xml-dev - Re: A question of SAX specification

[David Megginson <david@megginson.com>]

John Cowan <cowan@locke.ccil.org> writes:

> > The idea of Locator was simply to help get a user close to an error in
> > a document: exactly how it works is deliberately unspecified, mainly
> > to keep life easy for parser writers (since different parsers use
> > different tokenization and look-ahead schemes).  Locator is not
> > designed to let you extract text strings from the original document.
> 
> Yes, but it would have been nice to define whether the first column
> in each line is column 1 or column 0, which is obviously the problem
> above.  Ditto with line 1 or line 0.

See the JavaDoc documentation for the Locator interface: "The first
column in a line is position 1":

  http://www.megginson.com/SAX/javadoc/org.xml.sax.Locator.html#getColumnNumber()

(Granted, it doesn't say the same about the first line, but I've never
heard of zero-based line numbering).

That might not be the problem here in any case.  One parser is
returning the position of the last character in the start tag, while
the other is returning the position of the first character past the
end of the start tag -- both are OK (as would be the first character
of the start tag), because they're close enough to bring a human
reader to the right general vicinity in the source document.

Remember that a major goal of SAX 1.0 was to impose as little as
possible on the programmer: we didn't want to force programmers to
track a lot of extra information if they didn't want to.


All the best,


David

-- 
David Megginson                 david@megginson.com
           http://www.megginson.com/

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