Re^2: 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
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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 (Patriarch) 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` [download]	[reply] [d/l] [select]

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Re^3: How to split into paragraphs?
by ikegami (Patriarch) 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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