Source code for parce.language

# -*- coding: utf-8 -*-
#
# This file is part of the parce Python package.
#
# Copyright © 2019-2020 by Wilbert Berendsen <info@wilbertberendsen.nl>
#
# This module is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This module is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

"""
This module provides the Language class, which serves as the base class
for all language definitions.
"""

import parce
import parce.action as a


class _LanguageType(type):
    """Language meta type that prints a customized repr string."""
    def __repr__(cls):
        return '{}.{}'.format(cls.__module__, cls.__name__)


class Language(metaclass=_LanguageType):
    """A Language represents a set of Lexicons comprising a specific language.

    A Language is never instantiated. The class itself serves as a namespace
    and can be inherited from.

    """
    def __new__(cls):
        raise RuntimeError('Language should never be instantiated')

    @classmethod
    def comment_common(cls):
        """Provides subtle highlighting within comments.

        The default implementation highlights words like TODO, XXX, TEMP, etc.
        using Comment.Alert, and highlights URLs and email addresses with the
        Comment.Url and Comment.Email action respectively. Most bundled
        languages use this method for their comment lexicons.

        """
        yield r'\b\w+(?:[._%+-]\w+)*@\w+(?:[._-]\w+)*\b', a.Comment.Email
        yield r'(?:(?:https?|ftp):/|\bwww\.)(?:[\w_~:/#-]+([.?=][\w_~:/#-]+)*|\([\w._~:?/#-]*\))+', a.Comment.Url
        yield r"\b(ALERT|BUG|FIXME|TEMP|TODO|XXX+)\b", a.Comment.Alert
        yield parce.default_action, a.Comment