On 12/16/13 2:55 PM, "Ola Fosheim Grøstad"
<[email protected]>" wrote:
On Monday, 16 December 2013 at 21:45:40 UTC, Walter Bright wrote:
uint among(T, Us...)(T v, Us vals)
{
foreach (i, U; Us)
{
if (v == vals[i]) return i + 1;
}
return 0;
}
This has O(n) behavior, which might be unexpected for the user.
I would expect one table-lookup for this if vals contains strings, not N
ifs. If you look at the example, most of them could be done with perfect
hashing on a single character.
Is it possible for the compiler/template system to turn this into a
switch/dictionary? Or is there something in the language/compiler that
makes that impossible?
It's a good idea, but unfortunately we don't have partial evaluation.
We'd need to move whatever compile-time work is to be done in the
template arguments area, i.e.
value.among!("foo", "bar", "baz")
as opposed to
value.among("foo", "bar", "baz")
Now that I think of it we can easily support both forms.
Andrei
