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# Copyright 2006 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Fixer for print.
Change:
"print" into "print()"
"print ..." into "print(...)"
"print(...)" not changed
"print ... ," into "print(..., end=' ')"
"print >>x, ..." into "print(..., file=x)"
No changes are applied if print_function is imported from __future__
"""
# Local imports
from lib2to3 import patcomp, pytree, fixer_base
from lib2to3.pgen2 import token
from lib2to3.fixer_util import Name, Call, Comma, String
# from libmodernize import add_future
parend_expr = patcomp.compile_pattern(
"""atom< '(' [arith_expr|atom|power|term|STRING|NAME] ')' >"""
)
class FixPrint(fixer_base.BaseFix):
BM_compatible = True
PATTERN = """
simple_stmt< any* bare='print' any* > | print_stmt
"""
def transform(self, node, results):
assert results
bare_print = results.get("bare")
if bare_print:
# Special-case print all by itself.
bare_print.replace(Call(Name(u"print"), [],
prefix=bare_print.prefix))
# The "from __future__ import print_function"" declaration is added
# by the fix_print_with_import fixer, so we skip it here.
# add_future(node, u'print_function')
return
assert node.children[0] == Name(u"print")
args = node.children[1:]
if len(args) == 1 and parend_expr.match(args[0]):
# We don't want to keep sticking parens around an
# already-parenthesised expression.
return
sep = end = file = None
if args and args[-1] == Comma():
args = args[:-1]
end = " "
if args and args[0] == pytree.Leaf(token.RIGHTSHIFT, u">>"):
assert len(args) >= 2
file = args[1].clone()
args = args[3:] # Strip a possible comma after the file expression
# Now synthesize a print(args, sep=..., end=..., file=...) node.
l_args = [arg.clone() for arg in args]
if l_args:
l_args[0].prefix = u""
if sep is not None or end is not None or file is not None:
if sep is not None:
self.add_kwarg(l_args, u"sep", String(repr(sep)))
if end is not None:
self.add_kwarg(l_args, u"end", String(repr(end)))
if file is not None:
self.add_kwarg(l_args, u"file", file)
n_stmt = Call(Name(u"print"), l_args)
n_stmt.prefix = node.prefix
# Note that there are corner cases where adding this future-import is
# incorrect, for example when the file also has a 'print ()' statement
# that was intended to print "()".
# add_future(node, u'print_function')
return n_stmt
def add_kwarg(self, l_nodes, s_kwd, n_expr):
# XXX All this prefix-setting may lose comments (though rarely)
n_expr.prefix = u""
n_argument = pytree.Node(self.syms.argument,
(Name(s_kwd),
pytree.Leaf(token.EQUAL, u"="),
n_expr))
if l_nodes:
l_nodes.append(Comma())
n_argument.prefix = u" "
l_nodes.append(n_argument)
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