text: // ASM: a very small and fast Java bytecode manipulation framework
  // Copyright (c) 2000-2011 INRIA, France Telecom
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  package org.mvel2.asm;
  
  /**
   * A visitor to visit a Java annotation. The methods of this class must be called in the following
   * order: ( {@code visit} | {@code visitEnum} | {@code visitAnnotation} | {@code visitArray} )*
   * {@code visitEnd}.
   *
   * @author Eric Bruneton
   * @author Eugene Kuleshov
   */
  public abstract class AnnotationVisitor {
  
    /**
     * The ASM API version implemented by this visitor. The value of this field must be one of {@link
     * Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
     */
    protected final int api;
  
    /** The annotation visitor to which this visitor must delegate method calls. May be null. */
    protected AnnotationVisitor av;
  
    /**
     * Constructs a new {@link AnnotationVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of {@link
     *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
     */
    public AnnotationVisitor(final int api) {
      this(api, null);
    }
  
    /**
     * Constructs a new {@link AnnotationVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of {@link
     *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}.
     * @param annotationVisitor the annotation visitor to which this visitor must delegate method
     *     calls. May be null.
     */
    public AnnotationVisitor(final int api, final AnnotationVisitor annotationVisitor) {
      if (api != Opcodes.ASM6 && api != Opcodes.ASM5 && api != Opcodes.ASM4 && api != Opcodes.ASM7) {
        throw new IllegalArgumentException();
      }
      this.api = api;
      this.av = annotationVisitor;
    }
  
    /**
     * Visits a primitive value of the annotation.
     *
     * @param name the value name.
     * @param value the actual value, whose type must be {@link Byte}, {@link Boolean}, {@link
     *     Character}, {@link Short}, {@link Integer} , {@link Long}, {@link Float}, {@link Double},
     *     {@link String} or {@link Type} of {@link Type#OBJECT} or {@link Type#ARRAY} sort. This
     *     value can also be an array of byte, boolean, short, char, int, long, float or double values
     *     (this is equivalent to using {@link #visitArray} and visiting each array element in turn,
     *     but is more convenient).
     */
    public void visit(final String name, final Object value) {
      if (av != null) {
        av.visit(name, value);
      }
    }
  
    /**
     * Visits an enumeration value of the annotation.
     *
     * @param name the value name.
     * @param descriptor the class descriptor of the enumeration class.
     * @param value the actual enumeration value.
     */
    public void visitEnum(final String name, final String descriptor, final String value) {
      if (av != null) {
        av.visitEnum(name, descriptor, value);
      }
    }
  
    /**
     * Visits a nested annotation value of the annotation.
     *
     * @param name the value name.
     * @param descriptor the class descriptor of the nested annotation class.
     * @return a visitor to visit the actual nested annotation value, or {@literal null} if this
     *     visitor is not interested in visiting this nested annotation. <i>The nested annotation
     *     value must be fully visited before calling other methods on this annotation visitor</i>.
     */
    public AnnotationVisitor visitAnnotation(final String name, final String descriptor) {
      if (av != null) {
        return av.visitAnnotation(name, descriptor);
      }
      return null;
    }
  
    /**
     * Visits an array value of the annotation. Note that arrays of primitive types (such as byte,
     * boolean, short, char, int, long, float or double) can be passed as value to {@link #visit
     * visit}. This is what {@link ClassReader} does.
     *
     * @param name the value name.
     * @return a visitor to visit the actual array value elements, or {@literal null} if this visitor
     *     is not interested in visiting these values. The 'name' parameters passed to the methods of
     *     this visitor are ignored. <i>All the array values must be visited before calling other
     *     methods on this annotation visitor</i>.
     */
    public AnnotationVisitor visitArray(final String name) {
      if (av != null) {
        return av.visitArray(name);
      }
      return null;
    }
  
    /** Visits the end of the annotation. */
    public void visitEnd() {
      if (av != null) {
        av.visitEnd();
      }
    }
  }
  