Move common libs to libs/common

libs/common/babelfish/converters/__init__.py

@@ -0,0 +1,287 @@
+# 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