def _compute_relation_steps(self, plan, rqlst, to_select):
"""handle the selection of relations for an insert query"""
eidconsts = _extract_eid_consts(plan, rqlst)
for edef, rdefs in to_select.items():
# create a select rql st to fetch needed data
select = Select()
eschema = edef.entity.e_schema
for i, (rtype, term, reverse) in enumerate(rdefs):
if getattr(term, 'variable', None) in eidconsts:
value = eidconsts[term.variable]
else:
select.append_selected(term.copy(select))
value = _FROM_SUBSTEP
if reverse:
rdefs[i] = (rtype, InsertRelationsStep.REVERSE_RELATION,
value)
else:
rschema = eschema.subjrels[rtype]
if rschema.final or rschema.inlined:
rdefs[i] = (rtype, InsertRelationsStep.FINAL, value)
else:
rdefs[i] = (rtype, InsertRelationsStep.RELATION, value)
step = InsertRelationsStep(plan, edef, rdefs)
select = _build_substep_query(select, rqlst)
if select is not None:
step.children += self._select_plan(plan, select,
rqlst.solutions)
yield step
def _sel_relation_steps(self, plan, rqlst, relation):
"""handle the selection of relations for a delete query"""
select = Select()
lhs, rhs = relation.get_variable_parts()
select.append_selected(lhs.copy(select))
select.append_selected(rhs.copy(select))
select.set_where(relation.copy(select))
if rqlst.where is not None:
select.add_restriction(rqlst.where.copy(select))
if getattr(rqlst, 'having', None):
select.set_having([x.copy(select) for x in rqlst.having])
return self._select_plan(plan, select, rqlst.solutions)
def union(self, R, _parent=None):
_context = self.Context(_parent, self._scanner, 'union', [R])
_token = self._peek('r"\\("', 'DISTINCT', 'E_TYPE', context=_context)
if _token != 'r"\\("':
select = self.select(Select(), _context)
R.append(select)
return R
else: # == 'r"\\("'
self._scan('r"\\("', context=_context)
select = self.select(Select(), _context)
self._scan('r"\\)"', context=_context)
R.append(select)
while self._peek('UNION', "';'", 'r"\\)"', context=_context) == 'UNION':
self._scan('UNION', context=_context)
self._scan('r"\\("', context=_context)
select = self.select(Select(), _context)
self._scan('r"\\)"', context=_context)
R.append(select)
return R
def build_set_plan(self, plan, rqlst):
"""get an execution plan from an SET RQL query"""
getrschema = self.schema.rschema
select = Select() # potential substep query
selectedidx = {} # local state
updatedefs = [] # definition of update attributes/relations
selidx = residx = 0 # substep selection / resulting rset indexes
# search for eid const in the WHERE clause
eidconsts = _extract_eid_consts(plan, rqlst)
# build `updatedefs` describing things to update and add necessary
# variables to the substep selection
for i, relation in enumerate(rqlst.main_relations):
if relation.r_type in VIRTUAL_RTYPES:
raise QueryError('can not assign to %r relation' %
relation.r_type)
lhs, rhs = relation.get_variable_parts()
lhskey = lhs.as_string()
if lhskey not in selectedidx:
if lhs.variable in eidconsts:
eid = eidconsts[lhs.variable]
lhsinfo = (_CONSTANT, eid, residx)
else:
select.append_selected(lhs.copy(select))
lhsinfo = (_FROM_SUBSTEP, selidx, residx)
selidx += 1
residx += 1
selectedidx[lhskey] = lhsinfo
else:
lhsinfo = selectedidx[lhskey][:-1] + (None, )
rhskey = rhs.as_string()
if rhskey not in selectedidx:
if isinstance(rhs, Constant):
rhsinfo = (_CONSTANT, rhs.eval(plan.args), residx)
elif getattr(rhs, 'variable', None) in eidconsts:
eid = eidconsts[rhs.variable]
rhsinfo = (_CONSTANT, eid, residx)
else:
select.append_selected(rhs.copy(select))
rhsinfo = (_FROM_SUBSTEP, selidx, residx)
selidx += 1
residx += 1
selectedidx[rhskey] = rhsinfo
else:
rhsinfo = selectedidx[rhskey][:-1] + (None, )
rschema = getrschema(relation.r_type)
updatedefs.append((lhsinfo, rhsinfo, rschema))
# the update step
step = UpdateStep(plan, updatedefs)
# when necessary add substep to fetch yet unknown values
select = _build_substep_query(select, rqlst)
if select is not None:
# set distinct to avoid potential duplicate key error
select.distinct = True
step.children += self._select_plan(plan, select, rqlst.solutions)
return (step, )
def _sel_variable_step(self, plan, rqlst, etype, varref):
"""handle the selection of variables for a delete query"""
select = Select()
varref = varref.copy(select)
select.defined_vars = {varref.name: varref.variable}
select.append_selected(varref)
if rqlst.where is not None:
select.set_where(rqlst.where.copy(select))
if getattr(rqlst, 'having', None):
select.set_having([x.copy(select) for x in rqlst.having])
if etype != 'Any':
select.add_type_restriction(varref.variable, etype)
return self._select_plan(plan, select, rqlst.solutions)