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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.util.Optional;
import org.dbflute.exception.EntityAlreadyDeletedException;
/**
* @param The type of thing.
* @author jflute
* @since 1.0.5F (2014/05/05 Monday)
*/
public interface OptionalThing {
// ===================================================================================
// Constructor
// ===========
// using as object
/**
* @param The type of empty optional thing.
* @return The fixed instance as empty. (NotNull)
*/
public static OptionalThing empty() {
return OptionalObject.empty();
}
/**
* @param The type of thing wrapped in the optional thing.
* @param object The wrapped thing which is optional. (NotNull)
* @return The new-created instance as existing optional thing. (NotNull)
*/
public static OptionalThing of(THING object) {
return OptionalObject.of(object);
}
/**
* @param The type of thing wrapped in the optional thing.
* @param object The wrapped instance or thing. (NullAllowed)
* @param noArgLambda The callback for exception when illegal access. (NotNull)
* @return The new-created instance as existing or empty optional thing. (NotNull)
*/
public static OptionalThing ofNullable(THING object, OptionalThingExceptionThrower noArgLambda) {
return OptionalObject.ofNullable(object, noArgLambda);
}
/**
* @param The type of thing wrapped in the optional thing.
* @param java8opt The optional instance as Java8 standard optional. (NotNull)
* @param noArgLambda The callback for exception when illegal access. (NotNull)
* @return The new-created instance as existing or empty optional thing. (NotNull)
*/
public static OptionalThing migratedFrom(Optional java8opt, OptionalThingExceptionThrower noArgLambda) {
return OptionalObject.ofNullable(java8opt.orElse(null), noArgLambda);
}
/**
* @param The type of thing wrapped in the optional thing.
* @param dfopt The optional instance as optional thing DBFlute provides. (NotNull)
* @param noArgLambda The callback for exception when illegal access. (NotNull)
* @return The new-created instance as existing or empty optional thing. (NotNull)
*/
public static OptionalThing translatedFrom(OptionalThing dfopt, OptionalThingExceptionThrower noArgLambda) {
return OptionalObject.ofNullable(dfopt.orElse(null), noArgLambda);
}
// ===================================================================================
// Standard Handling
// =================
/**
* Handle the wrapped thing if it is present.
* You should call this if null object handling is unnecessary (do nothing if null).
* If exception is preferred when null object, use required().
* @param oneArgLambda The callback interface to consume the optional thing. (NotNull)
* @return The handler of after process when if not present. (NotNull)
*/
OptionalThingIfPresentAfter ifPresent(OptionalThingConsumer oneArgLambda);
/**
* Is the object instance present? (existing?)
* @return The determination, true or false.
*/
boolean isPresent();
/**
* Get the thing or exception if null.
* @return The instance of the wrapped thing. (NotNull)
* @throws EntityAlreadyDeletedException When the object instance wrapped in this optional thing is null, which means object has already been deleted (point is not found).
*/
THING get();
/**
* Filter the thing by the predicate.
* @param oneArgLambda The callback to predicate whether the object is remained. (NotNull)
* @return The filtered optional thing, might be empty. (NotNull)
*/
OptionalThing filter(OptionalThingPredicate oneArgLambda);
/**
* Apply the mapping of thing to result thing.
* @param The type of mapping result.
* @param oneArgLambda The callback interface to apply, null return allowed as empty. (NotNull)
* @return The optional thing as mapped result. (NotNull, EmptyOptionalAllowed: if not present or callback returns null)
*/
OptionalThing map(OptionalThingFunction oneArgLambda);
/**
* Apply the flat-mapping of thing to result thing.
* @param The type of mapping result.
* @param oneArgLambda The callback interface to apply, cannot return null. (NotNull)
* @return The optional thing as mapped result. (NotNull, EmptyOptionalAllowed: if not present or callback returns null)
*/
OptionalThing flatMap(OptionalThingFunction> oneArgLambda);
/**
* Get the wrapped instance or returns the specified thing.
* @param other The object instance to be returned when the optional is empty. (NullAllowed)
* @return The wrapped instance or specified other object. (NullAllowed:)
*/
THING orElse(THING other);
/**
* Get the thing or get from the supplier.
* @param noArgLambda The supplier of other instance if null. (NotNull)
* @return The object instance wrapped in this optional thing or specified value. (NullAllowed: if null specified)
*/
THING orElseGet(OptionalThingSupplier noArgLambda);
/**
* Get the thing or throw the exception.
* @param The type of cause.
* @param noArgLambda 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.
*/
THING orElseThrow(OptionalThingSupplier noArgLambda) throws CAUSE;
/**
* Get the thing or throw the exception with translating the cause.
* @param The type of original cause.
* @param The type of translated cause.
* @param oneArgLambda 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.
*/
THING orElseTranslatingThrow(
OptionalThingFunction oneArgLambda) throws TRANSLATED;
// ===================================================================================
// Standard Optional
// =================
/**
* Convert to Java standard optional class.
* For only when standard optional handling is needed, so basically you don't use this.
* @return The new-created instance or empty. (NotNull)
*/
Optional toOptional();
// ===================================================================================
// DBFlute Extension
// =================
/**
* Handle the thing in the optional thing or exception if not present.
* @param oneArgLambda The callback interface to consume the optional thing. (NotNull)
* @throws EntityAlreadyDeletedException When the object instance wrapped in this optional thing is null, which means object has already been deleted (point is not found).
*/
void alwaysPresent(OptionalThingConsumer oneArgLambda);
/**
* Get the object instance or null if not present.
* basically use ifPresent() if might be not present, this is for emergency
* @return The object instance wrapped in this optional thing or null. (NullAllowed: if not present)
* @deprecated basically use ifPresent() or use orElse(null)
*/
THING orElseNull();
}
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