Re: Checking that a template parameter is an enum

2015-10-02 Thread Per Nordlöw via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 22:37:57 UTC, Ali Çehreli wrote:

template allSame(V...)
if (isExpressions!(V))
{
bool impl_(V...)() {
static if (V.length > 1) {
foreach (i, _; V[0 .. $ - 1]) {
if (V[i] != V[i + 1]) {
return false;
}
}

return true;

} else {
return true;
}
}

enum allSame = impl_!V();
}


Will proposed `static foreach` reduce number of instantiations 
here?

Re: Checking that a template parameter is an enum

2015-10-02 Thread John Colvin via Digitalmars-d-learn 

On Friday, 2 October 2015 at 08:13:00 UTC, John Colvin wrote:

On Thursday, 1 October 2015 at 22:26:39 UTC, Nordlöw wrote:

On Thursday, 1 October 2015 at 02:06:48 UTC, Fusxfaranto wrote:

[...]


Thanks!

BTW: Is there some way to turn the recursive definition of 
`allSame`


template allSame(V...)
if (isExpressions!(V))
{
static if (V.length <= 1)
enum allSame = true;
else
enum allSame = V[0] == V[1] && allSame!(V[1..$]);
}

into an iterative definition?


Why? To avoid slowing down compilation with all those template 
instantiations?


How about a O(log2(N)) depth recursive version, something like 
this:


template allSame(V ...)
if (isExpressions!V)
{
static if (V.length <= 1)
enum allSame = true;
else static if(V.length & 1)
enum allSame = V[$-1] == V[0]
&& V[0 .. $/2] == V[$/2 .. $-1]
&& allSame!(V[0 .. $/2]);
else
enum allSame = V[0..$/2] == V[$/2 .. $]
&& allSame!(V[0 .. $/2]);
}


Although you should consider that isExpressions is instantiating 
V.length templates anyway (it uses a binary split to avoid 
excessive template recursion depth, but it ends up checking them 
all one-per-template in the end anyway.

Re: Checking that a template parameter is an enum

2015-10-02 Thread John Colvin via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 22:26:39 UTC, Nordlöw wrote:

On Thursday, 1 October 2015 at 02:06:48 UTC, Fusxfaranto wrote:

/** Returns: true iff all values $(D V) are the same. */
template allSame(V...)  // TODO restrict to values 
only

{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}


std.traits to the rescue!

http://dlang.org/phobos/std_traits.html#isExpressions

Using isExpressions!V as a template constraint looks like the 
behavior you're looking for.


Thanks!

BTW: Is there some way to turn the recursive definition of 
`allSame`


template allSame(V...)
if (isExpressions!(V))
{
static if (V.length <= 1)
enum allSame = true;
else
enum allSame = V[0] == V[1] && allSame!(V[1..$]);
}

into an iterative definition?


Why? To avoid slowing down compilation with all those template 
instantiations?


How about a O(log2(N)) depth recursive version, something like 
this:


template allSame(V ...)
if (isExpressions!V)
{
static if (V.length <= 1)
enum allSame = true;
else static if(V.length & 1)
enum allSame = V[$-1] == V[0]
&& V[0 .. $/2] == V[$/2 .. $-1]
&& allSame!(V[0 .. $/2]);
else
enum allSame = V[0..$/2] == V[$/2 .. $]
&& allSame!(V[0 .. $/2]);
}

Re: Checking that a template parameter is an enum

2015-10-02 Thread Meta via Digitalmars-d-learn 

On Friday, 2 October 2015 at 07:52:22 UTC, Nordlöw wrote:

On Friday, 2 October 2015 at 02:39:56 UTC, Meta wrote:
Highly doubtful as CTFE already allocates like there's no 
tomorrow.


Could that memory usage be tested somehow?


Your favourite process monitor I guess.

Re: Checking that a template parameter is an enum

2015-10-02 Thread Meta via Digitalmars-d-learn 

On Friday, 2 October 2015 at 18:52:22 UTC, Nordlöw wrote:

On Friday, 2 October 2015 at 16:21:22 UTC, Meta wrote:

Could that memory usage be tested somehow?


Your favourite process monitor I guess.


Any suggestions on an evil D snippet that stress tests 
different implementations of the above mentioned traits?


I don't know off the top of my head, but I remember somebody on 
these forums mentioning a certain CTFE program that caused DMD to 
take up over 100GB in RAM before the process was killed.

Re: Checking that a template parameter is an enum

2015-10-02 Thread Nordlöw via Digitalmars-d-learn 

On Friday, 2 October 2015 at 16:21:22 UTC, Meta wrote:

Could that memory usage be tested somehow?


Your favourite process monitor I guess.


Any suggestions on an evil D snippet that stress tests different 
implementations of the above mentioned traits?

Re: Checking that a template parameter is an enum

2015-10-02 Thread Nordlöw via Digitalmars-d-learn 

On Friday, 2 October 2015 at 02:39:56 UTC, Meta wrote:
Highly doubtful as CTFE already allocates like there's no 
tomorrow.


