public static UIComponent addTransient(
      FacesContext context, ServletRequest req, UIComponent parent, String prevId, Class childClass)
      throws Exception {
    if (context == null) context = FacesContext.getCurrentInstance();

    if (parent == null) {
      UIComponentClassicTagBase parentTag =
          (UIComponentClassicTagBase) req.getAttribute("caucho.jsf.parent");

      parent = parentTag.getComponentInstance();

      BodyContent body = parentTag.getBodyContent();

      if (body != null) addVerbatim(parent, body);
    }

    UIComponent child = null;
    ;

    if (child == null) child = (UIComponent) childClass.newInstance();

    child.setTransient(true);

    addChild(parent, prevId, child);

    return child;
  }
  public static UIComponent addFacet(
      FacesContext context,
      ServletRequest req,
      UIComponent parent,
      String facetName,
      ValueExpression binding,
      Class childClass)
      throws Exception {
    if (context == null) context = FacesContext.getCurrentInstance();

    if (parent == null) {
      UIComponentClassicTagBase parentTag =
          (UIComponentClassicTagBase) req.getAttribute("caucho.jsf.parent");

      parent = parentTag.getComponentInstance();
    }

    UIComponent child = null;

    if (binding != null) child = (UIComponent) binding.getValue(context.getELContext());

    if (child == null) child = (UIComponent) childClass.newInstance();

    if (parent != null) parent.getFacets().put(facetName, child);

    if (binding != null) binding.setValue(context.getELContext(), child);

    return child;
  }
  public static UIComponent addPersistent(
      FacesContext context,
      ServletRequest req,
      UIComponent parent,
      ValueExpression binding,
      Class childClass)
      throws Exception {
    if (context == null) context = FacesContext.getCurrentInstance();

    if (parent == null) {
      UIComponentClassicTagBase parentTag =
          (UIComponentClassicTagBase) req.getAttribute("caucho.jsf.parent");

      parent = parentTag.getComponentInstance();

      BodyContent body = parentTag.getBodyContent();

      addVerbatim(parent, body);
    }

    UIComponent child = null;

    if (binding != null) child = (UIComponent) binding.getValue(context.getELContext());

    if (child == null) {
      child = (UIComponent) childClass.newInstance();

      // jsf/3251
      if (binding != null) binding.setValue(context.getELContext(), child);
    }

    if (parent != null) parent.getChildren().add(child);

    return child;
  }
  /** Calculates a MD5 digest of the class. */
  public String getDigest() {
    try {
      if (_className == null || "".equals(_className)) return "";

      DynamicClassLoader loader =
          (DynamicClassLoader) Thread.currentThread().getContextClassLoader();

      ClassLoader tmpLoader = loader.getNewTempClassLoader();

      Class cl = Class.forName(_className, false, tmpLoader);

      if (cl == null) return "";

      MessageDigest digest = MessageDigest.getInstance("MD5");

      addDigest(digest, cl.getName());

      addDigest(digest, cl.getModifiers());

      Class superClass = cl.getSuperclass();
      if (superClass != null) addDigest(digest, superClass.getName());

      Class[] interfaces = cl.getInterfaces();
      for (int i = 0; i < interfaces.length; i++) addDigest(digest, interfaces[i].getName());

      Field[] fields = cl.getDeclaredFields();

      Arrays.sort(fields, new FieldComparator());

      if (_checkFields) {
        for (Field field : fields) {
          if (Modifier.isPrivate(field.getModifiers()) && !_checkPrivate) continue;
          if (Modifier.isProtected(field.getModifiers()) && !_checkProtected) continue;

          addDigest(digest, field.getName());
          addDigest(digest, field.getModifiers());
          addDigest(digest, field.getType().getName());

          addDigest(digest, field.getAnnotations());
        }
      }

      Method[] methods = cl.getDeclaredMethods();
      Arrays.sort(methods, new MethodComparator());

      for (int i = 0; i < methods.length; i++) {
        Method method = methods[i];

        if (Modifier.isPrivate(method.getModifiers()) && !_checkPrivate) continue;
        if (Modifier.isProtected(method.getModifiers()) && !_checkProtected) continue;
        if (Modifier.isStatic(method.getModifiers()) && !_checkStatic) continue;

        addDigest(digest, method.getName());
        addDigest(digest, method.getModifiers());
        addDigest(digest, method.getName());

        Class[] param = method.getParameterTypes();
        for (int j = 0; j < param.length; j++) addDigest(digest, param[j].getName());

        addDigest(digest, method.getReturnType().getName());

        Class[] exn = method.getExceptionTypes();
        for (int j = 0; j < exn.length; j++) addDigest(digest, exn[j].getName());

        addDigest(digest, method.getAnnotations());
      }

      byte[] digestBytes = new byte[256];

      int len = digest.digest(digestBytes, 0, digestBytes.length);

      return digestToBase64(digestBytes, len);
    } catch (Exception e) {
      log.log(Level.FINER, e.toString(), e);

      return "";
    }
  }