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Enum std.range.primitives.member hasSwappableElements
Returns true if R is an input range and has swappable
elements. The following code should compile for any range
with swappable elements.
R r; static assert(isInputRange!R); swap(r.front, r.front); static if (isBidirectionalRange!R) swap(r.back, r.front); static if (isRandomAccessRange!R) swap(r[], r.front);
Declaration
enum hasSwappableElements(R) = isInputRange!R && is(typeof((inout int = 0)
{
R r = R.init;
swap(r.front, r.front);
static if (isBidirectionalRange!R)
{
swap(r.back, r.front);
}
static if (isRandomAccessRange!R)
{
swap(r[0], r.front);
}
}
));
Example
static assert(!hasSwappableElements!(const int[])); static assert(!hasSwappableElements!(const(int)[])); static assert(!hasSwappableElements!(inout(int)[])); static assert( hasSwappableElements!(int[])); static assert(!hasSwappableElements!( string)); static assert(!hasSwappableElements!(dstring)); static assert(!hasSwappableElements!( char[])); static assert( hasSwappableElements!(dchar[]));
Authors
Andrei Alexandrescu, David Simcha, and Jonathan M Davis. Credit for some of the ideas in building this module goes to Leonardo Maffi.