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Subject: Re: [PHP-DEV] [RFC][Discussion] Parser extension API
From: cesar@rodas.me (Cesar Rodas)

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On 18/02/15 15:59, Nikita Popov wrote:
> On Wed, Feb 18, 2015 at 7:22 AM, Dmitry Stogov <dmitry@zend.com> wrote:=

>
>> Hi,
>>
>> On Tue, Feb 17, 2015 at 2:46 PM, Alexander Lisachenko <
>> lisachenko.it@gmail.com> wrote:
>>
>>> Hello, internals!
>>>
>>> I want to introduce a RFC for providing a userland API for accessing =
an
>>> Abstract Syntax Tree of the source code and to provide userland parse=
r
>>> hooks for source code modification:
>>> https://wiki.php.net/rfc/parser-extension-api
>>>
>>> Thanks!
>>>
>> The first part, describing https://github.com/nikic/php-ast , looks fi=
ne.
>> I see no problems including this extension into PHP-7.0 core distribut=
ion.
>> May be even making it required (like ext/reflection).
>>
>> Nikita, what do you think?
>>
>> The second part looks very interesting, however it has some uncovered
>> questions.
>> - API for AST modification
>> - AST validation (someone may insert "break" node in "parameter-list")=
=2E
>>
>> If you have enough experience, I would suggest you to try writing an
>> external extension that would implement this idea.
>> If you'll need some modification in PHP core (e.g adding callbacks), w=
e
>> may consider including them in PHP-7.0.
>>
>> Thanks. Dmitry.
>>
> I agree with Dmitry.
>
> Exporting the AST to userland in PHP 7.0 would be nice. With Dmitry's w=
ork
> on assertions we even have a pretty printer for it, which allows us to
> convert the AST back to PHP code.

In this matter, how would it be? It'd be awesome if function expects an
AST tree object instead of a value:

    function doQuery($table, *$where) {
       $where =3D convert_ast_toSqlWhere($where);
    }

    doQuery("foobar", $col1 =3D "something" AND $col2 =3D=3D $col3);

Or at least `ast(<expr>)`, although both would be nice to have.
>
> The bits about intercepting compilation, modifying the AST and importin=
g it
> back into the compiler are a LOT more complicated. Apart from many open=

> design questions, this will also require quite a bit of implementation
> effort because we must be very careful with the many assumptions the
> compiler makes about the structure of the AST (otherwise -> segfaults).=
 I'd
> prefer to delay this to a later PHP version (there's no problem to add =
it
> in a minor), preferably with a PoC extension being available beforehand=
=2E
>
> Alexander, I would recommend you to split this into two RFCs, one deali=
ng
> only with AST export (and maybe pretty printing) and the second one wit=
h
> the compilation hooks. There's probably a few questions about the expor=
t
> API that should be discussed that will be forgotten if everyone focuses=
 on
> the more complicated, and probably not yet relevant, question of
> compilation hooks.
>
> Nikita
>

--=20
C=C3=A9sar D. Rodas
Open Source developer
+595-983-161124
PGP: F9ED A265 A3AB C8A1 D145 7368 158A 0336 C707 0AA6



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