log: extract function that builds (revs, makefilematcher) from walkopts

"hg grep" and "hg churn" will use this interface.

mercurial/logcmdutil.py

@@ -1,1194 +1,1208
 # logcmdutil.py - utility for log-like commands
 #
 # Copyright 2005-2007 Matt Mackall <[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 itertools
 import os
 import posixpath
 
 from .i18n import _
 from .node import (
     nullid,
     wdirid,
     wdirrev,
 )
 
 from .thirdparty import attr
 
 from . import (
     dagop,
     error,
     formatter,
     graphmod,
     match as matchmod,
     mdiff,
     patch,
     pathutil,
     pycompat,
     revset,
     revsetlang,
     scmutil,
     smartset,
     templatekw,
     templater,
     util,
 )
 from .utils import (
     dateutil,
     stringutil,
 )
 
 
 if pycompat.TYPE_CHECKING:
     from typing import (
         Any,
+        Callable,
         Dict,
         List,
         Optional,
         Tuple,
     )
 
-    for t in (Any, Dict, List, Optional, Tuple):
+    for t in (Any, Callable, Dict, List, Optional, Tuple):
         assert t
 
 
 def getlimit(opts):
     """get the log limit according to option -l/--limit"""
     limit = opts.get(b'limit')
     if limit:
         try:
             limit = int(limit)
         except ValueError:
             raise error.Abort(_(b'limit must be a positive integer'))
         if limit <= 0:
             raise error.Abort(_(b'limit must be positive'))
     else:
         limit = None
     return limit
 
 
 def diffordiffstat(
     ui,
     repo,
     diffopts,
     ctx1,
     ctx2,
     match,
     changes=None,
     stat=False,
     fp=None,
     graphwidth=0,
     prefix=b'',
     root=b'',
     listsubrepos=False,
     hunksfilterfn=None,
 ):
     '''show diff or diffstat.'''
     if root:
         relroot = pathutil.canonpath(repo.root, repo.getcwd(), root)
     else:
         relroot = b''
     copysourcematch = None
 
     def compose(f, g):
         return lambda x: f(g(x))
 
     def pathfn(f):
         return posixpath.join(prefix, f)
 
     if relroot != b'':
         # XXX relative roots currently don't work if the root is within a
         # subrepo
         uipathfn = scmutil.getuipathfn(repo, legacyrelativevalue=True)
         uirelroot = uipathfn(pathfn(relroot))
         relroot += b'/'
         for matchroot in match.files():
             if not matchroot.startswith(relroot):
                 ui.warn(
                     _(b'warning: %s not inside relative root %s\n')
                     % (uipathfn(pathfn(matchroot)), uirelroot)
                 )
 
         relrootmatch = scmutil.match(ctx2, pats=[relroot], default=b'path')
         match = matchmod.intersectmatchers(match, relrootmatch)
         copysourcematch = relrootmatch
 
         checkroot = repo.ui.configbool(
             b'devel', b'all-warnings'
         ) or repo.ui.configbool(b'devel', b'check-relroot')
 
         def relrootpathfn(f):
             if checkroot and not f.startswith(relroot):
                 raise AssertionError(
                     b"file %s doesn't start with relroot %s" % (f, relroot)
                 )
             return f[len(relroot) :]
 
         pathfn = compose(relrootpathfn, pathfn)
 
     if stat:
         diffopts = diffopts.copy(context=0, noprefix=False)
         width = 80
         if not ui.plain():
             width = ui.termwidth() - graphwidth
         # If an explicit --root was given, don't respect ui.relative-paths
         if not relroot:
             pathfn = compose(scmutil.getuipathfn(repo), pathfn)
 
     chunks = ctx2.diff(
         ctx1,
         match,
         changes,
         opts=diffopts,
         pathfn=pathfn,
         copysourcematch=copysourcematch,
         hunksfilterfn=hunksfilterfn,
     )
 
     if fp is not None or ui.canwritewithoutlabels():
         out = fp or ui
         if stat:
             chunks = [patch.diffstat(util.iterlines(chunks), width=width)]
         for chunk in util.filechunkiter(util.chunkbuffer(chunks)):
             out.write(chunk)
     else:
         if stat:
             chunks = patch.diffstatui(util.iterlines(chunks), width=width)
         else:
             chunks = patch.difflabel(
                 lambda chunks, **kwargs: chunks, chunks, opts=diffopts
             )
         if ui.canbatchlabeledwrites():
 
             def gen():
                 for chunk, label in chunks:
                     yield ui.label(chunk, label=label)
 
             for chunk in util.filechunkiter(util.chunkbuffer(gen())):
                 ui.write(chunk)
         else:
             for chunk, label in chunks:
                 ui.write(chunk, label=label)
 
