contrib/check-py3-compat.py

hgweb: use strict equals, remove non-breaking space in followlines.js

The first hunk had a non-breaking space character just before "{", it's not an
error or anything, but let's fix it while we're at it. (This corresponds to
"nonbsp" option of jshint).

Hunks 2 and 3 change "==" (equals operator) to "===" (strict equals operator).
The difference between them is that the latter doesn't do any type coercions.
It's handy to compare string '1' to number 1 sometimes, but most of the time
using "==" is inadvertent and can be replaced by an explicit type conversion.
(This corresponds to "eqeqeq" option of jshint).

Most of this file already uses strict equals operator, and in the code affected
type coercion is not needed, because tagName and selectableTag are both strings
and endId and startId are both numbers.

#!/usr/bin/env python
#
# check-py3-compat - check Python 3 compatibility of Mercurial files
#
# Copyright 2015 Gregory Szorc <[e-mail]>
#
# 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

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 |= set(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)
    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:
        fn = check_compat_py3

    for f in sys.argv[1:]:
        fn(f)

    sys.exit(0)