This function determines where the first match (if any) occurs in the string. It does this by tokenizing the string and determining the length of the first token.

This function replaces the first match in the string by concatenating an anchor and reluctant wildcard to the beginning of the pattern. It is used by the get-matches-and-non-matches to help determine the length of any particular match.

declare namespace functx = "http://www.functx.com";
declare function functx:get-matches-and-non-matches
  ($string as xs:string?, $regex as xs:string) as element( )* {

   let $iomf := functx:index-of-match-first($string, $regex)
   return
   if (empty($iomf))
   then <non-match>{$string}</non-match>
   else if ($iomf > 1)
   then (<non-match>{substring($string,1,$iomf − 1)}</non-match>,
         functx:get-matches-and-non-matches
            substring($string,$iomf),$regex))
   else
   let $length :=
      string-length($string) -
      string-length(functx:replace-first($string, $regex,''))
   return (<match>{substring($string,1,$length)}</match>,
           if (string-length($string) > $length)
           then functx:get-matches-and-non-matches(
              substring($string,$length + 1),$regex)
           else ( ))
 } ;

declare function functx:index-of-match-first
  ($arg as xs:string?, $pattern as xs:string) as xs:integer? {
            if (matches($arg,$pattern))
  then string-length(tokenize($arg, $pattern)[1]) + 1
  else ( )
 } ;

declare function functx:replace-first
  ($arg as xs:string?, $pattern as xs:string,
    $replacement as xs:string )  as xs:string {

   replace($arg, concat('(^.*?)', $pattern),
             concat('$1',$replacement))
 } ;