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 *

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package javax.lang.model.util;

import javax.lang.model.type.*;

import javax.annotation.processing.SupportedSourceVersion;

import javax.lang.model.SourceVersion;

import static javax.lang.model.SourceVersion.*;

/**

 * A simple visitor of types 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.

 *

 * <p> 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.

 *

 * <p> <b>WARNING:</b> The {@code TypeVisitor} 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"}.

 *

 * <p>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 type 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.

 *

 * <p>Note that adding a default implementation of a new visit method

 * in a visitor class will occur instead of adding a <em>default

 * method</em> 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 <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.

 *

 * @author Joseph D. Darcy

 * @author Scott Seligman

 * @author Peter von der Ahé

 *

 * @see SimpleTypeVisitor7

 * @see SimpleTypeVisitor8

 * @since 1.6

 */

@SupportedSourceVersion(RELEASE_6)

public class SimpleTypeVisitor6<R, P> extends AbstractTypeVisitor6<R, P> {

    /**

     * 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 SimpleTypeVisitor6(){

        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 SimpleTypeVisitor6(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 type to process

     * @param p a visitor-specified parameter

     * @return {@code DEFAULT_VALUE} unless overridden

     */

    protected R defaultAction(TypeMirror e, P p) {

        return DEFAULT_VALUE;

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitPrimitive(PrimitiveType t, P p) {

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitNull(NullType t, P p){

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitArray(ArrayType t, P p){

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitDeclared(DeclaredType t, P p){

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitError(ErrorType t, P p){

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitTypeVariable(TypeVariable t, P p){

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitWildcard(WildcardType t, P p){

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitExecutable(ExecutableType t, P p) {

        return defaultAction(t, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param t {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    public R visitNoType(NoType t, P p){

        return defaultAction(t, p);

    }

}