javax.lang.model.util.SimpleElementVisitor6 Maven / Gradle / Ivy
/*
* Copyright (C) 2021 ZeoFlow SRL
*
* 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 javax.lang.model.util;
import javax.lang.model.SourceVersion;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.TypeParameterElement;
import javax.lang.model.element.VariableElement;
/**
* A simple visitor of program elements with default behavior
* appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}
* source version.
*
* Visit methods corresponding to {@code RELEASE_6} language
* constructs call {@link #defaultAction defaultAction}, passing their
* arguments to {@code defaultAction}'s corresponding parameters.
*
* For constructs introduced in {@code RELEASE_7} and later, {@code
* visitUnknown} is called instead.
*
*
Methods in this class may be overridden subject to their
* general contract. Note that annotating methods in concrete
* subclasses with {@link java.lang.Override @Override} will help
* ensure that methods are overridden as intended.
*
*
WARNING: The {@code ElementVisitor} interface
* implemented by this class may have methods added to it in the
* future to accommodate new, currently unknown, language structures
* added to future versions of the Java™ programming language.
* Therefore, methods whose names begin with {@code "visit"} may be
* added to this class in the future; to avoid incompatibilities,
* classes which extend this class should not declare any instance
* methods with names beginning with {@code "visit"}.
*
*
When such a new visit method is added, the default
* implementation in this class will be to call the {@link
* #visitUnknown visitUnknown} method. A new simple element visitor
* class will also be introduced to correspond to the new language
* level; this visitor will have different default behavior for the
* visit method in question. When the new visitor is introduced, all
* or portions of this visitor may be deprecated.
*
*
Note that adding a default implementation of a new visit method
* in a visitor class will occur instead of adding a default
* method directly in the visitor interface since a Java SE 8
* language feature cannot be used to this version of the API since
* this version is required to be runnable on Java SE 7
* implementations. Future versions of the API that are only required
* to run on Java SE 8 and later may take advantage of default methods
* in this situation.
*
* @param the return type of this visitor's methods. Use {@code Void}
* for visitors that do not need to return results.
* @param the type of the additional parameter to this visitor's methods. Use {@code Void}
* for visitors that do not need an additional parameter.
*
* @author Joseph D. Darcy
* @author Scott Seligman
* @author Peter von der Ahé
* @see SimpleElementVisitor7
* @see SimpleElementVisitor8
* @since 1.6
*/
@SupportedSourceVersion(SourceVersion.RELEASE_6)
public class SimpleElementVisitor6 extends AbstractElementVisitor6
{
/**
* Default value to be returned; {@link #defaultAction
* defaultAction} returns this value unless the method is
* overridden.
*/
protected final R DEFAULT_VALUE;
/**
* Constructor for concrete subclasses; uses {@code null} for the
* default value.
*/
protected SimpleElementVisitor6()
{
DEFAULT_VALUE = null;
}
/**
* Constructor for concrete subclasses; uses the argument for the
* default value.
*
* @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
*/
protected SimpleElementVisitor6(R defaultValue)
{
DEFAULT_VALUE = defaultValue;
}
/**
* The default action for visit methods. The implementation in
* this class just returns {@link #DEFAULT_VALUE}; subclasses will
* commonly override this method.
*
* @param e the element to process
* @param p a visitor-specified parameter
*
* @return {@code DEFAULT_VALUE} unless overridden
*/
protected R defaultAction(Element e, P p)
{
return DEFAULT_VALUE;
}
/**
* {@inheritDoc} This implementation calls {@code defaultAction}.
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
*
* @return the result of {@code defaultAction}
*/
public R visitPackage(PackageElement e, P p)
{
return defaultAction(e, p);
}
/**
* {@inheritDoc} This implementation calls {@code defaultAction}.
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
*
* @return the result of {@code defaultAction}
*/
public R visitType(TypeElement e, P p)
{
return defaultAction(e, p);
}
/**
* {@inheritDoc}
*
* This implementation calls {@code defaultAction}, unless the
* element is a {@code RESOURCE_VARIABLE} in which case {@code
* visitUnknown} is called.
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
*
* @return the result of {@code defaultAction} or {@code visitUnknown}
*/
public R visitVariable(VariableElement e, P p)
{
if (e.getKind() != ElementKind.RESOURCE_VARIABLE)
return defaultAction(e, p);
else
return visitUnknown(e, p);
}
/**
* {@inheritDoc} This implementation calls {@code defaultAction}.
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
*
* @return the result of {@code defaultAction}
*/
public R visitExecutable(ExecutableElement e, P p)
{
return defaultAction(e, p);
}
/**
* {@inheritDoc} This implementation calls {@code defaultAction}.
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
*
* @return the result of {@code defaultAction}
*/
public R visitTypeParameter(TypeParameterElement e, P p)
{
return defaultAction(e, p);
}
}