Rust library for reading the text files comprising the zoneinfo database, which records time zone changes and offsets across the world from multiple sources.
The zoneinfo database is distributed in one of two formats: a raw text format with one file per continent, and a compiled binary format with one file per time zone. This crate deals with the former; for the latter, see the zoneinfo_compiled crate instead.
The database itself is maintained by IANA. For more information, see IANA’s page on the time zone database. You can also find the text files themselves in the tz repository.
This crate works with Cargo. Add the following to your Cargo.toml dependencies section:
[dependencies]
datetime = "0.5"zoneinfo_parse = "0.5"The earliest version of Rust that this crate is tested against is Rust v1.31.0.
The zoneinfo files contains Zone, Rule, and Link information. Each type of line forms a variant in the line::Line enum.
To get started, here are a few lines representing what time is like in the Europe/Madrid time zone:
# Zone NAME GMTOFF RULES FORMAT [UNTIL]
Zone Europe/Madrid -0:14:44 - LMT 1901 Jan 1 0:00s
0:00 Spain WE%sT 1946 Sep 30
1:00 Spain CE%sT 1979
1:00 EU CE%sT
The first line is a comment. The second starts with Zone, so we know
So parsing these five lines would return the five following results:
- A
line::Line::Spacefor the comment, because the line doesn’t contain any information (but isn’t strictly invalid either). - A
line::Line::Zonefor the firstZoneentry. This contains aZonestruct that holds the name of the zone. All the other fields are stored in theZoneInfostruct. - A
line::Line::Continuationfor the next entry. This is different from the line above as it doesn’t contain a name field; it only has the information in aZoneInfostruct. - The fourth line contains the same types of data as the third.
- As does the fifth.
Lines with rule definitions look like this:
# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
Rule Spain 1917 only - May 5 23:00s 1:00 S
Rule Spain 1917 1919 - Oct 6 23:00s 0 -
Rule Spain 1918 only - Apr 15 23:00s 1:00 S
Rule Spain 1919 only - Apr 5 23:00s 1:00 S
All these lines follow the same pattern: A line::Line::Rule that contains a Rule struct, which has a field for each column of data.
Finally, there are lines that link one zone to another’s name:
Link Europe/Prague Europe/Bratislava
The Link struct simply contains the names of both the existing and new time zones.
Once the input lines have been parsed, they must be interpreted to form a table of time zone data.
The easiest way to do this is with a TableBuilder. You can add various lines to the builder, and it will throw an error as soon as it detects that something’s wrong, such as a duplicate or a missing entry. When all the lines have been fed to the builder, you can use the build method to produce a Table containing fields for the rule, zone, and link lines.
This crate is used to produce the data for the zoneinfo-data crate. For an example of its use, see the bundled data crate builder.