问Xquery在if条件内设置全局变量

EN

<Result>
{
let 
  $bits as xs:integer* := analyze-string(root/Input, '[01]')//*:match!xs:integer(.),
  $values as xs:string* := analyze-string(root/ReadInput, '.{4}')//*:match!string(),
  $element-names as xs:string* := (string-to-codepoints('A') to string-to-codepoints('Z'))!codepoints-to-string(.)!(. || . || . || .),
  $positions := $bits[. = 1]!index-of($bits, .),
  $output-elements as xs:string* := $element-names[position() = $positions]
return 
  for $n at $pos in $output-elements
  return element {$n} { $values[$pos] }
}
</Result>

<Result>
{
let 
  $bitString as xs:string := root/Input/string(),
  $bits as xs:integer* := for $p in 1 to string-length($bitString) return xs:integer(substring($bitString, $p, 1)),
  $valueString as xs:string := root/ReadInput/string(),
  $values as xs:string* := for $p in 0 to count($bits[. = 1]) - 1 return substring($valueString, 1 + $p * 4, 4),
  $element-names as xs:string* := (string-to-codepoints('A') to string-to-codepoints('Z'))!codepoints-to-string(.)!concat(., ., ., .),
  $positions := $bits[. = 1]!index-of($bits, .),
  $output-elements as xs:string* := $element-names[position() = $positions]
return 
  for $n at $pos in $output-elements
  return element {$n} { $values[$pos] }
}
</Result>

declare function local:f($root as element(root), $i as xs:integer, $j as xs:integer) {
  if (string-length($root/Input) le $i)
  then if ((substring($root/Input, $i, 1) eq '1')
       then (element { local:tag($i) }
                     { substring($root/ReadInput, $j, 4 },
             local:f($root, $i+1, $j+4))
       else local:f($root, $i+1, $j)
  else ()
};

declare function local:tag($i as xs:integer) {
  let $n := format-integer($i, 'A')
  return $n||$n||$n||$n
};

local:f(root, 1, 1)