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;
  }
  public static UIComponent findPersistent(
      FacesContext context, ServletRequest req, UIComponent parent, String id) throws Exception {
    if (context == null) context = FacesContext.getCurrentInstance();

    BodyContent body = null;

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

      parent = parentTag.getComponentInstance();

      body = parentTag.getBodyContent();
    }

    if (parent != null) {
      List<UIComponent> children = parent.getChildren();
      int size = children.size();

      String prevId = null;
      for (int i = 0; i < size; i++) {
        UIComponent child = children.get(i);

        if (id.equals(child.getId())) {
          if (body != null) addVerbatim(parent, prevId, body);

          return child;
        }

        if (child.getId() != null) prevId = child.getId();
      }
    }

    return null;
  }
  private static void addChild(UIComponent parent, String prevId, UIComponent child) {
    if (parent != null) {
      List<UIComponent> children = parent.getChildren();
      int size = children.size();
      boolean hasPrev = prevId == null;

      int i = 0;
      for (; i < size; i++) {
        UIComponent oldChild = children.get(i);

        if (hasPrev && oldChild.getId() != null) {
          children.add(i, child);

          return;
        } else if (prevId != null && prevId.equals(oldChild.getId())) hasPrev = true;
      }

      parent.getChildren().add(child);
    }
  }
  public static UIComponent addVerbatim(UIComponent parent, String text) throws Exception {
    HtmlOutputText verbatim = new HtmlOutputText();

    verbatim.setTransient(true);
    verbatim.setValue(text);
    verbatim.setEscape(false);

    parent.getChildren().add(verbatim);

    return verbatim;
  }