Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:62831
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain hoa-project.net from 95.130.12.24 cause and error)
Message-ID: <504707D9.2010303@hoa-project.net>
Date: Wed, 05 Sep 2012 10:05:45 +0200
Reply-To: ivan.enderlin@hoa-project.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/17.0 Thunderbird/17.0a2
MIME-Version: 1.0
To: internals@lists.php.net
References: <CAF+90c-+Hgcv5B4+eGDS+jEj6oNoyefBWO-M=kvThaVdckz62g@mail.gmail.com>
In-Reply-To: <CAF+90c-+Hgcv5B4+eGDS+jEj6oNoyefBWO-M=kvThaVdckz62g@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] Moving to an AST-based parsing/compilation process
From: ivan.enderlin@hoa-project.net ("Ivan Enderlin @ Hoa")

Hi,

On 04/09/12 21:57, Nikita Popov wrote:
> Hey folks!
>
> Some people asked me what the advantages of using an AST-based
> parsing/compilation process are, so I put together a few quick notes
> in an RFC:
>
> https://wiki.php.net/rfc/ast_based_parsing_compilation_process
>
> It would be nice to get a few comments from other core devs on this.
 From my personal point of view, I see more advantages than 
inconvenients of using an AST.

It is a more consistent and clever way to manipulate a language. We can 
have more optimizations processes, algorithms and heuristics. We have 
already spoken about consistency in the PHP syntax, but it will also be 
easier for contributors to suggest new patches in regards to the syntax 
and syntactic-sugar. An AST will also facilitate opcode caching (even a 
trivial approach at first would be promising I think), and again, it 
will egg on contributors to propose new patches for that. Moreover, 
there are a lot of well-known algorithms and heuristics in the 
literature to compensate for memory overhead. I think about 
lazy-compilation to avoid the build of the whole AST.
Even if the first feeling is that AST appears to bring some issues at 
first, it could be very quickly a benefit for PHP, in terms of 
consistency in the code, performance and memory usage.

Conversely, it requires a lot of work. I can help if needed.

Cheers.

-- 
Ivan Enderlin
Developer of Hoa
http://hoa.42/ or http://hoa-project.net/

PhD. student at DISC/Femto-ST (Vesontio) and INRIA (Cassis)
http://disc.univ-fcomte.fr/ and http://www.inria.fr/

Member of HTML and WebApps Working Group of W3C
http://w3.org/