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.
Conventions
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.
Functions
util:if
Template:Mark
Signatures
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util:if($condition as item()*, $then as item()*) as item()*
util:if($condition as item()*, $then as item()*, $else as item()*) as item()*
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Summary
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Alternative writing for the if/then/else expression:
- If the effective boolean value of
$condition is true, the $then branch will be evaluated.
- Otherwise,
$else will be evaluated. If no third argument is supplied, an empty sequence will be returned.
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Examples
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util:if(true(), 123, 456) returns 123 .
util:if(0, 'wrong!') returns an empty sequence.
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util:or
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Signatures
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util:or($items as item()*, $default as item()*) as item()*
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Summary
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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 $default .
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Examples
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util:or(123, 456) returns 123 .
util:or(1[. = 0], -1) returns -1 .
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util:item-at
Signatures
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util:item-at($sequence as item()*, $position as xs:double) as item()?
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Summary
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Returns the item from $sequence at the specified $position . Equivalent to $sequence[$position] .
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Examples
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util:item-at(reverse(1 to 5), 1) returns 5 .
util:item-at(('a','b'), 0) returns an empty sequence.
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util:item-range
Signatures
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util:item-range($sequence as item()*, $first as xs:double, $last as xs:double) as item()*
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Summary
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Returns items from $sequence , starting at position $first and ending at $last . Equivalent to subsequence($sequence, $first, $last - $first + 1) .
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Examples
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util:item-range(//item, 11, 20) returns all path results from (if available) position 11 to 20.
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util:last
Template:Mark: Renamed (before: util:last-from
).
Signatures
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util:last-from($sequence as item()*) as item()?
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Summary
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Returns last item of a $sequence . Equivalent to $sequence[last()] .
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Examples
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util:last(reverse(1 to 100)) returns 1 .
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util:init
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Signatures
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util:init($sequence as item()*) as item()*
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Summary
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Returns all items of a $sequence except for the last one. Equivalent to $sequence[position() < last()] .
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Examples
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util:init(1 to 4) returns 1 2 3 .
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util:replicate
Signatures
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util:replicate($sequence as item()*, $count as xs:integer) as item()*
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Summary
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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.
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Errors
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negative : The specified number is negative.
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Examples
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util:replicate('A', 3) returns A A A .
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Errors
Code
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Description
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negative
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The specified number is negative.
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Changelog
- Version 9.2
- Added: util:last renamed (before:
util:last-from
)
- Version 9.1
- Version 9.0
The Module was introduced with Version 8.5.