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Re: Brackets in XPATHS
Chris Maden wrote:
>>You can start with a node-set and refine it, but you can't reference a
>>node-set (the union of xpath2 and xpath3) as if it were the child of another
>>node-set (xpath1).
>>
>>(/xpath1/xpath2|/xpath1/xpath3)/xpath4 should work for you.
>
> That's not legal. A UnionExpr (with the '|' operator) can't be part
> of a Step like that; parentheses, in general, are not allowed in
> Steps.
Actually, it is legal. The () around the unioned paths indicate that
the start of the location path is an expression. The relevant
productions from the XPath Rec are:
[19] PathExpr ::= LocationPath
| FilterExpr
| FilterExpr '/' RelativeLocationPath
| FilterExpr '//' RelativeLocationPath
[20] FilterExpr ::= PrimaryExpr
| FilterExpr Predicate
[15] PrimaryExpr ::= VariableReference
| '(' Expr ')'
| Literal
| Number
| FunctionCall
Here we have a path expression that is a filter expression followed by
a '/' followed by a relative location path. The filter expression is a
primary expression consisting of '(', an expression, and ')'. The
expression is itself a path expression that is a location path.
Cheers,
Jeni
---
Jeni Tennison
http://www.jenitennison.com/
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