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A general programming library in Java
/*
* Copyright (C) 2015 HaiYang Li
*
* 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.landawn.abacus.util;
import com.landawn.abacus.util.function.Supplier;
import com.landawn.abacus.util.stream.Stream;
/**
*
* @since 0.8
*
* @author Haiyang Li
*/
abstract class Reference> {
private volatile T value;
protected Reference() {
this(null);
}
protected Reference(T value) {
this.value = value;
}
public T value() {
return value;
}
public T getValue() {
return value;
}
public R setValue(final T value) {
this.value = value;
return (R) this;
}
public T getAndSet(final T value) {
final T result = this.value;
this.value = value;
return result;
}
public T setAndGet(final T value) {
this.value = value;
return this.value;
}
public final T getAndUpdate(Try.UnaryOperator updateFunction) throws E {
final T res = value;
this.value = updateFunction.apply(value);
return res;
}
public final T updateAndGet(Try.UnaryOperator updateFunction) throws E {
this.value = updateFunction.apply(value);
return value;
}
/**
* Set with the specified new value and returns true if predicate returns true.
* Otherwise just return false without setting the value to new value.
*
* @param newValue
* @param predicate - test the current value.
* @return
*/
public boolean setIf(final T newValue, final Try.Predicate predicate) throws E {
if (predicate.test(value)) {
this.value = newValue;
return true;
}
return false;
}
/**
* Set with the specified new value and returns true if predicate returns true.
* Otherwise just return false without setting the value to new value.
*
* @param newValue
* @param predicate the first parameter is the current value, the second parameter is the new value.
* @return
*/
public boolean setIf(final T newValue, final Try.BiPredicate predicate) throws E {
if (predicate.test(value, newValue)) {
this.value = newValue;
return true;
}
return false;
}
public boolean isNotNull() {
return value != null;
}
public void ifNotNull(Try.Consumer consumer) throws E {
if (isNotNull()) {
consumer.accept(value);
}
}
public void ifNotNullOrElse(Try.Consumer action, Try.Runnable emptyAction) throws E, E2 {
if (isNotNull()) {
action.accept(value);
} else {
emptyAction.run();
}
}
public void accept(final Try.Consumer action) throws E {
action.accept(value);
}
/**
*
* @param action
* @throws E
* @deprecated replaced with {@code #ifNotNull(com.landawn.abacus.util.Try.Consumer)}.
*/
@Deprecated
public void acceptIfNotNull(final Try.Consumer action) throws E {
if (isNotNull()) {
action.accept(value);
}
}
public U map(final Try.Function mapper) throws E {
return mapper.apply(value);
}
/**
* Execute the specified action if value is not null, otherwise return null directly.
*
* @param mapper
* @return
*/
public Nullable mapIfNotNull(final Try.Function mapper) throws E {
return isNotNull() ? Nullable.of(mapper.apply(value)) : Nullable. empty();
}
public Nullable filter(final Try.Predicate predicate) throws E {
return predicate.test(value) ? Nullable.of(value) : Nullable. empty();
}
public Optional filterIfNotNull(final Try.Predicate predicate) throws E {
return isNotNull() && predicate.test(value) ? Optional.of(value) : Optional. empty();
}
public Stream stream() {
return Stream.of(value);
}
/**
*
* @return an empty Stream if the value is null.
*/
public Stream streamIfNotNull() {
return isNotNull() ? Stream.of(value) : Stream. empty();
}
/**
* Return the value is not null, otherwise return {@code other}.
*
* @param other the value to be returned if not present or null, may be null
* @return the value, if not present or null, otherwise {@code other}
*/
public T orIfNull(T other) {
return isNotNull() ? value : other;
}
/**
* Return the value is not null, otherwise invoke {@code other} and return the result of that invocation.
*
* @param other a {@code Supplier} whose result is returned if not present or null
* @return the value if not present or null otherwise the result of {@code other.get()}
* @throws IllegalArgumentException if value is not present and {@code other} is null
*/
public T orGetIfNull(Try.Supplier other) throws E {
return isNotNull() ? value : other.get();
}
/**
* Return the value is not null, otherwise throw an exception to be created by the provided supplier.
*
* @apiNote A method reference to the exception constructor with an empty
* argument list can be used as the supplier. For example,
* {@code IllegalStateException::new}
*
* @param Type of the exception to be thrown
* @param exceptionSupplier The supplier which will return the exception to be thrown
* @return the present value
* @throws X if not present or null
* @throws IllegalArgumentException if not present or null and
* {@code exceptionSupplier} is null
*/
public T orThrowIfNull(Supplier exceptionSupplier) throws X {
if (isNotNull()) {
return value;
} else {
throw exceptionSupplier.get();
}
}
/**
* Returns a non-empty {@code Nullable} with the {@code value}.
*
* @return
*/
public Nullable toNullable() {
return Nullable.of(value);
}
/**
* Returns an {@code Optional} with the {@code value} if {@code value} is not null, otherwise an empty {@code Optional} is returned.
*
* @return
*/
public Optional toOptional() {
return Optional.ofNullable(value);
}
@Override
public int hashCode() {
return (value == null) ? 0 : value.hashCode();
}
@SuppressWarnings("rawtypes")
@Override
public boolean equals(final Object obj) {
return this == obj || (obj instanceof Reference && N.equals(((Reference) obj).value, value));
}
@Override
public String toString() {
return N.toString(value);
}
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