/* ElementKindVisitor6.java -- An element visitor implementation for 1.6.
   Copyright (C) 2015  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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General Public License for more details.

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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
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.lang.model.util;

import javax.annotation.processing.SupportedSourceVersion;

import javax.lang.model.SourceVersion;

import javax.lang.model.element.Element;
import javax.lang.model.element.ElementVisitor;
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;

/**
 * <p>An implementation of {@link ElementVisitor} for the
 * 1.6 version of the Java programming language
 * ({@link SourceVersion#RELEASE_6}) which redirects each
 * {@code visitXYZ} method call to a more specific
 * {@code visitXYZAsKind} method, depending on the kind
 * of the first argument. For example, a call to
 * {@code visitExecutable} redirects to {@code visitExecutableAsConstructor},
 * {@code visitExecutableAsInstanceInit},
 * {@code visitExecutableAsMethod} or {@code visitExecutableAsStaticInit},
 * depending on the type of executable supplied. {@code visitXYZAsKind} then
 * redirects to {@code defaultAction(element, parameter)}.
 * Implementors may extend this class and provide alternative
 * implementations of {@link #defaultAction(Element, P)} and
 * the {@code visitXYZKind} methods as appropriate.</p>
 * <p>As the interface this class implements may be extended in future,
 * in order to support later language versions, methods beginning with
 * the phrase {@code "visit"} should be avoided in subclasses.  This
 * class itself will be extended to direct these new methods to the
 * {@link #visitUnknown(Element,P)} method and a new class will be
 * added to provide implementations for the new language version.
 * At this time, all or some of this class may be deprecated.</p>
 * 
 * @param <R> the return type of the visitor's methods.  {@code Void}
 *            can be used where there is no return value.
 * @param <P> the type of the additional parameter supplied to the visitor's
 *            methods. {@code Void} can be used if this is not needed.
 *
 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
 * @since 1.6
 */
@SupportedSourceVersion(SourceVersion.RELEASE_6)
public class ElementKindVisitor6<R,P> extends SimpleElementVisitor6<R,P>
{

  /**
   * Constructs a new {@link ElementKindVisitor6} with a {@code null}
   * default value.
   */
  protected ElementKindVisitor6()
  {
    this(null);
  }

  /**
   * Constructs a new {@link ElementKindVisitor6} with the specified
   * default value.
   *
   * @param defaultValue the value to assign to {@link SimpleElementVisitor6#DEFAULT_VALUE}.
   */
  protected ElementKindVisitor6(R defaultValue)
  {
    super(defaultValue);
  }

  /**
   * Visits an executable element.  This implementation dispatches
   * the call to the appropriate visit method, corresponding to the
   * exact kind of executable element: {@code CONSTRUCTOR},
   * {@code INSTANCE_INIT}, {@code METHOD} or {@code STATIC_INIT}.
   * For example, a constructor element will be redirected to the
   * {@link visitExecutableAsConstructor(ExecutableElement,P)} method.
   *
   * @param element the executable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of the kind-specific method.
   */
  @Override
  public R visitExecutable(ExecutableElement element, P parameter)
  {
    switch (element.getKind())
      {
      case CONSTRUCTOR:
	return visitExecutableAsConstructor(element, parameter);
      case INSTANCE_INIT:
	return visitExecutableAsInstanceInit(element, parameter);
      case METHOD:
	return visitExecutableAsMethod(element, parameter);
      case STATIC_INIT:
	return visitExecutableAsStaticInit(element, parameter);
      default:
	return super.visitExecutable(element, parameter);
      }
  }

