Java XPathContext.getNamespaceContext方法代码示例

import com.sun.org.apache.xpath.internal.XPathContext; //导入方法依赖的package包/类
/**
 * The dyn:evaluate function evaluates a string as an XPath expression and returns
 * the resulting value, which might be a boolean, number, string, node set, result
 * tree fragment or external object. The sole argument is the string to be evaluated.
 * <p>
 * If the expression string passed as the second argument is an invalid XPath
 * expression (including an empty string), this function returns an empty node set.
 * <p>
 * You should only use this function if the expression must be constructed dynamically,
 * otherwise it is much more efficient to use the expression literally.
 *
 * @param myContext The ExpressionContext passed by the extension processor
 * @param xpathExpr The XPath expression string
 *
 * @return The evaluation result
 */
public static XObject evaluate(ExpressionContext myContext, String xpathExpr)
  throws SAXNotSupportedException
{
  if (myContext instanceof XPathContext.XPathExpressionContext)
  {
    XPathContext xctxt = null;
    try
    {
      xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
      XPath dynamicXPath = new XPath(xpathExpr, xctxt.getSAXLocator(),
                                     xctxt.getNamespaceContext(),
                                     XPath.SELECT);

      return dynamicXPath.execute(xctxt, myContext.getContextNode(),
                                  xctxt.getNamespaceContext());
    }
    catch (TransformerException e)
    {
      return new XNodeSet(xctxt.getDTMManager());
    }
  }
  else
    throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext })); //"Invalid context passed to evaluate "
}
 

import com.sun.org.apache.xpath.internal.XPathContext; //导入方法依赖的package包/类
/**
 * Initialize the context values for this expression
 * after it is cloned.
 *
 * @param context The XPath runtime context for this
 * transformation.
 */
public void setRoot(int context, Object environment)
{

  m_context = context;

  XPathContext xctxt = (XPathContext)environment;
  m_execContext = xctxt;
  m_cdtm = xctxt.getDTM(context);

  m_currentContextNode = context; // only if top level?

  // Yech, shouldn't have to do this.  -sb
  if(null == m_prefixResolver)
      m_prefixResolver = xctxt.getNamespaceContext();

  m_lastFetched = DTM.NULL;
  m_foundLast = false;
  m_pos = 0;
  m_length = -1;

  if (m_isTopLevel)
    this.m_stackFrame = xctxt.getVarStack().getStackFrame();

  // reset();
}
 

import com.sun.org.apache.xpath.internal.XPathContext; //导入方法依赖的package包/类
/**
 * The dyn:max function calculates the maximum value for the nodes passed as
 * the first argument, where the value of each node is calculated dynamically
 * using an XPath expression passed as a string as the second argument.
 * <p>
 * The expressions are evaluated relative to the nodes passed as the first argument.
 * In other words, the value for each node is calculated by evaluating the XPath
 * expression with all context information being the same as that for the call to
 * the dyn:max function itself, except for the following:
 * <p>
 * <ul>
 *  <li>the context node is the node whose value is being calculated.</li>
 *  <li>the context position is the position of the node within the node set passed as
 *   the first argument to the dyn:max function, arranged in document order.</li>
 *  <li>the context size is the number of nodes passed as the first argument to the
 *   dyn:max function.</li>
 * </ul>
 * <p>
 * The dyn:max function returns the maximum of these values, calculated in exactly
 * the same way as for math:max.
 * <p>
 * If the expression string passed as the second argument is an invalid XPath
 * expression (including an empty string), this function returns NaN.
 * <p>
 * This function must take a second argument. To calculate the maximum of a set of
 * nodes based on their string values, you should use the math:max function.
 *
 * @param myContext The ExpressionContext passed by the extension processor
 * @param nl The node set
 * @param expr The expression string
 *
 * @return The maximum evaluation value
 */
public static double max(ExpressionContext myContext, NodeList nl, String expr)
  throws SAXNotSupportedException
{

  XPathContext xctxt = null;
  if (myContext instanceof XPathContext.XPathExpressionContext)
    xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
  else
    throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));

  if (expr == null || expr.length() == 0)
    return Double.NaN;

  NodeSetDTM contextNodes = new NodeSetDTM(nl, xctxt);
  xctxt.pushContextNodeList(contextNodes);

  double maxValue = - Double.MAX_VALUE;
  for (int i = 0; i < contextNodes.getLength(); i++)
  {
    int contextNode = contextNodes.item(i);
    xctxt.pushCurrentNode(contextNode);

    double result = 0;
    try
    {
      XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
                                     xctxt.getNamespaceContext(),
                                     XPath.SELECT);
      result = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext()).num();
    }
    catch (TransformerException e)
    {
      xctxt.popCurrentNode();
      xctxt.popContextNodeList();
      return Double.NaN;
    }

    xctxt.popCurrentNode();

    if (result > maxValue)
        maxValue = result;
  }

  xctxt.popContextNodeList();
  return maxValue;

