functiontable.java

java1.6众多例子参考

    m_functions[FUNC_SUBSTRING_BEFORE] = 
      com.sun.org.apache.xpath.internal.functions.FuncSubstringBefore.class;
    m_functions[FUNC_SUBSTRING_AFTER] = 
      com.sun.org.apache.xpath.internal.functions.FuncSubstringAfter.class;
    m_functions[FUNC_NORMALIZE_SPACE] = 
      com.sun.org.apache.xpath.internal.functions.FuncNormalizeSpace.class;
    m_functions[FUNC_TRANSLATE] = 
      com.sun.org.apache.xpath.internal.functions.FuncTranslate.class;
    m_functions[FUNC_CONCAT] = com.sun.org.apache.xpath.internal.functions.FuncConcat.class;
    m_functions[FUNC_SYSTEM_PROPERTY] = 
      com.sun.org.apache.xpath.internal.functions.FuncSystemProperty.class;
    m_functions[FUNC_EXT_FUNCTION_AVAILABLE] =
      com.sun.org.apache.xpath.internal.functions.FuncExtFunctionAvailable.class;
    m_functions[FUNC_EXT_ELEM_AVAILABLE] =
      com.sun.org.apache.xpath.internal.functions.FuncExtElementAvailable.class;
    m_functions[FUNC_SUBSTRING] = 
      com.sun.org.apache.xpath.internal.functions.FuncSubstring.class;
    m_functions[FUNC_STRING_LENGTH] = 
      com.sun.org.apache.xpath.internal.functions.FuncStringLength.class;
    m_functions[FUNC_DOCLOCATION] = 
      com.sun.org.apache.xpath.internal.functions.FuncDoclocation.class;
    m_functions[FUNC_UNPARSED_ENTITY_URI] =
      com.sun.org.apache.xpath.internal.functions.FuncUnparsedEntityURI.class;
  }

  static{
          m_functionID.put(Keywords.FUNC_CURRENT_STRING,
                          new Integer(FunctionTable.FUNC_CURRENT));
          m_functionID.put(Keywords.FUNC_LAST_STRING,
                          new Integer(FunctionTable.FUNC_LAST));
          m_functionID.put(Keywords.FUNC_POSITION_STRING,
                          new Integer(FunctionTable.FUNC_POSITION));
          m_functionID.put(Keywords.FUNC_COUNT_STRING,
                          new Integer(FunctionTable.FUNC_COUNT));
          m_functionID.put(Keywords.FUNC_ID_STRING,
                          new Integer(FunctionTable.FUNC_ID));
          m_functionID.put(Keywords.FUNC_KEY_STRING,
                          new Integer(FunctionTable.FUNC_KEY));
          m_functionID.put(Keywords.FUNC_LOCAL_PART_STRING,
                          new Integer(FunctionTable.FUNC_LOCAL_PART));
          m_functionID.put(Keywords.FUNC_NAMESPACE_STRING,
                          new Integer(FunctionTable.FUNC_NAMESPACE));
          m_functionID.put(Keywords.FUNC_NAME_STRING,
                          new Integer(FunctionTable.FUNC_QNAME));
          m_functionID.put(Keywords.FUNC_GENERATE_ID_STRING,
                          new Integer(FunctionTable.FUNC_GENERATE_ID));
          m_functionID.put(Keywords.FUNC_NOT_STRING,
                          new Integer(FunctionTable.FUNC_NOT));
          m_functionID.put(Keywords.FUNC_TRUE_STRING,
                          new Integer(FunctionTable.FUNC_TRUE));
          m_functionID.put(Keywords.FUNC_FALSE_STRING,
                          new Integer(FunctionTable.FUNC_FALSE));
          m_functionID.put(Keywords.FUNC_BOOLEAN_STRING,
                          new Integer(FunctionTable.FUNC_BOOLEAN));
          m_functionID.put(Keywords.FUNC_LANG_STRING,
                          new Integer(FunctionTable.FUNC_LANG));
          m_functionID.put(Keywords.FUNC_NUMBER_STRING,
                          new Integer(FunctionTable.FUNC_NUMBER));
          m_functionID.put(Keywords.FUNC_FLOOR_STRING,
                          new Integer(FunctionTable.FUNC_FLOOR));
          m_functionID.put(Keywords.FUNC_CEILING_STRING,
                          new Integer(FunctionTable.FUNC_CEILING));
          m_functionID.put(Keywords.FUNC_ROUND_STRING,
                          new Integer(FunctionTable.FUNC_ROUND));
          m_functionID.put(Keywords.FUNC_SUM_STRING,
                          new Integer(FunctionTable.FUNC_SUM));
          m_functionID.put(Keywords.FUNC_STRING_STRING,
                          new Integer(FunctionTable.FUNC_STRING));
          m_functionID.put(Keywords.FUNC_STARTS_WITH_STRING,
                          new Integer(FunctionTable.FUNC_STARTS_WITH));
          m_functionID.put(Keywords.FUNC_CONTAINS_STRING,
                          new Integer(FunctionTable.FUNC_CONTAINS));
          m_functionID.put(Keywords.FUNC_SUBSTRING_BEFORE_STRING,
                          new Integer(FunctionTable.FUNC_SUBSTRING_BEFORE));
          m_functionID.put(Keywords.FUNC_SUBSTRING_AFTER_STRING,
                          new Integer(FunctionTable.FUNC_SUBSTRING_AFTER));
          m_functionID.put(Keywords.FUNC_NORMALIZE_SPACE_STRING,
                          new Integer(FunctionTable.FUNC_NORMALIZE_SPACE));
          m_functionID.put(Keywords.FUNC_TRANSLATE_STRING,
                          new Integer(FunctionTable.FUNC_TRANSLATE));
          m_functionID.put(Keywords.FUNC_CONCAT_STRING,
                          new Integer(FunctionTable.FUNC_CONCAT));
          m_functionID.put(Keywords.FUNC_SYSTEM_PROPERTY_STRING,
                          new Integer(FunctionTable.FUNC_SYSTEM_PROPERTY));
          m_functionID.put(Keywords.FUNC_EXT_FUNCTION_AVAILABLE_STRING,
                        new Integer(FunctionTable.FUNC_EXT_FUNCTION_AVAILABLE));
          m_functionID.put(Keywords.FUNC_EXT_ELEM_AVAILABLE_STRING,
                          new Integer(FunctionTable.FUNC_EXT_ELEM_AVAILABLE));
          m_functionID.put(Keywords.FUNC_SUBSTRING_STRING,
                          new Integer(FunctionTable.FUNC_SUBSTRING));
          m_functionID.put(Keywords.FUNC_STRING_LENGTH_STRING,
                          new Integer(FunctionTable.FUNC_STRING_LENGTH));
          m_functionID.put(Keywords.FUNC_UNPARSED_ENTITY_URI_STRING,
                          new Integer(FunctionTable.FUNC_UNPARSED_ENTITY_URI));
          m_functionID.put(Keywords.FUNC_DOCLOCATION_STRING,
                          new Integer(FunctionTable.FUNC_DOCLOCATION));          
  }
  
