def preprocess_var_decls(tree):
"""Eliminate global variable declarations of the form
S = Set()
M = Map()
and return a list of pairs of variables names and type names (i.e.,
'Set' or 'Map').
"""
assert isinstance(tree, P.Module)
pat = P.Assign([P.Name(P.PatVar('_VAR'), P.Wildcard())],
P.Call(P.Name(P.PatVar('_KIND'), P.Load()), [], [], None,
None))
decls = OrderedSet()
body = []
changed = False
for stmt in tree.body:
match = P.match(pat, stmt)
if match is not None:
var, kind = match['_VAR'], match['_KIND']
if kind not in ['Set', 'Map']:
raise L.ProgramError(
'Unknown declaration initializer {}'.format(kind))
decls.add((var, kind))
changed = True
else:
body.append(stmt)
if changed:
tree = tree._replace(body=body)
return tree, list(decls)
def visit_Assign(self, node):
node = self.generic_visit(node)
# Translate multiple assignments as a single statement
# (e.g. "a = b = c") into sequential single assignments.
if len(node.targets) > 1:
stmts = []
values = list(node.targets) + [node.value]
for lhs, rhs in reversed(list(pairs(values))):
rhs_load = P.ContextSetter.run(rhs, P.Load)
stmts.append(P.Assign([lhs], rhs_load))
node = stmts
return node
