R1 and R2.choose
fn
auto choose(R1, R2)(bool condition, return scope R1 r1, return scope R2 r2) if (isInputRange!(Unqual!R1) && isInputRange!(Unqual!R2) &&
!is(CommonType!(ElementType!(Unqual!R1), ElementType!(Unqual!R2)) == void))Choose one of two ranges at runtime depending on a Boolean condition.
The ranges may be different, but they must have compatible element types (i.e. CommonType must exist for the two element types). The result is a range that offers the weakest capabilities of the two (e.g. ForwardRange if R1 is a random-access range and R2 is a forward range).
Parameters
condition | which range to choose: r1 if true, r2 otherwise |
r1 | the "true" range |
r2 | the "false" range |
Returns
A range type dependent on