def make_demand_query(symtab, query, left_clauses):
"""Create a demand query, update the query's demand_query attribute,
and return the new demand query symbol.
"""
ct = symtab.clausetools
demquery_name = N.get_query_demand_query_name(query.name)
demquery_tuple = L.tuplify(query.demand_params)
demquery_tuple_type = symtab.analyze_expr_type(demquery_tuple)
demquery_type = T.Set(demquery_tuple_type)
demquery_comp = L.Comp(demquery_tuple, left_clauses)
prefix = next(symtab.fresh_names.vars)
demquery_comp = ct.comp_rename_lhs_vars(demquery_comp,
lambda x: prefix + x)
demquery_sym = symtab.define_query(demquery_name,
type=demquery_type,
node=demquery_comp,
impl=query.impl)
query.demand_query = demquery_name
return demquery_sym
def make_comp(self, struct):
"""Return the Comp node corresponding to a structure."""
ct = self.symtab.clausetools
resname = N.get_resultset_name
if isinstance(struct, Filter):
filter = struct
vars = ct.lhs_vars(filter.clause)
pred_clauses = []
for t in filter.preds:
tag = self.tags_by_name[t]
pred_cl = L.RelMember([tag.tag_var], resname(tag.name))
pred_clauses.append(pred_cl)
return L.Comp(L.tuplify(vars), pred_clauses + [filter.clause])
elif isinstance(struct, Tag):
tag = struct
return L.Comp(L.tuplify([tag.tag_var]), [tag.clause])
else:
assert ()
def make_join_from_clauses(self, clauses):
"""Create a join from the given clauses."""
lhs_vars = self.lhs_vars_from_clauses(clauses)
resexp = L.tuplify(lhs_vars)
return L.Comp(resexp, clauses)
