Yeah, there's tons of special cases in the parser. I worked on phc (http://phpcompiler.org http://phpcompiler.org), so I've read the PHP parser and helped write

Yeah, there's tons of special cases in the parser. I worked on phc (http://phpcompiler.org http://phpcompiler.org), so I've read the PHP parser and helped write some of our own. We took the AST approach and it worked out pretty well. But PHP was written before its authors knew good interpreter design, and its currently very hard to refactor it out to a better design.