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package javax.lang.model.util;
import java.util.List;
import java.util.ArrayList;
import javax.lang.model.element.*;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import static javax.lang.model.SourceVersion.*;
{@preview Associated with records, a preview feature of the Java language.
This class is associated with records, a preview feature of the Java language. Preview features may be removed in a future release, or upgraded to permanent features of the Java language.} A scanning visitor of program elements with default behavior appropriate for the RELEASE_14 source version. The visitXyz methods in this class scan their component elements by calling scan on their enclosed elements, parameters, etc., as indicated in the individual method specifications. A subclass can control the order elements are visited by overriding the visitXyz methods. Note that clients of a scanner may get the desired behavior be invoking v.scan(e, p) rather than v.visit(e, p) on the root objects of interest. When a subclass overrides a visitXyz method, the
new method can cause the enclosed elements to be scanned in the
default way by calling super.visitXyz. In this
fashion, the concrete visitor can control the ordering of traversal
over the component elements with respect to the additional
processing; for example, consistently calling
super.visitXyz at the start of the overridden
methods will yield a preorder traversal, etc. If the component
elements should be traversed in some other order, instead of
calling super.visitXyz, an overriding visit method should call scan with the elements in the desired order.
Type parameters: See Also: API Note:
Methods in this class may be overridden subject to their general
contract. Since: 14
/**
* {@preview Associated with records, a preview feature of the Java language.
*
* This class is associated with <i>records</i>, a preview
* feature of the Java language. Preview features
* may be removed in a future release, or upgraded to permanent
* features of the Java language.}
*
* A scanning visitor of program elements with default behavior
* appropriate for the {@link SourceVersion#RELEASE_14 RELEASE_14}
* source version.
*
* The <code>visit<i>Xyz</i></code> methods in this
* class scan their component elements by calling {@code scan} on
* their {@linkplain Element#getEnclosedElements enclosed elements},
* {@linkplain ExecutableElement#getParameters parameters}, etc., as
* indicated in the individual method specifications. A subclass can
* control the order elements are visited by overriding the
* <code>visit<i>Xyz</i></code> methods. Note that clients of a scanner
* may get the desired behavior be invoking {@code v.scan(e, p)} rather
* than {@code v.visit(e, p)} on the root objects of interest.
*
* <p>When a subclass overrides a <code>visit<i>Xyz</i></code> method, the
* new method can cause the enclosed elements to be scanned in the
* default way by calling <code>super.visit<i>Xyz</i></code>. In this
* fashion, the concrete visitor can control the ordering of traversal
* over the component elements with respect to the additional
* processing; for example, consistently calling
* <code>super.visit<i>Xyz</i></code> at the start of the overridden
* methods will yield a preorder traversal, etc. If the component
* elements should be traversed in some other order, instead of
* calling <code>super.visit<i>Xyz</i></code>, an overriding visit method
* should call {@code scan} with the elements in the desired order.
*
* @apiNote
* Methods in this class may be overridden subject to their general
* contract.
*
* @param <R> the return type of this visitor's methods. Use {@link
* Void} for visitors that do not need to return results.
* @param <P> the type of the additional parameter to this visitor's
* methods. Use {@code Void} for visitors that do not need an
* additional parameter.
*
* @see <a href="ElementScanner6.html#note_for_subclasses"><strong>Compatibility note for subclasses</strong></a>
* @see ElementScanner6
* @see ElementScanner7
* @see ElementScanner8
* @see ElementScanner9
* @since 14
*/
@jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.RECORDS,
essentialAPI=false)
@SupportedSourceVersion(RELEASE_15)
public class ElementScanner14<R, P> extends ElementScanner9<R, P> {
Constructor for concrete subclasses; uses null for the default value. /**
* Constructor for concrete subclasses; uses {@code null} for the
* default value.
*/
protected ElementScanner14(){
super(null);
}
Constructor for concrete subclasses; uses the argument for the
default value.
Params: - defaultValue – the default value
/**
* Constructor for concrete subclasses; uses the argument for the
* default value.
*
* @param defaultValue the default value
*/
protected ElementScanner14(R defaultValue){
super(defaultValue);
}
{@inheritDoc}
Params: - e – {@inheritDoc}
- p – {@inheritDoc}
Implementation Requirements: This implementation scans the type parameters, if
any, and then the enclosed elements. Returns: the result of scanning
/**
* {@inheritDoc}
*
* @implSpec This implementation scans the type parameters, if
* any, and then the enclosed elements.
*
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitType(TypeElement e, P p) {
return scan(createScanningList(e, e.getEnclosedElements()), p);
}
{@inheritDoc}
Params: - e – {@inheritDoc}
- p – {@inheritDoc}
Implementation Requirements: This implementation first scans the type parameters, if any, and then
the parameters. Returns: the result of scanning
/**
* {@inheritDoc}
*
* @implSpec This implementation first scans the type parameters, if any, and then
* the parameters.
*
* @param e {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
public R visitExecutable(ExecutableElement e, P p) {
return scan(createScanningList(e, e.getParameters()), p);
}
private List<? extends Element> createScanningList(Parameterizable element,
List<? extends Element> toBeScanned) {
var typeParameters = element.getTypeParameters();
if (typeParameters.isEmpty()) {
return toBeScanned;
} else {
List<Element> scanningList = new ArrayList<>(typeParameters);
scanningList.addAll(toBeScanned);
return scanningList;
}
}
{@inheritDoc}
Params: - e – the element to visit
- p – a visitor-specified parameter
Implementation Requirements: This implementation scans the enclosed elements. Returns: the result of the scan
/**
* {@inheritDoc}
*
* @implSpec This implementation scans the enclosed elements.
*
* @param e the element to visit
* @param p a visitor-specified parameter
* @return the result of the scan
*/
@SuppressWarnings("preview")
@Override
public R visitRecordComponent(RecordComponentElement e, P p) {
return scan(e.getEnclosedElements(), p);
}
}