[xquery-talk] What does ``UnaryExpr ::= ( <UnaryMinus> |
<UnaryPlus> )* ValueExpr'' mean?
mhk at mhk.me.uk
Mon Jan 17 09:34:45 PST 2005
Since the grammar allows
$x + -1
it also allows
Not something that's especially useful, just there for consistency and
generality, on the principle of "no needless restrictions". It was in XPath
1.0 so it's been retained.
> -----Original Message-----
> From: talk-bounces at xquery.com
> [mailto:talk-bounces at xquery.com] On Behalf Of Zhimao Guo
> Sent: 17 January 2005 08:40
> To: talk at xquery.com
> Subject: [xquery-talk] What does ``UnaryExpr ::= (
> <UnaryMinus> | <UnaryPlus> )* ValueExpr'' mean?
> Dear all,
> I am reading XGrammar from W3C released in Oct. 2004.
> I am confused by this production rule. What does
> ( <UnaryMinus> | <UnaryPlus> )*
> mean? Why does the symbol ``*'' occur here?
> best regards,
> Zhimao Guo
> talk at xquery.com
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