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The runtime library of DBFlute
/*
* Copyright 2014-2019 the original author or authors.
*
* 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 org.dbflute.optional;
import java.io.Serializable;
import java.util.Optional;
/**
* The base class for optional object.
* @param The type of wrapped object in the optional object.
* @author jflute
* @author pull/23 (2015/03/04 Wednesday)
* @since 1.0.5F (2014/05/10 Saturday)
*/
public abstract class BaseOptional implements OptionalThing, Serializable {
// ===================================================================================
// Definition
// ==========
// basically for optional entity of relation
// if this is not serializable, must have default constructor even so cannot serialize
private static final long serialVersionUID = 1L;
protected static final OptionalThingIfPresentAfter IF_PRESENT_AFTER_EMPTY = noArgLambda -> {};
protected static final OptionalThingIfPresentAfter IF_PRESENT_AFTER_NONE_FIRE = noArgLambda -> {
if (noArgLambda == null) {
String msg = "The argument 'noArgLambda' should not be null.";
throw new IllegalArgumentException(msg);
}
noArgLambda.process();
};
// ===================================================================================
// Attribute
// =========
/** The wrapped object for this optional object. (NullAllowed) */
protected final OBJ _obj;
/** The exception thrower e.g. when wrapped object is not found. (NotNull) */
protected final OptionalThingExceptionThrower _thrower;
// ===================================================================================
// Constructor
// ===========
public BaseOptional(OBJ obj, OptionalThingExceptionThrower thrower) { // basically called by DBFlute
_obj = obj; // may be null
if (thrower == null) {
String msg = "The argument 'thrower' should not be null: obj=" + obj;
throw new IllegalArgumentException(msg);
}
_thrower = thrower;
}
// ===================================================================================
// Object Handling
// ===============
// -----------------------------------------------------
// Present
// -------
/**
* Is the wrapped object present? (existing?)
* @return The determination, true or false.
*/
protected boolean exists() {
return _obj != null;
}
/**
* @param objLambda The callback interface to consume the wrapped value. (NotNull)
*/
protected void callbackAlwaysPresent(OptionalThingConsumer objLambda) {
if (objLambda == null) {
String msg = "The argument 'objLambda' should not be null.";
throw new IllegalArgumentException(msg);
}
if (_obj == null) {
_thrower.throwNotFoundException();
}
objLambda.accept(_obj);
}
/**
* @param consumer The callback interface to consume the wrapped object. (NotNull)
* @return The handler of after process when if not present. (NotNull)
*/
protected OptionalThingIfPresentAfter callbackIfPresent(OptionalThingConsumer consumer) {
if (consumer == null) {
String msg = "The argument 'consumer' should not be null.";
throw new IllegalArgumentException(msg);
}
if (exists()) {
consumer.accept(_obj);
return IF_PRESENT_AFTER_EMPTY;
} else {
return IF_PRESENT_AFTER_NONE_FIRE;
}
}
// -----------------------------------------------------
// get()
// -----
/**
* @return The object instance wrapped in this optional object. (NotNull)
*/
protected OBJ directlyGet() {
if (!exists()) {
_thrower.throwNotFoundException();
}
return _obj;
}
/**
* @param other The other instance to be returned if null. (NullAllowed: if null, returns null when entity is null)
* @return The object instance wrapped in this optional object or specified value. (NullAllowed: if null specified)
*/
protected OBJ directlyGetOrElse(OBJ other) {
return exists() ? _obj : other;
}
/**
* @param supplier The supplier of other instance if null. (NotNull)
* @return The object instance wrapped in this optional object or specified value. (NullAllowed: if null specified)
*/
protected OBJ directlyGetOrElseGet(OptionalThingSupplier supplier) {
if (supplier == null) {
String msg = "The argument 'supplier' should not be null.";
throw new IllegalArgumentException(msg);
}
return exists() ? _obj : supplier.get();
}
/**
* @param The type of cause.
* @param supplier The supplier of exception if null. (NotNull)
* @return The object instance wrapped in this optional object. (NotNull: if null, exception)
* @throws CAUSE When the value is null.
*/
protected OBJ directlyGetOrElseThrow(OptionalThingSupplier supplier) throws CAUSE {
if (supplier == null) {
String msg = "The argument 'supplier' should not be null.";
throw new IllegalArgumentException(msg);
}
if (exists()) {
return directlyGet();
} else {
throw supplier.get();
}
}
/**
* @param The type of original cause.