     node2 = ctx2.node()
     for subpath, sub in scmutil.itersubrepos(ctx1, ctx2):
         tempnode2 = node2
         try:
             if node2 is not None:
                 tempnode2 = ctx2.substate[subpath][1]
         except KeyError:
             # A subrepo that existed in node1 was deleted between node1 and
             # node2 (inclusive). Thus, ctx2's substate won't contain that
             # subpath. The best we can do is to ignore it.
             tempnode2 = None
         submatch = matchmod.subdirmatcher(subpath, match)
         subprefix = repo.wvfs.reljoin(prefix, subpath)
         if listsubrepos or match.exact(subpath) or any(submatch.files()):
             sub.diff(
                 ui,
                 diffopts,
                 tempnode2,
                 submatch,
                 changes=changes,
                 stat=stat,
                 fp=fp,
                 prefix=subprefix,
             )
 
 
 class changesetdiffer(object):
     """Generate diff of changeset with pre-configured filtering functions"""
 
     def _makefilematcher(self, ctx):
         return scmutil.matchall(ctx.repo())
 
     def _makehunksfilter(self, ctx):
         return None
 
     def showdiff(self, ui, ctx, diffopts, graphwidth=0, stat=False):
         diffordiffstat(
             ui,
             ctx.repo(),
             diffopts,
             ctx.p1(),
             ctx,
             match=self._makefilematcher(ctx),
             stat=stat,
             graphwidth=graphwidth,
             hunksfilterfn=self._makehunksfilter(ctx),
         )
 
 
 def changesetlabels(ctx):
     labels = [b'log.changeset', b'changeset.%s' % ctx.phasestr()]
     if ctx.obsolete():
         labels.append(b'changeset.obsolete')
     if ctx.isunstable():
         labels.append(b'changeset.unstable')
         for instability in ctx.instabilities():
             labels.append(b'instability.%s' % instability)
     return b' '.join(labels)
 
 
 class changesetprinter(object):
     '''show changeset information when templating not requested.'''
 
     def __init__(self, ui, repo, differ=None, diffopts=None, buffered=False):
         self.ui = ui
         self.repo = repo
         self.buffered = buffered
         self._differ = differ or changesetdiffer()
         self._diffopts = patch.diffallopts(ui, diffopts)
         self._includestat = diffopts and diffopts.get(b'stat')
         self._includediff = diffopts and diffopts.get(b'patch')
         self.header = {}
         self.hunk = {}
         self.lastheader = None
         self.footer = None
         self._columns = templatekw.getlogcolumns()
 
     def flush(self, ctx):
         rev = ctx.rev()
         if rev in self.header:
             h = self.header[rev]
             if h != self.lastheader:
                 self.lastheader = h
                 self.ui.write(h)
             del self.header[rev]
         if rev in self.hunk:
             self.ui.write(self.hunk[rev])
             del self.hunk[rev]
 
     def close(self):
         if self.footer:
             self.ui.write(self.footer)
 
     def show(self, ctx, copies=None, **props):
         props = pycompat.byteskwargs(props)
         if self.buffered:
             self.ui.pushbuffer(labeled=True)
             self._show(ctx, copies, props)
             self.hunk[ctx.rev()] = self.ui.popbuffer()
         else:
             self._show(ctx, copies, props)
 
     def _show(self, ctx, copies, props):
         '''show a single changeset or file revision'''
         changenode = ctx.node()
         graphwidth = props.get(b'graphwidth', 0)
 
         if self.ui.quiet:
             self.ui.write(
                 b"%s\n" % scmutil.formatchangeid(ctx), label=b'log.node'
             )
             return
 
         columns = self._columns
         self.ui.write(
             columns[b'changeset'] % scmutil.formatchangeid(ctx),
             label=changesetlabels(ctx),
         )
 
         # branches are shown first before any other names due to backwards
         # compatibility
         branch = ctx.branch()
         # don't show the default branch name
         if branch != b'default':
             self.ui.write(columns[b'branch'] % branch, label=b'log.branch')
 
         for nsname, ns in pycompat.iteritems(self.repo.names):
             # branches has special logic already handled above, so here we just
             # skip it
             if nsname == b'branches':
                 continue
             # we will use the templatename as the color name since those two
             # should be the same
             for name in ns.names(self.repo, changenode):
                 self.ui.write(ns.logfmt % name, label=b'log.%s' % ns.colorname)
         if self.ui.debugflag:
             self.ui.write(
                 columns[b'phase'] % ctx.phasestr(), label=b'log.phase'
             )
         for pctx in scmutil.meaningfulparents(self.repo, ctx):
             label = b'log.parent changeset.%s' % pctx.phasestr()
             self.ui.write(
                 columns[b'parent'] % scmutil.formatchangeid(pctx), label=label
             )
 
         if self.ui.debugflag:
             mnode = ctx.manifestnode()
             if mnode is None:
                 mnode = wdirid
                 mrev = wdirrev
             else:
                 mrev = self.repo.manifestlog.rev(mnode)
             self.ui.write(
                 columns[b'manifest']
                 % scmutil.formatrevnode(self.ui, mrev, mnode),
                 label=b'ui.debug log.manifest',
             )
         self.ui.write(columns[b'user'] % ctx.user(), label=b'log.user')
         self.ui.write(
             columns[b'date'] % dateutil.datestr(ctx.date()), label=b'log.date'
         )
 
         if ctx.isunstable():
             instabilities = ctx.instabilities()
             self.ui.write(
                 columns[b'instability'] % b', '.join(instabilities),
                 label=b'log.instability',
             )
 
