Change the `parse_datetime()` function so that it parses both a
reference date and a time delta from one string. The new implementation
attempts to parse the datetime from the longest possible prefix of the
string. The remainder of the string is parsed as the time delta. This
allows us to parse more combinations of reference dates and time deltas
more easily.
Fixes#104
Change the way dates without times are parsed by just parsing the date
as-is and applying the placeholder time (00:00:00) after parsing
instead of before.
Simulate greedy parsing of an absolute datetime in the prefix of a
string before parsing a subsequent time delta in the suffix of the
string. This does not change the behavior of `parse_datetime`, it just
prepares the code for a future change that allows parsing both the
absolute datetime and the time delta from the same string.
Greedy parsing is implemented by iterating over a list of patterns in
decreasing order of length so that longer patterns are tried before
shorter patterns. This guarantees that if there is an absolute datetime
present at the beginning of the string, then it will definitely be
parsed and the remaining part of the string is assumed to contain a time
delta.
Protect against a situation where adding one month to the current day
would cause an overflow in the next month in some unit tests of
`parse_relative_time`. For example, adding one month to March 31
should overflow to May 1 because April only has 30 days. This is a
difference in the behavior we want for our library compared with the
behavior of `chrono`.
Change the behavior of `parse_relative_time_at_date()` so that adding
months to a given date causes surplus days to overflow to the next
month. For example, adding 1 month to 1996-03-31 would be 1996-04-31,
but April only has 30 days, so the surplus day rolls over to the next
month, resulting in 1996-05-01.
Closes#98
Add parsing for timezone offsets of the form +N or -N. As a side effect
of this change, parsing timezone offsets like +0700, UTC+2, and Z-1 are
now supported.
Sylvestre Ledru
jfinkels
Jeffrey Finkelstein
Daniel Hofstetter