Source code for coalib.bearlib.languages.Language

from collections import OrderedDict
from itertools import chain
from inspect import isclass, getmembers
import operator
import re
from operator import itemgetter

from coalib.settings.Annotations import typechain


class LanguageUberMeta(type):
    """
    This class is used to hide the `all` attribute from the Language class.
    """
    all = []


convert_int_float = typechain(int, float)


def parse_lang_str(string):
    """
    Parses any given language string into name
    and a list of float versions (ignores leading whitespace):

    >>> parse_lang_str("Python")
    ('Python', [])
    >>> parse_lang_str("Python 3.3")
    ('Python', [3.3])
    >>> parse_lang_str("Python 3.6, 3.3")
    ('Python', [3.6, 3.3])
    >>> parse_lang_str("Objective C 3.6, 3.3")
    ('Objective C', [3.6, 3.3])
    >>> parse_lang_str("               Objective C 3.6, 3.3")
    ('Objective C', [3.6, 3.3])
    >>> parse_lang_str("Cobol, stupid!")  # +ELLIPSIS
    Traceback (most recent call last):
     ...
    ValueError: Couldn't convert value 'stupid!' ...
    """
    name, *str_versions = re.split(r',\s*', str(string))
    versions = list(map(convert_int_float, str_versions))
    try:
        name, version = name.rsplit(maxsplit=1)
        version = convert_int_float(version)
    except (ValueError, TypeError):
        pass
    else:
        versions.insert(0, version)

    return name.strip(), versions


class LanguageMeta(type, metaclass=LanguageUberMeta):
    """
    Metaclass for :class:`coalib.bearlib.languages.Language.Language`.

    Allows it being used as a decorator as well as implements the
    `__contains__` operation and stores all languages created with the
    decorator.

    The operators are defined on the class as well, so you can do the
    following:

    >>> @Language
    ... class SomeLang:
    ...     versions = 2.7, 3.3, 3.4, 3.5, 3.6
    >>> Language.SomeLang > 3.4
    SomeLang 3.5, 3.6
    >>> Language.SomeLang < 3.4
    SomeLang 2.7, 3.3
    >>> Language.SomeLang >= 3.4
    SomeLang 3.4, 3.5, 3.6
    >>> Language.SomeLang <= 3.4
    SomeLang 2.7, 3.3, 3.4
    >>> Language.SomeLang == 3.4
    SomeLang 3.4
    >>> Language.SomeLang != 3.4
    SomeLang 2.7, 3.3, 3.5, 3.6
    >>> Language.SomeLang == 1.0
    Traceback (most recent call last):
     ...
    ValueError: No versions left
    """

    def __new__(mcs, clsname, bases, clsattrs):
        for base in bases:
            if issubclass(base, Language) and base is not Language:
                for name, obj in base._attributes.items():
                    clsattrs.setdefault(name, obj)

        return type.__new__(mcs, clsname, bases, clsattrs)

    def __hash__(cls):
        """
        >>> isinstance(hash(Language), int)
        True
        """
        return type.__hash__(cls)

    def __dir__(cls):
        return super().__dir__() + [lang.__name__ for lang in type(cls).all]

    def __getattr__(cls, item):
        try:
            return next(lang for lang in type(cls).all if item in lang)
        except StopIteration:
            raise AttributeError

    def __getitem__(cls, item):
        if isinstance(item, cls):
            return item
        if isclass(item) and issubclass(item, cls):
            return item()

        name, versions = parse_lang_str(item)

        language = getattr(cls, name)
        if not versions:
            return language()

        return language(*set(chain(*((language == v).versions
                                     for v in versions))))

    def __call__(cls, *args):
        if cls is Language:
            assert len(args) == 1
            arg = args[0]
            assert isclass(arg), \
                'This decorator is made for classes. Did you mean to use ' \
                '`Language[%s]`?' % (repr(arg[0]),)

            class SubLanguageMeta(type(cls)):
                # Override __getattr__ of the LanguageMeta to get a dict with
                # the attributes

                def __getattr__(self, item):
                    try:
                        return OrderedDict(
                            (version, self._attributes[item])
                            for version in self.versions)
                    except KeyError:
                        raise AttributeError

            forbidden_attributes = list(
                chain(map(itemgetter(0), getmembers(Language)),
                      ('versions', 'aliases')))

            class Sub(cls, metaclass=SubLanguageMeta):
                __qualname__ = arg.__qualname__
                versions = tuple(sorted(getattr(arg, 'versions', ())))
                aliases = tuple(sorted(getattr(arg, 'aliases', ())))
                _attributes = {name: member for name, member in getmembers(arg)
                               if not name.startswith('_')
                               and name not in forbidden_attributes}

