Re: limiting preceding axis by ancestor

I have a document where there are many instances of <foo>. Each <foo> may
have many <bar> children. <bar> is itself recursive to several levels.

<foo>
	<bar>
	<bar>
<foo>
	<bar>
		<bar>
			<bar>

I want to test to see if any preceding <bar> has the same value as the
current <bar> but limit the test to those <bar> elements are children of the
immediate <foo> ancestor.   In other words, I want to exclude any <bar>
children of the ancestor::foo's preceding-sibling:foo

Try preceding::bar[generate-id()=generate-id(current()/ancestor::foo)]
or ancestor::foo//bar[following::bar[count(.|current())=1]]
Either can be inefficient, depending on the actual XML.