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Enum member std.range.primitives.hasMobileElements
Returns true
iff R
is an input range that supports the
moveFront
primitive, as well as moveBack
and moveAt
if it's a
bidirectional or random access range. These may be explicitly implemented, or
may work via the default behavior of the module level functions moveFront
and friends. The following code should compile for any range
with mobile elements.
enum hasMobileElements(R)
= isInputRange!R && is(typeof(moveFront(lvalueOf!R)) == ElementType!R) && (!isBidirectionalRange!R || is(typeof(moveBack(lvalueOf!R)) == ElementType!R)) && (!isRandomAccessRange!R || is(typeof(moveAt(lvalueOf!R, 0)) == ElementType!R));
alias E = ElementType!R;
R r;
static assert(isInputRange!R);
static assert(is(typeof(moveFront(r)) == E));
static if (isBidirectionalRange!R)
static assert(is(typeof(moveBack(r)) == E));
static if (isRandomAccessRange!R)
static assert(is(typeof(moveAt(r, 0)) == E));
Example
import std .algorithm .iteration : map;
import std .range : iota, repeat;
static struct HasPostblit
{
this(this) {}
}
auto nonMobile = map!"a"(repeat(HasPostblit .init));
static assert(!hasMobileElements!(typeof(nonMobile)));
static assert( hasMobileElements!(int[]));
static assert( hasMobileElements!(inout(int)[]));
static assert( hasMobileElements!(typeof(iota(1000))));
static assert( hasMobileElements!( string));
static assert( hasMobileElements!(dstring));
static assert( hasMobileElements!( char[]));
static assert( hasMobileElements!(dchar[]));
Authors
Andrei Alexandrescu, David Simcha, and Jonathan M Davis. Credit for some of the ideas in building this module goes to Leonardo Maffi.
License
Copyright © 1999-2022 by the D Language Foundation | Page generated by ddox.