htmlvalidator.java

gcc的组建

   * content model recommends to insert making the situation
   * ok. If Boolean.True is returned, the content model current
   * position is moved forward. Otherwise this position remains
   * the same.
   * @param tElement
   * @return
   */
  public Object tagIsValidForContext(TagElement tElement)
  {
    // Check the current content model, if one is available.
    node cv = getCurrentContentModel();

    if (cv != null)
      return cv.show(tElement.getElement());

    // Check exclusions and inclusions.
    ListIterator iter = stack.listIterator(stack.size());
    hTag t;
    final int idx = tElement.getElement().index;

    // Check only known tags.
    if (idx >= 0)
      {
        BitSet inclusions = new BitSet();
        while (iter.hasPrevious())
          {
            t = (hTag) iter.previous();
            if (!t.forcibly_closed)
              {
                if (t.element.exclusions != null &&
                    t.element.exclusions.get(idx)
                   )
                  return Boolean.FALSE;

                if (t.element.inclusions != null)
                  inclusions.or(t.element.inclusions);
              }
          }
        if (!inclusions.get(idx))
          return Boolean.FALSE;
      }
    return Boolean.TRUE;
  }

  /**
   * Validate tag without storing in into the tag stack. This is called
   * for the empty tags and results the subsequent calls to the openTag
   * and closeTag.
   */
  public void validateTag(TagElement tElement, htmlAttributeSet parameters)
  {
    openTag(tElement, parameters);
    closeTag(tElement);
  }

  /**
   * Check for mandatory elements, subsequent to the last tag:
   * @param tElement The element that will be inserted next.
   */
  protected void checkContentModel(TagElement tElement, boolean first)
  {
    if (stack.isEmpty())
      return;

    hTag last = (hTag) stack.getLast();
    if (last.validationTrace == null)
      return;

    Object r = last.validationTrace.show(tElement.getElement());
    if (r == Boolean.FALSE)
      s_error("The <" + last.element + "> does not match the content model " +
              last.validationTrace
             );
    else if (r instanceof Element) // The content model recommends insertion of this element
      {
        if (!first)
          closeTag(last.tgElement);
        handleSupposedStartTag((Element) r);
        openTag(new TagElement((Element) r), null);
      }
  }

  /**
   * The method is called when the tag must be closed because
   * it does not allow the subsequent elements inside its context
   * or the end of stream has been reached. The parser is only
   * informed if the element being closed does not require the
   * end tag (the "omitEnd" flag is set).
   * The closing message must be passed to the parser mechanism
   * before passing message about the opening the next tag.
   *
   * @param element The tag being fictionally (forcibly) closed.
   */
  protected abstract void handleSupposedEndTag(Element element);

  /**
   * The method is called when the validator decides to open the
   * tag on its own initiative. This may happen if the content model
   * includes the element with the optional (supposed) start tag.
   *
   * @param element The tag being opened.
   */
  protected abstract void handleSupposedStartTag(Element element);

  /**
   * Handles the error message. This method must be overridden to pass
   * the message where required.
   * @param msg The message text.
   */
  protected abstract void s_error(String msg);

  /**
   * Validate the parameters, report the error if the given parameter is
   * not in the parameter set, valid for the given attribute. The information
   * about the valid parameter set is taken from the Element, enclosed
   * inside the tag. The method does not validate the default parameters.
   * @param tag The tag
   * @param parameters The parameters of this tag.
   */
  protected void validateParameters(TagElement tag, htmlAttributeSet parameters)
  {
    if (parameters == null ||
        parameters == htmlAttributeSet.EMPTY_HTML_ATTRIBUTE_SET ||
        parameters == SimpleAttributeSet.EMPTY
       )
      return;

    Enumeration enumeration = parameters.getAttributeNames();

    while (enumeration.hasMoreElements())
      {
        validateAttribute(tag, parameters, enumeration);
      }

