[issue3218] 2to3 Fix_imports optimization

[Nick Edds]

New submission from Nick Edds <nedds at uchicago.edu>:

This is an optimization in pytree.py specifically for the bare_name
pattern from fix_imports.py. It also has the isinstance change I
previously suggested piggybacked onto it. Because the bare_name pattern
is so massive (764 nodes!), it is very slow to call _recursive_matches
on it. This fix has a special bare_name_matches fix that uses an
iterative matching solution specifically tailored to the bare_name
pattern. From preliminary testing, it appears to be roughly 25-30%
faster than the previous version of 2to3. If I uncomment the fix_imports
test, it fails 6 of them, but they are the same ones failed by the
current version of 2to3 and it fails them in the same way, so I think it
works. As with my previous isinstance chance, a one line change to
test_pytree is required.

----------
assignee: collinwinter
components: 2to3 (2.x to 3.0 conversion tool)
files: pytree.py
messages: 68840
nosy: collinwinter, nedds
severity: normal
status: open
title: 2to3 Fix_imports optimization
type: performance
Added file: http://bugs.python.org/file10751/pytree.py

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue3218>
_______________________________________