def enterUpdateStmt(self):
self._actualFilter = UpdateManipulator(self.__alu)
def enterDeleteStmt(self):
self._actualFilter = DeleteManipulator(self.__alu)
class FilterVisitor(QueryVisitor):
'''
this will instantiate all filters on the streams
meaning
UPDATE DELETE
'''
def __init__(self, relations, alu):
'''
@param relations: a map of all known relations with name as key and the
relation itself as value.
@type relations: map<str, RelationProxy>
@param alu: the ALU to be used to operate.
@type alu: ALU
'''
super(FilterVisitor, self).__init__()
self._log = logging.getLogger(__name__+'.'+self.__class__.__name__)
self.__expr = ExpressionEvalBuilder(alu)
self.__logic = LogicBuilder(alu)
self.__rels = relations
self.__alu = alu
self._actualFilter = None # should the visit be considered.
self._actualRelName = None
self._actualSel = None
self._exprStack = None
def enterUpdateStmt(self):
self._actualFilter = UpdateManipulator(self.__alu)
def leaveUpdateStmt(self):
name = self._actualRelName
if not self.__rels.has_key(name):
raise IllegalCondition('update on unknown relation "%s"' % name)
self.__rels[name].addFilter(self._actualFilter)
self._actualFilter = None
self._actualRelName = None
self._actualSel = None
self._exprStack = None
def enterDeleteStmt(self):
self._actualFilter = DeleteManipulator(self.__alu)
def leaveDeleteStmt(self):
name = self._actualRelName
if not self.__rels.has_key(name):
raise IllegalCondition('delete on unknown relation "%s"' % name)
self.__rels[name].addFilter(self._actualFilter)
self._actualFilter = None
self._actualRelName = None
self._actualSel = None
self._exprStack = None
def setTargetRelation(self, name):
if self._actualFilter is not None:
self._actualRelName = name
def enterSelection(self):
if self._actualFilter is not None:
pass
def leaveSelection(self):
if self._actualFilter is not None:
self._actualFilter.setSelection(self.__logic.getResult())
def enterAlteration(self):
if self._actualFilter is not None:
self._exprStack = list()
def leaveAlteration(self):
if self._exprStack is not None:
path = self._exprStack[0]
expr = self._exprStack[1]
self._actualFilter.addAlteration(path, expr)
self._exprStack = None
def enterDrop(self):
self._exprStack = list()
def leaveDrop(self):
self._actualFilter.addRemoval(self._exprStack[0])
self._exprStack = None
def acceptLogic(self, logic):
if self._actualFilter is not None:
logic.walk(self.__logic)
def acceptExpression(self, expr):
if self._actualFilter is None:
return
if self._exprStack is None:
expr.walk(self.__expr)
else:
if len(self._exprStack)==0:
self._exprStack.append(expr)
else:
expr.walk(self.__expr)
self._exprStack.append(self.__expr.getResult())
