Current File : //lib/python3/dist-packages/pythran/transformations/unshadow_parameters.py
"""
UnshadowParameters prevents the shadow parameter phenomenon
"""
from pythran.analyses import Identifiers
from pythran.passmanager import Transformation
import gast as ast
class UnshadowParameters(Transformation):
'''
Prevents parameter shadowing by creating new variable.
>>> import gast as ast
>>> from pythran import passmanager, backend
>>> node = ast.parse("def foo(a): a = 1")
>>> pm = passmanager.PassManager("test")
>>> _, node = pm.apply(UnshadowParameters, node)
>>> print(pm.dump(backend.Python, node))
def foo(a):
a_ = a
a_ = 1
'''
def __init__(self):
Transformation.__init__(self, Identifiers)
def visit_FunctionDef(self, node):
self.argsid = {arg.id for arg in node.args.args}
self.renaming = {}
[self.visit(n) for n in node.body]
# do it twice to make sure all renaming are done
[self.visit(n) for n in node.body]
for k, v in self.renaming.items():
node.body.insert(
0,
ast.Assign(
[ast.Name(v, ast.Store(), None, None)],
ast.Name(k, ast.Load(), None, None),
None)
)
self.update |= bool(self.renaming)
return node
def update_name(self, node):
if isinstance(node, ast.Name) and node.id in self.argsid:
if node.id not in self.renaming:
new_name = node.id
while new_name in self.identifiers:
new_name = new_name + "_"
self.renaming[node.id] = new_name
def visit_Assign(self, node):
for target in node.targets:
self.update_name(target)
try:
self.generic_visit(node)
except AttributeError:
pass
return node
def visit_AugAssign(self, node):
self.update_name(node.target)
return self.generic_visit(node)
def visit_Name(self, node):
if node.id in self.renaming:
node.id = self.renaming[node.id]
return node
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