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""" NormalizeIsNone detects is None patterns. """
from pythran.passmanager import Transformation
from pythran.analyses import Ancestors
from pythran.syntax import PythranSyntaxError
from functools import reduce
import gast as ast
def is_none(expr):
# py3
if isinstance(expr, ast.Constant) and expr.value is None:
return True
# py2
if not isinstance(expr, ast.Attribute):
return False
return expr.attr == "None"
def is_is_none(expr):
if not isinstance(expr, ast.Compare):
return None
if len(expr.ops) != 1:
exprs = [expr.left] + expr.comparators
if any(is_none(expr) for expr in exprs):
raise PythranSyntaxError("is None in complex condition", expr)
return None
if not isinstance(expr.ops[0], (ast.Eq, ast.Is)):
return None
if is_none(expr.left):
return expr.comparators[0]
if is_none(expr.comparators[0]):
return expr.left
return None
def is_is_not_none(expr):
if not isinstance(expr, ast.Compare):
return None
if len(expr.ops) != 1:
exprs = [expr.left] + expr.comparators
if any(is_none(expr) for expr in exprs):
raise PythranSyntaxError("is None in complex condition", expr)
return None
if not isinstance(expr.ops[0], (ast.NotEq, ast.IsNot)):
return None
if is_none(expr.left):
return expr.comparators[0]
if is_none(expr.comparators[0]):
return expr.left
return None
class NormalizeIsNone(Transformation):
table = {ast.And: ast.BitAnd, ast.Or: ast.BitOr}
def __init__(self):
super(NormalizeIsNone, self).__init__(Ancestors)
@staticmethod
def match_is_none(node):
noned_var = is_is_none(node)
if noned_var is None:
noned_var = is_is_not_none(node)
negated = noned_var is not None
else:
negated = False
return noned_var, negated
def visit_BoolOp(self, node):
values = list(node.values)
self.generic_visit(node)
if any(x != y for x, y in zip(values, node.values)):
self.update = True
expr = reduce(lambda x, y:
ast.BinOp(x,
NormalizeIsNone.table[type(node.op)](), y),
node.values)
return expr
else:
return node
def visit_Compare(self, node):
self.generic_visit(node)
noned_var, negated = self.match_is_none(node)
if noned_var is None:
return node
call = ast.Call(
ast.Attribute(
ast.Attribute(
ast.Name('builtins', ast.Load(), None, None),
'pythran',
ast.Load()
),
'is_none',
ast.Load()),
[noned_var], [])
self.update = True
if negated:
return ast.UnaryOp(ast.Not(), call)
else:
return call
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