Re: findvalue is very slow

On pá 23. května 2008, Vincent Lefevre wrote:
> Hi,
>
> Is there any reason why findvalue is very slow?

(In XML::LibXML, that is)

At least two factors make your findvalue test much slower than the 
others: 1st it employs the whole XPath machinery (creating context, 
parsing the XPath expression, evaulating the XPath expression) 
rather than simply askin for a struct value like the others, 2nd 
looking at the implementation one discoveres that findvalue 
involves several Perl subroutine calls, including creating an 
object and then serializing it back. Surely, there is quite some 
space for optimizing it ( patches that optimize but do not alter 
the behavior are welcome).

sub findvalue {
   my ($node, $xpath) = @_;
    my $res;
    eval {
        $res = $node->find($xpath);
    };
    if  ( $@ ) {
        die $@;
    }
    return $res->to_literal->value;
}

sub find {
    my ($node, $xpath) = @_;
    my ($type, @params) = $node->_find($xpath);
    if ($type) {
        return $type->new(@params);
    }
    return undef;
}

-- Petr
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