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Re^2: Why XML not well formed?

by nan (Novice)
on Jun 30, 2005 at 15:49 UTC ( #471373=note: print w/replies, xml ) Need Help??


in reply to Re: Why XML not well formed?
in thread Why XML not well formed?

Hi Don,

Yes you are right, but how can I overcome this '&' problem? I've tried to put '\' before '&' but it's doesn't work.

many thanks!

Nan

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Re^3: Why XML not well formed?
by BaldPenguin (Friar) on Jun 30, 2005 at 16:03 UTC
    You could regex the &:
    $line =~ s/(&)/$1amp;/g;

    Don
    WHITEPAGES.COM | INC

    Edit by castaway: Closed small tag in signature

      That would potentially disastrous effects if the XML contained any entities.

      --
      <http://www.dave.org.uk>

      "The first rule of Perl club is you do not talk about Perl club."
      -- Chip Salzenberg

        Yup. better to make it a bit more restrictive.
        s/"(http[^"]+)&(?!amp;)/$1&amp;/g;


        holli, /regexed monk/
      I think the proper way to control this sort of operation -- and keep it from screwing up other entity references (like &egrave; and &lt;, etc) is something like this:
      s/&(?!\w+;)/&amp;/;
      This is just assuming that every valid entity reference that might exist in the original text is limited to alphanumerics and underscores between the initial ampersand and the final semi-colon, which is probably a safe-enough assumption.

      But keep a backup of the original. If the data still causes parse errors after this simple edit, they might be different problems you haven't fixed yet, or they might be problems created by this simple edit. Careful diagnosis would be needed in that case.

      Hi Don,

      Sorry I used $line =~ s/(&)/(& amp;)/g; would it be different with yours?

      Many thanks, Nan

        First, the parens in the pattern part of the regex collect the value we find, then the $1 in the replace puts it back in. In that respect the follwing regex would do nothing but spin cycles;
        $line =~ s/(&)/$1/g;
        So, in your regex the first set of parens save the & for later use. But you don't use it, instead you find all of the &s and replace them literaly with "(&amp;)" including the parens.

        That said, the regex I posted would work only if no other entites existed. Take a look at the other regexs above, they do a better job of 'thinking' ahead, to prevent possible errors in the future.

        Somebody could, and I have seen it done, place other entities in the url, such as:
        http://www.test.me/test.pl?me=1&you=1&string=Montr&eacute;al
        In this case the regex I posted would tranlate to Montr&eacute;al. Not what you want.

        Don
        WHITEPAGES.COM | INC

        Edit by castaway: Closed small tag in signature

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