Class Column

tests/comparison/common.py:245–296

A representation of a column. All TableExprs will have Columns. So a Column may belong to an InlineView as well as a standard Table. This class is used in two ways: 1) As a piece of metadata in a table definiton. In this usage the col isn't intended to represent an val.

class Column(ValExpr):
  '''A representation of a column. All TableExprs will have Columns. So a Column
     may belong to an InlineView as well as a standard Table.

     This class is used in two ways:

       1) As a piece of metadata in a table definiton. In this usage the col isn't
          intended to represent an val.

       2) As an expr in a query, for example an item being selected or as part of
          a JOIN condition. In this usage the col is more like a val, which is why
          it implements/extends ValExpr.

     This class can also be used to represent Map keys, Map values, Array pos,
     scalar struct field, and scalar array item.
  '''

  def __init__(self, owner, name, exact_type):
    self.owner = owner
    self.name = name
    self._exact_type = exact_type
    self.is_primary_key = False

  @property
  def exact_type(self):
    return self._exact_type

  @exact_type.setter
  def exact_type(self, exact_type):
    self._exact_type = exact_type

  def __hash__(self):
    return hash(self.name)

  def __eq__(self, other):
    if not isinstance(other, Column):
      return False
    if self is other:
      return True
    return self.name == other.name and self.owner.identifier == other.owner.identifier

  @property
  def cols(self):
    return ValExprList([self])

  def __repr__(self):
    return '%s<name: %s, type: %s>' % (
        type(self).__name__, self.name, self.exact_type.__name__)

  def __deepcopy__(self, memo):
    # Don't return a deep copy of owner, since that is a circular reference
    return Column(self.owner, self.name, self.exact_type)


class ValExprList(list):