Perl使用STDIN死于大型XML文件

Question

I get this error when I run a perl script:

unclosed token at line 1, column 0, byte 0 at /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level/XML/Parser.pm line 187.

at mysscript.pl line 8.

Heres line 8 at mysscript.pl

$twig->parse( \*STDIN);

I tried some other variations like:

$twig->parse(\*STDIN);
$twig->parse(*STDIN);

But they didn't work, I know that it also says that there is something wrong with my perl system files but i doubt that, i found someone that had the same problem and he had to fix his code instead.

Answer 1

That's an XML error, not a Perl error. It does suggest you've got broken XML. You can trap it by eval in the parse.

But actually - thinking about it - the problem is probably that you're only reading the first line of STDIN with your parse . Try adding:

{ 
    local $/;
    $twig -> parse ( <STDIN> );
}

However, for large XML files, I quite like XML::Twig , because it has a purge method, which lets you throw away XML you've already processed. One of the downsides of XML is that it's memory footprint is approx 10x the raw file size. So it's possible you're running out of memory if your file is particularly huge.

Answer 2

$twig->parse( \\*STDIN) is the proper syntax, so that's not what causing the error.

So it looks like either there is a problem with your XML or there is a bug somewhere. Did you try checking your XML (with xmlwf or xmllint or a similar tool)? If it parses, then what is the encoding of the XML? If it's UTF-16 then that might be the problem, libexpat (on which XML::Twig is based) seems to have trouble with this encoding.

Answer 3

The XML::Twig module has only two basic ways of reading the XML to be parsed:

• parse , which expects a string containing the XML data as a parameter

• parsefile , which expects a string that specifies the name (and path) of an XML file to be read

The is no option to pass an open file handle, and if you write $twig->parse(\\*STDIN) or $twig->parse(*STDIN) then you will be passing (something like) the strings GLOB(0x44b574) and *main::STDIN respectively, which is clearly not valid XML.

I presume you can work out from there what your call should look like. If you are passing the file name as a parameter on the command line then the simplest solution is to write

$twig->parsefile(shift)

but without more information I can't help you any further.