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Re^2: How to split into paragraphs?

by jrw (Scribe)
on Nov 16, 2006 at 12:36 UTC ( #584446=note: print w/ replies, xml ) Need Help??


in reply to Re: How to split into paragraphs?
in thread How to split into paragraphs?

ikegami: I hadn't thought of using map to generate a list when given only a single input -- that's an interesting idea.

One thing I'm trying to do is avoid repeating the pattern used for detecting the start of each substring. When I try to capture using m//, I end up having to repeat the pattern to stop each match:

/(START_PATTERN.*?)(?!START_PATTERN)/g

split seems to say what I want: "here is the thing that separates the paragraphs from each other". But then I have to piece the parts back together again (see my original post's code) and I'm trying to avoid that.


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Re^3: How to split into paragraphs?
by ikegami (Pope) on Nov 16, 2006 at 14:02 UTC

    Ah, I see. Well, I've already provided the building blocks, but they are well hidden. Let me expose them.

    You need something along the lines of /[^$chars]*/, but instead of negatively matching chars, you want to negatively match a regexp.

    The direct equivalent of
    /[^$chars]*/
    for regexps is
    /(?:(?!$re).)*/

    In context,

    # Input the string. my $in = do { local $/; <DATA> }; # Must move "pos" on a match. # Zero-width match won't work. my $start_pat = qr/^\S+/m; # Break the input into paragraghs. my @paras = $in =~ / \G ( $start_pat (?: (?!$start_pat). )* ) /xgs; # Manipulate the paragraghs. @paras = map { "<$_>" } @paras; # Recombine the paragraphs. my $out = join '', @paras; # Output the string. print($out); __DATA__ abc: asdf1 asdf2 def: asdf3 ghi: asdf4 asdf5

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