title: Context-free grammar describing regular expressions?
body: <p>I'm trying to write a regular expression engine. I'd like to write a recursive descent parser by hand. What would a context-free grammar without left recursion for the language of regular expressions (not the languages that can be described by regular expressions) look like? Would it be easiest to re-factor out the syntactic sugar, i.e. change <code>a+</code> to <code>aa*</code> ? Thanks in advance!</p>