Mercurial > hg
view mercurial/policy.py @ 33822:42ad7cc645a4
copies: add more details to the documentation of mergecopies()
This documentation is very helpful for any developer to understand what
copytracing is and what the function does. Since this is the main function of
doing copytracing, I have also included bits about copytracing in it.
This additions are picked from a doc by Stash@Fb. So thanks to him.
Differential Revision: https://phab.mercurial-scm.org/D409
author | Pulkit Goyal <7895pulkit@gmail.com> |
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date | Wed, 16 Aug 2017 00:25:20 +0530 |
parents | f5fc54e7e467 |
children | 2c37f9dabc32 |
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# policy.py - module policy logic for Mercurial. # # 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 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, fall back to the pure modules so the in-place build can # run without recompiling the C extensions. This will be overridden by # __modulepolicy__ generated by setup.py. policy = b'allow' _packageprefs = { # policy: (versioned package, pure package) b'c': (r'cext', None), b'allow': (r'cext', r'pure'), b'cffi': (r'cffi', None), b'cffi-allow': (r'cffi', r'pure'), b'py': (None, r'pure'), } 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 r'__pypy__' in sys.builtin_module_names: policy = b'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 r'HGMODULEPOLICY' in os.environ: policy = os.environ[r'HGMODULEPOLICY'].encode(r'utf-8') else: policy = os.environ.get(r'HGMODULEPOLICY', policy) def _importfrom(pkgname, modname): # from .<pkgname> import <modname> (where . is looked through this module) fakelocals = {} pkg = __import__(pkgname, globals(), fakelocals, [modname], level=1) try: fakelocals[modname] = mod = getattr(pkg, modname) except AttributeError: raise ImportError(r'cannot import name %s' % modname) # force import; fakelocals[modname] may be replaced with the real module getattr(mod, r'__doc__', None) return fakelocals[modname] # keep in sync with "version" in C modules _cextversions = { (r'cext', r'base85'): 1, (r'cext', r'bdiff'): 1, (r'cext', r'diffhelpers'): 1, (r'cext', r'mpatch'): 1, (r'cext', r'osutil'): 1, (r'cext', r'parsers'): 1, } # map import request to other package or module _modredirects = { (r'cext', r'charencode'): (r'cext', r'parsers'), (r'cffi', r'base85'): (r'pure', r'base85'), (r'cffi', r'charencode'): (r'pure', r'charencode'), (r'cffi', r'diffhelpers'): (r'pure', r'diffhelpers'), (r'cffi', r'parsers'): (r'pure', r'parsers'), } def _checkmod(pkgname, modname, mod): expected = _cextversions.get((pkgname, modname)) actual = getattr(mod, r'version', None) if actual != expected: raise ImportError(r'cannot import module %s.%s ' r'(expected version: %d, actual: %r)' % (pkgname, modname, expected, actual)) def importmod(modname): """Import module according to policy and check API version""" try: verpkg, purepkg = _packageprefs[policy] except KeyError: raise ImportError(r'invalid HGMODULEPOLICY %r' % policy) assert verpkg or purepkg if verpkg: pn, mn = _modredirects.get((verpkg, modname), (verpkg, modname)) try: mod = _importfrom(pn, mn) if pn == verpkg: _checkmod(pn, mn, mod) return mod except ImportError: if not purepkg: raise pn, mn = _modredirects.get((purepkg, modname), (purepkg, modname)) return _importfrom(pn, mn)