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.
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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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  // THE POSSIBILITY OF SUCH DAMAGE.
  package clojure.asm;
  
  /**
   * A visitor to visit a Java module. The methods of this class must be called in the following
   * order: <tt>visitMainClass</tt> | ( <tt>visitPackage</tt> | <tt>visitRequire</tt> |
   * <tt>visitExport</tt> | <tt>visitOpen</tt> | <tt>visitUse</tt> | <tt>visitProvide</tt> )*
   * <tt>visitEnd</tt>.
   *
   * @author Remi Forax
   * @author Eric Bruneton
   */
  public abstract class ModuleVisitor {
    /**
     * The ASM API version implemented by this visitor. The value of this field must be one of {@link
     * Opcodes#ASM6} or {@link Opcodes#ASM7_EXPERIMENTAL}.
     */
    protected final int api;
  
    /** The module visitor to which this visitor must delegate method calls. May be null. */
    protected ModuleVisitor mv;
  
    /**
     * Constructs a new {@link ModuleVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of {@link Opcodes#ASM6}
     *     or {@link Opcodes#ASM7_EXPERIMENTAL}.
     */
    public ModuleVisitor(final int api) {
      this(api, null);
    }
  
    /**
     * Constructs a new {@link ModuleVisitor}.
     *
     * @param api the ASM API version implemented by this visitor. Must be one of {@link Opcodes#ASM6}
     *     or {@link Opcodes#ASM7_EXPERIMENTAL}.
     * @param moduleVisitor the module visitor to which this visitor must delegate method calls. May
     *     be null.
     */
    public ModuleVisitor(final int api, final ModuleVisitor moduleVisitor) {
      if (api != Opcodes.ASM6 && api != Opcodes.ASM7_EXPERIMENTAL) {
        throw new IllegalArgumentException();
      }
      this.api = api;
      this.mv = moduleVisitor;
    }
  
    /**
     * Visit the main class of the current module.
     *
     * @param mainClass the internal name of the main class of the current module.
     */
    public void visitMainClass(final String mainClass) {
      if (mv != null) {
        mv.visitMainClass(mainClass);
      }
    }
  
    /**
     * Visit a package of the current module.
     *
     * @param packaze the internal name of a package.
     */
    public void visitPackage(final String packaze) {
      if (mv != null) {
        mv.visitPackage(packaze);
      }
    }
  
    /**
     * Visits a dependence of the current module.
     *
     * @param module the fully qualified name (using dots) of the dependence.
     * @param access the access flag of the dependence among {@code ACC_TRANSITIVE}, {@code
     *     ACC_STATIC_PHASE}, {@code ACC_SYNTHETIC} and {@code ACC_MANDATED}.
     * @param version the module version at compile time, or <tt>null</tt>.
     */
    public void visitRequire(final String module, final int access, final String version) {
      if (mv != null) {
        mv.visitRequire(module, access, version);
      }
    }
  
    /**
     * Visit an exported package of the current module.
     *
     * @param packaze the internal name of the exported package.
     * @param access the access flag of the exported package, valid values are among {@code
     *     ACC_SYNTHETIC} and {@code ACC_MANDATED}.
     * @param modules the fully qualified names (using dots) of the modules that can access the public
     *     classes of the exported package, or <tt>null</tt>.
     */
    public void visitExport(final String packaze, final int access, final String... modules) {
      if (mv != null) {
        mv.visitExport(packaze, access, modules);
      }
    }
  
    /**
     * Visit an open package of the current module.
     *
     * @param packaze the internal name of the opened package.
     * @param access the access flag of the opened package, valid values are among {@code
     *     ACC_SYNTHETIC} and {@code ACC_MANDATED}.
     * @param modules the fully qualified names (using dots) of the modules that can use deep
     *     reflection to the classes of the open package, or <tt>null</tt>.
     */
    public void visitOpen(final String packaze, final int access, final String... modules) {
      if (mv != null) {
        mv.visitOpen(packaze, access, modules);
      }
    }
  
    /**
     * Visit a service used by the current module. The name must be the internal name of an interface
     * or a class.
     *
     * @param service the internal name of the service.
     */
    public void visitUse(final String service) {
      if (mv != null) {
        mv.visitUse(service);
      }
    }
  
    /**
     * Visit an implementation of a service.
     *
     * @param service the internal name of the service.
     * @param providers the internal names of the implementations of the service (there is at least
     *     one provider).
     */
    public void visitProvide(final String service, final String... providers) {
      if (mv != null) {
        mv.visitProvide(service, providers);
      }
    }
  
    /**
     * Visits the end of the module. This method, which is the last one to be called, is used to
     * inform the visitor that everything have been visited.
     */
    public void visitEnd() {
      if (mv != null) {
        mv.visitEnd();
      }
    }
  }
  