         elif ctx.obsolete():
             self._showobsfate(ctx)
 
         self._exthook(ctx)
 
         if self.ui.debugflag:
             files = ctx.p1().status(ctx)
             for key, value in zip(
                 [b'files', b'files+', b'files-'],
                 [files.modified, files.added, files.removed],
             ):
                 if value:
                     self.ui.write(
                         columns[key] % b" ".join(value),
                         label=b'ui.debug log.files',
                     )
         elif ctx.files() and self.ui.verbose:
             self.ui.write(
                 columns[b'files'] % b" ".join(ctx.files()),
                 label=b'ui.note log.files',
             )
         if copies and self.ui.verbose:
             copies = [b'%s (%s)' % c for c in copies]
             self.ui.write(
                 columns[b'copies'] % b' '.join(copies),
                 label=b'ui.note log.copies',
             )
 
         extra = ctx.extra()
         if extra and self.ui.debugflag:
             for key, value in sorted(extra.items()):
                 self.ui.write(
                     columns[b'extra'] % (key, stringutil.escapestr(value)),
                     label=b'ui.debug log.extra',
                 )
 
         description = ctx.description().strip()
         if description:
             if self.ui.verbose:
                 self.ui.write(
                     _(b"description:\n"), label=b'ui.note log.description'
                 )
                 self.ui.write(description, label=b'ui.note log.description')
                 self.ui.write(b"\n\n")
             else:
                 self.ui.write(
                     columns[b'summary'] % description.splitlines()[0],
                     label=b'log.summary',
                 )
         self.ui.write(b"\n")
 
         self._showpatch(ctx, graphwidth)
 
     def _showobsfate(self, ctx):
         # TODO: do not depend on templater
         tres = formatter.templateresources(self.repo.ui, self.repo)
         t = formatter.maketemplater(
             self.repo.ui,
             b'{join(obsfate, "\n")}',
             defaults=templatekw.keywords,
             resources=tres,
         )
         obsfate = t.renderdefault({b'ctx': ctx}).splitlines()
 
         if obsfate:
             for obsfateline in obsfate:
                 self.ui.write(
                     self._columns[b'obsolete'] % obsfateline,
                     label=b'log.obsfate',
                 )
 
     def _exthook(self, ctx):
         '''empty method used by extension as a hook point
         '''
 
     def _showpatch(self, ctx, graphwidth=0):
         if self._includestat:
             self._differ.showdiff(
                 self.ui, ctx, self._diffopts, graphwidth, stat=True
             )
         if self._includestat and self._includediff:
             self.ui.write(b"\n")
         if self._includediff:
             self._differ.showdiff(
                 self.ui, ctx, self._diffopts, graphwidth, stat=False
             )
         if self._includestat or self._includediff:
             self.ui.write(b"\n")
 
 
 class changesetformatter(changesetprinter):
     """Format changeset information by generic formatter"""
 
     def __init__(
         self, ui, repo, fm, differ=None, diffopts=None, buffered=False
     ):
         changesetprinter.__init__(self, ui, repo, differ, diffopts, buffered)
         self._diffopts = patch.difffeatureopts(ui, diffopts, git=True)
         self._fm = fm
 
     def close(self):
         self._fm.end()
 
     def _show(self, ctx, copies, props):
         '''show a single changeset or file revision'''
         fm = self._fm
         fm.startitem()
         fm.context(ctx=ctx)
         fm.data(rev=scmutil.intrev(ctx), node=fm.hexfunc(scmutil.binnode(ctx)))
 
         datahint = fm.datahint()
         if self.ui.quiet and not datahint:
             return
 
         fm.data(
             branch=ctx.branch(),
             phase=ctx.phasestr(),
             user=ctx.user(),
             date=fm.formatdate(ctx.date()),
             desc=ctx.description(),
             bookmarks=fm.formatlist(ctx.bookmarks(), name=b'bookmark'),
             tags=fm.formatlist(ctx.tags(), name=b'tag'),
             parents=fm.formatlist(
                 [fm.hexfunc(c.node()) for c in ctx.parents()], name=b'node'
             ),
         )
 
         if self.ui.debugflag or b'manifest' in datahint:
             fm.data(manifest=fm.hexfunc(ctx.manifestnode() or wdirid))
         if self.ui.debugflag or b'extra' in datahint:
             fm.data(extra=fm.formatdict(ctx.extra()))
 
         if (
             self.ui.debugflag
             or b'modified' in datahint
             or b'added' in datahint
             or b'removed' in datahint
         ):
             files = ctx.p1().status(ctx)
             fm.data(
                 modified=fm.formatlist(files.modified, name=b'file'),
                 added=fm.formatlist(files.added, name=b'file'),
                 removed=fm.formatlist(files.removed, name=b'file'),
             )
 
         verbose = not self.ui.debugflag and self.ui.verbose
         if verbose or b'files' in datahint:
             fm.data(files=fm.formatlist(ctx.files(), name=b'file'))
         if verbose and copies or b'copies' in datahint:
             fm.data(
                 copies=fm.formatdict(copies or {}, key=b'name', value=b'source')
             )
 
         if self._includestat or b'diffstat' in datahint:
             self.ui.pushbuffer()
             self._differ.showdiff(self.ui, ctx, self._diffopts, stat=True)
             fm.data(diffstat=self.ui.popbuffer())
         if self._includediff or b'diff' in datahint:
             self.ui.pushbuffer()
             self._differ.showdiff(self.ui, ctx, self._diffopts, stat=False)
             fm.data(diff=self.ui.popbuffer())
 
 
 class changesettemplater(changesetprinter):
     '''format changeset information.
 
