Add range primitive sameHead

This commit is contained in:
Eugen Wissner 2018-11-04 06:31:38 +01:00
parent 8aec781e2a
commit 184d307e40

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@ -2051,3 +2051,41 @@ template hasSwappableElements(R)
} }
static assert(!hasSwappableElements!R2); static assert(!hasSwappableElements!R2);
} }
/**
* Determines whether `r1.front` and `r2.front` point to the same element.
*
* Params:
* r1 = First range.
* r2 = Second range.
*
* Returns: $(D_KEYWORD true) if $(D_PARAM r1) and $(D_PARAM r2) have the same
* head, $(D_KEYWORD false) otherwise.
*/
bool sameHead(Range)(Range r1, Range r2) @trusted
if (isInputRange!Range && hasLvalueElements!Range)
{
return &r1.front is &r2.front;
}
///
@nogc nothrow pure @safe unittest
{
const int[2] array;
auto r1 = array[];
auto r2 = array[];
assert(sameHead(r1, r2));
}
///
@nogc nothrow pure @safe unittest
{
const int[2] array;
auto r1 = array[];
auto r2 = array[1 .. $];
assert(!sameHead(r1, r2));
}