mercurial/logcmdutil.py

copies: avoid unwanted side effect from one branch to another

Without this copy, change in a one descendant branch (With "remove" change
only) could affect computation on another descendant branches.

This was not caugh by the test because the test graph are "too simple". I
started writing more test in that regards, but I a submitting this changes
earlier because I want to get more code landed to allow other optimisation work
to happens.

Differential Revision: https://phab.mercurial-scm.org/D9416

# 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, 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'command-templates', b'log')
        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. [command-templates] setting 'log'
    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

    # filter revisions by file patterns, which should be disabled only if
    # you want to include revisions where files were unmodified
    filter_revisions_by_pats = attr.ib(default=True)  # 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() 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 a log-like command should build 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 wopts.filter_revisions_by_pats and slowpath:
        # 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 wopts.filter_revisions_by_pats and 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 makewalker(repo, wopts):
    # type: (Any, walkopts) -> Tuple[smartset.abstractsmartset, Optional[Callable[[Any], matchmod.basematcher]]]
    """Build (revs, makefilematcher) to scan revision/file history

    - 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 get_bookmark_revs(repo, bookmark, walk_opts):
    # type: (Any, bookmark, walk_opts) -> 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, walk_opts)
    if not revs:
        return revs, None
    differ = changesetdiffer()
    differ._makefilematcher = filematcher

    if bookmark:
        if bookmark not in repo._bookmarks:
            raise error.Abort(_(b"bookmark '%s' not found") % bookmark)
        revs = scmutil.bookmarkrevs(repo, bookmark)

    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'command-templates', b'graphnode')
    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)