As.java
/*
* *********************************************************************************************************************
*
* TheseFoolishThings: Miscellaneous utilities
* http://tidalwave.it/projects/thesefoolishthings
*
* Copyright (C) 2009 - 2023 by Tidalwave s.a.s. (http://tidalwave.it)
*
* *********************************************************************************************************************
*
* 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.
*
* *********************************************************************************************************************
*
* git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
* git clone https://github.com/tidalwave-it/thesefoolishthings-src
*
* *********************************************************************************************************************
*/
package it.tidalwave.util;
import javax.annotation.Nonnull;
import java.util.Collection;
import java.util.Optional;
import it.tidalwave.role.impl.AsDelegate;
import lombok.EqualsAndHashCode;
import lombok.RequiredArgsConstructor;
import lombok.ToString;
/***********************************************************************************************************************
*
* Objects implementing this interface can provide am adapter of the required type. The adapter can be found with a
* variety of approaches that depend on the implementation. This capability can be used to implement a design based
* on the Data, Context and Interaction pattern (DCI). For further details, please look at the
* <a href="http://tidalwave.it/projects/thesefoolishthings">project website</a>, where a tutorial is available.
*
* @author Fabrizio Giudici
* @it.tidalwave.javadoc.stable
*
**********************************************************************************************************************/
public interface As
{
/*******************************************************************************************************************
*
* A type reference for roles that can be used in place of a class literal, especially when roles with generics are
* used. Example of usage:
* <pre>
*
* interface DataRetriever<T>
* {
* public List<T> retrieve();
* }
*
* class CodeSample
* {
* private static final As.Type<DataRetriever<String>> _StringRetriever_ = As.type(DataRetriever.class);
*
* public void method (As object)
* {
* List<String> f3 = object.as(_StringRetriever_).retrieve();
* }
* }
* </pre>
*
* @since 3.2-ALPHA-12
*
******************************************************************************************************************/
@RequiredArgsConstructor @EqualsAndHashCode @ToString
public static final class Type<T>
{
@Nonnull
private final Class<?> type;
@Nonnull @SuppressWarnings("unchecked")
/* package */ Class<T> getType()
{
return (Class<T>)type;
}
}
/*******************************************************************************************************************
*
* Creates an {@code As} implementation delegate for the given object (or returns the object itself if it is the
* default implementation of {@code As}).
*
* @param object the object
* @return the implementation
* @since 3.2-ALPHA-12
*
******************************************************************************************************************/
@Nonnull
public static As forObject (@Nonnull final Object object)
{
return (object instanceof AsDelegate) ? (As)object : new AsDelegate(object);
}
/*******************************************************************************************************************
*
* Creates an {@code As} implementation delegate for the given object. It accepts a single pre-instantiated role,
* or a {@link RoleFactory} that will be invoked to create additional roles.
*
* @param object the object
* @param role the role or {@link it.tidalwave.util.RoleFactory}
* @return the implementation
* @since 3.2-ALPHA-13
*
******************************************************************************************************************/
@Nonnull
public static As forObject (@Nonnull final Object object, @Nonnull final Object role)
{
return new AsDelegate(object, role);
}
/*******************************************************************************************************************
*
* Creates an {@code As} implementation delegate for the given object. It accepts a collection of pre-instantiated
* roles, or instances of {@link RoleFactory} that will be invoked to create additional roles.
*
* @param object the object
* @param roles roles or {@link it.tidalwave.util.RoleFactory} instances
* @return the implementation
* @since 3.2-ALPHA-13
*
******************************************************************************************************************/
@Nonnull
public static As forObject (@Nonnull final Object object, @Nonnull final Collection<Object> roles)
{
return new AsDelegate(object, roles);
}
/*******************************************************************************************************************
*
* Returns an adapter to this object of the specified type. If the implementation can find multiple compliant
* adapters, only one will be returned.
*
* @param <T> the static type
* @param type the dynamic type
* @return the adapter
* @throws AsException if no adapter is found
*
******************************************************************************************************************/
@Nonnull
public default <T> T as (@Nonnull final Class<? extends T> type)
{
return maybeAs(type).orElseThrow(() -> new AsException(type));
}
/*******************************************************************************************************************
*
* Returns the requested role or an empty {@link Optional}.
*
* @param <T> the static type
* @param type the dynamic type
* @return the optional role
* @since 3.2-ALPHA-3
*
******************************************************************************************************************/
@Nonnull
public <T> Optional<T> maybeAs (@Nonnull Class<? extends T> type);
/*******************************************************************************************************************
*
* Searches for multiple adapters of the given type and returns them.
*
* @param <T> the static type
* @param type the dynamic type
* @return a collection of adapters, possibly empty
*
******************************************************************************************************************/
@Nonnull
public <T> Collection<T> asMany (@Nonnull Class<? extends T> type);
/*******************************************************************************************************************
*
* Creates a role type reference.
*
* @param <T> the static type
* @param type the dynamic type
* @return the type reference
* @since 3.2-ALPHA-12
*
******************************************************************************************************************/
@Nonnull
public static <T> Type<T> type (@Nonnull final Class<?> type) // FIXME: there's no static check of the argument
{
return new Type<>(type);
}
/*******************************************************************************************************************
*
* Returns a role for this object of the specified type. If the implementation can find multiple compliant
* roles, only one will be returned.
*
* @param <T> the static type
* @param type the type reference
* @return the role
* @since 3.2-ALPHA-12
*
******************************************************************************************************************/
@Nonnull
public default <T> T as (@Nonnull final Type<? extends T> type)
{
return as(type.getType());
}
/*******************************************************************************************************************
*
* Returns the requested role or an empty {@link Optional}.
*
* @param <T> the static type
* @param type the type reference
* @return the optional role
* @since 3.2-ALPHA-12
*
******************************************************************************************************************/
@Nonnull
public default <T> Optional<T> maybeAs (@Nonnull final Type<? extends T> type)
{
return maybeAs(type.getType());
}
/*******************************************************************************************************************
*
* Returns the requested role or an empty {@link Optional}.
*
* @param <T> the static type
* @param type the type reference
* @return the roles
* @since 3.2-ALPHA-12
*
******************************************************************************************************************/
@Nonnull
public default <T> Collection<T> asMany (@Nonnull final Type<? extends T> type)
{
return asMany(type.getType());
}
}