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bazarr/libs/babelfish/converters/__init__.py
2018-09-16 20:33:04 -04:00

287 lines
9 KiB
Python

# Copyright (c) 2013 the BabelFish authors. All rights reserved.
# Use of this source code is governed by the 3-clause BSD license
# that can be found in the LICENSE file.
#
import collections
from pkg_resources import iter_entry_points, EntryPoint
from ..exceptions import LanguageConvertError, LanguageReverseError
# from https://github.com/kennethreitz/requests/blob/master/requests/structures.py
class CaseInsensitiveDict(collections.MutableMapping):
"""A case-insensitive ``dict``-like object.
Implements all methods and operations of
``collections.MutableMapping`` as well as dict's ``copy``. Also
provides ``lower_items``.
All keys are expected to be strings. The structure remembers the
case of the last key to be set, and ``iter(instance)``,
``keys()``, ``items()``, ``iterkeys()``, and ``iteritems()``
will contain case-sensitive keys. However, querying and contains
testing is case insensitive:
cid = CaseInsensitiveDict()
cid['English'] = 'eng'
cid['ENGLISH'] == 'eng' # True
list(cid) == ['English'] # True
If the constructor, ``.update``, or equality comparison
operations are given keys that have equal ``.lower()``s, the
behavior is undefined.
"""
def __init__(self, data=None, **kwargs):
self._store = dict()
if data is None:
data = {}
self.update(data, **kwargs)
def __setitem__(self, key, value):
# Use the lowercased key for lookups, but store the actual
# key alongside the value.
self._store[key.lower()] = (key, value)
def __getitem__(self, key):
return self._store[key.lower()][1]
def __delitem__(self, key):
del self._store[key.lower()]
def __iter__(self):
return (casedkey for casedkey, mappedvalue in self._store.values())
def __len__(self):
return len(self._store)
def lower_items(self):
"""Like iteritems(), but with all lowercase keys."""
return (
(lowerkey, keyval[1])
for (lowerkey, keyval)
in self._store.items()
)
def __eq__(self, other):
if isinstance(other, collections.Mapping):
other = CaseInsensitiveDict(other)
else:
return NotImplemented
# Compare insensitively
return dict(self.lower_items()) == dict(other.lower_items())
# Copy is required
def copy(self):
return CaseInsensitiveDict(self._store.values())
def __repr__(self):
return '%s(%r)' % (self.__class__.__name__, dict(self.items()))
class LanguageConverter(object):
"""A :class:`LanguageConverter` supports converting an alpha3 language code with an
alpha2 country code and a script code into a custom code
.. attribute:: codes
Set of possible custom codes
"""
def convert(self, alpha3, country=None, script=None):
"""Convert an alpha3 language code with an alpha2 country code and a script code
into a custom code
:param string alpha3: ISO-639-3 language code
:param country: ISO-3166 country code, if any
:type country: string or None
:param script: ISO-15924 script code, if any
:type script: string or None
:return: the corresponding custom code
:rtype: string
:raise: :class:`~babelfish.exceptions.LanguageConvertError`
"""
raise NotImplementedError
class LanguageReverseConverter(LanguageConverter):
"""A :class:`LanguageConverter` able to reverse a custom code into a alpha3
ISO-639-3 language code, alpha2 ISO-3166-1 country code and ISO-15924 script code
"""
def reverse(self, code):
"""Reverse a custom code into alpha3, country and script code
:param string code: custom code to reverse
:return: the corresponding alpha3 ISO-639-3 language code, alpha2 ISO-3166-1 country code and ISO-15924 script code
:rtype: tuple
:raise: :class:`~babelfish.exceptions.LanguageReverseError`
"""
raise NotImplementedError
class LanguageEquivalenceConverter(LanguageReverseConverter):
"""A :class:`LanguageEquivalenceConverter` is a utility class that allows you to easily define a
:class:`LanguageReverseConverter` by only specifying the dict from alpha3 to their corresponding symbols.
