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digitalmars.D.learn - Vector Swizzling in D

reply "Boscop" <nospam example.com> writes:
Hi everyone,

I wrote a blog post for people who know a bit of D and want to 
dig deeper, it shows different approaches to get vector swizzling 
syntax in D:

http://boscop.tk/blog/?p=1

There is nothing revolutionary involved but it might still be 
useful to someone.
Comments and criticism are welcome.
Mar 14 2012
next sibling parent reply Dmitry Olshansky <dmitry.olsh gmail.com> writes:
On 14.03.2012 18:57, Boscop wrote:

 Hi everyone,

 I wrote a blog post for people who know a bit of D and want to dig
 deeper, it shows different approaches to get vector swizzling syntax in D:

 http://boscop.tk/blog/?p=1

 There is nothing revolutionary involved but it might still be useful to
 someone.
 Comments and criticism are welcome.



Why I'm not seeing opDispatch anywhere ?
Take it as criticism :)

-- 
Dmitry Olshansky
Mar 14 2012
parent Dmitry Olshansky <dmitry.olsh gmail.com> writes:
On 14.03.2012 19:03, Dmitry Olshansky wrote:

 On 14.03.2012 18:57, Boscop wrote:

 Hi everyone,

 I wrote a blog post for people who know a bit of D and want to dig
 deeper, it shows different approaches to get vector swizzling syntax
 in D:

 http://boscop.tk/blog/?p=1

 There is nothing revolutionary involved but it might still be useful to
 someone.
 Comments and criticism are welcome.



 Why I'm not seeing opDispatch anywhere ?
 Take it as criticism :)




-- 
Dmitry Olshansky
Mar 14 2012
prev sibling next sibling parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Wed, Mar 14, 2012 at 03:57:02PM +0100, Boscop wrote:

 Hi everyone,
 
 I wrote a blog post for people who know a bit of D and want to dig
 deeper, it shows different approaches to get vector swizzling syntax
 in D:
 
 http://boscop.tk/blog/?p=1
 
 There is nothing revolutionary involved but it might still be useful
 to someone.
 Comments and criticism are welcome.



I like it. It's a good way to show off what's possible with opDispatch.
:-) Reminds me of implementing Roman numerals with opDispatch, that was
discussed recently.


T

-- 
Prosperity breeds contempt, and poverty breeds consent. -- Suck.com
Mar 14 2012
prev sibling next sibling parent reply Don Clugston <dac nospam.com> writes:
On 14/03/12 15:57, Boscop wrote:

 Hi everyone,

 I wrote a blog post for people who know a bit of D and want to dig
 deeper, it shows different approaches to get vector swizzling syntax in D:

 http://boscop.tk/blog/?p=1

 There is nothing revolutionary involved but it might still be useful to
 someone.
 Comments and criticism are welcome.



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.
Mar 14 2012
parent Don Clugston <dac nospam.com> writes:
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];




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'];}





 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?)
Mar 15 2012
prev sibling next sibling parent "Boscop" <nospam example.com> writes:
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;
		foreach(i; s.length .. 4) p ~= p[$-1];
		int i(char c) {return [3,0,1,2][c-'w'];}
		return Vec(v[i(p[0])], v[i(p[1])], v[i(p[2])], v[i(p[3])]);
	}
}
unittest {
	assert(Vec(5,6,7,8).zyzx == Vec(7, 6, 7, 5));
	assert(Vec(5,6,7,8).zyx  == Vec(7, 6, 5, 5));
	assert(Vec(5,6,7,8).wy   == Vec(8, 6, 6, 6));
	assert(Vec(5,6,7,8).z    == Vec(7, 7, 7, 7));
}
---
(I was using reduce here only to demonstrate D's functional 
features and nice lambda syntax. Maybe that's what prevented 
inlining?)
Mar 14 2012
prev sibling parent "Boscop" <nospam example.com> writes:
Thanks for the suggestions, I updated the article with an 
improved CTFE version at the end.
Mar 15 2012