def select(self, name, columns, where):
results = ResultsTable(name, columns)
for row in self.rows:
match = True
if where:
ctx = RqlContext()
ctx.variables.update(row)
match = ctx.evaluate(where.predicate)
if match:
results.insert([row[field] for field in columns])
return results
def Select(self, stmt):
alias_map = {}
alias_rmap = {}
# Extract the tables to scan
source_tables = set()
tables = {}
for source in stmt.get_data_sources():
if source.query:
name = source.alias or str(source.query)
tables[name] = Select(source.query)
else:
name = source.name.name
source_tables.add(name)
tables[name] = self.tables[name]
if source.alias:
alias_map[source.alias] = name
alias_rmap[name] = source.aliases
# Map where-clauses result-fields to tables
expr_fields = []
table_results_map = defaultdict(list)
for index, result in enumerate(stmt.results):
if isinstance(result, SqlColumnWild):
for source in source_tables:
table_results_map[source].extend(alias_map.get(k, k) for k in self.tables[source].columns)
elif isinstance(result, SqlTableWild):
table_results_map[result.table].extend(alias_map.get(k, k) for k in self.tables[source].columns)
elif isinstance(result.expr, RqlIdentifier):
field_name = result.expr.name
index = field_name.rfind('.')
if index > 0:
source = field_name[:index]
field_name = field_name[1+index:]
table_results_map[source].append(field_name)
else:
for source in source_tables:
table = self.tables[source]
if field_name in table.columns:
table_results_map[source].append(field_name)
break
# TODO: Extract where clause for the field
else:
# TODO: Expr may contains references to a table
expr_fields.append((index, result))
if result.alias:
name = str(result.expr)
alias_map[result.alias] = name
alias_rmap[name] = result.alias
# Scan each source
results = []
for source, fields in table_results_map.iteritems():
result = self.tables[source].select(source, fields, stmt.where)
results.append(result)
# Join and apply where-clauses
if len(results) > 1:
results = list(reversed(results))
# TODO: Apply the proper join...
while len(results) >= 2:
res_a = results.pop()
res_b = results.pop()
join_result = cross_join(res_a, res_b)
results.append(join_result)
results = results[0]
if expr_fields:
for row in results.rows:
new_values = []
for index, field in expr_fields:
ctx = RqlContext()
ctx.variables.update(dict(zip(results.columns, row)))
ctx.variables.update({alias_map.get(k, k): v for k, v in zip(results.columns, row)})
value = ctx.evaluate(field.expr)
new_values.append((index, value))
for index, value in new_values:
row.insert(index, value)
for index, field in expr_fields:
results.columns.insert(index, str(field.expr))
# Replace column names with the alias
# blah.. move up to the result_table.aliases
results.columns = [alias_map.get(name, name) for name in results.columns]
if stmt.group_by:
key = stmt.group_by.groups[0].name
results = group_by(results, key)
if stmt.order_by:
results.sort([(o.column, -1 if o.order_type == 'DESC' else 1) for o in stmt.order_by])
return results
def Insert(self, stmt):
table = self.tables[stmt.destination.name]
ctx = RqlContext()
table.insert({name: ctx.evaluate(expr) for name, expr in zip(stmt.columns, stmt.values)})