     Note: there are a variety of convenience functions to build a
     changesettemplater for common cases. See functions such as:
     maketemplater, changesetdisplayer, buildcommittemplate, or other
     functions that use changesest_templater.
     '''
 
     # Arguments before "buffered" used to be positional. Consider not
     # adding/removing arguments before "buffered" to not break callers.
     def __init__(
         self, ui, repo, tmplspec, differ=None, diffopts=None, buffered=False
     ):
         changesetprinter.__init__(self, ui, repo, differ, diffopts, buffered)
         # tres is shared with _graphnodeformatter()
         self._tresources = tres = formatter.templateresources(ui, repo)
         self.t = formatter.loadtemplater(
             ui,
             tmplspec,
             defaults=templatekw.keywords,
             resources=tres,
             cache=templatekw.defaulttempl,
         )
         self._counter = itertools.count()
 
         self._tref = tmplspec.ref
         self._parts = {
             b'header': b'',
             b'footer': b'',
             tmplspec.ref: tmplspec.ref,
             b'docheader': b'',
             b'docfooter': b'',
             b'separator': b'',
         }
         if tmplspec.mapfile:
             # find correct templates for current mode, for backward
             # compatibility with 'log -v/-q/--debug' using a mapfile
             tmplmodes = [
                 (True, b''),
                 (self.ui.verbose, b'_verbose'),
                 (self.ui.quiet, b'_quiet'),
                 (self.ui.debugflag, b'_debug'),
             ]
             for mode, postfix in tmplmodes:
                 for t in self._parts:
                     cur = t + postfix
                     if mode and cur in self.t:
                         self._parts[t] = cur
         else:
             partnames = [p for p in self._parts.keys() if p != tmplspec.ref]
             m = formatter.templatepartsmap(tmplspec, self.t, partnames)
             self._parts.update(m)
 
         if self._parts[b'docheader']:
             self.ui.write(self.t.render(self._parts[b'docheader'], {}))
 
     def close(self):
         if self._parts[b'docfooter']:
             if not self.footer:
                 self.footer = b""
             self.footer += self.t.render(self._parts[b'docfooter'], {})
         return super(changesettemplater, self).close()
 
     def _show(self, ctx, copies, props):
         '''show a single changeset or file revision'''
         props = props.copy()
         props[b'ctx'] = ctx
         props[b'index'] = index = next(self._counter)
         props[b'revcache'] = {b'copies': copies}
         graphwidth = props.get(b'graphwidth', 0)
 
         # write separator, which wouldn't work well with the header part below
         # since there's inherently a conflict between header (across items) and
         # separator (per item)
         if self._parts[b'separator'] and index > 0:
             self.ui.write(self.t.render(self._parts[b'separator'], {}))
 
         # write header
         if self._parts[b'header']:
             h = self.t.render(self._parts[b'header'], props)
             if self.buffered:
                 self.header[ctx.rev()] = h
             else:
                 if self.lastheader != h:
                     self.lastheader = h
                     self.ui.write(h)
 
         # write changeset metadata, then patch if requested
         key = self._parts[self._tref]
         self.ui.write(self.t.render(key, props))
         self._exthook(ctx)
         self._showpatch(ctx, graphwidth)
 
         if self._parts[b'footer']:
             if not self.footer:
                 self.footer = self.t.render(self._parts[b'footer'], props)
 
 
 def templatespec(tmpl, mapfile):
     assert not (tmpl and mapfile)
     if mapfile:
         return formatter.mapfile_templatespec(b'changeset', mapfile)
     else:
         return formatter.literal_templatespec(tmpl)
 
 
 def _lookuptemplate(ui, tmpl, style):
     """Find the template matching the given template spec or style
 
     See formatter.lookuptemplate() for details.
     """
 
     # ui settings
     if not tmpl and not style:  # template are stronger than style
         tmpl = ui.config(b'ui', b'logtemplate')
         if tmpl:
             return formatter.literal_templatespec(templater.unquotestring(tmpl))
         else:
             style = util.expandpath(ui.config(b'ui', b'style'))
 
     if not tmpl and style:
         mapfile = style
         fp = None
         if not os.path.split(mapfile)[0]:
             (mapname, fp) = templater.try_open_template(
                 b'map-cmdline.' + mapfile
             ) or templater.try_open_template(mapfile)
             if mapname:
                 mapfile = mapname
         return formatter.mapfile_templatespec(b'changeset', mapfile, fp)
 
     return formatter.lookuptemplate(ui, b'changeset', tmpl)
 
 
 def maketemplater(ui, repo, tmpl, buffered=False):
     """Create a changesettemplater from a literal template 'tmpl'
     byte-string."""
     spec = formatter.literal_templatespec(tmpl)
     return changesettemplater(ui, repo, spec, buffered=buffered)
 
 
 def changesetdisplayer(ui, repo, opts, differ=None, buffered=False):
     """show one changeset using template or regular display.
 
