dtd.java

gcc的组建

  {
    Element e = newElement(name);
    e.type = type;
    e.oStart = headless;
    e.oEnd = tailless;
    e.content = content;
    e.exclusions = exclusions;
    e.inclusions = inclusions;
    e.atts = attributes;

    return e;
  }

  /**
   * Creates, intializes and adds to the entity table the new
   * entity.
   * @param name the name of the entity
   * @param type the type of the entity
   * @param data the data section of the entity
   * @return the created entity
   */
  public Entity defineEntity(String name, int type, char[] data)
  {
    Entity e = newEntity(name, type);
    e.data = data;

    return e;
  }

  /** Place this DTD into the DTD table. */
  public static void putDTDHash(String name, DTD dtd)
  {
    dtdHash.put(name, dtd);
  }

  /**
   * <p>Reads DTD from an archived format. This format is not standardized
   * and differs between implementations.</p><p> This implementation
   * reads and defines all entities and elements using
   * ObjectInputStream. The elements and entities can be written into the
   * stream in any order. The objects other than elements and entities
   * are ignored.</p>
   * @param stream A data stream to read from.
   * @throws java.io.IOException If one is thrown by the input stream
   */
  public void read(DataInputStream stream)
            throws java.io.IOException
  {
    ObjectInputStream oi = new ObjectInputStream(stream);
    Object def;
    try
      {
        while (true)
          {
            def = oi.readObject();
            if (def instanceof Element)
              {
                Element e = (Element) def;
                elementHash.put(e.name.toLowerCase(), e);
                assignField(e);
              }
            else if (def instanceof Entity)
              {
                Entity e = (Entity) def;
                entityHash.put(e.name, e);
              }
          }
      }
    catch (ClassNotFoundException ex)
      {
        throw new IOException(ex.getMessage());
      }
    catch (EOFException ex)
      {
        // ok EOF
      }
  }

  /**
   * Returns the name of this instance of DTD.
   */
  public String toString()
  {
    return name;
  }

  /**
   * Creates and returns new attribute (not an attribute list).
   * @param name the name of this attribute
   * @param type the type of this attribute (FIXED, IMPLIED or
   * REQUIRED from <code>DTDConstants</code>).
   * @param modifier the modifier of this attribute
   * @param default_value the default value of this attribute
   * @param allowed_values the allowed values of this attribute. The multiple
   * possible values in this parameter are supposed to be separated by
   * '|', same as in SGML DTD <code>&lt;!ATTLIST </code>tag. This parameter
   * can be null if no list of allowed values is specified.
   * @param atts the previous attribute of this element. This is
   * placed to the field
   * {@link javax.swing.text.html.parser.AttributeList#next },
   * creating a linked list.
   * @return The attributes.
   */
  protected AttributeList defAttributeList(String name, int type, int modifier,
                                           String default_value,
                                           String allowed_values,
                                           AttributeList atts
                                          )
  {
    AttributeList al = new AttributeList(name);
    al.modifier = modifier;
    al.value = default_value;
    al.next = atts;

    if (allowed_values != null)
      {
        StringTokenizer st = new StringTokenizer(allowed_values, " \t|");
        Vector v = new Vector(st.countTokens());

        while (st.hasMoreTokens())
          v.add(st.nextToken());

        al.values = v;
      }

    return al;
  }

  /**
   * Creates a new content model.
   * @param type specifies the BNF operation for this content model.
   * The valid operations are documented in the
   * {@link javax.swing.text.html.parser.ContentModel#type }.
   * @param content the content of this content model
   * @param next if the content model is specified by BNF-like
   * expression, contains the rest of this expression.
   * @return The newly created content model.
   */
  protected ContentModel defContentModel(int type, Object content,
                                         ContentModel next
                                        )
  {
    ContentModel model = new ContentModel();
    model.type = type;
    model.next = next;
    model.content = content;

