compiler.java

java1.6众多例子参考

      addMagicSelf = false;
      argLen = getOp(opPos + OpMap.MAPINDEX_LENGTH);
      pattern = new FunctionPattern(compileFunction(opPos), Axis.PARENT, Axis.CHILD);
      break;
    case OpCodes.FROM_ROOT :
      if(DEBUG)
        System.out.println("FROM_ROOT, "+m_currentPattern);
      addMagicSelf = false;
      argLen = getArgLengthOfStep(opPos);
      opPos = getFirstChildPosOfStep(opPos);
      pattern = new StepPattern(DTMFilter.SHOW_DOCUMENT | 
                                DTMFilter.SHOW_DOCUMENT_FRAGMENT,
                                Axis.PARENT, Axis.CHILD);
      break;
    case OpCodes.MATCH_ATTRIBUTE :
     if(DEBUG)
        System.out.println("MATCH_ATTRIBUTE: "+getStepLocalName(startOpPos)+", "+m_currentPattern);
      argLen = getArgLengthOfStep(opPos);
      opPos = getFirstChildPosOfStep(opPos);
      pattern = new StepPattern(DTMFilter.SHOW_ATTRIBUTE,
                                getStepNS(startOpPos),
                                getStepLocalName(startOpPos),
                                Axis.PARENT, Axis.ATTRIBUTE);
      break;
    case OpCodes.MATCH_ANY_ANCESTOR :
      if(DEBUG)
        System.out.println("MATCH_ANY_ANCESTOR: "+getStepLocalName(startOpPos)+", "+m_currentPattern);
      argLen = getArgLengthOfStep(opPos);
      opPos = getFirstChildPosOfStep(opPos);
      int what = getWhatToShow(startOpPos);
      // bit-o-hackery, but this code is due for the morgue anyway...
      if(0x00000500 == what)
        addMagicSelf = false;
      pattern = new StepPattern(getWhatToShow(startOpPos),
                                        getStepNS(startOpPos),
                                        getStepLocalName(startOpPos),
                                        Axis.ANCESTOR, Axis.CHILD);
      break;
    case OpCodes.MATCH_IMMEDIATE_ANCESTOR :
      if(DEBUG)
        System.out.println("MATCH_IMMEDIATE_ANCESTOR: "+getStepLocalName(startOpPos)+", "+m_currentPattern);
      argLen = getArgLengthOfStep(opPos);
      opPos = getFirstChildPosOfStep(opPos);
      pattern = new StepPattern(getWhatToShow(startOpPos),
                                getStepNS(startOpPos),
                                getStepLocalName(startOpPos),
                                Axis.PARENT, Axis.CHILD);
      break;
    default :
      error(XPATHErrorResources.ER_UNKNOWN_MATCH_OPERATION, null);  //"unknown match operation!");

      return null;
    }

    pattern.setPredicates(getCompiledPredicates(opPos + argLen));
    if(null == ancestorPattern)
    {
      // This is the magic and invisible "." at the head of every 
      // match pattern, and corresponds to the current node in the context 
      // list, from where predicates are counted.
      // So, in order to calculate "foo[3]", it has to count from the 
      // current node in the context list, so, from that current node, 
      // the full pattern is really "self::node()/child::foo[3]".  If you 
      // translate this to a select pattern from the node being tested, 
      // which is really how we're treating match patterns, it works out to 
      // self::foo/parent::node[child::foo[3]]", or close enough.
	/*      if(addMagicSelf && pattern.getPredicateCount() > 0)
      {
        StepPattern selfPattern = new StepPattern(DTMFilter.SHOW_ALL, 
                                                  Axis.PARENT, Axis.CHILD);
        // We need to keep the new nodetest from affecting the score...
        XNumber score = pattern.getStaticScore();
        pattern.setRelativePathPattern(selfPattern);
        pattern.setStaticScore(score);
        selfPattern.setStaticScore(score);
	}*/
    }
    else
    {
      // System.out.println("Setting "+ancestorPattern+" as relative to "+pattern);
      pattern.setRelativePathPattern(ancestorPattern);
    }