     Display format will be the first non-empty hit of:
     1. option 'template'
     2. option 'style'
     3. [ui] setting 'logtemplate'
     4. [ui] setting 'style'
     If all of these values are either the unset or the empty string,
     regular display via changesetprinter() is done.
     """
     postargs = (differ, opts, buffered)
     spec = _lookuptemplate(ui, opts.get(b'template'), opts.get(b'style'))
 
     # machine-readable formats have slightly different keyword set than
     # plain templates, which are handled by changesetformatter.
     # note that {b'pickle', b'debug'} can also be added to the list if needed.
     if spec.ref in {b'cbor', b'json'}:
         fm = ui.formatter(b'log', opts)
         return changesetformatter(ui, repo, fm, *postargs)
 
     if not spec.ref and not spec.tmpl and not spec.mapfile:
         return changesetprinter(ui, repo, *postargs)
 
     return changesettemplater(ui, repo, spec, *postargs)
 
 
 @attr.s
 class walkopts(object):
     """Options to configure a set of revisions and file matcher factory
     to scan revision/file history
     """
 
     # raw command-line parameters, which a matcher will be built from
     pats = attr.ib()  # type: List[bytes]
     opts = attr.ib()  # type: Dict[bytes, Any]
 
     # a list of revset expressions to be traversed; if follow, it specifies
     # the start revisions
     revspec = attr.ib()  # type: List[bytes]
 
     # miscellaneous queries to filter revisions (see "hg help log" for details)
     branches = attr.ib(default=attr.Factory(list))  # type: List[bytes]
     date = attr.ib(default=None)  # type: Optional[bytes]
     keywords = attr.ib(default=attr.Factory(list))  # type: List[bytes]
     no_merges = attr.ib(default=False)  # type: bool
     only_merges = attr.ib(default=False)  # type: bool
     prune_ancestors = attr.ib(default=attr.Factory(list))  # type: List[bytes]
     users = attr.ib(default=attr.Factory(list))  # type: List[bytes]
 
     # miscellaneous matcher arguments
     include_pats = attr.ib(default=attr.Factory(list))  # type: List[bytes]
     exclude_pats = attr.ib(default=attr.Factory(list))  # type: List[bytes]
 
     # 0: no follow, 1: follow first, 2: follow both parents
     follow = attr.ib(default=0)  # type: int
 
     # do not attempt filelog-based traversal, which may be fast but cannot
     # include revisions where files were removed
     force_changelog_traversal = attr.ib(default=False)  # type: bool
 
     # sort revisions prior to traversal: 'desc', 'topo', or None
     sort_revisions = attr.ib(default=None)  # type: Optional[bytes]
 
     # limit number of changes displayed; None means unlimited
     limit = attr.ib(default=None)  # type: Optional[int]
 
 
 def parseopts(ui, pats, opts):
     # type: (Any, List[bytes], Dict[bytes, Any]) -> walkopts
     """Parse log command options into walkopts
 
-    The returned walkopts will be passed in to getrevs().
+    The returned walkopts will be passed in to getrevs() or makewalker().
     """
     if opts.get(b'follow_first'):
         follow = 1
     elif opts.get(b'follow'):
         follow = 2
     else:
         follow = 0
 
     if opts.get(b'graph'):
         if ui.configbool(b'experimental', b'log.topo'):
             sort_revisions = b'topo'
         else:
             sort_revisions = b'desc'
     else:
         sort_revisions = None
 
     return walkopts(
         pats=pats,
         opts=opts,
         revspec=opts.get(b'rev', []),
         # branch and only_branch are really aliases and must be handled at
         # the same time
         branches=opts.get(b'branch', []) + opts.get(b'only_branch', []),
         date=opts.get(b'date'),
         keywords=opts.get(b'keyword', []),
         no_merges=bool(opts.get(b'no_merges')),
         only_merges=bool(opts.get(b'only_merges')),
         prune_ancestors=opts.get(b'prune', []),
         users=opts.get(b'user', []),
         include_pats=opts.get(b'include', []),
         exclude_pats=opts.get(b'exclude', []),
         follow=follow,
         force_changelog_traversal=bool(opts.get(b'removed')),
         sort_revisions=sort_revisions,
         limit=getlimit(opts),
     )
 
 
 def _makematcher(repo, revs, wopts):
     """Build matcher and expanded patterns from log options
 
     If --follow, revs are the revisions to follow from.
 
