Enum member std.range.primitives.isInfinite
Returns true
if R
is an infinite input range. An
infinite input range is an input range that has a statically-defined
enumerated member called empty
that is always false
,
for example:
enum isInfinite(R)
= !R .empty;
struct MyInfiniteRange
{
enum bool empty = false;
...
}
Example
import std .range : Repeat;
static assert(!isInfinite!(int[]));
static assert( isInfinite!(Repeat!(int)));
}
/**
Returns `true` if `R` offers a slicing operator with integral boundaries
that returns a forward range type.
For finite ranges, the result of `opSlice` must be of the same type as the
original range type. If the range defines `opDollar`, then it must support
subtraction.
For infinite ranges, when <i>not</i> using `opDollar`, the result of
`opSlice` must be the result of <code class="lang-d"><span class="pln">take</span></code> or <code class="lang-d"><span class="pln">takeExactly</span></code> on the
original range (they both return the same type for infinite ranges). However,
when using `opDollar`, the result of `opSlice` must be that of the
original range type.
The following expression must be true for `hasSlicing` to be `true`:
isForwardRange!R && !isNarrowString!R && is(ReturnType!((R r) => r[1 .. 1].length) == size_t) && (is(typeof(lvalueOf!R[1 .. 1]) == R) || isInfinite!R) && (!is(typeof(lvalueOf!R[0 .. $])) || is(typeof(lvalueOf!R[0 .. $]) == R)) && (!is(typeof(lvalueOf!R[0 .. $])) || isInfinite!R || is(typeof(lvalueOf!R[0 .. $ - 1]) == R)) && is(typeof((ref R r) { static assert(isForwardRange!(typeof(r[1 .. 2])));
Authors
Andrei Alexandrescu, David Simcha, and Jonathan M Davis. Credit for some of the ideas in building this module goes to Leonardo Maffi.