software.amazon.smithy.build.transforms.ConfigurableProjectionTransformer Maven / Gradle / Ivy
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/*
* Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 software.amazon.smithy.build.transforms;
import java.util.List;
import java.util.Optional;
import java.util.function.BiFunction;
import software.amazon.smithy.build.ProjectionTransformer;
import software.amazon.smithy.build.TransformContext;
import software.amazon.smithy.model.Model;
import software.amazon.smithy.model.node.NodeMapper;
import software.amazon.smithy.utils.ListUtils;
/**
* An abstract class used to more easily implement a Smithy build projection
* transformer that expects configuration input in a specific type, {@code T}.
*
* This class will automatically deserialize the given {@code Node}
* value in the {@code T} and invoke {@link #transformWithConfig(TransformContext, Object)}
* with the deserialized configuration of type {@code T}.
*
*
If your build transformer requires configuration, then you typically
* should just extend this class.
*
* Note: if you override {@link #getAdditionalProjectionsFunction()} and
* do not override {@link #transform(TransformContext)}, the configuration for
* your transformer will be deserialized twice during execution.
*
* @param The configuration setting type (e.g., a POJO).
*/
public abstract class ConfigurableProjectionTransformer implements ProjectionTransformer {
/**
* Gets the configuration class type.
*
* The referenced {@code configType} class must be a public POJO with a
* public, zero-arg constructor, getters, and setters. If the POJO has a
* public static {@code fromNode} method, it will be invoked and is
* expected to deserialize the Node. If the POJO has a public static
* {@code builder} method, it will be invoked, setters will be called
* on the builder POJO, and finally the result of calling the
* {@code build} method is used as the configuration type. Finally,
* the deserializer will attempt to create the type and call setters on
* the instantiated object that correspond to property names (either named
* "set" + property name, or just property name).
*
* @return Returns the configuration class (a POJO with setters/getters).
*/
public abstract Class getConfigType();
@Override
public Model transform(TransformContext context) {
NodeMapper mapper = new NodeMapper();
T config = mapper.deserialize(context.getSettings(), getConfigType());
return transformWithConfig(context, config);
}
@Override
public List getAdditionalProjections(TransformContext context) {
return getAdditionalProjectionsFunction().map(fn -> {
NodeMapper mapper = new NodeMapper();
T config = mapper.deserialize(context.getSettings(), getConfigType());
return fn.apply(context, config);
}).orElseGet(ListUtils::of);
}
/**
* Executes the transform using the deserialized configuration object.
*
* @param context Transform context.
* @param config Deserialized configuration object.
* @return Returns the transformed model.
*/
protected abstract Model transformWithConfig(TransformContext context, T config);
/**
* @return an Optional of either a BiFunction that returns the additional
* projections to run after this one, or empty to indicate this
* projection will never compose other ones.
*/
protected Optional>> getAdditionalProjectionsFunction() {
return Optional.empty();
}
}