     Returns (match, pats, slowpath) where
     - match: a matcher built from the given pats and -I/-X opts
     - pats: patterns used (globs are expanded on Windows)
     - slowpath: True if patterns aren't as simple as scanning filelogs
     """
     # pats/include/exclude are passed to match.match() directly in
     # _matchfiles() revset but walkchangerevs() builds its matcher with
     # scmutil.match(). The difference is input pats are globbed on
     # platforms without shell expansion (windows).
     wctx = repo[None]
     match, pats = scmutil.matchandpats(wctx, wopts.pats, wopts.opts)
     slowpath = match.anypats() or (
         not match.always() and wopts.force_changelog_traversal
     )
     if not slowpath:
         if wopts.follow and wopts.revspec:
             # There may be the case that a path doesn't exist in some (but
             # not all) of the specified start revisions, but let's consider
             # the path is valid. Missing files will be warned by the matcher.
             startctxs = [repo[r] for r in revs]
             for f in match.files():
                 found = False
                 for c in startctxs:
                     if f in c:
                         found = True
                     elif c.hasdir(f):
                         # If a directory exists in any of the start revisions,
                         # take the slow path.
                         found = slowpath = True
                 if not found:
                     raise error.Abort(
                         _(
                             b'cannot follow file not in any of the specified '
                             b'revisions: "%s"'
                         )
                         % f
                     )
         elif wopts.follow:
             for f in match.files():
                 if f not in wctx:
                     # If the file exists, it may be a directory, so let it
                     # take the slow path.
                     if os.path.exists(repo.wjoin(f)):
                         slowpath = True
                         continue
                     else:
                         raise error.Abort(
                             _(
                                 b'cannot follow file not in parent '
                                 b'revision: "%s"'
                             )
                             % f
                         )
                 filelog = repo.file(f)
                 if not filelog:
                     # A file exists in wdir but not in history, which means
                     # the file isn't committed yet.
                     raise error.Abort(
                         _(b'cannot follow nonexistent file: "%s"') % f
                     )
         else:
             for f in match.files():
                 filelog = repo.file(f)
                 if not filelog:
                     # A zero count may be a directory or deleted file, so
                     # try to find matching entries on the slow path.
                     slowpath = True
 
         # We decided to fall back to the slowpath because at least one
         # of the paths was not a file. Check to see if at least one of them
         # existed in history - in that case, we'll continue down the
         # slowpath; otherwise, we can turn off the slowpath
         if slowpath:
             for path in match.files():
                 if path == b'.' or path in repo.store:
                     break
             else:
                 slowpath = False
 
     return match, pats, slowpath
 
 
 def _fileancestors(repo, revs, match, followfirst):
     fctxs = []
     for r in revs:
         ctx = repo[r]
         fctxs.extend(ctx[f].introfilectx() for f in ctx.walk(match))
 
     # When displaying a revision with --patch --follow FILE, we have
     # to know which file of the revision must be diffed. With
     # --follow, we want the names of the ancestors of FILE in the
     # revision, stored in "fcache". "fcache" is populated as a side effect
     # of the graph traversal.
     fcache = {}
 
     def filematcher(ctx):
         return scmutil.matchfiles(repo, fcache.get(scmutil.intrev(ctx), []))
 
     def revgen():
         for rev, cs in dagop.filectxancestors(fctxs, followfirst=followfirst):
             fcache[rev] = [c.path() for c in cs]
             yield rev
 
     return smartset.generatorset(revgen(), iterasc=False), filematcher
 
 
 def _makenofollowfilematcher(repo, pats, opts):
     '''hook for extensions to override the filematcher for non-follow cases'''
     return None
 
 
 _opt2logrevset = {
     b'no_merges': (b'not merge()', None),
     b'only_merges': (b'merge()', None),
     b'_matchfiles': (None, b'_matchfiles(%ps)'),
     b'date': (b'date(%s)', None),
     b'branch': (b'branch(%s)', b'%lr'),
     b'_patslog': (b'filelog(%s)', b'%lr'),
     b'keyword': (b'keyword(%s)', b'%lr'),
     b'prune': (b'ancestors(%s)', b'not %lr'),
     b'user': (b'user(%s)', b'%lr'),
 }
 
 
 def _makerevset(repo, wopts, slowpath):
     """Return a revset string built from log options and file patterns"""
     opts = {
         b'branch': [repo.lookupbranch(b) for b in wopts.branches],
         b'date': wopts.date,
         b'keyword': wopts.keywords,
         b'no_merges': wopts.no_merges,
         b'only_merges': wopts.only_merges,
         b'prune': wopts.prune_ancestors,
         b'user': wopts.users,
     }
 
     if slowpath:
         # See walkchangerevs() slow path.
         #
         # pats/include/exclude cannot be represented as separate
         # revset expressions as their filtering logic applies at file
         # level. For instance "-I a -X b" matches a revision touching
         # "a" and "b" while "file(a) and not file(b)" does
         # not. Besides, filesets are evaluated against the working
         # directory.
         matchargs = [b'r:', b'd:relpath']
         for p in wopts.pats:
             matchargs.append(b'p:' + p)
         for p in wopts.include_pats:
             matchargs.append(b'i:' + p)
         for p in wopts.exclude_pats:
             matchargs.append(b'x:' + p)
         opts[b'_matchfiles'] = matchargs
     elif not wopts.follow:
         opts[b'_patslog'] = list(wopts.pats)
 
