1 """Fixer for function definitions with tuple parameters.
2
3 def func(((a, b), c), d):
4 ...
5
6 ->
7
8 def func(x, d):
9 ((a, b), c) = x
10 ...
11
12 It will also support lambdas:
13
14 lambda (x, y): x + y -> lambda t: t[0] + t[1]
15
16 # The parens are a syntax error in Python 3
17 lambda (x): x + y -> lambda x: x + y
18 """
19 # Author: Collin Winter
20
21 # Local imports
22 from .. import pytree
23 from ..pgen2 import token
24 from .. import fixer_base
25 from ..fixer_util import Assign, Name, Newline, Number, Subscript, syms
26
27 def is_docstring(stmt):
28 return isinstance(stmt, pytree.Node) and \
29 stmt.children[0].type == token.STRING
30
31 class ESC[4;38;5;81mFixTupleParams(ESC[4;38;5;149mfixer_baseESC[4;38;5;149m.ESC[4;38;5;149mBaseFix):
32 run_order = 4 #use a lower order since lambda is part of other
33 #patterns
34 BM_compatible = True
35
36 PATTERN = """
37 funcdef< 'def' any parameters< '(' args=any ')' >
38 ['->' any] ':' suite=any+ >
39 |
40 lambda=
41 lambdef< 'lambda' args=vfpdef< '(' inner=any ')' >
42 ':' body=any
43 >
44 """
45
46 def transform(self, node, results):
47 if "lambda" in results:
48 return self.transform_lambda(node, results)
49
50 new_lines = []
51 suite = results["suite"]
52 args = results["args"]
53 # This crap is so "def foo(...): x = 5; y = 7" is handled correctly.
54 # TODO(cwinter): suite-cleanup
55 if suite[0].children[1].type == token.INDENT:
56 start = 2
57 indent = suite[0].children[1].value
58 end = Newline()
59 else:
60 start = 0
61 indent = "; "
62 end = pytree.Leaf(token.INDENT, "")
63
64 # We need access to self for new_name(), and making this a method
65 # doesn't feel right. Closing over self and new_lines makes the
66 # code below cleaner.
67 def handle_tuple(tuple_arg, add_prefix=False):
68 n = Name(self.new_name())
69 arg = tuple_arg.clone()
70 arg.prefix = ""
71 stmt = Assign(arg, n.clone())
72 if add_prefix:
73 n.prefix = " "
74 tuple_arg.replace(n)
75 new_lines.append(pytree.Node(syms.simple_stmt,
76 [stmt, end.clone()]))
77
78 if args.type == syms.tfpdef:
79 handle_tuple(args)
80 elif args.type == syms.typedargslist:
81 for i, arg in enumerate(args.children):
82 if arg.type == syms.tfpdef:
83 # Without add_prefix, the emitted code is correct,
84 # just ugly.
85 handle_tuple(arg, add_prefix=(i > 0))
86
87 if not new_lines:
88 return
89
90 # This isn't strictly necessary, but it plays nicely with other fixers.
91 # TODO(cwinter) get rid of this when children becomes a smart list
92 for line in new_lines:
93 line.parent = suite[0]
94
95 # TODO(cwinter) suite-cleanup
96 after = start
97 if start == 0:
98 new_lines[0].prefix = " "
99 elif is_docstring(suite[0].children[start]):
100 new_lines[0].prefix = indent
101 after = start + 1
102
103 for line in new_lines:
104 line.parent = suite[0]
105 suite[0].children[after:after] = new_lines
106 for i in range(after+1, after+len(new_lines)+1):
107 suite[0].children[i].prefix = indent
108 suite[0].changed()
109
110 def transform_lambda(self, node, results):
111 args = results["args"]
112 body = results["body"]
113 inner = simplify_args(results["inner"])
114
115 # Replace lambda ((((x)))): x with lambda x: x
116 if inner.type == token.NAME:
117 inner = inner.clone()
118 inner.prefix = " "
119 args.replace(inner)
120 return
121
122 params = find_params(args)
123 to_index = map_to_index(params)
124 tup_name = self.new_name(tuple_name(params))
125
126 new_param = Name(tup_name, prefix=" ")
127 args.replace(new_param.clone())
128 for n in body.post_order():
129 if n.type == token.NAME and n.value in to_index:
130 subscripts = [c.clone() for c in to_index[n.value]]
131 new = pytree.Node(syms.power,
132 [new_param.clone()] + subscripts)
133 new.prefix = n.prefix
134 n.replace(new)
135
136
137 ### Helper functions for transform_lambda()
138
139 def simplify_args(node):
140 if node.type in (syms.vfplist, token.NAME):
141 return node
142 elif node.type == syms.vfpdef:
143 # These look like vfpdef< '(' x ')' > where x is NAME
144 # or another vfpdef instance (leading to recursion).
145 while node.type == syms.vfpdef:
146 node = node.children[1]
147 return node
148 raise RuntimeError("Received unexpected node %s" % node)
149
150 def find_params(node):
151 if node.type == syms.vfpdef:
152 return find_params(node.children[1])
153 elif node.type == token.NAME:
154 return node.value
155 return [find_params(c) for c in node.children if c.type != token.COMMA]
156
157 def map_to_index(param_list, prefix=[], d=None):
158 if d is None:
159 d = {}
160 for i, obj in enumerate(param_list):
161 trailer = [Subscript(Number(str(i)))]
162 if isinstance(obj, list):
163 map_to_index(obj, trailer, d=d)
164 else:
165 d[obj] = prefix + trailer
166 return d
167
168 def tuple_name(param_list):
169 l = []
170 for obj in param_list:
171 if isinstance(obj, list):
172 l.append(tuple_name(obj))
173 else:
174 l.append(obj)
175 return "_".join(l)