* @param The type of translated cause.
* @param translator The translator function of exception if null. (NotNull)
* @return The object instance wrapped in this optional object. (NotNull: if null, exception)
* @throws TRANSLATED When the value is null.
*/
protected OBJ directlyGetOrElseTranslatingThrow(
OptionalThingFunction translator) throws TRANSLATED {
if (translator == null) {
String msg = "The argument 'supplier' should not be null.";
throw new IllegalArgumentException(msg);
}
try {
return directlyGet();
} catch (Throwable e) {
@SuppressWarnings("unchecked")
final CAUSE cause = (CAUSE) e;
throw translator.apply(cause);
}
}
// -----------------------------------------------------
// filter()
// --------
/**
* @param mapper The callback interface to apply. (NotNull)
* @return The optional thing as mapped result. (NotNull, EmptyOptionalAllowed: if not present or callback returns null)
*/
protected OptionalThing callbackFilter(OptionalThingPredicate mapper) {
if (mapper == null) {
String msg = "The argument 'mapper' should not be null.";
throw new IllegalArgumentException(msg);
}
if (exists()) {
if (mapper.test(_obj)) {
return this;
} else {
return createOptionalFilteredObject(null);
}
} else {
return createOptionalFilteredObject(null);
}
}
/**
* @param The type of value for optional thing.
* @param obj The plain object for the optional thing. (NullAllowed: if null, return s empty optional)
* @return The new-created instance of optional thing. (NotNull)
*/
protected abstract OptionalThing createOptionalFilteredObject(ARG obj);
// -----------------------------------------------------
// map()
// -----
/**
* @param The type of mapping result.
* @param mapper The callback interface to apply, null return allowed as empty. (NotNull)
* @return The optional object as mapped result. (NotNull, EmptyOptionalAllowed: if not present or callback returns null)
*/
protected OptionalThing callbackMapping(OptionalThingFunction mapper) {
if (mapper == null) {
String msg = "The argument 'mapper' should not be null.";
throw new IllegalArgumentException(msg);
}
final RESULT result = exists() ? mapper.apply(_obj) : null;
return createOptionalMappedObject(result);
}
/**
* @param The type of value for optional thing.
* @param obj The plain object for the optional thing. (NullAllowed: if null, return s empty optional)
* @return The new-created instance of optional thing. (NotNull)
*/
protected abstract OptionalThing createOptionalMappedObject(ARG obj);
/**
* @param The type of mapping result.
* @param mapper The callback interface to apply, cannot return null. (NotNull)
* @return The optional thing as flat-mapped result. (NotNull, EmptyOptionalAllowed: when not present)
*/
protected OptionalThing callbackFlatMapping(OptionalThingFunction> mapper) {
if (mapper == null) {
String msg = "The argument 'mapper' should not be null.";
throw new IllegalArgumentException(msg);
}
// pull request, thanks! https://github.com/dbflute/dbflute-core/pull/23
if (exists()) {
final OptionalThing applied = mapper.apply(_obj);
if (applied == null) { // same specification as official optional's flatMap
String msg = "The function of your flatMap returned null: function=" + mapper;
throw new IllegalStateException(msg);
} else {
return applied;
}
} else {
return createOptionalFlatMappedObject(null);
}
}
/**
* @param The type of value for optional thing.
* @param obj The plain object for the optional thing. (NullAllowed: if null, return s empty optional)
* @return The new-created instance of optional thing. (NotNull)
*/
protected abstract OptionalThing createOptionalFlatMappedObject(ARG obj);
// ===================================================================================
// Standard Optional
// =================
/** {@inheritDoc} */
public Optional toOptional() {
return Optional.ofNullable(directlyGetOrElse(null));
}
// ===================================================================================
// Basic Override
// ==============
@Override
public int hashCode() {
return _obj != null ? _obj.hashCode() : 0;
}
@Override
public boolean equals(Object obj) {
if (getClass().isInstance(obj)) {
final BaseOptional other = (BaseOptional) obj;
if (_obj != null) {
return _obj.equals(other.directlyGet());
} else { // null v.s. null?
return !other.exists();
}
}
return false;
}
@Override
public String toString() {
return "opt:{" + (_obj != null ? _obj.toString() : "null") + "}";
}
}
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