     expr = []
     for op, val in sorted(pycompat.iteritems(opts)):
         if not val:
             continue
         revop, listop = _opt2logrevset[op]
         if revop and b'%' not in revop:
             expr.append(revop)
         elif not listop:
             expr.append(revsetlang.formatspec(revop, val))
         else:
             if revop:
                 val = [revsetlang.formatspec(revop, v) for v in val]
             expr.append(revsetlang.formatspec(listop, val))
 
     if expr:
         expr = b'(' + b' and '.join(expr) + b')'
     else:
         expr = None
     return expr
 
 
 def _initialrevs(repo, wopts):
     """Return the initial set of revisions to be filtered or followed"""
     if wopts.revspec:
         revs = scmutil.revrange(repo, wopts.revspec)
     elif wopts.follow and repo.dirstate.p1() == nullid:
         revs = smartset.baseset()
     elif wopts.follow:
         revs = repo.revs(b'.')
     else:
         revs = smartset.spanset(repo)
         revs.reverse()
     return revs
 
 
-def getrevs(repo, wopts):
-    # type: (Any, walkopts) -> Tuple[smartset.abstractsmartset, Optional[changesetdiffer]]
-    """Return (revs, differ) where revs is a smartset
+def makewalker(repo, wopts):
+    # type: (Any, walkopts) -> Tuple[smartset.abstractsmartset, Optional[Callable[[Any], matchmod.basematcher]]]
+    """Build (revs, makefilematcher) to scan revision/file history
 
-    differ is a changesetdiffer with pre-configured file matcher.
+    - revs is the smartset to be traversed.
+    - makefilematcher is a function to map ctx to a matcher for that revision
     """
     revs = _initialrevs(repo, wopts)
     if not revs:
         return smartset.baseset(), None
     # TODO: might want to merge slowpath with wopts.force_changelog_traversal
     match, pats, slowpath = _makematcher(repo, revs, wopts)
     wopts = attr.evolve(wopts, pats=pats)
 
     filematcher = None
     if wopts.follow:
         if slowpath or match.always():
             revs = dagop.revancestors(repo, revs, followfirst=wopts.follow == 1)
         else:
             assert not wopts.force_changelog_traversal
             revs, filematcher = _fileancestors(
                 repo, revs, match, followfirst=wopts.follow == 1
             )
         revs.reverse()
     if filematcher is None:
         filematcher = _makenofollowfilematcher(repo, wopts.pats, wopts.opts)
     if filematcher is None:
 
         def filematcher(ctx):
             return match
 
     expr = _makerevset(repo, wopts, slowpath)
     if wopts.sort_revisions:
         assert wopts.sort_revisions in {b'topo', b'desc'}
         if wopts.sort_revisions == b'topo':
             if not revs.istopo():
                 revs = dagop.toposort(revs, repo.changelog.parentrevs)
                 # TODO: try to iterate the set lazily
                 revs = revset.baseset(list(revs), istopo=True)
         elif not (revs.isdescending() or revs.istopo()):
             # User-specified revs might be unsorted
             revs.sort(reverse=True)
     if expr:
         matcher = revset.match(None, expr)
         revs = matcher(repo, revs)
     if wopts.limit is not None:
         revs = revs.slice(0, wopts.limit)
 
+    return revs, filematcher
+
+
+def getrevs(repo, wopts):
+    # type: (Any, walkopts) -> Tuple[smartset.abstractsmartset, Optional[changesetdiffer]]
+    """Return (revs, differ) where revs is a smartset
+
+    differ is a changesetdiffer with pre-configured file matcher.
+    """
+    revs, filematcher = makewalker(repo, wopts)
+    if not revs:
+        return revs, None
     differ = changesetdiffer()
     differ._makefilematcher = filematcher
     return revs, differ
 
 
 def _parselinerangeopt(repo, opts):
     """Parse --line-range log option and return a list of tuples (filename,
     (fromline, toline)).
     """
     linerangebyfname = []
     for pat in opts.get(b'line_range', []):
         try:
             pat, linerange = pat.rsplit(b',', 1)
         except ValueError:
             raise error.Abort(_(b'malformatted line-range pattern %s') % pat)
         try:
             fromline, toline = map(int, linerange.split(b':'))
         except ValueError:
             raise error.Abort(_(b"invalid line range for %s") % pat)
         msg = _(b"line range pattern '%s' must match exactly one file") % pat
         fname = scmutil.parsefollowlinespattern(repo, None, pat, msg)
         linerangebyfname.append(
             (fname, util.processlinerange(fromline, toline))
         )
     return linerangebyfname
 
 
 def getlinerangerevs(repo, userrevs, opts):
     """Return (revs, differ).
 
     "revs" are revisions obtained by processing "line-range" log options and
     walking block ancestors of each specified file/line-range.
 
