For XPath custom functions (because XPath1.0 functions are very limited)

Function

Want a matching function for a regular expression, but there is no XPath1.0 between the
Have to expand one by themselves, search the Internet a bit, there is a good article,
Http://www.microsoft.com/china/MSDN/library/data/xml/AddingCustomFunctionstoXpath.mspx?mfr=true
The article defines a split, a replace, but there is no match,
Had to expand on it on the basis of

With a closer look at the code, it's easy to extend a function, as long as you change these paragraphs:

1:customcontext.cs

Function to resolve references to my custom functions.
public override IXsltContextFunction resolvefunction (string prefix,
String name, xpathresulttype[] argtypes)
{
Xpathregexextensionfunction func = null;
Create an instance of appropriate extension function class.
Switch (name)
{
Case "Match":
Usage
Myfunctions:matches (string source, String regex_pattern) returns Boolean
Func = new Xpathregexextensionfunction ("Match", 2, 2, new
Xpathresulttype[] {xpathresulttype.string, xpathresulttype.string}
, Xpathresulttype.boolean);
Break
Case "Split":
Usage
Myfunctions:split (string source, string regex_pattern, int n) returns string
Func = new Xpathregexextensionfunction ("Split", 3, 3, new)
Xpathresulttype[] {xpathresulttype.string, xpathresulttype.string,
Xpathresulttype.number}, xpathresulttype.string);
Break
Case "Replace":
Usage
Myfunctions:replace (string source, String Regex_pattern, String replacement_string) returns string
Func = new Xpathregexextensionfunction ("Replace", 3, 3, new
Xpathresulttype[] {xpathresulttype.string, xpathresulttype.string,
Xpathresulttype.string}, xpathresulttype.string);
Break
}
return func;
}

2:xpathregexextensionfunction.cs

This are invoked at run time to execute the user defined function.
public Object Invoke (XsltContext xsltcontext, object[] args,
XPathNavigator Doccontext)
{
Regex R;
string str = NULL;
The two custom XPath extension functions
Switch (m_functionname)
{
Case "Match":
R = new Regex (args[1). ToString ());
MatchCollection m = r.matches (Args[0]. ToString ());
if (m.count = 0)
{
return false;
}
Else
{
return true;
}
Break

Case "Split":
R = new Regex (args[1). ToString ());
string[] S1 = r.split (args[0). ToString ());
int n = convert.toint32 (args[2]);
if (S1. Length < N)
str = "";
Else
str = s1[n-1];
Break
Case "Replace":
R = new Regex (args[1). ToString ());
String s2 = R.replace (Args[0]. ToString (), args[2]. ToString ());
str = s2;
Break
}
Return (object) str;
}

Another file XPathExtensionVariable.cs actually does not have much relationship with the function extension, which is set the parameter.

Once this file has been modified, you can call:

query = Navigator.compile ("Xdutil:match (9, ' \\d ')");
Customcontext cntxt = new Customcontext ();
Add a namespace definition for myfunctions prefix.
Cntxt. AddNamespace ("Xdutil", "http://myXPathExtensionFunctions");
Query. SetContext (Cntxt);
Evaluate (query, navigator);
Of course, it would be nice to support XPath2.0, XPath2.0 These functions are built-in support, but it seems not yet supported.

All the code is here:
Http://cleo.cnblogs.com/Files/cleo/XPathExtFunction.rar

Source: Cleo BLOG