Compile-time sets and hash tables

[Philippe Sigaud]

On Thu, Nov 14, 2013 at 9:31 PM, Andrej Mitrovic
<andrej.mitrovich at gmail.com> wrote:
> On 11/14/13, Philippe Sigaud <philippe.sigaud at gmail.com> wrote:
>  - I'd greatly like for those sets or hash tables to be
>> CTFE-compatible.
>
> Well if it's only used in CTFE, I'd imagine a simple struct wrapping
> an array and doing "!canFind" when adding elements would do the job,
> no?

The trick is, I don't use them only during CT evaluation. In that
case, yes, linear search would do the trick.
But my code is used at runtime and also, from time to time, during
compilation (a new Pegged parser engine).
Hence my need.

But no worries, I spent the day writing and testing code for a small
set/hash implementation. It supports user-defined types (it
automatically creates a reasonable hashing function), support sets of
sets (unlike AA which do not accept other AA as keys) and is both
runtime and compile-time compatible. It's a bit slower than the
builtin, but I'm using the code only to generate other code, not in
performance-critical code.

I also wrote a small string mixin that generates a big switch
statement and it's 40% faster than a standard AA. That's fun. Not
useful, mind, but fun.