On 14/03/12 18:46, Boscop wrote:
On Wednesday, 14 March 2012 at 17:35:06 UTC, Don Clugston wrote:
In the last bit of code, why not use CTFE for valid(string s) instead
of templates?
bool valid(string s)
{
foreach(c; s)
{
if (c < 'w' || c > 'z') return false;
}
return true;
}
In fact you can use CTFE for the other template functions as well.
In the original version I actually did this, but even with -O -inline
-release the opDispatchs call didn't get inlined. I thought it was
caused by CTFE-code that prevented the inlining.
FWIW, this was the original code using CTFE:
---
import std.algorithm: reduce;
struct Vec {
double[4] v;
@property auto X() {return v[0];}
@property auto Y() {return v[1];}
@property auto Z() {return v[2];}
@property auto W() {return v[3];}
this(double x, double y, double z, double w) {v = [x,y,z,w];}
@property auto opDispatch(string s)() if(s.length <= 4 &&
reduce!((s,c)=>s && 'w' <= c && c <= 'z')(true, s)) {
char[] p = s.dup;
This won't be CTFEd, because it's not forced to be a compile-time constant.
foreach(i; s.length .. 4) p ~= p[$-1];
This too.
But, you can do something like:
enum p = extend(s);
since p is an enum, it must use CTFE.
int i(char c) {return [3,0,1,2][c-'w'];}
this isn't forced to be CTFE either.
return Vec(v[i(p[0])], v[i(p[1])], v[i(p[2])], v[i(p[3])]);
}
---
(I was using reduce here only to demonstrate D's functional features and
nice lambda syntax. Maybe that's what prevented inlining?)