    StepPattern relativePathPattern = stepPattern(endStep, stepCount + 1,
                                        pattern);

    return (null != relativePathPattern) ? relativePathPattern : pattern;
  }

  /**
   * Compile a zero or more predicates for a given match pattern.
   * 
   * @param opPos The position of the first predicate the m_opMap array.
   *
   * @return reference to array of {@link com.sun.org.apache.xpath.internal.Expression} instances.
   *
   * @throws TransformerException if a error occurs creating the Expression.
   */
  public Expression[] getCompiledPredicates(int opPos)
          throws TransformerException
  {

    int count = countPredicates(opPos);

    if (count > 0)
    {
      Expression[] predicates = new Expression[count];

      compilePredicates(opPos, predicates);

      return predicates;
    }

    return null;
  }

  /**
   * Count the number of predicates in the step.
   *
   * @param opPos The position of the first predicate the m_opMap array.
   *
   * @return The number of predicates for this step.
   *
   * @throws TransformerException if a error occurs creating the Expression.
   */
  public int countPredicates(int opPos) throws TransformerException
  {

    int count = 0;

    while (OpCodes.OP_PREDICATE == getOp(opPos))
    {
      count++;

      opPos = getNextOpPos(opPos);
    }

    return count;
  }

  /**
   * Compiles predicates in the step.
   *
   * @param opPos The position of the first predicate the m_opMap array.
   * @param predicates An empty pre-determined array of 
   *            {@link com.sun.org.apache.xpath.internal.Expression}s, that will be filled in.
   *
   * @throws TransformerException
   */
  private void compilePredicates(int opPos, Expression[] predicates)
          throws TransformerException
  {

    for (int i = 0; OpCodes.OP_PREDICATE == getOp(opPos); i++)
    {
      predicates[i] = predicate(opPos);
      opPos = getNextOpPos(opPos);
    }
  }

  /**
   * Compile a built-in XPath function.
   * 
   * @param opPos The current position in the m_opMap array.
   *
   * @return reference to {@link com.sun.org.apache.xpath.internal.functions.Function} instance.
   *
   * @throws TransformerException if a error occurs creating the Expression.
   */
  Expression compileFunction(int opPos) throws TransformerException
  {

    int endFunc = opPos + getOp(opPos + 1) - 1;

    opPos = getFirstChildPos(opPos);

    int funcID = getOp(opPos);

    opPos++;

    if (-1 != funcID)
    {
      Function func = m_functionTable.getFunction(funcID);
      
      /**
       * It is a trick for function-available. Since the function table is an
       * instance field, insert this table at compilation time for later usage
       */
      
      if (func instanceof FuncExtFunctionAvailable)
          ((FuncExtFunctionAvailable) func).setFunctionTable(m_functionTable);

      func.postCompileStep(this);
      
      try
      {
        int i = 0;

        for (int p = opPos; p < endFunc; p = getNextOpPos(p), i++)
        {

          // System.out.println("argPos: "+ p);
          // System.out.println("argCode: "+ m_opMap[p]);
          func.setArg(compile(p), i);
        }

        func.checkNumberArgs(i);
      }
      catch (WrongNumberArgsException wnae)
      {
        java.lang.String name = m_functionTable.getFunctionName(funcID);

        m_errorHandler.fatalError( new TransformerException(
                  XSLMessages.createXPATHMessage(XPATHErrorResources.ER_ONLY_ALLOWS, 
                      new Object[]{name, wnae.getMessage()}), m_locator)); 
              //"name + " only allows " + wnae.getMessage() + " arguments", m_locator));
      }

      return func;
    }
    else
    {
      error(XPATHErrorResources.ER_FUNCTION_TOKEN_NOT_FOUND, null);  //"function token not found.");

      return null;
    }
  }

  // The current id for extension functions.
  private static long s_nextMethodId = 0;