You must specify the dict of equivalence as a class variable named SYMBOLS.
If you also set the class variable CASE_SENSITIVE to ``True`` then the reverse conversion function will be
case-sensitive (it is case-insensitive by default).
Example::
class MyCodeConverter(babelfish.LanguageEquivalenceConverter):
CASE_SENSITIVE = True
SYMBOLS = {'fra': 'mycode1', 'eng': 'mycode2'}
"""
CASE_SENSITIVE = False
def __init__(self):
self.codes = set()
self.to_symbol = {}
if self.CASE_SENSITIVE:
self.from_symbol = {}
else:
self.from_symbol = CaseInsensitiveDict()
for alpha3, symbol in self.SYMBOLS.items():
self.to_symbol[alpha3] = symbol
self.from_symbol[symbol] = (alpha3, None, None)
self.codes.add(symbol)
def convert(self, alpha3, country=None, script=None):
try:
return self.to_symbol[alpha3]
except KeyError:
raise LanguageConvertError(alpha3, country, script)
def reverse(self, code):
try:
return self.from_symbol[code]
except KeyError:
raise LanguageReverseError(code)
class CountryConverter(object):
"""A :class:`CountryConverter` supports converting an alpha2 country code
into a custom code
.. attribute:: codes
Set of possible custom codes
"""
def convert(self, alpha2):
"""Convert an alpha2 country code into a custom code
:param string alpha2: ISO-3166-1 language code
:return: the corresponding custom code
:rtype: string
:raise: :class:`~babelfish.exceptions.CountryConvertError`
"""
raise NotImplementedError
class CountryReverseConverter(CountryConverter):
"""A :class:`CountryConverter` able to reverse a custom code into a alpha2
ISO-3166-1 country code
"""
def reverse(self, code):
"""Reverse a custom code into alpha2 code
:param string code: custom code to reverse
:return: the corresponding alpha2 ISO-3166-1 country code
:rtype: string
:raise: :class:`~babelfish.exceptions.CountryReverseError`
"""
raise NotImplementedError
class ConverterManager(object):
"""Manager for babelfish converters behaving like a dict with lazy loading
Loading is done in this order:
* Entry point converters
* Registered converters
* Internal converters
.. attribute:: entry_point
The entry point where to look for converters
.. attribute:: internal_converters
Internal converters with entry point syntax
"""
entry_point = ''
internal_converters = []
def __init__(self):
#: Registered converters with entry point syntax
self.registered_converters = []
#: Loaded converters
self.converters = {}
def __getitem__(self, name):
"""Get a converter, lazy loading it if necessary"""
if name in self.converters:
return self.converters[name]
for ep in iter_entry_points(self.entry_point):
if ep.name == name:
self.converters[ep.name] = ep.load()()
return self.converters[ep.name]
for ep in (EntryPoint.parse(c) for c in self.registered_converters + self.internal_converters):
if ep.name == name:
# `require` argument of ep.load() is deprecated in newer versions of setuptools
if hasattr(ep, 'resolve'):
plugin = ep.resolve()
elif hasattr(ep, '_load'):
plugin = ep._load()
else:
plugin = ep.load(require=False)
self.converters[ep.name] = plugin()
return self.converters[ep.name]
raise KeyError(name)
def __setitem__(self, name, converter):
"""Load a converter"""
self.converters[name] = converter
def __delitem__(self, name):
"""Unload a converter"""
del self.converters[name]
def __iter__(self):
"""Iterator over loaded converters"""
return iter(self.converters)
def register(self, entry_point):
"""Register a converter
:param string entry_point: converter to register (entry point syntax)
:raise: ValueError if already registered
"""
if entry_point in self.registered_converters:
raise ValueError('Already registered')
self.registered_converters.insert(0, entry_point)
def unregister(self, entry_point):
"""Unregister a converter
:param string entry_point: converter to unregister (entry point syntax)
"""
self.registered_converters.remove(entry_point)
def __contains__(self, name):
return name in self.converters