On Sunday, 4 March 2018 at 19:58:14 UTC, ag0aep6g wrote:
On 03/04/2018 08:54 PM, aliak wrote:
wait a minute... so I can't use any std.range functions on a
type if I add the range primitives as free functions? O.o
Yes. In other words: You can't implement range primitives as
free functions. Because std.range (and std.algorithm, etc.)
doesn't know about them.
isn't this what DIP 1005 tried to solve?
as long as you dont want to role your own test its not possible.
module moda;
struct Imports
{
string importString;
}
template isInputRange(R)
{
import std.traits: hasUDA, getUDAs, ReturnType;
static if(hasUDA!(R, Imports))
static foreach(u; getUDAs!(R, Imports))
mixin(u.importString);
enum bool isInputRange =
is(typeof(R.init) == R)
&& is(ReturnType!((R r) => r.empty) == bool)
&& is(typeof((return ref R r) => r.front))
&& !is(ReturnType!((R r) => r.front) == void)
&& is(typeof((R r) => r.popFront));
}
-----
module test;
import std.stdio;
import moda;
void main(string[] args)
{
isInputRange!Type.writeln;
}
bool empty(Type t) { return true; }
int front(Type t) { return 42; }
void popFront(Type t) {}
@Imports("import test: empty, front, popFront;")
struct Type
{
}
