Sets the element value.
*
* @param t
* the value to set
*
* @return the previous value
*/
public T put(T t) {
final T result = value;
value = t;
return result;
}
/**
* Sets the element value to {@code null} and returns its original value.
*
* @return the original value
*/
public T clear() {
return put(null);
}
/**
* Computes the new value of the element, updates the element and returns
* its new value.
*
* @param mapping
* the mapping function to apply. It must not be {@code null}.
*
* @return this instance
*
* @see #compute(Function)
*/
public Box patch(Function mapping) {
value = mapping.apply(value);
return this;
}
/**
* Computes the new value of the element, updates the element and returns
* its new value.
*
* @param mapping
* the mapping function to apply; it gets the given value as the
* first argument and the current value as the second argument.
* It must not be {@code null}.
* @param t
* the value to pass as the first argument to the mapping
* function
*
* @return this instance
*
* @see #compute(BiFunction, Object)
*/
public Box patch(BiFunction mapping, T t) {
value = mapping.apply(t, value);
return this;
}
/**
* @see net.yetamine.lang.containers.values.Value#use(java.util.function.Consumer)
*/
public Box use(Consumer consumer) {
consumer.accept(value);
return this;
}
}