            Sub.__name__ = arg.__name__
            type(cls).all.append(Sub)
            return Sub

        return super().__call__(*args)

    def __contains__(cls, item):
        name, versions = parse_lang_str(item)

        return str(name).lower() in map(
            str.lower, chain(cls.aliases, [cls.__qualname__, cls.__name__])
        ) and (not versions or all(version in cls.versions
                                   for version in versions))

    def __gt__(cls, other):
        return cls is not Language and cls() > other

    def __lt__(cls, other):
        return cls is not Language and cls() < other

    def __ge__(cls, other):
        return cls is not Language and cls() >= other

    def __le__(cls, other):
        return cls is not Language and cls() <= other

    def __eq__(cls, other):
        return cls is not Language and cls() == other

    def __ne__(cls, other):
        return cls is not Language and cls() != other


class Language(metaclass=LanguageMeta):
    """
    This class defines programming languages and their versions.

    You can define a new programming language as follows:

    >>> @Language
    ... class TrumpScript:
    ...     __qualname__ = "America is great."
    ...     aliases = 'ts',
    ...     versions = 2.7, 3.3, 3.4, 3.5, 3.6
    ...     comment_delimiter = '#'
    ...     string_delimiter = {"'": "'"}

    From a bear, you can simply parse the user given language string to get
    the instance of the Language you desire:

    >>> Language['trumpscript']
    America is great. 2.7, 3.3, 3.4, 3.5, 3.6
    >>> Language['ts 3.4, 3.6']
    America is great. 3.4, 3.6
    >>> Language['TS 3']
    America is great. 3.3, 3.4, 3.5, 3.6
    >>> Language['tS 1']
    Traceback (most recent call last):
     ...
    ValueError: No versions left

    The attributes are not accessible unless you have selected one - and only
    one - version of your language:

    >>> Language.TrumpScript(3.3, 3.4).comment_delimiter
    Traceback (most recent call last):
     ...
    AttributeError: You have to specify ONE version ...
    >>> Language.TrumpScript(3.3).comment_delimiter
    '#'

    If you don't know which version is the right one, just use this:

    >>> Language.TrumpScript().get_default_version()
    America is great. 3.6

    To see which attributes are available, use the ``attributes`` property:

    >>> Language.TrumpScript(3.3).attributes
    ['comment_delimiter', 'string_delimiter']

    You can access a dictionary of the attribute values for every version from
    the class:

    >>> Language.TrumpScript.comment_delimiter
    OrderedDict([(2.7, '#'), (3.3, '#'), (3.4, '#'), (3.5, '#'), (3.6, '#')])

    Any nonexistent item will of course not be served:

    >>> Language.TrumpScript.unknown_delimiter
    Traceback (most recent call last):
     ...
    AttributeError

    **You now know the most important parts for writing a bear using languages.
    Read ahead if you want to know more about working with multiple versions of
    programming languages as well as derivative languages!**

    We can define derivative languages as follows:

    >>> @Language
    ... class TrumpScriptDerivative(Language.TrumpScript):
    ...     __qualname__ = 'Shorter'
    ...     comment_delimiter = '//'
    ...     keywords = None

    >>> Language.TrumpScriptDerivative()
    Shorter 2.7, 3.3, 3.4, 3.5, 3.6

    >>> Language.TrumpScriptDerivative().get_default_version().attributes
    ['comment_delimiter', 'keywords', 'string_delimiter']
    >>> Language.TrumpScriptDerivative().get_default_version().keywords
    >>> Language.TrumpScriptDerivative().get_default_version().comment_delimiter
    '//'
    >>> Language.TrumpScriptDerivative().get_default_version().string_delimiter
    {"'": "'"}

    We can get an instance via this syntax as well:

    >>> Language[Language.TrumpScript]
    America is great. 2.7, 3.3, 3.4, 3.5, 3.6
    >>> Language[Language.TrumpScript(3.6)]
    America is great. 3.6

    As you see, you can use the `__qualname__` property. This will also affect
    the string representation and work as an implicit alias:

    >>> str(Language.TrumpScript(3.4))
    'America is great. 3.4'

    We can specify the version by instantiating the TrumpScript class now:

    >>> str(Language.TrumpScript(3.6))
    'America is great. 3.6'

    You can also define ranges of versions of languages:

    >>> (Language.TrumpScript > 3.3) <= 3.5
    America is great. 3.4, 3.5

    >>> Language.TrumpScript == 3
    America is great. 3.3, 3.4, 3.5, 3.6

    Those can be combined by the or operator:

