/// <summary>
/// Sets up the context for expression execution.
/// </summary>
private static XmlNamespaceManager PrepareContext(XPathNavigator source,
XmlNamespaceManager context, XmlPrefix[] prefixes, XPathVariable[] variables)
{
XmlNamespaceManager ctx = context;
// If we have variables, we need the dynamic context.
if (variables != null)
{
DynamicContext dyn;
if (ctx != null)
dyn = new DynamicContext(ctx);
else
dyn = new DynamicContext();
// Add the variables we received.
foreach (XPathVariable var in variables)
{
dyn.AddVariable(var.Name, var.Value);
}
ctx = dyn;
}
// If prefixes were added, append them to context.
if (prefixes != null)
{
if (ctx == null) ctx = new XmlNamespaceManager(source.NameTable);
foreach (XmlPrefix prefix in prefixes)
ctx.AddNamespace(prefix.Prefix, prefix.NamespaceURI);
}
return ctx;
}
/// <summary>
/// Evaluates the given expression and returns the typed result.
/// </summary>
public static object Evaluate(string expression, XPathNavigator source,
XmlPrefix[] prefixes, params XPathVariable[] variables)
{
XPathExpression expr = GetCompiledExpression(expression, source);
expr.SetContext(PrepareContext(source, null, prefixes, variables));
return source.Evaluate(expr);
}
/// <summary>
/// Selects a node set using the specified XPath expression.
/// </summary>
public static XPathNodeIterator SelectSorted(string expression, XPathNavigator source,
object sortExpression, IComparer comparer,
XmlPrefix[] prefixes, params XPathVariable[] variables)
{
XPathExpression expr = GetCompiledExpression(expression, source);
XmlNamespaceManager ctx = PrepareContext(source, null, prefixes, variables);
expr.SetContext(ctx);
PrepareSort(expr, source, sortExpression, comparer, ctx);
return source.Select(expr);
}
/// <summary>
/// Selects the first XmlNode that matches the XPath expression.
/// </summary>
public static XmlNode SelectSingleNode(string expression, XmlNode source, XmlPrefix[] prefixes, params XPathVariable[] variables)
{
foreach (XmlNode node in SelectNodes(expression, source, prefixes, variables))
return node;
return null;
}
/// <summary>
/// Selects a node set using the specified XPath expression.
/// </summary>
public static XmlNodeList SelectNodesSorted(string expression, XmlNode source,
object sortExpression, IComparer comparer,
XmlPrefix[] prefixes, params XPathVariable[] variables)
{
return XmlNodeListFactory.CreateNodeList(
SelectSorted(expression, source.CreateNavigator(), sortExpression,
comparer, prefixes, variables));
}
/// <summary>
/// Selects a node set using the specified XPath expression.
/// </summary>
public static XmlNodeList SelectNodesSorted(string expression, XmlNode source,
object sortExpression, XmlSortOrder order, XmlCaseOrder caseOrder, string lang, XmlDataType dataType,
XmlPrefix[] prefixes, params XPathVariable[] variables)
{
return XmlNodeListFactory.CreateNodeList(
SelectSorted(expression, source.CreateNavigator(), sortExpression,
order, caseOrder, lang, dataType, prefixes, variables));
}
/// <summary>
/// Selects a list of nodes matching the XPath expression.
/// </summary>
public static XmlNodeList SelectNodes(string expression, XmlNode source, XmlPrefix[] prefixes, params XPathVariable[] variables)
{
XPathNodeIterator it = Select(expression, source.CreateNavigator(), prefixes, variables);
return XmlNodeListFactory.CreateNodeList(it);
}