------------------------------
This is the alpha version of release 1.0.0 for pvl, and the items
here and in other 'alpha' entries may be consolidated when 1.0.0
is released. This work is categorized as 1.0.0-alpha because
backwards-incompatible changes are being introduced to the codebase.
* Refactored code so that it will no longer support Python 2,
and is only guaranteed to work with Python 3.6 and above.
* Rigorously implemented the three dialects of PVL text: PVL itself,
ODL, and the PDS3 Label Standard. There is a fourth de-facto
dialect, that of ISIS cube labels that is also handled. These
dialects each have their own grammars, parsers, decoders, and
encoders, and there are also some 'Omni' versions of same that
handle the widest possible range of PVL text.
* When parsing via the loaders, ``pvl`` continues to consume as
wide a variety of PVL text as is reasonably possible, just like
always. However, now when encoding via the dumpers, ``pvl`` will
default to writing out PDS3 Label Standard format PVL text, one
of the strictest dialects, but other options are available. This
behavior is different from the pre-1.0 version, which wrote out
more generic PVL text.
* Removed the dependency on the ``six`` library that provided Python 2
compatibility.
* Removed the dependency on the ``pytz`` library that provided 'timezone'
support, as that functionality is replaced with the Standard Library's
``datetime`` module.
* The private ``pvl/_numbers.py`` file was removed, as its capability is now
accomplished with the Python Standard Library.
* The private ``pvl/_datetimes.py`` file was removed, as its capability is now
accomplished with the Standard Library's ``datetime`` module.
* the private ``pvl/_strings.py`` file was removed, as its capabilities are now
mostly replaced with the new grammar module and some functions in other new
modules.
* Internally, the library is now working with string objects, not byte literals,
so the ``pvl/stream.py`` module is no longer needed.
* Added an optional dependency on the 3rd party ``dateutil`` library, to parse
more exotic date and time formats. If this library is not present, the
``pvl`` library will gracefully fall back to not parsing more exotic
formats.
* Implmented a more formal approach to parsing PVL text: The properties
of the PVL language are represented by a grammar object. A string is
broken into tokens by the lexer function. Those tokens are parsed by a
parser object, and when a token needs to be converted to a Python object,
a decoder object does that job. When a Python object must be converted to
PVL text, an encoder object does that job.
* Since the tests in ``tests/test_decoder.py`` and ``tests/test_encoder.py``
were really just exercising the loader and dumper functions, those tests were
moved to ``tests/test_pvl.py``, but all still work (with light modifications for
the new defaults). Unit tests were added for most of the new classes and
functions. All docstring tests now also pass doctest testing and are now
included in the ``make test`` target.
* Functionality to correctly parse dash (-) continuation lines written by ISIS
as detailed in 34 is implemented and tested.
* Functionality to use ``pathlib.Path`` objects for ``pvl.load()`` and
``pvl.dump()`` as requested in 20 and 31 is implemented and tested.
* Functionality to accept already-opened file objects that were opened in
'r' mode or 'rb' mode as alluded to in 6 is implemented and tested.
* The library now properly parses quoted strings that include backslashes
as detailed in 33.
* Utility programs pvl_validate and pvl_translate were added.
* Documentation was updated and expanded.