view mercurial/policy.py @ 31758:04ec317b8128

hgweb: expose a followlines UI in filerevision view

In filerevision view (/file/<rev>/<fname>) we add some event listeners on
mouse clicks of <span> elements in the <pre class="sourcelines"> block.
Those listeners will capture a range of lines selected between two mouse
clicks and a box inviting to follow the history of selected lines will then
show up. Selected lines (i.e. the block of lines) get a CSS class which make
them highlighted. Selection can be cancelled (and restarted) by either
clicking on the cancel ("x") button in the invite box or clicking on any other
source line. Also clicking twice on the same line will abort the selection and
reset event listeners to restart the process.

As a first step, this action is only advertised by the "cursor: cell" CSS rule
on source lines elements as any other mechanisms would make the code
significantly more complicated. This might be improved later.

All JavaScript code lives in a new "linerangelog.js" file, sourced in
filerevision template (only in "paper" style for now).

# policy.py - module policy logic for Mercurial.
#
# 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

import os
import sys

# Rules for how modules can be loaded. Values are:
#
#    c - require C extensions
#    allow - allow pure Python implementation when C loading fails
#    cffi - required cffi versions (implemented within pure module)
#    cffi-allow - allow pure Python implementation if cffi version is missing
#    py - only load pure Python modules
#
# By default, require the C extensions for performance reasons.
policy = b'c'
policynoc = (b'cffi', b'cffi-allow', b'py')
policynocffi = (b'c', b'py')

try:
    from . import __modulepolicy__
    policy = __modulepolicy__.modulepolicy
except ImportError:
    pass

# PyPy doesn't load C extensions.
#
# The canonical way to do this is to test platform.python_implementation().
# But we don't import platform and don't bloat for it here.
if '__pypy__' in sys.builtin_module_names:
    policy = 'cffi'

# Our C extensions aren't yet compatible with Python 3. So use pure Python
# on Python 3 for now.
if sys.version_info[0] >= 3:
    policy = b'py'

# Environment variable can always force settings.
if sys.version_info[0] >= 3:
    if 'HGMODULEPOLICY' in os.environ:
        policy = os.environ['HGMODULEPOLICY'].encode('utf-8')
else:
    policy = os.environ.get('HGMODULEPOLICY', policy)