    return model;
  }

  /**
   * Defines a new element and adds it to the element table.
   * If the element alredy exists,
   * overrides it settings with the specified values.
   * @param name the name of the new element
   * @param type the type of the element
   * @param headless true if the element needs no starting tag
   * @param tailless true if the element needs no closing tag
   * @param content the element content.
   * @param exclusions the elements that must be excluded from the
   * content of this element, in all levels of the hierarchy.
   * @param inclusions the elements that can be included as the
   * content of this element.
   * @param attributes the element attributes.
   * @return the created or updated element.
   */
  protected Element defElement(String name, int type, boolean headless,
                               boolean tailless, ContentModel content,
                               String[] exclusions, String[] inclusions,
                               AttributeList attributes
                              )
  {
    // compute the bit sets
    BitSet exclude = bitSet(exclusions);
    BitSet include = bitSet(inclusions);

    Element e =
      defineElement(name, type, headless, tailless, content, exclude, include,
                    attributes
                   );

    return e;
  }

  /**
   * Creates, intializes and adds to the entity table the new
   * entity.
   * @param name the name of the entity
   * @param type the type of the entity
   * @param data the data section of the entity
   * @return the created entity
   */
  protected Entity defEntity(String name, int type, String data)
  {
    Entity e = newEntity(name, type);
    e.data = data.toCharArray();

    return e;
  }

  private void assignField(Element e)
  {
    String element_name = e.name;
    try
      {
        // Assign the field via reflection.
        Field f = getClass().getField(element_name.toLowerCase());
        if ((f.getModifiers() & Modifier.PUBLIC) != 0)
          if ((f.getModifiers() & Modifier.STATIC) == 0)
            if (f.getType().isAssignableFrom(e.getClass()))
              f.set(this, e);
      }
    catch (IllegalAccessException ex)
      {
        unexpected(ex);
      }
    catch (NoSuchFieldException ex)
      {
        // This is ok.
      }

    // Some virtual machines may still lack the proper
    // implementation of reflection. As the tag fields
    // are not used anywhere in this implementation,
    // (and this class is also rarely used by the end user),
    // it may be better not to crash everything by throwing an error
    // for each case when the HTML parsing is required.
    catch (Throwable t)
      {
        // This VM has no reflection mechanism implemented!
        if (t instanceof OutOfMemoryError)
          throw (Error) t;
      }
  }

  /**
   * Create the bit set for this array of elements.
   * The unknown elements are automatically defined and added
   * to the element table.
   * @param elements
   * @return The bit set.
   */
  private BitSet bitSet(String[] elements)
  {
    BitSet b = new BitSet();

    for (int i = 0; i < elements.length; i++)
      {
        Element e = getElement(elements [ i ]);

        if (e == null)
          e = newElement(elements [ i ]);

        b.set(e.index);
      }

    return b;
  }

  /**
   * Find the element with the given name in the element table.
   * If not find, create a new element with this name and add to the
   * table.
   * @param name the name of the element
   * @return the found or created element.
   */
  private Element newElement(String name)
  {
    Element e = (Element) elementHash.get(name.toLowerCase());

    if (e == null)
      {
        e = new Element();
        e.name = name;
        e.index = elements.size();
        elements.add(e);
        elementHash.put(e.name.toLowerCase(), e);
        assignField(e);
      }
    return e;
  }

  /**
   * Creates and adds to the element table the entity with an
   * unitialized data section. Used internally.
   * @param name the name of the entity
   * @param type the type of the entity, a bitwise combination
   * of GENERAL, PARAMETER, SYSTEM and PUBLIC.
   *
   * @return the created entity
   */
  private Entity newEntity(String name, int type)
  {
    Entity e = new Entity(name, type, null);
    entityHash.put(e.name, e);
    return e;
  }

  private void unexpected(Exception ex)
  {
    throw new Error("This should never happen, report a bug", ex);
  }
}