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.
Sylvestre Ledru
Daniel Hofstetter
Dan Hipschman
renovate[bot]
jfinkels
Jeffrey Finkelstein