/* AnnotationValueVisitor.java -- A visitor of annotation values.
Copyright (C) 2012 Free Software Foundation, Inc.
This file is part of GNU Classpath.
GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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02110-1301 USA.
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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modules, and to copy and distribute the resulting executable under
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package javax.lang.model.element;
import java.util.List;
import javax.lang.model.type.TypeMirror;
/**
*
A visitor for annotation values. Unlike other visitors, such
* as {@link ElementVisitor} and {@link javax.lang.model.type.TypeVisitor},
* which work on a concrete type hierarchy, this visitor dispatches based
* on the type of data stored in the annotation, some of which don't have
* distinct subclasses for storing them (e.g. primitives like {@code boolean}
* and {@code int}.
* The visitor is used when the specific type is not known at compile
* time. A visitor instance is passed to the
* {@link AnnotationValue#accept(AnnotationValueVisitor,P)} method of
* the type, which then calls the specific {@code visitN} method
* appropriate to that specific type.
* The additional parameter supplied to visitor methods may or
* may not be optional, and so the class is free to throw a
* {@code NullPointerException} if {@code null} is passed as the
* additional parameter.
* As this interface may be extended to accomodate future language
* versions, implementators are encouraged to extend one of the
* appropriate abstract classes rather than implementating this
* interface. However, this interface should be used as the type
* for parameters and return values.
*
* @param the return type of the visitor's methods. {@code Void}
* can be used where there is no return value.
* @param the type of the additional parameter supplied to the visitor's
* methods.
*
* @author Andrew John Hughes (gnu_andrew@member.fsf.org)
* @since 1.6
*/
public interface AnnotationValueVisitor
{
/**
* A convenience method for use when there is no additional
* parameter to pass. This is equivalent to {@code #visit(value, null)}.
*
* @param value the value to visit.
* @return the return value specific to the visitor.
*/
R visit(AnnotationValue value);
/**
* Visits a value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visit(AnnotationValue value, P param);
/**
* Visits an annotation value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitAnnotation(AnnotationMirror value, P param);
/**
* Visits an array value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitArray(List extends AnnotationValue> value, P param);
/**
* Visits a boolean value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitBoolean(boolean value, P param);
/**
* Visits a byte value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitByte(byte value, P param);
/**
* Visits a character value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitChar(char value, P param);
/**
* Visits a double value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitDouble(double value, P param);
/**
* Visits an enum value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitEnumConstant(VariableElement value, P param);
/**
* Visits a float value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitFloat(float value, P param);
/**
* Visits an int value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitInt(int value, P param);
/**
* Visits a long value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitLong(long value, P param);
/**
* Visits a short value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitShort(short value, P param);
/**
* Visits a {@code String} value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitString(String value, P param);
/**
* Visits a type value.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
*/
R visitType(TypeMirror value, P param);
/**
* Visits an unknown type of value. This method is called if
* a new type is added to the hierarchy which isn't yet
* handled by the visitor.
*
* @param value the value to visit.
* @param param the additional parameter, specific to the visitor.
* May be {@code null} if permitted by the visitor.
* @return the return value specific to the visitor.
* @throws UnknownAnnotationValueException if the implementation
* chooses to.
*/
R visitUnknown(AnnotationValue value, P param);
}