Feature discussion: __traits(getSource, function)

[Nick Sabalausky]

"Adam D. Ruppe" <destructionator at gmail.com> wrote in message 
news:i9cud5$1um2$1 at digitalmars.com...
> Well, it sounds like I'm not the only one who'd find this useful, so I 
> took a look
> at the compiler.
>
> It seems to only store file and line internally (I might have missed 
> something
> though) so the path of least resistance seems to be exposing that, and 
> then
> pulling the source with a library function.
>
> But I'll keep looking, since avoiding the library function would be nice 
> (no -J
> and no bugs!).

I've been dealing with ddmd's source a bit lately. Unless it's different in 
dmd, the entirety of the source file should be available here:

// Relevent snippets from ddmd, probably similar in dmd:
class Module // in Module.d
{
    File srcfile;
}

class File // in File.d
{
    ubyte* buffer;    // data for our file
    uint len;     // amount of data in buffer[]
}

So if you have a "Module myModule", then you can get the full original 
source code of the module with (D-ified):

myModule.srcfile.buffer[0..myModule.srcfile.len];

You're right that aside from the Module, dmd only keeps track of filename 
and line number (via the "Loc" struct, which is a member of most classes in 
the AST). You should be able to add members to Loc for "starting index in 
source file" and "ending index", and then just use those to index into 
Module.srcfile.buffer. (Although at that point, it's not really a "Line Of 
Code", more like "Location Of Code"...and for all I know there might be 
places that are reliant on it actually having the semantic meaning of "line 
of code", expecialy since Loc appears to have an "equals(Loc)" member).

I'd probably start by adding those members to Loc's ctors, searching all the 
files for all Loc instantiations, and updating them as relevent. You'll 
probably also have to find wherever dmd keeps track of the current line 
number (probably in the lexer or parser somewere, but I've never looked into 
those, so I don't even know where they are), and keep track of the current 
srcIndex, etc. along with it.