Re: [xml] Length xmlTextReaderConst... contents?

[Daniel Veillard <veillard redhat com>]

On Fri, Apr 11, 2008 at 01:10:01PM +0300, Andrew W. Nosenko wrote:
> On Fri, Apr 11, 2008 at 8:58 AM, Ralf Junker <ralfjunker gmx de> wrote:
> >  I need the length to pass it to other functions which do not work on #0-terminated, but 
> > length-terminated string functions.

  actually no, the parser computed the lenght at some point for example
when interning the string.
  Have you actually tried to do a fine grained analysis, i really doubt
the strlen is taking any noticeable time compared to any useful processing
on top... beware of unchecked performance opinion :-)

> Hmm...  What about following idea:
>
> You may try to cache length of strings.
> Const family of functions returns pointer to the "interned" string
> from the internal Reader dictionary.  It relates to node and attribute
> names.
>
> You may prefill it with strings need for- or expected by you using
> xmlTextReaderConstString().  In the same time you can calculate
> strlen() and fill both (pointer to the interned string and its length)
> into e.g. array.
>
> After that you can both save time by eliminating strcmp() and using
> direct pointer comparison, and avoid strlen() calls using lookup
> inside this prefilled array.
>
> If lookup fails (unknown node or attribute), then you may fallback to
> the "usual" strlen() or just ignore unknown element depending of logic
> of your application.

  Hum, most compilers optimize strlen() very well, your solution may actually
be more expensive than the speudo call as soon as your array includes more
than a dozen entry which sounds like a very short vocabulary.
  But yes this should return the interned strings,

Daniel

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