}
 

import com.sun.org.apache.xpath.internal.XPathContext; //导入方法依赖的package包/类
/**
 * The dyn:min function calculates the minimum value for the nodes passed as the
 * first argument, where the value of each node is calculated dynamically using
 * an XPath expression passed as a string as the second argument.
 * <p>
 * The expressions are evaluated relative to the nodes passed as the first argument.
 * In other words, the value for each node is calculated by evaluating the XPath
 * expression with all context information being the same as that for the call to
 * the dyn:min function itself, except for the following:
 * <p>
 * <ul>
 *  <li>the context node is the node whose value is being calculated.</li>
 *  <li>the context position is the position of the node within the node set passed
 *    as the first argument to the dyn:min function, arranged in document order.</li>
 *  <li>the context size is the number of nodes passed as the first argument to the
 *    dyn:min function.</li>
 * </ul>
 * <p>
 * The dyn:min function returns the minimum of these values, calculated in exactly
 * the same way as for math:min.
 * <p>
 * If the expression string passed as the second argument is an invalid XPath expression
 * (including an empty string), this function returns NaN.
 * <p>
 * This function must take a second argument. To calculate the minimum of a set of
 * nodes based on their string values, you should use the math:min function.
 *
 * @param myContext The ExpressionContext passed by the extension processor
 * @param nl The node set
 * @param expr The expression string
 *
 * @return The minimum evaluation value
 */
public static double min(ExpressionContext myContext, NodeList nl, String expr)
  throws SAXNotSupportedException
{

  XPathContext xctxt = null;
  if (myContext instanceof XPathContext.XPathExpressionContext)
    xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
  else
    throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));

  if (expr == null || expr.length() == 0)
    return Double.NaN;

  NodeSetDTM contextNodes = new NodeSetDTM(nl, xctxt);
  xctxt.pushContextNodeList(contextNodes);

  double minValue = Double.MAX_VALUE;
  for (int i = 0; i < nl.getLength(); i++)
  {
    int contextNode = contextNodes.item(i);
    xctxt.pushCurrentNode(contextNode);

    double result = 0;
    try
    {
      XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
                                     xctxt.getNamespaceContext(),
                                     XPath.SELECT);
      result = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext()).num();
    }
    catch (TransformerException e)
    {
      xctxt.popCurrentNode();
      xctxt.popContextNodeList();
      return Double.NaN;
    }

    xctxt.popCurrentNode();

    if (result < minValue)
        minValue = result;
  }

  xctxt.popContextNodeList();
  return minValue;

}
 

import com.sun.org.apache.xpath.internal.XPathContext; //导入方法依赖的package包/类
/**
 * Execute the expression.  Meant for reuse by other FilterExpr iterators
 * that are not derived from this object.
 */
public static XNodeSet executeFilterExpr(int context, XPathContext xctxt,
                                                                                              PrefixResolver prefixResolver,
                                                                                              boolean isTopLevel,
                                                                                              int stackFrame,
                                                                                              Expression expr )
  throws com.sun.org.apache.xml.internal.utils.WrappedRuntimeException
{
  PrefixResolver savedResolver = xctxt.getNamespaceContext();
  XNodeSet result = null;

  try
  {
    xctxt.pushCurrentNode(context);
    xctxt.setNamespaceContext(prefixResolver);

    // The setRoot operation can take place with a reset operation,
    // and so we may not be in the context of LocPathIterator#nextNode,
    // so we have to set up the variable context, execute the expression,
    // and then restore the variable context.

    if (isTopLevel)
    {
      // System.out.println("calling m_expr.execute(getXPathContext())");
      VariableStack vars = xctxt.getVarStack();

      // These three statements need to be combined into one operation.
      int savedStart = vars.getStackFrame();
      vars.setStackFrame(stackFrame);

      result = (com.sun.org.apache.xpath.internal.objects.XNodeSet) expr.execute(xctxt);
      result.setShouldCacheNodes(true);

      // These two statements need to be combined into one operation.
      vars.setStackFrame(savedStart);
    }
    else
        result = (com.sun.org.apache.xpath.internal.objects.XNodeSet) expr.execute(xctxt);

  }
  catch (javax.xml.transform.TransformerException se)
  {

    // TODO: Fix...
    throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(se);
  }
  finally
  {
    xctxt.popCurrentNode();
    xctxt.setNamespaceContext(savedResolver);
  }
  return result;
}