     "differ" is a changesetdiffer with pre-configured file matcher and hunks
     filter.
     """
     wctx = repo[None]
 
     # Two-levels map of "rev -> file ctx -> [line range]".
     linerangesbyrev = {}
     for fname, (fromline, toline) in _parselinerangeopt(repo, opts):
         if fname not in wctx:
             raise error.Abort(
                 _(b'cannot follow file not in parent revision: "%s"') % fname
             )
         fctx = wctx.filectx(fname)
         for fctx, linerange in dagop.blockancestors(fctx, fromline, toline):
             rev = fctx.introrev()
             if rev is None:
                 rev = wdirrev
             if rev not in userrevs:
                 continue
             linerangesbyrev.setdefault(rev, {}).setdefault(
                 fctx.path(), []
             ).append(linerange)
 
     def nofilterhunksfn(fctx, hunks):
         return hunks
 
     def hunksfilter(ctx):
         fctxlineranges = linerangesbyrev.get(scmutil.intrev(ctx))
         if fctxlineranges is None:
             return nofilterhunksfn
 
         def filterfn(fctx, hunks):
             lineranges = fctxlineranges.get(fctx.path())
             if lineranges is not None:
                 for hr, lines in hunks:
                     if hr is None:  # binary
                         yield hr, lines
                         continue
                     if any(mdiff.hunkinrange(hr[2:], lr) for lr in lineranges):
                         yield hr, lines
             else:
                 for hunk in hunks:
                     yield hunk
 
         return filterfn
 
     def filematcher(ctx):
         files = list(linerangesbyrev.get(scmutil.intrev(ctx), []))
         return scmutil.matchfiles(repo, files)
 
     revs = sorted(linerangesbyrev, reverse=True)
 
     differ = changesetdiffer()
     differ._makefilematcher = filematcher
     differ._makehunksfilter = hunksfilter
     return smartset.baseset(revs), differ
 
 
 def _graphnodeformatter(ui, displayer):
     spec = ui.config(b'ui', b'graphnodetemplate')
     if not spec:
         return templatekw.getgraphnode  # fast path for "{graphnode}"
 
     spec = templater.unquotestring(spec)
     if isinstance(displayer, changesettemplater):
         # reuse cache of slow templates
         tres = displayer._tresources
     else:
         tres = formatter.templateresources(ui)
     templ = formatter.maketemplater(
         ui, spec, defaults=templatekw.keywords, resources=tres
     )
 
     def formatnode(repo, ctx, cache):
         props = {b'ctx': ctx, b'repo': repo}
         return templ.renderdefault(props)
 
     return formatnode
 
 
 def displaygraph(ui, repo, dag, displayer, edgefn, getcopies=None, props=None):
     props = props or {}
     formatnode = _graphnodeformatter(ui, displayer)
     state = graphmod.asciistate()
     styles = state.styles
 
     # only set graph styling if HGPLAIN is not set.
     if ui.plain(b'graph'):
         # set all edge styles to |, the default pre-3.8 behaviour
         styles.update(dict.fromkeys(styles, b'|'))
     else:
         edgetypes = {
             b'parent': graphmod.PARENT,
             b'grandparent': graphmod.GRANDPARENT,
             b'missing': graphmod.MISSINGPARENT,
         }
         for name, key in edgetypes.items():
             # experimental config: experimental.graphstyle.*
             styles[key] = ui.config(
                 b'experimental', b'graphstyle.%s' % name, styles[key]
             )
             if not styles[key]:
                 styles[key] = None
 
         # experimental config: experimental.graphshorten
         state.graphshorten = ui.configbool(b'experimental', b'graphshorten')
 
     formatnode_cache = {}
     for rev, type, ctx, parents in dag:
         char = formatnode(repo, ctx, formatnode_cache)
         copies = getcopies(ctx) if getcopies else None
         edges = edgefn(type, char, state, rev, parents)
         firstedge = next(edges)
         width = firstedge[2]
         displayer.show(
             ctx, copies=copies, graphwidth=width, **pycompat.strkwargs(props)
         )
         lines = displayer.hunk.pop(rev).split(b'\n')
         if not lines[-1]:
             del lines[-1]
         displayer.flush(ctx)
         for type, char, width, coldata in itertools.chain([firstedge], edges):
             graphmod.ascii(ui, state, type, char, lines, coldata)
             lines = []
     displayer.close()
 
 
 def displaygraphrevs(ui, repo, revs, displayer, getrenamed):
     revdag = graphmod.dagwalker(repo, revs)
     displaygraph(ui, repo, revdag, displayer, graphmod.asciiedges, getrenamed)
 
 
 def displayrevs(ui, repo, revs, displayer, getcopies):
     for rev in revs:
         ctx = repo[rev]
         copies = getcopies(ctx) if getcopies else None
         displayer.show(ctx, copies=copies)
         displayer.flush(ctx)
     displayer.close()
 
 
 def checkunsupportedgraphflags(pats, opts):
     for op in [b"newest_first"]:
         if op in opts and opts[op]:
             raise error.Abort(
                 _(b"-G/--graph option is incompatible with --%s")
                 % op.replace(b"_", b"-")
             )
 
 
 def graphrevs(repo, nodes, opts):
     limit = getlimit(opts)
     nodes.reverse()
     if limit is not None:
         nodes = nodes[:limit]
     return graphmod.nodes(repo, nodes)