• =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= (21/21) Sep 01 2014 Forgetting to do
• monarch_dodra (7/13) Sep 02 2014 AFAIK, those produce the same results 99% of the time. The only
• =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= (15/20) Sep 02 2014 Yes, I'm writing this wrapper because call to r.front in
• monarch_dodra (5/27) Sep 02 2014 In that case, I'm not sure what you mean by "fastest" in the
• =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= (4/8) Sep 02 2014 No, it's only the R/E that lacks emptyness check.
• monarch_dodra (4/6) Sep 02 2014 Also, this assumes your ranges have front at all. AFAIK, skipOver

=?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:

Forgetting to do


import std.functional: binaryFun;


before trying to compile

bool skipOverSafe(alias pred = "a == b", R1, R2)(ref R1 r1, R2 r2)
      safe pure if (is(typeof(binaryFun!pred(r1.front, r2.front))))
{
     return r1.length >= r2.length && skipOver!pred(r1, r2); // 
TODO: Can we prevent usage of .length?
}

unittest
{
     auto s1 = "Hello world";
     assert(!skipOverSafe(s1, "Ha"));
}


gives no clue about the missing import in the diagnostics.

Is this a other/newer preferred way to describe the template 
restriction, using for example __traits(compiles, ...)? Is

is(typeof(...

the fastest way to do this?

BTW: Is there a way to prevent the calls to r1.length and 
r2.length in this case?

"monarch_dodra" <monarchdodra gmail.com> writes:

On Monday, 1 September 2014 at 22:46:52 UTC, Nordlöw wrote:
 Is this a other/newer preferred way to describe the template 
 restriction, using for example __traits(compiles, ...)? Is

 is(typeof(...

AFAIK, those produce the same results 99% of the time. The only 
cases where they differ are borderline buggy.

 the fastest way to do this?

Are you talking about constraints, or implementation of 
safeSkipOver?

 BTW: Is there a way to prevent the calls to r1.length and 
 r2.length in this case?

Hum... Are you writing this function because skipOver will 
actually fail? AFAIK, it shouldn't. We should fix skipOver...

=?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:

On Tuesday, 2 September 2014 at 10:22:49 UTC, monarch_dodra wrote:
 the fastest way to do this?

 Are you talking about constraints, or implementation of 
 safeSkipOver?

The constraint.

 Hum... Are you writing this function because skipOver will 
 actually fail? AFAIK, it shouldn't. We should fix skipOver...

Yes, I'm writing this wrapper because call to r.front in

bool skipOver(alias pred = "a == b", R, E)(ref R r, E e)
if (is(typeof(binaryFun!pred(r.front, e))))
{
     if (!binaryFun!pred(r.front, e))
         return false;
     r.popFront();
     return true;
}

fails when r is empty.

It believe it should be

     if (r.empty || !binaryFun!pred(r.front, e))

right? Should I do a PR?

"monarch_dodra" <monarchdodra gmail.com> writes:

On Tuesday, 2 September 2014 at 11:41:51 UTC, Nordlöw wrote:
 On Tuesday, 2 September 2014 at 10:22:49 UTC, monarch_dodra 
 wrote:
 the fastest way to do this?

 Are you talking about constraints, or implementation of 
 safeSkipOver?

 The constraint.

In that case, I'm not sure what you mean by "fastest" in the 
context of "constraints", which are compile-time.

 Hum... Are you writing this function because skipOver will 
 actually fail? AFAIK, it shouldn't. We should fix skipOver...

 Yes, I'm writing this wrapper because call to r.front in

 bool skipOver(alias pred = "a == b", R, E)(ref R r, E e)
 if (is(typeof(binaryFun!pred(r.front, e))))
 {
     if (!binaryFun!pred(r.front, e))
         return false;
     r.popFront();
     return true;
 }

 fails when r is empty.

 It believe it should be

     if (r.empty || !binaryFun!pred(r.front, e))

 right? Should I do a PR?

I think so yes. That's the "R/E" version though. Is the "R/R" 
version also subject to this issue?

=?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:

On Tuesday, 2 September 2014 at 12:14:01 UTC, monarch_dodra wrote:
 In that case, I'm not sure what you mean by "fastest" in the 
 context of "constraints", which are compile-time.

With performance I mean compilation speed.

 I think so yes. That's the "R/E" version though. Is the "R/R" 
 version also subject to this issue?

No, it's only the R/E that lacks emptyness check.

PR: https://github.com/D-Programming-Language/phobos/pull/2481

"monarch_dodra" <monarchdodra gmail.com> writes:

On Monday, 1 September 2014 at 22:46:52 UTC, Nordlöw wrote:
 BTW: Is there a way to prevent the calls to r1.length and 
 r2.length in this case?

Also, this assumes your ranges have front at all. AFAIK, skipOver 
operates on forward ranges. Related: Your condition could fail if 
R1/R2 are strings of un-matching widths.