Fwd: Re: Comparison evaluation in XPath (resend)

Date: Fri, 14 Mar 2003 11:43:44 -0500
To: xsl-lists@xxxxxxxxxxxxxxxxxxxxxx
From: "G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>
Subject: Re:  Comparison evaluation in XPath

At 2003-03-13 16:56 -0800, Gregory Murphy wrote:

Looking at the grammar for XPath, it appears that the comparison and
equality operators are left-associative. So,

x > y > z

should be evaluated as if it were

( x > y ) > z

How then should the value be obtained? If evaluation is performed at each
branch of an LALR(1) parse of an XPath expression, then an expression like

3 > 2 > 1

would be reduced first to

true > 1

which would evaluate to false. But shouldn't the answer be true?

Whenever ">" or "<" is used in the operator, both operands are cast to numbers. The number() function on "true()" returns the number 1 ... and 1 is not greater than 1.

I hope this helps.

.............. Ken

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