On Saturday, 2 September 2017 at 01:41:14 UTC, Nicholas Wilson
wrote:
On Friday, 1 September 2017 at 11:33:15 UTC, Biotronic wrote:
On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson
wrote:
So I have the following types
struct DevicePointer(T) { T* ptr; }
struct Buffer(T)
{
void* driverObject;
T[] hostMemory;
}
and a function
auto enqueue(alias k)(HostArgsOf!k) { ... }
where k would be a function like
void foo( DevicePointer!float a, float b , int c) { ... }
How can I write HostArgsOf such that HostArgsOf!foo yields:
AliasSeq!(Buffer!float, float, int)
preferably in such a way that I can add additional
transformations to it later on?
i.e. it substitutes the template DevicePointer for the
template Buffer in Parameters!foo,
The templates can be assumed to not be nested templates, i.e.
DevicePointer!(DevicePointer!(float)) will never occur
neither will Buffer!(Buffer!(float) or any cross templates)
template k(alias fn) {
import std.meta, std.traits;
alias k = staticMap!(ReplaceTemplate!(DevicePointer,
Buffer), Parameters!fn);
}
template ReplaceTemplate(alias needle, alias replacement) {
template ReplaceTemplate(alias T) {
static if (is(T : needle!Args, Args...)) {
alias ReplaceTemplate = replacement!Args;
} else {
alias ReplaceTemplate = T;
}
}
}
Hmm, it seems I oversimplified the example a bit and this
doesn't quite work for my actual usecase.
struct DevicePointer(int n,T) { T* ptr; }
alias GlobalPointer(T) = DevicePointer!(1,T);
k!foo yields
DevicePointer!(cast(AddrSpace)1u, float), float, int
instead of
Buffer!float, float, int
I think because the is(T : needle!Args, Args...) fails.
It really shouldn't work at all - the is(T : ...) works great,
but gives Args as (1, float), and fails to instantiate Buffer
with those arguments. This should give a compilation error.
Anyways, updated code that should work:
template ReplaceTemplate(alias needle, alias replacement) {
template ReplaceTemplate(alias T) {
static if (is(T : needle!Args, Args...)) {
alias ReplaceTemplate = replacement!(Args[1]);
} else {
alias ReplaceTemplate = T;
}
}
}
If you only ever use this for DevicePointer and Buffer, a less
generic solution might be more understandable for maintainers:
template ReplaceDevicePointer(alias T) {
static if (is(T : DevicePointer!(n, T), int n, T)) {
alias ReplaceDevicePointer = Buffer!T;
} else {
alias ReplaceDevicePointer = T;
}
}
--
Biotronic
