PHP uses one-pass compiler + additional pass for bytecode fixup. Usage of AST will require at least two passes and as result more time and memory. One-pass compiler is always faster, but not any language can be compiled in one pass (PHP can).
I think AST is not a good representation for type inference and optimization. Various kind of graphs, webs and "static assignment" forms are used for code optimization in modern compilers. I knew only one old Modula-2 compiler from DEC those did optimization on AST level. So some optimizations may be done fine on AST level too. Thanks. Dmitry. > -----Original Message----- > From: William Candillon [mailto:[EMAIL PROTECTED] > Sent: Friday, April 14, 2006 12:07 PM > To: internals@lists.php.net > Subject: Re: [PHP-DEV] PHP Abstract Syntax Tree > > > I already wrote an program which converts PHP source code to > AST but I don't understand why the native PHP compiler > doesn't use this approach. > > On 4/14/06, Tomas Matousek <[EMAIL PROTECTED]> wrote: > > > > Hi William, > > if you are interested in converting PHP source code to AST, you may > > find the Phalanger system useful. > > See http://php-compiler.net. > > > > Tomas > > > > ----- Original Message ----- > > Hi, > > > > Is it planned to modify the PHP compiler in order to create an > > abstract syntax tree rather than generating directly the > opcode ? It > > will allow to perform tasks like Type inference, optimization etc... > > > > Best regards, > > > > William > > > > -- > > William Candillon > > Telecom Lille Student > > E-mail: [EMAIL PROTECTED] > > Tel: +33(0) 6 67 99 13 16 > > Resume: http://wcandillon.netcv.org > > > > > > -- > William Candillon > Telecom Lille Student > E-mail: [EMAIL PROTECTED] > Tel: +33(0) 6 67 99 13 16 > Resume: http://wcandillon.netcv.org > -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
