[cfe-dev] parsing code snippets

[Olaf Krzikalla]

Hi,

Am 05.05.2011 16:01, schrieb Douglas Gregor:
>
> On May 5, 2011, at 12:43 AM, Olaf Krzikalla wrote:
> Why not turn the "#pragma scout vectorize" token sequence into a special token (tok::pragma_scout_vectorize), then have the parser recognize that token (in whatever contexts is makes sense, e.g., a statement context for this case) and handle the actual #pragma parsing?

Hmm, that still means heavy changes in the parser itself, doesn't it? At 
least I haven't found any callback or customization machinery there.
Another thing I have to consider is that I want to switch to C0xx 
attributes as fast as possible. That is, in the future the code shall 
look like this:

    [[scout::vectorize, scout::aligned(a)]]
    for (int i = 0; i < 100; ++i)
      a[i] = 0.0;

My current approach is a dirty hack, which however worked out so far:
I published Parser::ParseExpression and Parser::ConsumeAnyToken (the 
latter is necessary in order to move Parser::Tok away from the "pragma")
and store a global pointer to the parser in clang::ParseAST, which I 
later retrieve from my pragma handler. Of course this is 
proof-of-concept only. However, judging from N2418, sec.10:

attribute-argument: assignment-expression | type-id

clang will need such a feature in the future anyway in order to support 
custom attributes (I hope that such a feature is planned).
My questions are:
1. Do you have any headaches if the Parser have two public functions 
ParseExpression and ParseTypeName (which internally might do some 
preparation work before calling their private counterparts)?
2. How can we expose the current parser obejct to custom handlers 
(attribute or pragma)?


Best regards
Olaf Krzikalla