--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/utils/diffutil.py	Thu Jun 28 16:11:13 2018 +0200
@@ -0,0 +1,107 @@
+# diffutil.py - utility functions related to diff and patch
+#
+# Copyright 2006 Brendan Cully <brendan@kublai.com>
+# Copyright 2007 Chris Mason <chris.mason@oracle.com>
+# Copyright 2018 Octobus <octobus@octobus.net>
+#
+# 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
+
+from ..i18n import _
+
+from .. import (
+    mdiff,
+    pycompat,
+)
+
+def diffallopts(ui, opts=None, untrusted=False, section='diff'):
+    '''return diffopts with all features supported and parsed'''
+    return difffeatureopts(ui, opts=opts, untrusted=untrusted, section=section,
+                           git=True, whitespace=True, formatchanging=True)
+
+diffopts = diffallopts
+
+def difffeatureopts(ui, opts=None, untrusted=False, section='diff', git=False,
+                    whitespace=False, formatchanging=False):
+    '''return diffopts with only opted-in features parsed
+
+    Features:
+    - git: git-style diffs
+    - whitespace: whitespace options like ignoreblanklines and ignorews
+    - formatchanging: options that will likely break or cause correctness issues
+      with most diff parsers
+    '''
+    def get(key, name=None, getter=ui.configbool, forceplain=None):
+        if opts:
+            v = opts.get(key)
+            # diffopts flags are either None-default (which is passed
+            # through unchanged, so we can identify unset values), or
+            # some other falsey default (eg --unified, which defaults
+            # to an empty string). We only want to override the config
+            # entries from hgrc with command line values if they
+            # appear to have been set, which is any truthy value,
+            # True, or False.
+            if v or isinstance(v, bool):
+                return v
+        if forceplain is not None and ui.plain():
+            return forceplain
+        return getter(section, name or key, untrusted=untrusted)
+
+    # core options, expected to be understood by every diff parser
+    buildopts = {
+        'nodates': get('nodates'),
+        'showfunc': get('show_function', 'showfunc'),
+        'context': get('unified', getter=ui.config),
+    }
+    buildopts['worddiff'] = ui.configbool('experimental', 'worddiff')
+    buildopts['xdiff'] = ui.configbool('experimental', 'xdiff')
+
+    if git:
+        buildopts['git'] = get('git')
+
+        # since this is in the experimental section, we need to call
+        # ui.configbool directory
+        buildopts['showsimilarity'] = ui.configbool('experimental',
+                                                    'extendedheader.similarity')
+
+        # need to inspect the ui object instead of using get() since we want to
+        # test for an int
+        hconf = ui.config('experimental', 'extendedheader.index')
+        if hconf is not None:
+            hlen = None
+            try:
+                # the hash config could be an integer (for length of hash) or a
+                # word (e.g. short, full, none)
+                hlen = int(hconf)
+                if hlen < 0 or hlen > 40:
+                    msg = _("invalid length for extendedheader.index: '%d'\n")
+                    ui.warn(msg % hlen)
+            except ValueError:
+                # default value
+                if hconf == 'short' or hconf == '':
+                    hlen = 12
+                elif hconf == 'full':
+                    hlen = 40
+                elif hconf != 'none':
+                    msg = _("invalid value for extendedheader.index: '%s'\n")
+                    ui.warn(msg % hconf)
+            finally:
+                buildopts['index'] = hlen
+
+    if whitespace:
+        buildopts['ignorews'] = get('ignore_all_space', 'ignorews')
+        buildopts['ignorewsamount'] = get('ignore_space_change',
+                                          'ignorewsamount')
+        buildopts['ignoreblanklines'] = get('ignore_blank_lines',
+                                            'ignoreblanklines')
+        buildopts['ignorewseol'] = get('ignore_space_at_eol', 'ignorewseol')
+    if formatchanging:
+        buildopts['text'] = opts and opts.get('text')
+        binary = None if opts is None else opts.get('binary')
+        buildopts['nobinary'] = (not binary if binary is not None
+                                 else get('nobinary', forceplain=False))
+        buildopts['noprefix'] = get('noprefix', forceplain=False)
+
+    return mdiff.diffopts(**pycompat.strkwargs(buildopts))