Class SelectClause

tests/comparison/query.py:180–219

This encapsulates the SELECT part of a query. It is convenient to separate non-agg items from agg items so that it is simple to know if the query is an agg query or not.

class SelectClause(object):
  '''This encapsulates the SELECT part of a query. It is convenient to separate
     non-agg items from agg items so that it is simple to know if the query
     is an agg query or not.
  '''

  def __init__(self, select_items):
    self.items = select_items
    self.distinct = False

  @property
  def basic_items(self):
    '''Returns a list of SelectItems that are also basic items. Deletions from
       this list will be propagated but additions will not be.
    '''
    return SelectItemSubList(self.items, lambda item: item.is_basic)

  @property
  def agg_items(self):
    '''Returns a list of SelectItems that are also aggregate items. Deletions from
       this list will be propagated but additions will not be.
    '''
    return SelectItemSubList(self.items, lambda item: item.is_agg)

  @property
  def analytic_items(self):
    '''Returns a list of SelectItems that are also analytic items. Deletions from
       this list will be propagated but additions will not be.
    '''
    return SelectItemSubList(self.items, lambda item: item.is_analytic)

  @property
  def contains_approximate_types(self):
    '''Returns true if there is a select item that is approximate (such as Float).'''
    return any(item.type.is_approximate() for item in self.items)

  def __deepcopy__(self, memo):
    other = SelectClause([deepcopy(item, memo) for item in self.items])
    other.distinct = self.distinct
    return other


# This is used in the query simplifier (not yet checked in) to simplify reduction