bhgomes/oeis

# -*- coding: utf-8 -*- #
#
# oeis/base.py
#
#
# MIT License
#
# Copyright (c) 2019 Brandon Gomes
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#

"""
Interface to the OEIS.

"""

# -------------- Standard Library -------------- #

import re

# ---------------- oeis Library ---------------- #

from .util import is_int


__all__ = (
    "InvalidID",
    "MissingID",
    "name",
    "number",
    "OEIS_ID_REGEX",
    "find_references",
)


class FromKeyMixin:
    """
    FromKey Mixin Class.

    """

    def __init_subclass__(cls, key_text="{}", **kwargs):
        """Initialize Subclasses."""
        super().__init_subclass__(**kwargs)

        def from_key(c, key):
            return c(key_text.format(key))

        cls.from_key = classmethod(from_key)


class InvalidID(KeyError, FromKeyMixin, key_text="Key {} not a valid OEIS id."):
    """
    Invalid OEIS ID.

    """


class MissingID(KeyError, FromKeyMixin, key_text="Key {} missing from OEIS."):
    """
    Missing OEIS ID.

    """


def _convert_string(key):
    """Convert OEIS String to Integer."""
    if isinstance(key, str):
        key = int(key.strip().upper().strip("A"))
    return key


def name(key):
    """Get Full Name for OEIS Sequence."""
    if hasattr(key, "__oeis_name__"):
        return key.__oeis_name__
    try:
        key = _convert_string(key)
        if is_int(key):
            return "A{key:06d}".format(key=key)
    except ValueError:
        pass
    raise InvalidID.from_key(key)


def number(key):
    """Get Index of OEIS Sequence."""
    if hasattr(key, "__oeis_name__"):
        return key.__oeis_name__
    try:
        key = _convert_string(key)
        if is_int(key):
            return key
    except ValueError:
        pass
    raise InvalidID.from_key(key)


OEIS_ID_REGEX = re.compile(r"(A\d+)", re.MULTILINE | re.UNICODE)


def find_references(text):
    """Find references to OEIS Sequences."""
    for match in re.finditer(OEIS_ID_REGEX, text):
        yield match.groups()