  public FunctionTable(){
  }
  
  /**
   * Return the name of the a function in the static table. Needed to avoid
   * making the table publicly available.
   */
  String getFunctionName(int funcID) {
      if (funcID < NUM_BUILT_IN_FUNCS) return m_functions[funcID].getName();
      else return m_functions_customer[funcID - NUM_BUILT_IN_FUNCS].getName();
  }

  /**
   * Obtain a new Function object from a function ID.
   *
   * @param which  The function ID, which may correspond to one of the FUNC_XXX 
   *    values found in {@link com.sun.org.apache.xpath.internal.compiler.FunctionTable}, but may 
   *    be a value installed by an external module. 
   *
   * @return a a new Function instance.
   *
   * @throws javax.xml.transform.TransformerException if ClassNotFoundException, 
   *    IllegalAccessException, or InstantiationException is thrown.
   */
  Function getFunction(int which)
          throws javax.xml.transform.TransformerException
  {
          try{
              if (which < NUM_BUILT_IN_FUNCS) 
                  return (Function) m_functions[which].newInstance();
              else 
                  return (Function) m_functions_customer[
                      which-NUM_BUILT_IN_FUNCS].newInstance();                  
          }catch (IllegalAccessException ex){
                  throw new TransformerException(ex.getMessage());
          }catch (InstantiationException ex){
                  throw new TransformerException(ex.getMessage());
          }
  }
  
  /**
   * Obtain a function ID from a given function name
   * @param key the function name in a java.lang.String format.
   * @return a function ID, which may correspond to one of the FUNC_XXX values
   * found in {@link com.sun.org.apache.xpath.internal.compiler.FunctionTable}, but may be a 
   * value installed by an external module.
   */
  Object getFunctionID(String key){
          Object id = m_functionID_customer.get(key);
          if (null == id) id = m_functionID.get(key);
          return id;
  }
  
  /**
   * Install a built-in function.
   * @param name The unqualified name of the function, must not be null
   * @param func A Implementation of an XPath Function object.
   * @return the position of the function in the internal index.
   */
  public int installFunction(String name, Class func)
  {

    int funcIndex;
    Object funcIndexObj = getFunctionID(name);

    if (null != funcIndexObj)
    {
      funcIndex = ((Integer) funcIndexObj).intValue();
      
      if (funcIndex < NUM_BUILT_IN_FUNCS){
              funcIndex = m_funcNextFreeIndex++;
              m_functionID_customer.put(name, new Integer(funcIndex)); 
      }
      m_functions_customer[funcIndex - NUM_BUILT_IN_FUNCS] = func;          
    }
    else
    {
            funcIndex = m_funcNextFreeIndex++;
                          
            m_functions_customer[funcIndex-NUM_BUILT_IN_FUNCS] = func;
                    
            m_functionID_customer.put(name, 
                new Integer(funcIndex));   
    }
    return funcIndex;
  }

  /**
   * Tell if a built-in, non-namespaced function is available.
   *
   * @param methName The local name of the function.
   *
   * @return True if the function can be executed.
   */
  public boolean functionAvailable(String methName)
  {
      Object tblEntry = m_functionID.get(methName);
      if (null != tblEntry) return true;
      else{
              tblEntry = m_functionID_customer.get(methName);
              return (null != tblEntry)? true : false;
      }
  }
}