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""" NormalizeIfElse transform early exit in if into if-else. """
from pythran.analyses import Ancestors
from pythran.passmanager import Transformation
import gast as ast
class NormalizeIfElse(Transformation):
'''
>>> import gast as ast
>>> from pythran import passmanager, backend
>>> node = ast.parse("""
... def foo(y):
... if y: return 1
... return 2""")
>>> pm = passmanager.PassManager("test")
>>> _, node = pm.apply(NormalizeIfElse, node)
>>> print(pm.dump(backend.Python, node))
def foo(y):
if y:
return 1
else:
return 2
>>> node = ast.parse("""
... def foo(y):
... if y:
... z = y + 1
... if z:
... return 1
... else:
... return 3
... return 2""")
>>> pm = passmanager.PassManager("test")
>>> _, node = pm.apply(NormalizeIfElse, node)
>>> print(pm.dump(backend.Python, node))
def foo(y):
if y:
z = (y + 1)
if z:
return 1
else:
return 3
else:
return 2
'''
def __init__(self):
super(NormalizeIfElse, self).__init__(Ancestors)
def check_lasts(self, node):
if isinstance(node, (ast.Return, ast.Break, ast.Return)):
return True
if isinstance(node, ast.If):
if not self.check_lasts(node.body[-1]):
return False
return node.orelse and self.check_lasts(node.orelse[-1])
def visit_If(self, node):
self.generic_visit(node)
if not self.check_lasts(node.body[-1]):
return node
parent = self.ancestors[node][-1]
for attr in ('body', 'orelse', 'finalbody'):
try:
body = getattr(parent, attr)
index = body.index(node)
if index == len(body) - 1:
return node
if not node.orelse:
node.orelse = []
node.orelse.extend(body[index + 1:])
body[index + 1:] = []
self.update = True
return node
except ValueError:
continue
except AttributeError:
continue
return node
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