114 lines
3.1 KiB
Python
114 lines
3.1 KiB
Python
# Relational
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# Copyright (C) 2008-2020 Salvo "LtWorf" Tomaselli
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#
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# Relation is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# author Salvo "LtWorf" Tomaselli <tiposchi@tiscali.it>
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#
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# Custom types for relational algebra.
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# Purpose of this module is having the isFloat function and
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# implementing dates to use in selection.
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import datetime
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import keyword
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import re
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from typing import Union, Set, Any, Callable, Type, Optional
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from dataclasses import dataclass
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from gettext import gettext as _
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RELATION_NAME_REGEXP = re.compile(r'^[_a-z][_a-z0-9]*$', re.IGNORECASE)
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_date_regexp = re.compile(
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r'^([0-9]{1,4})(\\|-|/)([0-9]{1,2})(\\|-|/)([0-9]{1,2})$'
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)
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CastValue = Optional[Union[str, int, float, 'Rdate']]
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def guess_type(value: str) -> Set[Union[Callable[[Any], Any], Type['Rdate']]]:
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r: Set[Union[Callable[[Any], Any], Type['Rdate']]] = {str}
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if _date_regexp.match(value) is not None:
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r.add(Rdate)
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try:
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int(value)
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r.add(int)
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except ValueError:
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pass
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try:
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float(value)
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r.add(float)
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except ValueError:
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pass
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return r
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def cast(value: str, guesses: Set) -> CastValue:
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if int in guesses:
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return int(value)
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if Rdate in guesses:
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return Rdate.create(value)
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if float in guesses:
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return float(value)
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return value
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@dataclass(frozen=True)
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class Rdate:
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'''Represents a date'''
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year: int
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month: int
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day: int
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@property
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def intdate(self) -> datetime.date:
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return datetime.date(self.year, self.month, self.day)
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@property
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def weekday(self) -> int:
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return self.intdate.weekday()
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@staticmethod
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def create(date: str) -> 'Rdate':
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'''date: A string representing a date YYYY-MM-DD'''
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r = _date_regexp.match(date)
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if not r:
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raise ValueError(_('%s is not a valid date') % date)
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year = int(r.group(1))
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month = int(r.group(3))
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day = int(r.group(5))
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return Rdate(year, month, day)
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def __str__(self):
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return self.intdate.__str__()
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def __ge__(self, other):
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return self.intdate >= other.intdate
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def __gt__(self, other):
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return self.intdate > other.intdate
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def __le__(self, other):
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return self.intdate <= other.intdate
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def __lt__(self, other):
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return self.intdate < other.intdate
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def is_valid_relation_name(name: str) -> bool:
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'''Checks if a name is valid for a relation.
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Returns boolean'''
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return re.match(RELATION_NAME_REGEXP, name) != None and not keyword.iskeyword(name)
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