Could that memory usage be tested somehow?

Re: Checking that a template parameter is an enum

2015-10-01 Thread Nordlöw via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 02:06:48 UTC, Fusxfaranto wrote:

/** Returns: true iff all values $(D V) are the same. */
template allSame(V...)  // TODO restrict to values only
{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}


std.traits to the rescue!

http://dlang.org/phobos/std_traits.html#isExpressions

Using isExpressions!V as a template constraint looks like the 
behavior you're looking for.


Thanks!

BTW: Is there some way to turn the recursive definition of 
`allSame`


template allSame(V...)
if (isExpressions!(V))
{
static if (V.length <= 1)
enum allSame = true;
else
enum allSame = V[0] == V[1] && allSame!(V[1..$]);
}

into an iterative definition?

Re: Checking that a template parameter is an enum

2015-10-01 Thread Nordlöw via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 02:06:48 UTC, Fusxfaranto wrote:

/** Returns: true iff all values $(D V) are the same. */
template allSame(V...)  // TODO restrict to values only
{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}


std.traits to the rescue!

http://dlang.org/phobos/std_traits.html#isExpressions

Using isExpressions!V as a template constraint looks like the 
behavior you're looking for.


Thanks!

BTW: Is there some way to turn the recursive definition of 
`allSame` into an iterative definition?

Re: Checking that a template parameter is an enum

2015-10-01 Thread Ali Çehreli via Digitalmars-d-learn 

On 10/01/2015 03:26 PM, Nordlöw wrote:

On Thursday, 1 October 2015 at 02:06:48 UTC, Fusxfaranto wrote:

/** Returns: true iff all values $(D V) are the same. */
template allSame(V...)  // TODO restrict to values only
{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}


std.traits to the rescue!

http://dlang.org/phobos/std_traits.html#isExpressions

Using isExpressions!V as a template constraint looks like the behavior
you're looking for.


Thanks!

BTW: Is there some way to turn the recursive definition of `allSame`

template allSame(V...)
 if (isExpressions!(V))
{
 static if (V.length <= 1)
 enum allSame = true;
 else
 enum allSame = V[0] == V[1] && allSame!(V[1..$]);
}

into an iterative definition?


Very quickly:

import std.traits;

template allSame(V...)
if (isExpressions!(V))
{
bool impl_(V...)() {
static if (V.length > 1) {
foreach (i, _; V[0 .. $ - 1]) {
if (V[i] != V[i + 1]) {
return false;
}
}

return true;

} else {
return true;
}
}

enum allSame = impl_!V();
}

unittest
{
static assert( allSame!());
static assert( allSame!(42));
static assert( allSame!(42, 42, 42));
static assert(!allSame!(42, 43, 42));
}

Ali

Re: Checking that a template parameter is an enum

2015-10-01 Thread Nordlöw via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 22:37:57 UTC, Ali Çehreli wrote:

Very quickly:

import std.traits;

template allSame(V...)
if (isExpressions!(V))
{
bool impl_(V...)() {
static if (V.length > 1) {
foreach (i, _; V[0 .. $ - 1]) {
if (V[i] != V[i + 1]) {
return false;
}
}

return true;

} else {
return true;
}
}

enum allSame = impl_!V();
}


Will this spare memory in DMD? If so there are a few traits that 
should be update accordingly, for instance `allSatisfy` and 
`anySatisfy`.


Thanks!

Re: Checking that a template parameter is an enum

2015-10-01 Thread Meta via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 22:41:21 UTC, Nordlöw wrote:
Will this spare memory in DMD? If so there are a few traits 
that should be update accordingly, for instance `allSatisfy` 
and `anySatisfy`.


Thanks!


Highly doubtful as CTFE already allocates like there's no 
tomorrow.

Checking that a template parameter is an enum

2015-09-30 Thread Nordlöw via Digitalmars-d-learn 
How do I check that a template parameter is a CT-value or an enum 
symbol?


I want this to restrict the following template:

/** Returns: true iff all values $(D V) are the same. */
template allSame(V...)  // TODO restrict to values only
{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}

unittest
{
static assert(!allSame!(41, 42));
static assert(allSame!(42, 42, 42));
}

Re: Checking that a template parameter is an enum

2015-09-30 Thread Fusxfaranto via Digitalmars-d-learn 

On Thursday, 1 October 2015 at 00:04:18 UTC, Nordlöw wrote:
How do I check that a template parameter is a CT-value or an 
enum symbol?


I want this to restrict the following template:

/** Returns: true iff all values $(D V) are the same. */
template allSame(V...)  // TODO restrict to values only
{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}

unittest
{
static assert(!allSame!(41, 42));
static assert(allSame!(42, 42, 42));
}


std.traits to the rescue!

http://dlang.org/phobos/std_traits.html#isExpressions

Using isExpressions!V as a template constraint looks like the 
behavior you're looking for.