On Mon, 1 Nov 2021 22:27:08 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java >> line 3269: >> >>> 3267: return false; >>> 3268: } >>> 3269: int val = value.intValue(); // NANO_OF_SECOND must fit in >>> an int and can't be negative >> >> Unfortunately, this is not a valid assumption, and it affects the logic of >> the optimization more generally (methods where non-negative is assumed). >> >> Basically, NANO_OF_SECOND (and all other fields in the formatter) can have >> any `long` value. Despite immediate appearances, the value is not limited to >> 0 to 999,999,999. This is because you are allowed to create an >> implementation of `Temporal` that returns values outside that range. No such >> class exists in the JDK, but such a class would be perfectly legal. As a >> related example, it would be perfectly value to write a time class that ran >> from 03:00 to 26:59 each day, thus HOUROF_DAY cannot be assumed by the >> formatter to be between 0 and 23. > > The commentary on this line could probably be improved, but this is in a > private printer-parser that will only be used for NANO_OF_SECOND and not any > arbitrary `TemporalField` (see line 704), thus I fail to see how this > assumption can fail (since NANO_OF_SECOND specifies a value range from 0 to > 999,999,999). > > I considered writing a more generic integral-fraction printer parser that > would optimize for any value-range that fits in an int, but seeing how > NANO_OF_SECOND is likely the only one used in practice and with a high demand > for better efficiency I opted to specialize for it more directly. I see what you're saying that an arbitrary `Temporal` could define its own fields with its own ranges, but I would consider it a design bug if such an implementation at a whim redefines the value ranges of well-defined constants such as `ChronoField.NANO_OF_SECOND` or `HOUR_OF_DAY`. I'd expect such a `Temporal` would have to define its own enumeration of allowed `TemporalField`s. ------------- PR: https://git.openjdk.java.net/jdk/pull/6188