    >>> (Language.TrumpScript == 3.6) | (Language.TrumpScript == 2)
    America is great. 2.7, 3.6

    The `__contains__` operator of the class is defined as well for strings
    and instances. This is case insensitive and aliases are allowed:

    >>> Language.TrumpScript(3.6) in Language.TrumpScript
    True
    >>> 'ts 3.6, 3.5' in Language.TrumpScript
    True
    >>> 'TrumpScript 2.6' in Language.TrumpScript
    False
    >>> 'TrumpScript' in Language.TrumpScript
    True

    This also works on instances:

    >>> 'ts 3.6, 3.5' in (Language.TrumpScript == 3)
    True
    >>> 'ts 3.6,3.5' in ((Language.TrumpScript == 2)
    ...                  | Language.TrumpScript(3.5))
    False
    >>> Language.TrumpScript(2.7, 3.5) in (Language.TrumpScript == 3)
    False
    >>> Language.TrumpScript(3.5) in (Language.TrumpScript == 3)
    True

    Any undefined language will obviously not be available:

    >>> Language.Cobol
    Traceback (most recent call last):
     ...
    AttributeError
    """

    def __init__(self, *versions):
        assert all(version in type(self).versions for version in versions)
        if not versions:
            self.versions = type(self).versions
        else:
            self.versions = tuple(sorted(versions))

    def __getattr__(self, item):
        if len(self.versions) > 1:
            raise AttributeError('You have to specify ONE version of your '
                                 'language to retrieve attributes for it.')
        try:
            return self._attributes[item]
        except KeyError:
            if len(self.attributes) == 0:
                message = 'There are no available attributes for this language.'
            else:
                message = ('This is not a valid attribute! '
                           '\nThe following attributes are available:')
                message += '\n'.join(self.attributes)
            raise AttributeError(message)

    def __str__(self):
        result = type(self).__qualname__
        if self.versions:
            result += ' ' + ', '.join(map(str, self.versions))
        return result

    def __repr__(self):
        return str(self)

    def __gt__(self, other):
        return limit_versions(self, other, operator.gt)

    def __lt__(self, other):
        return limit_versions(self, other, operator.lt)

    def __ge__(self, other):
        return limit_versions(self, other, operator.ge)

    def __le__(self, other):
        return limit_versions(self, other, operator.le)

    def __eq__(self, other):
        return limit_versions(self, other, operator.eq)

    def __ne__(self, other):
        return limit_versions(self, other, operator.ne)

    def __or__(self, other):
        return type(self)(*chain(self.versions, other.versions))

    def __contains__(self, item):
        item = Language[item]
        return (type(self) is type(item)
                and set(item.versions).issubset(set(self.versions)))

    @property
    def attributes(self):
        """
        Retrieves the names of all attributes that are available for this
        language.
        """
        return sorted(self._attributes.keys())

    def get_default_version(self):
        """
        Retrieves the latest version the user would want to choose from the
        given versions in self.

        (At a later point this might also retrieve a default version
        specifiable by the language definition, so keep using this!)
        """
        return type(self)(self.versions[-1]) if self.versions else type(self)()


def limit_versions(language, limit, operator):
    """
    Limits given languages with the given operator:

    :param language:
        A `Language` instance.
    :param limit:
        A number to limit the versions.
    :param operator:
        The operator to use for the limiting.
    :return:
        A new `Language` instance with limited versions.
    :raises ValueError:
        If no version is left anymore.
    """
    if isinstance(limit, int):
        versions = [version for version in language.versions
                    if operator(int(version), limit)]
    else:

        versions = [version for version in language.versions
                    if operator(version, limit)]
    if not versions:
        raise ValueError('No versions left')
    return type(language)(*versions)


class Languages(tuple):
    """
    A ``tuple``-based container for :class:`coalib.bearlib.languages.Language`
    instances. It supports language identifiers in any format accepted by
    ``Language[...]``:

    >>> Languages(['C#', Language.Python == 3])
    (C#, Python 3.3, 3.4, 3.5, 3.6)

    It provides :meth:`.__contains__` for checking if a given language
    identifier is included:

    >>> 'Python 2.7, 3.5' in Languages([Language.Python()])
    True
    >>> 'Py 3.3' in Languages(['Python 2'])
    False
    >>> 'csharp' in Languages(['C#', Language.Python == 3])
    True
    """

    def __new__(cls, items):
        return tuple.__new__(cls, (Language[i] for i in items))

    def __contains__(self, item):
        return any(item in lang for lang in self)