Indented or Markdown list to HTML Unordered List

indent-to-ul.rb

#!/usr/bin/ruby

# ruby script to make an unordered list from indented data. 

data = %x{__CF_USER_TEXT_ENCODING=$UID:0x8000100:0x8000100 pbpaste}.strip

result = "<ul>\n"

last_leading_space = ""
g_tab_width = 4
g_list_level = 0
last_list_level = 0

item = leading_space = ''

data.split("\n").each {|line|
  next if line =~ /^[\s\t]*$/
  parts = line.match(/^([\t ]*)(\d+\. |[\*\+\-] )?\s*(.*)/)
  leading_space = parts[1]
  item = parts[3]
  leading_space.gsub!(/\t/,'    ')
  
  if leading_space.length > last_leading_space.length + 3
    last_list_level = g_list_level
    g_list_level += 1
    last_leading_space = leading_space
    last_list_level = g_list_level
    result += "<ul>\n"
  elsif leading_space.length + 3 < last_leading_space.length
    g_list_level = leading_space.length / 4
    last_leading_space = leading_space
    g_list_level-last_list_level.times do
      result += "</ul>\n"
    end
    last_list_level = g_list_level
  end
  indent = ""

  result += "<li>#{item}</li>\n"
} 

puts result + "</ul>"

I didn't mention it in the comments, but this is heavily cribbed from one of Fletcher Penney's TextMate commands. Just for the record.