dirstate-tree: Add tree traversal/iteration
Like Python’s, Rust’s iterators are "external" in that they are driven
by a caller who calls a `next` method. This is as opposed to "internal"
iterators who drive themselves and call a callback for each item.
Writing an internal iterator traversing a tree is easy with recursion,
but internal iterators cannot rely on the call stack in that way,
they must save in an explicit object all state that they need to be
preserved across two `next` calls.
This algorithm uses a `Vec` as a stack that contains what would be
local variables on the call stack if we could use recursion.
Differential Revision: https://phab.mercurial-scm.org/D10370
#!/usr/bin/env python3
#
# check-py3-compat - check Python 3 compatibility of Mercurial files
#
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import, print_function
import ast
import importlib
import os
import sys
import traceback
import warnings
def check_compat_py2(f):
"""Check Python 3 compatibility for a file with Python 2"""
with open(f, 'rb') as fh:
content = fh.read()
root = ast.parse(content)
# Ignore empty files.
if not root.body:
return
futures = set()
haveprint = False
for node in ast.walk(root):
if isinstance(node, ast.ImportFrom):
if node.module == '__future__':
futures |= {n.name for n in node.names}
elif isinstance(node, ast.Print):
haveprint = True
if 'absolute_import' not in futures:
print('%s not using absolute_import' % f)
if haveprint and 'print_function' not in futures:
print('%s requires print_function' % f)
def check_compat_py3(f):
"""Check Python 3 compatibility of a file with Python 3."""
with open(f, 'rb') as fh:
content = fh.read()
try:
ast.parse(content, filename=f)
except SyntaxError as e:
print('%s: invalid syntax: %s' % (f, e))
return
# Try to import the module.
# For now we only support modules in packages because figuring out module
# paths for things not in a package can be confusing.
if f.startswith(
('hgdemandimport/', 'hgext/', 'mercurial/')
) and not f.endswith('__init__.py'):
assert f.endswith('.py')
name = f.replace('/', '.')[:-3]
try:
importlib.import_module(name)
except Exception as e:
exc_type, exc_value, tb = sys.exc_info()
# We walk the stack and ignore frames from our custom importer,
# import mechanisms, and stdlib modules. This kinda/sorta
# emulates CPython behavior in import.c while also attempting
# to pin blame on a Mercurial file.
for frame in reversed(traceback.extract_tb(tb)):
if frame.name == '_call_with_frames_removed':
continue
if 'importlib' in frame.filename:
continue
if 'mercurial/__init__.py' in frame.filename:
continue
if frame.filename.startswith(sys.prefix):
continue
break
if frame.filename:
filename = os.path.basename(frame.filename)
print(
'%s: error importing: <%s> %s (error at %s:%d)'
% (f, type(e).__name__, e, filename, frame.lineno)
)
else:
print(
'%s: error importing module: <%s> %s (line %d)'
% (f, type(e).__name__, e, frame.lineno)
)
if __name__ == '__main__':
if sys.version_info[0] == 2:
fn = check_compat_py2
else:
# check_compat_py3 will import every filename we specify as long as it
# starts with one of a few prefixes. It does this by converting
# specified filenames like 'mercurial/foo.py' to 'mercurial.foo' and
# importing that. When running standalone (not as part of a test), this
# means we actually import the installed versions, not the files we just
# specified. When running as test-check-py3-compat.t, we technically
# would import the correct paths, but it's cleaner to have both cases
# use the same import logic.
sys.path.insert(0, '.')
fn = check_compat_py3
for f in sys.argv[1:]:
with warnings.catch_warnings(record=True) as warns:
fn(f)
for w in warns:
print(
warnings.formatwarning(
w.message, w.category, w.filename, w.lineno
).rstrip()
)
sys.exit(0)