Difference between revisions of "Utility Module"

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m (Corrected function name in Signature for util:last)
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| width='120' | '''Signatures'''
| width='120' | '''Signatures'''
|{{Func|util:last-from|$sequence as item()*|item()?}}<br/>
|{{Func|util:last|$sequence as item()*|item()?}}<br/>
| '''Summary'''
| '''Summary'''

Revision as of 17:15, 12 February 2019

This XQuery Module contains various small utility and helper functions. Please note that some of the functions are used for internal query rewritings. They may be renamed or moved to other modules in future versions of BaseX.


All functions and errors in this module and errors are assigned to the http://basex.org/modules/util namespace, which is statically bound to the util prefix.



Introduced with Version 9.1:

Signatures util:if($condition as item()*, $then as item()*) as item()*
util:if($condition as item()*, $then as item()*, $else as item()*) as item()*
Summary Alternative writing for the if/then/else expression:
  • If the effective boolean value of $condition is true, the $then branch will be evaluated.
  • Otherwise, $else will be evaluated. If no third argument is supplied, an empty sequence will be returned.
  • util:if(true(), 123, 456) returns 123.
  • util:if(0, 'wrong!') returns an empty sequence.


Introduced with Version 9.1:

Signatures util:or($items as item()*, $default as item()*) as item()*
Summary Returns $items if it is a non-empty sequence. Otherwise, returns $default. The function is equivalent to the expression if(exists($items)) then $items else $default.
  • util:or(123, 456) returns 123.
  • util:or(1[. = 0], -1) returns -1.

Positional Access


Updated with Version 9.2: Renamed (before: util:item-at).

Signatures util:item($sequence as item()*, $position as xs:double) as item()?
Summary Returns the item from $sequence at the specified $position. Equivalent to $sequence[$position].
  • util:item(reverse(1 to 5), 1) returns 5.
  • util:item(('a','b'), 0) returns an empty sequence.


Updated with Version 9.2: Renamed (before: util:item-range).

Signatures util:range($sequence as item()*, $first as xs:double, $last as xs:double) as item()*
Summary Returns items from $sequence, starting at position $first and ending at $last. Equivalent to subsequence($sequence, $first, $last - $first + 1).
  • util:range(//item, 11, 20) returns all path results from (if available) position 11 to 20.


Updated with Version 9.2: Renamed (before: util:last-from).

Signatures util:last($sequence as item()*) as item()?
Summary Returns last item of a $sequence. Equivalent to $sequence[last()].
  • util:last(reverse(1 to 100)) returns 1.


Introduced with Version 9.2:

Signatures util:init($sequence as item()*) as item()*
Summary Returns all items of a $sequence except for the last one. Equivalent to $sequence[position() < last()].
  • util:init(1 to 4) returns 1 2 3.

Helper Functions


Signatures util:replicate($sequence as item()*, $count as xs:integer) as item()*
Summary Returns $count instances of the specified $sequence. A similar result can be generated with (1 to $count) ! $sequence, but in the latter case, the right-hand expression will be evaluated multiple times.
Errors negative: The specified number is negative.
  • util:replicate('A', 3) returns A A A.


Code Description
negative The specified number is negative.


Version 9.2
Version 9.1
Version 9.0

The Module was introduced with Version 8.5.