Mastering Regular Expression 代码介绍 1 - HTML 格式转换

#! /usr/bin/perl

undef $/; # Enter "file-slurp" mode.
$text = <>; # Slurp up the first file given on the command line.

$text =~ s/&/&amp;/g; # Make the basic HTML . . .
$text =~ s/</&lt;/g; # . . . characters &, <, and > . . .
$text =~ s/>/&gt;/g; # . . . HTML safe.

$text =~ s/^\s*$/<p>/mg; # Separate paragraphs.

# Turn email addresses into links . . .
$text =~ s{
\b
# Capture the address to $1 . . .
(
\w[-.\w]* # username
\@
[-a-z0-9]+(\.[-a-z0-9]+)*\.(com|edu|info) # hostname
)
\b
}{<a href="mailto:$1">$1</a>}gix;

print $text; # Finally, display the HTML-ized text.