  /**
   * Visits a {@code CONSTRUCTOR} executable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the constructor element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitExecutableAsConstructor(ExecutableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits an {@code INSTANCE_INIT} executable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the instance initializer element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitExecutableAsInstanceInit(ExecutableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code METHOD} executable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the method element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitExecutableAsMethod(ExecutableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code STATIC_INIT} executable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the static initializer element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitExecutableAsStaticInit(ExecutableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a package element.  This implementation simply
   * calls {@code defaultAction(element, parameter)}.
   *
   * @param element the package element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  @Override
  public R visitPackage(PackageElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a type element.  This implementation dispatches
   * the call to the appropriate visit method, corresponding to the
   * exact kind of type element: {@code ANNOTATION_TYPE},
   * {@code CLASS}, {@code ENUM} or {@code INTERFACE}.
   * For example, an annotation type element will be redirected to the
   * {@link visitTypeAsAnnotationType(TypeElement,P)} method.
   *
   * @param element the type element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of the kind-specific method.
   */
  @Override
  public R visitType(TypeElement element, P parameter)
  {
    switch (element.getKind())
      {
      case ANNOTATION_TYPE:
	return visitTypeAsAnnotationType(element, parameter);
      case CLASS:
	return visitTypeAsClass(element, parameter);
      case ENUM:
	return visitTypeAsEnum(element, parameter);
      case INTERFACE:
	return visitTypeAsInterface(element, parameter);
      default:
	return super.visitType(element, parameter);
      }
  }

  /**
   * Visits an {@code ANNOTATION_TYPE} type element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the annotation type element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitTypeAsAnnotationType(TypeElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code CLASS} type element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the class element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitTypeAsClass(TypeElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code ENUM} type element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the enumeration element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitTypeAsEnum(TypeElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits an {@code INTERFACE} type element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the interface element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitTypeAsInterface(TypeElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a type parameter element.  This implementation simply
   * calls {@code defaultAction(element, parameter)}.
   *
   * @param element the type parameter element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  @Override
  public R visitTypeParameter(TypeParameterElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a variable element.  This implementation dispatches
   * the call to the appropriate visit method, corresponding to the
   * exact kind of variable element: {@code ENUM_CONSTANT},
   * {@code EXCEPTION_PARAMETER}, {@code FIELD}, {@code LOCAL_VARIABLE},
   * {@code PARAMETER} or {@code RESOURCE_VARIABLE}.
   * For example, a field variable element will be redirected to the
   * {@link visitVariableAsField(TypeElement,P)} method.
   *
   * @param element the variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of the kind-specific method.
   */
  @Override
  public R visitVariable(VariableElement element, P parameter)
  {
    switch (element.getKind())
      {
      case ENUM_CONSTANT:
	return visitVariableAsEnumConstant(element, parameter);
      case EXCEPTION_PARAMETER:
	return visitVariableAsExceptionParameter(element, parameter);
      case FIELD:
	return visitVariableAsField(element, parameter);
      case LOCAL_VARIABLE:
	return visitVariableAsField(element, parameter);
      case PARAMETER:
	return visitVariableAsParameter(element, parameter);
      case RESOURCE_VARIABLE:
	return visitVariableAsResourceVariable(element, parameter);
      default:
	return super.visitVariable(element, parameter);
      }
  }

  /**
   * Visits an {@code ENUM_CONSTANT} variable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the enum constant variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitVariableAsEnumConstant(VariableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits an {@code EXCEPTION_PARAMETER} variable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the exception parameter variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitVariableAsExceptionParameter(VariableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code FIELD} variable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the field variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitVariableAsField(VariableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code LOCAL_VARIABLE} variable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the local variable variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitVariableAsLocalVariable(VariableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code PARAMETER} variable element.  This implementation
   * simply calls {@code defaultAction(element, parameter)}.
   *
   * @param element the parameter variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitVariableAsParameter(VariableElement element, P parameter)
  {
    return defaultAction(element, parameter);
  }

  /**
   * Visits a {@code RESOURCE_VARIABLE} variable element.  This implementation
   * calls {@code visitUnknown(element, parameter)}.
   *
   * @param element the resource variable element to visit.
   * @param parameter the additional parameter, specific to the visitor.
   *        May be {@code null}.
   * @return the result of {@code defaultAction(element, parameter)}.
   */
  public R visitVariableAsResourceVariable(VariableElement element, P parameter)
  {
    return visitUnknown(element, parameter);
  }

}