text: ﻿# Copyright (c) 2021, LE GOFF Vincent
  # All rights reserved.
  
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are met:
  
  # * Redistributions of source code must retain the above copyright notice, this
  #   list of conditions and the following disclaimer.
  
  # * Redistributions in binary form must reproduce the above copyright notice,
  #   this list of conditions and the following disclaimer in the documentation
  #   and/or other materials provided with the distribution.
  
  # * Neither the name of ytranslate nor the names of its
  #   contributors may be used to endorse or promote products derived from
  #   this software without specific prior written permission.
  
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  # DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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  # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  """Module containing the field class, defining database columns."""
  
  from typing import Any
  
  _NOT_SET = object()
  
  class Field:
  
      """A field, to represent a database column."""
  
      def __init__(self, field_type, primary_key=False,
              name=None, default=_NOT_SET):
          self.field_type = field_type
          self.primary_key = primary_key
          self.name = name
          self.default = default
  
      def __hash__(self):
          return hash(self.name)
  
      def __repr__(self):
          return f"<Field {self.name!r}>"
  
      def __str__(self):
          text = f"{self.name!r} of type {self.field_type.__name__}"
          if self.primary_key:
              text += " (primary key)"
  
          return text
  
      @property
      def set_by_database(self):
          """This field is to be set by the database only."""
          return self.field_type is int and self.primary_key
  
      @property
      def has_default(self):
          """Has this field got a default value?"""
          return self.default is not _NOT_SET
  
      def accept(self, value: Any) -> bool:
          """Return whether this value is accepted."""
          accepted = self.field_type
          if accepted in (int, float, str, bytes):
              return isinstance(value, accepted)
  
          return True
  