  /**
   * Get the next available method id
   */
  synchronized private long getNextMethodId()
  {
    if (s_nextMethodId == Long.MAX_VALUE)
      s_nextMethodId = 0;
    
    return s_nextMethodId++;
  }
  
  /**
   * Compile an extension function.
   * 
   * @param opPos The current position in the m_opMap array.
   *
   * @return reference to {@link com.sun.org.apache.xpath.internal.functions.FuncExtFunction} instance.
   *
   * @throws TransformerException if a error occurs creating the Expression.
   */
  private Expression compileExtension(int opPos)
          throws TransformerException
  {

    int endExtFunc = opPos + getOp(opPos + 1) - 1;

    opPos = getFirstChildPos(opPos);

    java.lang.String ns = (java.lang.String) getTokenQueue().elementAt(getOp(opPos));

    opPos++;

    java.lang.String funcName =
      (java.lang.String) getTokenQueue().elementAt(getOp(opPos));

    opPos++;

    // We create a method key to uniquely identify this function so that we
    // can cache the object needed to invoke it.  This way, we only pay the
    // reflection overhead on the first call.

    Function extension = new FuncExtFunction(ns, funcName, String.valueOf(getNextMethodId()));

    try
    {
      int i = 0;

      while (opPos < endExtFunc)
      {
        int nextOpPos = getNextOpPos(opPos);

        extension.setArg(this.compile(opPos), i);

        opPos = nextOpPos;

        i++;
      }
    }
    catch (WrongNumberArgsException wnae)
    {
      ;  // should never happen
    }

    return extension;
  }

  /**
   * Warn the user of an problem.
   *
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  public void warn(String msg, Object[] args) throws TransformerException
  {

    java.lang.String fmsg = XSLMessages.createXPATHWarning(msg, args);

    if (null != m_errorHandler)
    {
      m_errorHandler.warning(new TransformerException(fmsg, m_locator));
    }
    else
    {
      System.out.println(fmsg
                          +"; file "+m_locator.getSystemId()
                          +"; line "+m_locator.getLineNumber()
                          +"; column "+m_locator.getColumnNumber());
    }
  }

  /**
   * Tell the user of an assertion error, and probably throw an
   * exception.
   *
   * @param b  If false, a runtime exception will be thrown.
   * @param msg The assertion message, which should be informative.
   * 
   * @throws RuntimeException if the b argument is false.
   */
  public void assertion(boolean b, java.lang.String msg)
  {

    if (!b)
    {
      java.lang.String fMsg = XSLMessages.createXPATHMessage(
        XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
        new Object[]{ msg });

      throw new RuntimeException(fMsg);
    }
  }

  /**
   * Tell the user of an error, and probably throw an
   * exception.
   *
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  public void error(String msg, Object[] args) throws TransformerException
  {

    java.lang.String fmsg = XSLMessages.createXPATHMessage(msg, args);
    

    if (null != m_errorHandler)
    {
      m_errorHandler.fatalError(new TransformerException(fmsg, m_locator));
    }
    else
    {

      // System.out.println(te.getMessage()
      //                    +"; file "+te.getSystemId()
      //                    +"; line "+te.getLineNumber()
      //                    +"; column "+te.getColumnNumber());
      throw new TransformerException(fmsg, (SAXSourceLocator)m_locator);
    }
  }

  /**
   * The current prefixResolver for the execution context.
   */
  private PrefixResolver m_currentPrefixResolver = null;

  /**
   * Get the current namespace context for the xpath.
   *
   * @return The current prefix resolver, *may* be null, though hopefully not.
   */
  public PrefixResolver getNamespaceContext()
  {
    return m_currentPrefixResolver;
  }

  /**
   * Set the current namespace context for the xpath.
   *
   * @param pr The resolver for prefixes in the XPath expression.
   */
  public void setNamespaceContext(PrefixResolver pr)
  {
    m_currentPrefixResolver = pr;
  }

  /** The error listener where errors will be sent.  If this is null, errors 
   *  and warnings will be sent to System.err.  May be null.    */
  ErrorListener m_errorHandler;

  /** The source locator for the expression being compiled.  May be null. */
  SourceLocator m_locator;
  
  /**
   * The FunctionTable for all xpath build-in functions
   */
  private FunctionTable m_functionTable;
}