gistfile1.rb

def esc(text)
  text.upcase
end

def esc_sub(text, patterns)
  patterns.each do |pattern, replacement|
    if text =~ /^(.*)#{pattern}(.*)$/
      return [esc_sub($1, patterns), replacement, esc_sub($2, patterns)].join
    end
  end  

  esc(text)
end

PATTERNS = [[/TILDE/, "mjau"], [/BORK/, 'xx']]

esc_sub("kattBORKvavuewreruhTILDEuasfasdfa", PATTERNS) # => "KATTxxVAVUEWRERUHmjauUASFASDFA"