def _is_ordering_expression(expression):
"""
Test an expression whether it is an ordering clause
"""
if hasattr(expression, 'operator') and is_ordering_modifier(expression.operator):
return True
if hasattr(expression, 'modifier') and is_ordering_modifier(expression.modifier):
return True
return False
def _is_ordering_expression(expression):
"""
Test an expression whether it is an ordering clause
"""
if hasattr(expression, 'operator') and is_ordering_modifier(expression.operator):
return True
if hasattr(expression, 'modifier') and is_ordering_modifier(expression.modifier):
return True
return False
def unwrap_order_by(clause):
"""Break up an 'order by' expression into individual column-expressions,
without DESC/ASC/NULLS FIRST/NULLS LAST"""
cols = util.column_set()
stack = deque([clause])
while stack:
t = stack.popleft()
if isinstance(t, expression.ColumnElement) and (
not isinstance(t, expression._UnaryExpression) or not operators.is_ordering_modifier(t.modifier)
):
cols.add(t)
else:
for c in t.get_children():
stack.append(c)
return cols
def unwrap_order_by(clause):
"""Break up an 'order by' expression into individual column-expressions,
without DESC/ASC/NULLS FIRST/NULLS LAST"""
cols = util.column_set()
stack = deque([clause])
while stack:
t = stack.popleft()
if isinstance(t, expression.ColumnElement) and \
(
not isinstance(t, expression._UnaryExpression) or \
not operators.is_ordering_modifier(t.modifier)
):
cols.add(t)
else:
for c in t.get_children():
stack.append(c)
return cols