Re: Compile-time variadic equality

[Nordlöw via Digitalmars-d-learn]

On Saturday, 10 March 2018 at 08:49:19 UTC, Nordlöw wrote:
How do I most conveniently merge these into one single 
`allSame` that can operate on mixtures of values and types?


I found the privately defined `isSame` in std.meta that does this.

Re: Compile-time variadic equality

[Nordlöw via Digitalmars-d-learn]

On Friday, 9 March 2018 at 22:13:39 UTC, Simen Kjærås wrote:

static if (allEqual!(staticMap!(ElementEncodingType, Rs)))
{
// compare Rs byCodeUnit
}


NoDuplicates!V.length == 1


BTW, `NoDuplicates` can handle both types and values (mixed) 
opposite to my `allSame` and `allSameType` defined as:


template allSame(V...)
if (isExpressions!V)
{
static if (V.length <= 1)
{
enum allSame = true;
}
else static if (V.length & 1) // odd count
{
enum allSame = (V[0] == V[$ - 1] && // first equals last
V[0 .. $/2] == V[$/2 .. $-1] && // (first 
half) equals (second half minus last element)

allSame!(V[0 .. $/2]));
}
else// event count
{
enum allSame = (V[0 .. $/2] == V[$/2 .. $] && // (first 
half) equals (second half)

allSame!(V[0 .. $/2]));
}
}

and

template allSameType(V...)
// TODO should have template restriction on `V`
{
static if (V.length <= 1)
{
enum allSameType = true;
}
else static if (V.length & 1) // odd count
{
enum allSameType = (is(V[0] == V[$ - 1]) && // first 
equals last
is(V[0 .. $/2] == V[$/2 .. $-1]) && 
// (first half) equals (second half minus last element)

allSameType!(V[0 .. $/2]));
}
else// even count
{
enum allSameType = (is(V[0 .. $/2] == V[$/2 .. $]) && // 
(first half) equals (second half)

allSameType!(V[0 .. $/2]));
}
}

How do I most conveniently merge these into one single `allSame` 
that can operate on mixtures of values and types?

Re: Compile-time variadic equality

[Simen Kjærås via Digitalmars-d-learn]

On Friday, 9 March 2018 at 19:24:03 UTC, Nordlöw wrote:
I'm looking for a function (that probably should be placed in 
std.meta) named something like `areEqual` that checks whether 
all it's arguments are equal or not.


Is there such as function already in Phobos?

My usage is

static if (allEqual!(staticMap!(ElementEncodingType, Rs)))
{
// compare Rs byCodeUnit
}


NoDuplicates!V.length == 1

--
  Simen

Re: Compile-time variadic equality

[Nordlöw via Digitalmars-d-learn]

On Friday, 9 March 2018 at 19:24:03 UTC, Nordlöw wrote:
I'm looking for a function (that probably should be placed in 
std.meta) named something like `areEqual` that checks whether 
all it's arguments are equal or not.


Is there such as function already in Phobos?

My usage is

static if (allEqual!(staticMap!(ElementEncodingType, Rs)))
{
// compare Rs byCodeUnit
}


My current own implementation is

/** Returns: true iff all values $(D V) are the same.
See also: 
http://forum.dlang.org/post/iflpslqgrixdjwrlq...@forum.dlang.org
See also: 
http://forum.dlang.org/post/mheumktihihfsxxxa...@forum.dlang.org

*/
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]));
}
}

Should this go into std.meta?

Compile-time variadic equality

[Nordlöw via Digitalmars-d-learn]

I'm looking for a function (that probably should be placed in 
std.meta) named something like `areEqual` that checks whether all 
it's arguments are equal or not.


Is there such as function already in Phobos?

My usage is

static if (allEqual!(staticMap!(ElementEncodingType, Rs)))
{
// compare Rs byCodeUnit
}