    // Check for missing required values.
    AttributeList a = tag.getElement().getAttributes();

    while (a != null)
      {
        if (a.getModifier() == DTDConstants.REQUIRED)
          if (parameters.getAttribute(a.getName()) == null)
            {
              s_error("Missing required attribute '" + a.getName() + "' for <" +
                      tag.getHTMLTag() + ">"
                     );
            }
        a = a.next;
      }
  }

  private node getCurrentContentModel()
  {
    if (!stack.isEmpty())
      {
        hTag last = (hTag) stack.getLast();
        return last.validationTrace;
      }
    else
      return null;
  }

  private void closeLast()
  {
    handleSupposedEndTag(((hTag) stack.getLast()).element);
    stack.removeLast();
  }

  private void openFictionalTag(Element e)
  {
    handleSupposedStartTag(e);
    stack.add(new hTag(new TagElement(e, true)));
    if (!e.omitStart())
      s_error("<" + e + "> is expected (supposing it)");
  }

  private void validateAttribute(TagElement tag, htmlAttributeSet parameters,
                                 Enumeration enumeration
                                )
  {
    Object foundAttribute;
    AttributeList dtdAttribute;
    foundAttribute = enumeration.nextElement();
    dtdAttribute = tag.getElement().getAttribute(foundAttribute.toString());
    if (dtdAttribute == null)
      {
        StringBuffer valid =
          new StringBuffer("The tag <" + tag.getHTMLTag() +
                           "> cannot contain the attribute '" + foundAttribute +
                           "'. The valid attributes for this tag are: "
                          );

        AttributeList a = tag.getElement().getAttributes();

        while (a != null)
          {
            valid.append(a.name.toUpperCase());
            valid.append(' ');
            a = a.next;
          }
        s_error(valid.toString());
      }

    else
      {
        String value = parameters.getAttribute(foundAttribute).toString();

        if (dtdAttribute.type == DTDConstants.NUMBER)
          validateNumberAttribute(tag, foundAttribute, value);

        if (dtdAttribute.type == DTDConstants.NAME ||
            dtdAttribute.type == DTDConstants.ID
           )
          validateNameOrIdAttribute(tag, foundAttribute, value);

        if (dtdAttribute.values != null)
          validateAttributeWithValueList(tag, foundAttribute, dtdAttribute,
                                         value
                                        );
      }
  }

  private void validateAttributeWithValueList(TagElement tag,
                                              Object foundAttribute,
                                              AttributeList dtdAttribute,
                                              String value
                                             )
  {
    if (!dtdAttribute.values.contains(value.toLowerCase()) &&
        !dtdAttribute.values.contains(value.toUpperCase())
       )
      {
        StringBuffer valid;
        if (dtdAttribute.values.size() == 1)
          valid =
            new StringBuffer("The attribute '" + foundAttribute +
                             "' of the tag <" + tag.getHTMLTag() +
                             "> cannot have the value '" + value +
                             "'. The only valid value is "
                            );
        else
          valid =
            new StringBuffer("The attribute '" + foundAttribute +
                             "' of the tag <" + tag.getHTMLTag() +
                             "> cannot have the value '" + value + "'. The " +
                             dtdAttribute.values.size() +
                             " valid values are: "
                            );

        Enumeration vv = dtdAttribute.values.elements();
        while (vv.hasMoreElements())
          {
            valid.append('"');
            valid.append(vv.nextElement());
            valid.append("\"  ");
          }
        s_error(valid.toString());
      }
  }

  private void validateNameOrIdAttribute(TagElement tag, Object foundAttribute,
                                         String value
                                        )
  {
    boolean ok = true;

    if (!Character.isLetter(value.charAt(0)))
      ok = false;

    char c;
    for (int i = 0; i < value.length(); i++)
      {
        c = value.charAt(i);
        if (!(
              Character.isLetter(c) || Character.isDigit(c) ||
              "".indexOf(c) >= 0
            )
           )
          ok = false;
      }
    if (!ok)
      s_error("The '" + foundAttribute + "' attribute of the tag <" +
              tag.getHTMLTag() + "> must start from letter and consist of " +
              "letters, digits, hypens, colons, underscores and periods. " +
              "It cannot be '" + value + "'"
             );
  }

  private void validateNumberAttribute(TagElement tag, Object foundAttribute,
                                       String value
                                      )
  {
    try
      {
        Integer.parseInt(value);
      }
    catch (NumberFormatException ex)
      {
        s_error("The '" + foundAttribute + "' attribute of the tag <" +
                tag.getHTMLTag() + "> must be a valid number and not '" +
                value + "'"
               );
      }
  }
}