On 5/13/15 10:58 PM, rcorre wrote:
Actually, this doesn't even seem to work with a custom range:
import std.range;
import std.stdio;
import std.algorithm;
struct MyContainer {
@nogc auto opSlice() {
struct Range {
@property bool empty() { return true; }
@property int front() { return 9; }
void popFront() { }
}
return Range();
}
}
/// Return a slice of aa[key], or an empty slice if not found
@nogc auto maybeGetRange(MyContainer[string] aa, string key) {
alias RangeType = typeof(MyContainer.init[]);
auto val = key in aa;
return (val is null) ? takeNone!RangeType :
(*val)[].take(size_t.max);
}
Is there any way to create an empty MyContainer.Range() without creating
a new container?
It depends on the guts of MyContainer.Range.
I'm assuming MyContainer.Range has SOME sort of references (i.e.
pointers) to the data in the container, so why not just have:
bool empty() { return someRef == null || yourCurrentTest; }
-Steve
