http://asm.ow2.org/: ASM, a very small and fast Java bytecode manipulation framework (OW2)
  • Eric Bruneton
  • Eugene Kuleshov
  • Remi Forax 
// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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package org.objectweb.asm;


A visitor to visit a Java annotation. The methods of this class must be called in the following order: ( visit | visitEnum | visitAnnotation | visitArray )* visitEnd. 
Author:Eric Bruneton, Eugene Kuleshov
/**
 * 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 Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7. 
/**
   * 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. 
/** The annotation visitor to which this visitor must delegate method calls. May be null. */
  protected AnnotationVisitor av;

  
Constructs a new AnnotationVisitor. 
Params:
/**
   * 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 AnnotationVisitor. 
Params:
/**
   * 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.ASM7 && api != Opcodes.ASM6 && api != Opcodes.ASM5 && api != Opcodes.ASM4) {
      throw new IllegalArgumentException("Unsupported api " + api);
    }
    this.api = api;
    this.av = annotationVisitor;
  }

  
Visits a primitive value of the annotation.

Params:
/**
   * 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.

Params:
  • name – the value name.
  • descriptor – the class descriptor of the enumeration class.
  • value – the actual enumeration 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.

Params:
  • name – the value name.
  • descriptor – the class descriptor of the nested annotation class.
Returns:a visitor to visit the actual nested annotation value, or null if this visitor is not interested in visiting this nested annotation. The nested annotation
    value must be fully visited before calling other methods on this annotation visitor.
/**
   * 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 
visit. This is what ClassReader does. 
Params:
  • name – the value name.
Returns:a visitor to visit the actual array value elements, or null if this visitor is not interested in visiting these values. The 'name' parameters passed to the methods of this visitor are ignored. All the array values must be visited before calling other
    methods on this annotation visitor.
/**
   * 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. 
/** Visits the end of the annotation. */
  public void visitEnd() {
    if (av != null) {
      av.visitEnd();
    }
  }
}