"""
For the ``future`` package.
Adds this import line:
from __future__ import division
at the top and changes any old-style divisions to be calls to
past.utils.old_div so the code runs as before on Py2.6/2.7 and has the same
behaviour on Py3.
If "from __future__ import division" is already in effect, this fixer does
nothing.
"""
import re
from lib2to3.fixer_util import Leaf, Node, Comma
from lib2to3 import fixer_base
from libfuturize.fixer_util import (token, future_import, touch_import_top,
wrap_in_fn_call)
def match_division(node):
u"""
__future__.division redefines the meaning of a single slash for division,
so we match that and only that.
"""
slash = token.SLASH
return node.type == slash and not node.next_sibling.type == slash and \
not node.prev_sibling.type == slash
const_re = re.compile('^[0-9]*[.][0-9]*$')
def is_floaty(node):
return _is_floaty(node.prev_sibling) or _is_floaty(node.next_sibling)
def _is_floaty(expr):
if isinstance(expr, list):
expr = expr[0]
if isinstance(expr, Leaf):
# If it's a leaf, let's see if it's a numeric constant containing a '.'
return const_re.match(expr.value)
elif isinstance(expr, Node):
# If the expression is a node, let's see if it's a direct cast to float
if isinstance(expr.children[0], Leaf):
return expr.children[0].value == u'float'
return False
class FixDivisionSafe(fixer_base.BaseFix):
# BM_compatible = True
run_order = 4 # this seems to be ignored?
_accept_type = token.SLASH
PATTERN = """
term<(not('/') any)+ '/' ((not('/') any))>
"""
def start_tree(self, tree, name):
"""
Skip this fixer if "__future__.division" is already imported.
"""
super(FixDivisionSafe, self).start_tree(tree, name)
self.skip = "division" in tree.future_features
def match(self, node):
u"""
Since the tree needs to be fixed once and only once if and only if it
matches, we can start discarding matches after the first.
"""
if node.type == self.syms.term:
matched = False
skip = False
children = []
for child in node.children:
if skip:
skip = False
continue
if match_division(child) and not is_floaty(child):
matched = True
# Strip any leading space for the first number:
children[0].prefix = u''
children = [wrap_in_fn_call("old_div",
children + [Comma(), child.next_sibling.clone()],
prefix=node.prefix)]
skip = True
else:
children.append(child.clone())
if matched:
# In Python 2.6, `Node` does not have the fixers_applied attribute
# https://github.com/python/cpython/blob/8493c0cd66cfc181ac1517268a74f077e9998701/Lib/lib2to3/pytree.py#L235
if hasattr(Node, "fixers_applied"):
return Node(node.type, children, fixers_applied=node.fixers_applied)
else:
return Node(node.type, children)
return False
def transform(self, node, results):
if self.skip:
return
future_import(u"division", node)
touch_import_top(u'past.utils', u'old_div', node)
return results
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