Quick text manipulation with Ruby

Here’s a nice trick I like to use to quickly transform some random piece of text using Ruby and Textmate:

string = DATA.read
# do stuff here...
__END__
Text to transform goes here

By using the __END__ line you tell Ruby to not executre all that follows, but capture it in an IO which you can read. You can then quickly whip up a script and have Textmate run it using ⌘R. The script’s output can then be copied and pasted.

I use this all the time to transform plain text into HTML, crunch some numbers or filter some text. Think of it as a ‘filter through command’ (⌥⌘R) on steroids.

Here’s a quick example to convert ugly plain-text fractions in an HTML page to pretty entities:

input = DATA.read
{
  '1/2' => '&frac12;',
  '1/4' => '&frac14;',
  '3/4' => '&frac34;'
}.each_pair do |plain_text, html_entity|
  input.gsub!(/\b#{plain_text}\b/, html_entity)
end
puts input
__END__
1/2 an egg and 1/4 pint of milk