Please correct any misunderstanding I may have, but from the
documentation I concluded that search:unparse was meant to reverse the
action of search:parse and construct a query string functionally
identical to the original (functionally identical because it is
reconstructed from the cts:query tree and might not have redundant
parentheses and such); If the output of search:unparse is indeed
functionally identical then one should be able to reparse it and obtain
an identical cts:query tree as obtained from the original search:parse.
However it looks to me like there are cases where search:unparse does
not properly render even a trivial cts:query tree created via
search:parse, even using the default grammar returned by
search:get-default-options(). Referring to the output from the attached
snippet, where $query := 'pos -(neg1 OR neg2)', with a simplified tree
notation:
(a) search:parse( $query, $opts ) => AND( pos, NOT( OR( neg1, neg2 )
) ) as expected.
(b) search:unparse of (a) => omits the parentheses grouping the
target of the NOT eg. 'pos -neg1 OR neg2'
(c) search:parse of ( b ) => parses the misrendering as expected eg.
AND( pos, OR( NOT( neg1 ), neg2 ) )
Query trees (a) and (c) are obviously not functionally identical, since
in the first case neg1 is prohibited and the second it is required. The
same behavior can be seen with -(neg1 neg2), or other cases with a
complex cts:not-query target.
As a workaround I created my own implementation of unparse, and it seems
simple enough to parenthesize clauses which don't confirm to the default
operator precedence simply by passing the parent clause strength down
the recursion and parenthesizing whenever a sub-clause's binding
strength is less than the parent; it works for a few test cases at
least. Can't the built-in search:unparse do that?
- J.J. Larrea
xquery version "1.0-ml";
import module namespace search="http://marklogic.com/appservices/search";
at "/MarkLogic/appservices/search/search.xqy";
declare variable $query := 'pos -(neg1 OR neg2)';
let $options := search:get-default-options()
let $parsed := search:parse( $query, $options )
let $unparsed := search:unparse( $parsed )
let $reparsed := search:parse( $unparsed, $options )
return (
"Original:",
$query,
"Unparsed:",
$unparsed,
"Parsed Tree:",
$parsed,
"Reparsed Tree:",
$reparsed,
"Options (default):",
$options
)_______________________________________________
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