On Sunday, 9 October 2016 at 05:21:32 UTC, Manu wrote:
On 9 October 2016 at 14:03, Nicholas Wilson via Digitalmars-d
<digitalmars-d@puremagic.com> wrote:
How far would `r.inBatchesOf!(N)` go in terms of compiler
optimisations
(e.g. vectorisation) if N is a power of 2?
auto inBatchesOf(size_t N,R)(R r) if(N!=0 &&isInputRange!R &&
hasLength!R)
{
struct InBatchesOfN
{
R r;
ElementType!(R)[N] batch;
this(R _r)
{
assert(_r.length % N ==0);// could have overloads
where
undefined elements == ElementType!(R).init
r = _r;
foreach( i; 0..N)
{
batch[i] = r.front;
r.popFront;
}
}
bool empty() { return r.empty; }
auto front { return batch; }
void popFront()
{
foreach( i; 0..N)
{
batch[i] = r.front;
r.popFront;
}
}
}
return InBatchesOfN(r);
}
Well the trouble is the lambda that you might give to 'map'
won't work anymore. Operators don't work on batches, you need
to use a completely different API, and I think that's
unfortunate.
How? All you need is an extra `each` e.g.
r.inBatchesOf!(8).each!(a =>a[].map!(convertColor!RGBA8))
perhaps define a helper function for it that does each + the
explicit slice + map, but it certainly doesn't scream completely
different API to me.
