UDA + Pegged AST Hack

[Robik]

On Wednesday, 28 November 2012 at 21:40:35 UTC, Daniel N wrote:
> Thanks to the wonderful UDA implementation in 2.061, I thought 
> of a little hack, which may interest at least someone.
>
> I'm using it for prototyping ctfe ast transformations together 
> with: https://github.com/PhilippeSigaud/Pegged
>
> Yes, it was possible to do similar stuff before and 
> "examples/dgrammar.d" from Pegged is quite impressive, but not 
> bug free.
>
> This UDA-line-hack-way is actually significantly cleaner, 
> because when using __LINE__ you are certain that there will be 
> at least one [__LINE__] which is not inside a string or comment 
> on the attributed line... this allows one to make a very 
> limited grammar/parser which doesn't have to 
> know/parse/understand the entire file.
>
> I know my proof-of-concept doesn't handle multi-line, but it 
> can be added, and doesn't matter for the sake of prototyping 
> AST manipulations.
>
> If anyone else have fun UDA hacks, considering that it's a new 
> feature, please share.
>
> import std.string;
> import std.range;
>
> struct magic
> {
>   [__LINE__] int var1;
>   [__LINE__] int var2;
>   [__LINE__] int var3;
> }
>
> enum dsrc = import(__FILE__).splitLines(KeepTerminator.yes);
>
> string parse()
> {
>   string result = "";
>
>   foreach(m; __traits(allMembers, magic))
>     result ~= dsrc.drop(__traits(getAttributes, mixin("magic." 
> ~ m))[0]-1).takeOne().front;
>
>   // insert pegged parsing / transformations here.
>
>   return result;
> }
>
> mixin("struct magic2\n{\n" ~ parse() ~"}");

I made two, but not as cool as yours: 
http://dpaste.dzfl.pl/32536704 http://dpaste.dzfl.pl/15e4591b