"""Fixer for function definitions with tuple parameters.
def func(((a, b), c), d):
...
->
def func(x, d):
((a, b), c) = x
...
It will also support lambdas:
lambda (x, y): x + y -> lambda t: t[0] + t[1]
# The parens are a syntax error in Python 3
lambda (x): x + y -> lambda x: x + y
"""
# Author: Collin Winter
# Local imports
from .. import pytree
from ..pgen2 import token
from .. import fixer_base
from ..fixer_util import Assign,Name,Newline,Number,Subscript,syms
def is_docstring(stmt):
return isinstance(stmt, pytree.Node) and \
stmt.children[0].type == token.STRING
class FixTupleParams(fixer_base.BaseFix):
PATTERN = """
funcdef< 'def' any parameters< '(' args=any ')' >
['->' any] ':' suite=any+ >
|
lambda=
lambdef< 'lambda' args=vfpdef< '(' inner=any ')' >
':' body=any
>
"""
def transform(self, node, results):
if "lambda" in results:
return self.transform_lambda(node, results)
new_lines = []
suite = results["suite"]
args = results["args"]
# This crap is so "def foo(...): x = 5; y = 7" is handled correctly.
# TODO(cwinter): suite-cleanup
if suite[0].children[1].type == token.INDENT:
start = 2
indent = suite[0].children[1].value
end = Newline()
else:
start = 0
indent = "; "
end = pytree.Leaf(token.INDENT, "")
# We need access to self for new_name(), and making this a method
# doesn't feel right. Closing over self and new_lines makes the
# code below cleaner.
def handle_tuple(tuple_arg, add_prefix=False):
n = Name(self.new_name())
arg = tuple_arg.clone()
arg.prefix = ""
stmt = Assign(arg, n.clone())
if add_prefix:
n.prefix = " "
tuple_arg.replace(n)
new_lines.append(pytree.Node(syms.simple_stmt,
[stmt, end.clone()]))
if args.type == syms.tfpdef:
handle_tuple(args)
elif args.type == syms.typedargslist:
for i, arg in enumerate(args.children):
if arg.type == syms.tfpdef:
# Without add_prefix, the emitted code is correct,
# just ugly.
handle_tuple(arg, add_prefix=(i > 0))
if not new_lines:
return
# This isn't strictly necessary, but it plays nicely with other fixers.
# TODO(cwinter) get rid of this when children becomes a smart list
for line in new_lines:
line.parent = suite[0]
# TODO(cwinter) suite-cleanup
after = start
if start == 0:
new_lines[0].prefix = " "
elif is_docstring(suite[0].children[start]):
new_lines[0].prefix = indent
after = start + 1
for line in new_lines:
line.parent = suite[0]
suite[0].children[after:after] = new_lines
for i in range(after+1, after+len(new_lines)+1):
suite[0].children[i].prefix = indent
suite[0].changed()
def transform_lambda(self, node, results):
args = results["args"]
body = results["body"]
inner = simplify_args(results["inner"])
# Replace lambda ((((x)))): x with lambda x: x
if inner.type == token.NAME:
inner = inner.clone()
inner.prefix = " "
args.replace(inner)
return
params = find_params(args)
to_index = map_to_index(params)
tup_name = self.new_name(tuple_name(params))
new_param = Name(tup_name, prefix=" ")
args.replace(new_param.clone())
for n in body.post_order():
if n.type == token.NAME and n.value in to_index:
subscripts = [c.clone() for c in to_index[n.value]]
new = pytree.Node(syms.power,
[new_param.clone()] + subscripts)
new.prefix = n.prefix
n.replace(new)
### Helper functions for transform_lambda()
def simplify_args(node):
if node.type in (syms.vfplist, token.NAME):
return node
elif node.type == syms.vfpdef:
# These look like vfpdef< '(' x ')' > where x is NAME
# or another vfpdef instance (leading to recursion).
while node.type == syms.vfpdef:
node = node.children[1]
return node
raise RuntimeError("Received unexpected node %s" % node)
def find_params(node):
if node.type == syms.vfpdef:
return find_params(node.children[1])
elif node.type == token.NAME:
return node.value
return [find_params(c) for c in node.children if c.type != token.COMMA]
def map_to_index(param_list, prefix=[], d=None):
if d is None:
d = {}
for i, obj in enumerate(param_list):
trailer = [Subscript(Number(i))]
if isinstance(obj, list):
map_to_index(obj, trailer, d=d)
else:
d[obj] = prefix + trailer
return d
def tuple_name(param_list):
l = []
for obj in param_list:
if isinstance(obj, list):
l.append(tuple_name(obj))
else:
l.append(obj)
return "_".join(l)
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