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/Lib/lib2to3/fixes/fix_print.py

http://unladen-swallow.googlecode.com/
Python | 90 lines | 81 code | 2 blank | 7 comment | 7 complexity | 478786e57412307d598aee1a20595102 MD5 | raw file
 1# Copyright 2006 Google, Inc. All Rights Reserved.
 2# Licensed to PSF under a Contributor Agreement.
 3
 4"""Fixer for print.
 5
 6Change:
 7    'print'          into 'print()'
 8    'print ...'      into 'print(...)'
 9    'print ... ,'    into 'print(..., end=" ")'
10    'print >>x, ...' into 'print(..., file=x)'
11
12No changes are applied if print_function is imported from __future__
13
14"""
15
16# Local imports
17from .. import patcomp
18from .. import pytree
19from ..pgen2 import token
20from .. import fixer_base
21from ..fixer_util import Name, Call, Comma, String, is_tuple
22
23
24parend_expr = patcomp.compile_pattern(
25              """atom< '(' [atom|STRING|NAME] ')' >"""
26              )
27
28
29class FixPrint(fixer_base.ConditionalFix):
30
31    PATTERN = """
32              simple_stmt< any* bare='print' any* > | print_stmt
33              """
34
35    skip_on = '__future__.print_function'
36
37    def transform(self, node, results):
38        assert results
39
40        if self.should_skip(node):
41            return
42
43        bare_print = results.get("bare")
44
45        if bare_print:
46            # Special-case print all by itself
47            bare_print.replace(Call(Name("print"), [],
48                               prefix=bare_print.get_prefix()))
49            return
50        assert node.children[0] == Name("print")
51        args = node.children[1:]
52        if len(args) == 1 and parend_expr.match(args[0]):
53            # We don't want to keep sticking parens around an
54            # already-parenthesised expression.
55            return
56
57        sep = end = file = None
58        if args and args[-1] == Comma():
59            args = args[:-1]
60            end = " "
61        if args and args[0] == pytree.Leaf(token.RIGHTSHIFT, ">>"):
62            assert len(args) >= 2
63            file = args[1].clone()
64            args = args[3:] # Strip a possible comma after the file expression
65        # Now synthesize a print(args, sep=..., end=..., file=...) node.
66        l_args = [arg.clone() for arg in args]
67        if l_args:
68            l_args[0].set_prefix("")
69        if sep is not None or end is not None or file is not None:
70            if sep is not None:
71                self.add_kwarg(l_args, "sep", String(repr(sep)))
72            if end is not None:
73                self.add_kwarg(l_args, "end", String(repr(end)))
74            if file is not None:
75                self.add_kwarg(l_args, "file", file)
76        n_stmt = Call(Name("print"), l_args)
77        n_stmt.set_prefix(node.get_prefix())
78        return n_stmt
79
80    def add_kwarg(self, l_nodes, s_kwd, n_expr):
81        # XXX All this prefix-setting may lose comments (though rarely)
82        n_expr.set_prefix("")
83        n_argument = pytree.Node(self.syms.argument,
84                                 (Name(s_kwd),
85                                  pytree.Leaf(token.EQUAL, "="),
86                                  n_expr))
87        if l_nodes:
88            l_nodes.append(Comma())
89            n_argument.set_prefix(" ")
90        l_nodes.append(n_argument)