RE: [SMARTY-DEV] Smarty compiler

> Since the grammar in smarty is very simple, you can write a basic > token-based parser in PHP that does what we want, and doesn't _limit_ us > with what regexps can do. I don't care about the speed at all when > compiling, but I think we are limited by the way Smarty works now. +1 for this concept, if we're going with a "real" compiler, let's go this route... It accomplishes the stated goals, without introducing the unneeded complexity of a context-free grammar, a lexical analyzer, and parser generator. It also discourages making the smarty grammar (and thus the feature set) too complex in the future - which, again, I also discourage. I dare say, something like this would significantly clean up the smarty compiler code, and allow for much more full-featured compiler plugins. In addition to setting the stage for introducing simple mathematical operations into smarty - which I'm also in favor of. One more thing that pops to mind...if we used this approach, and separated the tokenizer/parser from the compiler[/optimizer] then we could, effectively make the entire grammar and syntax of smarty "pluggable". For example: ------------ Smarty->display('my.tpl'); 1) Smarty determines that a compile is needed, so it loads my.tpl, 2) and passes it to SmartyParser, which tokenizes it, and returns the token tree. 3) Now Smarty dispatches the tree to SmartyCompiler, which returns php code. 4) Now smarty can write that code out to the compile directory, and call it. ...If we made it possible to swap out the implementation of SmartyParser...then imagine the possibilities... If designed correctly, this would provide a TON of flexibility for people with existing templates in some other format, and for people who need to seriously enhance the grammar for some reason... -Lee -----Original Message----- From: Victor [mailto:vboivie@home.se] Sent: Wednesday, November 06, 2002 3:52 PM To: smarty-dev@lists.php.net Subject: Re: [SMARTY-DEV] Smarty compiler > The overhead of regular expressions isn't such a big issue, it only does > this at compile time. I see many drawbacks with a compiled solution, > some already mentioned. Maybe I've misunderstood it all, but who says you have to write a C-version of smarty to do this? Since the grammar in smarty is very simple, you can write a basic token-based parser in PHP that does what we want, and doesn't _limit_ us with what regexps can do. I don't care about the speed at all when compiling, but I think we are limited by the way Smarty works now. Let's say that you want to add the ability to use: {$myvar + 5} in a template. Right now you have to rewrite 5 complex regular expressions to even allow simple math to not be completely cut off in this expression. With a real compiler it wouldn't be that difficult at all to add this feature (theoretically). > One other would be the ability for everyone to > contribute plugins/patches, etc. I'm sure there are a lot more php-savvy > users than there are C-savvy, and we'd be cutting our own throats by > limiting who can contribute. Plugins would still be allowed in my way. I have swept together a smarty-compatible (no, not at all ;) parser written in PHP that generates a tree from a given source file. I guess I don't have to tell you that it's far easier to use the tree to generate good PHP-code compared to now. Look at http://p22.ryd.student.liu.se/~yweb/pc/ I didn't write it, but one of my codevelopers. // Victor (PS, this is somewhat what the code looks like $components["text"]["container"] = false; $components["b"]["container"] = true; $components["link"]["container"] = false; $components["counter"]["container"] = false; $data = "{{ Hi, this is \"a string\" and this is {b}something in bold. Not that {this tag} doesn't get parsed.{/b}. This is a {link url=\"http://www.google.com\" title=\"link\"/} escaped in XML syntax (do we want that? - it's possible anyway!) and this is a {counter cheat=100} counter"; $parser = new Parser($components); $tree = $parser->parse($data); print_r($tree); ) -- Smarty Development Mailing List (http://smarty.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php