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Function std.range.choose
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).
Prototype
auto choose(R1, R2)( bool condition, R1 r1, R2 r2 ) if (isInputRange!(Unqual!R1) && isInputRange!(Unqual!R2) && !is(CommonType!(ElementType!(Unqual!R1), ElementType!(Unqual!R2)) == void));
Parameters
| Name | Description |
|---|---|
| condition | which range to choose: true, |
| r1 | the "true" range |
| r2 | the "false" range |
Returns
A range type dependent on R1 and R2.
Bugs
Authors
Andrei Alexandrescu, David Simcha, and Jonathan M Davis. Credit for some of the ideas in building this module goes to Leonardo Maffi.