I have a string that looks like key: value pairs. A couple of the keys are "headings". I want to:
- Add a space above the first heading
- Indent everything from the 1st heading to the 2nd heading by 2 spaces
- Indent everything from the 2nd heading to the end of the section by 2 spaces
The heading names and end-of-section keys are known.

Here is what I came up with. It works as desired, but seems to me mighty inefficient as it traverses the string #-of-headings * #-of-items-to-indent times. I wonder if it can be done in fewer iterations...

#!/usr/bin/perl

local $/ = undef;
my $string = <DATA>;

$string =~ s/^(Heading Here:)$/\n$1/m;
while ( $string =~ s/^(Heading Here:.*\n)(\S.+)(\nAnother Heading:)$/$
+1  $2$3/gsm ) {}
while ( $string =~ s/^(Another Heading:.*\n)(\S.+)(\nEnd of section:)/
+$1  $2$3/gsm ) {}

print $string;

__DATA__
Key: Value
Item:
Another Item: Text
Etc Etc: Whatever
Heading Here:
Indent This: Stuff
By 2 spaces:
Every line: Until
The Next: Heading
Efficiently: If possible
Another Heading:
More:
Stuff:
To: Indent
End of section: Stop indenting
Random: Test
There: Is more stuff
Further down: The string
[download]

Output:

Key: Value
Item:
Another Item: Text
Etc Etc: Whatever

Heading Here:
  Indent This: Stuff
  By 2 spaces:
  Every line: Until
  The Next: Heading
  Efficiently: If possible
Another Heading:
  More:
  Stuff:
  To: Indent
End of section: Stop indenting
Random: Test
There: Is more stuff
Further down: The string
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.