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from typed_ast import ast27
from typed_ast import ast3
def py2to3(ast):
"""Converts a typed Python 2.7 ast to a typed Python 3.5 ast. The returned
ast is a valid Python 3 ast with two exceptions:
- `arg` objects may contain Tuple objects instead of just identifiers
in the case of Python 2 function definitions/lambdas that use the tuple
unpacking syntax.
- `Raise` objects will have a `traceback` attribute added if the 3
argument version of the Python 2 raise is used.
Strange and Rare Uncovered Edge Cases:
- Raise: if the second argument to a raise statement is a tuple, its
contents are unpacked as arguments to the exception constructor. This
case is handled correctly if it's a literal tuple, but not if it's any
other sort of tuple expression.
"""
return _AST2To3().visit(ast)
def _copy_attributes(new_value, old_value):
attrs = getattr(old_value, '_attributes', None)
if attrs is not None:
for attr in attrs:
setattr(new_value, attr, getattr(old_value, attr))
return new_value
class _AST2To3(ast27.NodeTransformer):
# note: None, True, and False are *not* translated into NameConstants.
def __init__(self):
pass
def visit(self, node):
"""Visit a node."""
method = 'visit_' + node.__class__.__name__
visitor = getattr(self, method, self.generic_visit)
ret = _copy_attributes(visitor(node), node)
return ret
def maybe_visit(self, node):
if node is not None:
return self.visit(node)
else:
return None
def generic_visit(self, node):
class_name = node.__class__.__name__
converted_class = getattr(ast3, class_name)
new_node = converted_class()
for field, old_value in ast27.iter_fields(node):
if isinstance(old_value, (ast27.AST, list)):
setattr(new_node, field, self.visit(old_value))
else:
setattr(new_node, field, old_value)
return new_node
def visit_list(self, l):
return [self.visit(e) if isinstance(e, (ast27.AST, list)) else e for e in l]
def visit_FunctionDef(self, n):
new = self.generic_visit(n)
new.returns = None
return new
def visit_ClassDef(self, n):
new = self.generic_visit(n)
new.keywords = []
return new
def visit_TryExcept(self, n):
return ast3.Try(self.visit(n.body),
self.visit(n.handlers),
self.visit(n.orelse),
[])
def visit_TryFinally(self, n):
if len(n.body) == 1 and isinstance(n.body[0], ast27.TryExcept):
new = self.visit(n.body[0])
new.finalbody = self.visit(n.finalbody)
return new
else:
return ast3.Try(self.visit(n.body),
[],
[],
self.visit(n.finalbody))
def visit_ExceptHandler(self, n):
if n.name is None:
name = None
elif isinstance(n.name, ast27.Name):
name = n.name.id
else:
raise RuntimeError("'{}' has non-Name name.".format(ast27.dump(n)))
return ast3.ExceptHandler(self.maybe_visit(n.type),
name,
self.visit(n.body))
def visit_Print(self, n):
keywords = []
if n.dest is not None:
keywords.append(ast3.keyword("file", self.visit(n.dest)))
if not n.nl:
keywords.append(ast3.keyword("end",
ast3.Str(s=" ", kind='', lineno=n.lineno, col_offset=-1)))
return ast3.Expr(ast3.Call(ast3.Name("print", ast3.Load(), lineno=n.lineno, col_offset=-1),
self.visit(n.values),
keywords,
lineno=n.lineno, col_offset=-1))
def visit_Raise(self, n):
e = None
if n.type is not None:
e = self.visit(n.type)
if n.inst is not None and not (isinstance(n.inst, ast27.Name) and n.inst.id == "None"):
inst = self.visit(n.inst)
if isinstance(inst, ast3.Tuple):
args = inst.elts
else:
args = [inst]
e = ast3.Call(e, args, [], lineno=e.lineno, col_offset=-1)
ret = ast3.Raise(e, None)
if n.tback is not None:
ret.traceback = self.visit(n.tback)
return ret
def visit_Exec(self, n):
new_globals = self.maybe_visit(n.globals)
if new_globals is None:
new_globals = ast3.Name("None", ast3.Load(), lineno=-1, col_offset=-1)
new_locals = self.maybe_visit(n.locals)
if new_locals is None:
new_locals = ast3.Name("None", ast3.Load(), lineno=-1, col_offset=-1)
return ast3.Expr(ast3.Call(ast3.Name("exec", ast3.Load(), lineno=n.lineno, col_offset=-1),
[self.visit(n.body), new_globals, new_locals],
[],
lineno=n.lineno, col_offset=-1))
# TODO(ddfisher): the name repr could be used locally as something else; disambiguate
def visit_Repr(self, n):
return ast3.Call(ast3.Name("repr", ast3.Load(), lineno=n.lineno, col_offset=-1),
[self.visit(n.value)],
[])
# TODO(ddfisher): this will cause strange behavior on multi-item with statements with type comments
def visit_With(self, n):
return ast3.With([ast3.withitem(self.visit(n.context_expr), self.maybe_visit(n.optional_vars))],
self.visit(n.body),
n.type_comment)
def visit_Call(self, n):
args = self.visit(n.args)
if n.starargs is not None:
args.append(ast3.Starred(self.visit(n.starargs), ast3.Load(), lineno=n.starargs.lineno, col_offset=n.starargs.col_offset))
keywords = self.visit(n.keywords)
if n.kwargs is not None:
keywords.append(ast3.keyword(None, self.visit(n.kwargs)))
return ast3.Call(self.visit(n.func),
args,
keywords)
# TODO(ddfisher): find better attributes to give Ellipses
def visit_Ellipsis(self, n):
# ellipses in Python 2 only exist as a slice index
return ast3.Index(ast3.Ellipsis(lineno=-1, col_offset=-1))
def visit_arguments(self, n):
def convert_arg(arg, type_comment):
if isinstance(arg, ast27.Name):
v = arg.id
elif isinstance(arg, ast27.Tuple):
v = self.visit(arg)
else:
raise RuntimeError("'{}' is not a valid argument.".format(ast27.dump(arg)))
return ast3.arg(v, None, type_comment, lineno=arg.lineno, col_offset=arg.col_offset)
def get_type_comment(i):
if i < len(n.type_comments) and n.type_comments[i] is not None:
return n.type_comments[i]
return None
args = [convert_arg(arg, get_type_comment(i)) for i, arg in enumerate(n.args)]
vararg = None
if n.vararg is not None:
vararg = ast3.arg(n.vararg,
None,
get_type_comment(len(args)),
lineno=-1, col_offset=-1)
kwarg = None
if n.kwarg is not None:
kwarg = ast3.arg(n.kwarg,
None,
get_type_comment(len(args) + (0 if n.vararg is None else 1)),
lineno=-1, col_offset=-1)
defaults = self.visit(n.defaults)
return ast3.arguments(args,
vararg,
[],
[],
kwarg,
defaults)
def visit_Str(self, s):
if isinstance(s.s, bytes):
return ast3.Bytes(s.s, s.kind)
else:
return ast3.Str(s.s, s.kind)
def visit_Num(self, n):
new = self.generic_visit(n)
if new.n < 0:
# Python 3 uses a unary - operator for negative literals.
new.n = -new.n
return ast3.UnaryOp(op=ast3.USub(),
operand=_copy_attributes(new, n))
else:
return new
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