Perhaps a better way to implement this would be to use Ruby's string interpolation, which I'm pretty sure allows arbitrary expressions and unlimited levels of n

Perhaps a better way to implement this would be to use Ruby's string interpolation, which I'm pretty sure allows arbitrary expressions and unlimited levels of nesting. For example, this ERB document: <html> <%= form_for @stuff do |f| %> <%= f.text_field :things %> <% end %> </html> would be transformed into this Ruby: _buffer << " <html> #{ form_for @stuff do |f| _buffer << " #{ f.text_field :things } " end } </html> " So, ERB goes back to being a very simple transformation with no special cases and you can use any partial syntax in <%= %> blocks that would make sense. EDIT: Ok, I'm pretty much giving up on this as I can't think of a good enough solution. The two best options I came up with are: 1. Feed the embedded code to Ripper as it comes in and use that to keep track of the lexical context. Ripper is pretty fast so it might not be a significant performance hit, but it only works in Ruby 1.9 and I don't know if a comparable parser for 1.8 exists. 2. Use a setter method like _buf= to append to the output buffer, and don't wrap the embedded expressions in parens. Because the = operator has such low precendence, the generated code will almost always behave as intended, but there are a few lower precendence operators that will break like "and", "or", and postfix "if", "unless", "while" and "until".