code: // ASM: a very small and fast Java bytecode manipulation framework
  // Copyright (c) 2000-2011 INRIA, France Telecom
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  //    notice, this list of conditions and the following disclaimer in the
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  //    contributors may be used to endorse or promote products derived from
  //    this software without specific prior written permission.
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  package clojure.asm;
  
  /**
   * A visitor to visit a Java field. The methods of this class must be called in the following order:
   * ( <tt>visitAnnotation</tt> | <tt>visitTypeAnnotation</tt> | <tt>visitAttribute</tt> )*
   * <tt>visitEnd</tt>.
   *
   * @author Eric Bruneton
   */
  public abstract class FieldVisitor {
  
    /**
     * 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_EXPERIMENTAL}.
     */
    protected final int api;
  
    /** The field visitor to which this visitor must delegate method calls. May be null. */
    protected FieldVisitor fv;
  
    /**
     * Constructs a new {@link FieldVisitor}.
     *
     * @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_EXPERIMENTAL}.
     */
    public FieldVisitor(final int api) {
      this(api, null);
    }
  
    /**
     * Constructs a new {@link FieldVisitor}.
     *
     * @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_EXPERIMENTAL}.
     * @param fieldVisitor the field visitor to which this visitor must delegate method calls. May be
     *     null.
     */
    public FieldVisitor(final int api, final FieldVisitor fieldVisitor) {
      if (api != Opcodes.ASM6
          && api != Opcodes.ASM5
          && api != Opcodes.ASM4
          && api != Opcodes.ASM7_EXPERIMENTAL) {
        throw new IllegalArgumentException();
      }
      this.api = api;
      this.fv = fieldVisitor;
    }
  
    /**
     * Visits an annotation of the field.
     *
     * @param descriptor the class descriptor of the annotation class.
     * @param visible <tt>true</tt> if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or <tt>null</tt> if this visitor is not
     *     interested in visiting this annotation.
     */
    public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
      if (fv != null) {
        return fv.visitAnnotation(descriptor, visible);
      }
      return null;
    }
  
    /**
     * Visits an annotation on the type of the field.
     *
     * @param typeRef a reference to the annotated type. The sort of this type reference must be
     *     {@link TypeReference#FIELD}. See {@link TypeReference}.
     * @param typePath the path to the annotated type argument, wildcard bound, array element type, or
     *     static inner type within 'typeRef'. May be <tt>null</tt> if the annotation targets
     *     'typeRef' as a whole.
     * @param descriptor the class descriptor of the annotation class.
     * @param visible <tt>true</tt> if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or <tt>null</tt> if this visitor is not
     *     interested in visiting this annotation.
     */
    public AnnotationVisitor visitTypeAnnotation(
        final int typeRef, final TypePath typePath, final String descriptor, final boolean visible) {
      if (api < Opcodes.ASM5) {
        throw new UnsupportedOperationException();
      }
      if (fv != null) {
        return fv.visitTypeAnnotation(typeRef, typePath, descriptor, visible);
      }
      return null;
    }
  
    /**
     * Visits a non standard attribute of the field.
     *
     * @param attribute an attribute.
     */
    public void visitAttribute(final Attribute attribute) {
      if (fv != null) {
        fv.visitAttribute(attribute);
      }
    }
  
    /**
     * Visits the end of the field. This method, which is the last one to be called, is used to inform
     * the visitor that all the annotations and attributes of the field have been visited.
     */
    public void visitEnd() {
      if (fv != null) {
        fv.visitEnd();
      }
    }
  }
  