Re: Making recursively-defined traits iterative using `static foreach`
On Saturday, 10 March 2018 at 18:26:48 UTC, Simen Kjærås wrote:
Is there a way to break the `static foreach` loop prematurely
as quickly as `allSameTypeIterative` becomes false?
Sure:
@property
bool allSameTypeIterative(V...)()
//if (allSatisfy!(isType, V))
{
foreach (Vi; V)
if (Vi != V[0]) return false;
return true;
}
No, it's not quite the same, but it's easier to read and gives
the same result.
--
Simen
That will trigger CTFE, but I'm trying to avoid that.
Re: Making recursively-defined traits iterative using `static foreach`
On Saturday, 10 March 2018 at 13:30:18 UTC, Nordlöw wrote:
On Saturday, 10 March 2018 at 09:47:55 UTC, Nordlöw wrote:
Now that we have `static foreach` I just realized we can
start...
My recent definition now looks like
template allSameTypeIterative(V...)
// TODO restrict `V` to types only
{
static if (V.length <= 1)
{
enum allSameTypeIterative = true;
}
else
{
static foreach (Vi; V[1 .. $])
{
static if (!is(typeof(allSameTypeIterative) ==
bool) && // not yet defined
!is(V[0] == Vi)) // 10% faster than
`!isSame(V[0], Vi)`
{
enum allSameTypeIterative = false;
}
}
static if (!is(typeof(allSameTypeIterative) == bool))
// if not yet defined
{
enum allSameTypeIterative = true;
}
}
}
Is there a way to break the `static foreach` loop prematurely
as quickly as `allSameTypeIterative` becomes false?
Sure:
@property
bool allSameTypeIterative(V...)()
//if (allSatisfy!(isType, V))
{
foreach (Vi; V)
if (Vi != V[0]) return false;
return true;
}
No, it's not quite the same, but it's easier to read and gives
the same result.
--
Simen
Re: Making recursively-defined traits iterative using `static foreach`
On Saturday, 10 March 2018 at 13:30:18 UTC, Nordlöw wrote:
On Saturday, 10 March 2018 at 09:47:55 UTC, Nordlöw wrote:
Now that we have `static foreach` I just realized we can
start...
My recent definition now looks like
template allSameTypeIterative(V...)
// TODO restrict `V` to types only
{
static if (V.length <= 1)
{
enum allSameTypeIterative = true;
}
else
{
static foreach (Vi; V[1 .. $])
{
static if (!is(typeof(allSameTypeIterative) ==
bool) && // not yet defined
!is(V[0] == Vi)) // 10% faster than
`!isSame(V[0], Vi)`
{
enum allSameTypeIterative = false;
}
}
static if (!is(typeof(allSameTypeIterative) == bool))
// if not yet defined
{
enum allSameTypeIterative = true;
}
}
}
Is there a way to break the `static foreach` loop prematurely
as quickly as `allSameTypeIterative` becomes false?
After benchmarking using
https://github.com/nordlow/phobos-next/blob/master/benchmarks/iterative-traits/source/app.d
the iterative-version speed-up ranges from 1.1 to 10x for my
specific sets of input. The higher speed-up is thanks to
- reducing the template instantiation count from log(n), in the
recursive case, to 1 in iterative case and
- a static if loop that prevents successive calls when, for
instance,
- predicate is true in `anySatisfyIterative and
- predicate is false in `allSatisfyIterative and
At
https://github.com/nordlow/phobos-next/blob/master/benchmarks/iterative-traits/source/app.d
the compilation-times are written in the comments for each kind
of benchmark.
Re: Making recursively-defined traits iterative using `static foreach`
On Saturday, 10 March 2018 at 09:47:55 UTC, Nordlöw wrote:
Now that we have `static foreach` I just realized we can
start...
My recent definition now looks like
template allSameTypeIterative(V...)
// TODO restrict `V` to types only
{
static if (V.length <= 1)
{
enum allSameTypeIterative = true;
}
else
{
static foreach (Vi; V[1 .. $])
{
static if (!is(typeof(allSameTypeIterative) == bool)
&& // not yet defined
!is(V[0] == Vi)) // 10% faster than
`!isSame(V[0], Vi)`
{
enum allSameTypeIterative = false;
}
}
static if (!is(typeof(allSameTypeIterative) == bool)) //
if not yet defined
{
enum allSameTypeIterative = true;
}
}
}
Is there a way to break the `static foreach` loop prematurely as
quickly as `allSameTypeIterative` becomes false?
Re: Making recursively-defined traits iterative using `static foreach`
On Saturday, 10 March 2018 at 09:47:55 UTC, Nordlöw wrote:
static if (V[0] != Vi)
{
enum allSameIterative = false;
}
Perhaps even better to do
static if (!is(typeof(allSameIterative) == bool) &&
// not yet defined
V[0] != Vi)
{
enum allSameIterative = false;
}
Making recursively-defined traits iterative using `static foreach`
Now that we have `static foreach` I just realized we can start
making recursive implementations of traits such as
template allSame(V...)
if (isExpressions!V)
{
static if (V.length <= 1)
{
enum allSame = true;
}
else static if (V.length & 1) // odd count
{
enum allSame = (V[0] == V[$ - 1] &&
V[0 .. $/2] == V[$/2 .. $-1]
allSame!(V[0 .. $/2]));
}
else// event count
{
enum allSame = (V[0 .. $/2] == V[$/2 .. $]
allSame!(V[0 .. $/2]));
}
}
iterative as
template allSameIterative(V...)
{
static if (V.length <= 1)
{
enum allSameIterative = true;
}
else
{
static foreach (Vi; V[1 .. $])
{
static if (V[0] != Vi)
{
enum allSameIterative = false;
}
}
static if (!is(typeof(allSameIterative) == bool)) // if
not yet defined
{
enum allSameIterative = true;
}
}
}
Is this preferred, typically in terms of compile-time memory
usage and speed?
