webcommands: document "comparison" web command

mercurial/hgweb/webcommands.py

@@ -1,1287 +1,1302 b''
 #
 # Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
 # 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.
 
 import os, mimetypes, re, cgi, copy
 import webutil
 from mercurial import error, encoding, archival, templater, templatefilters
 from mercurial.node import short, hex
 from mercurial import util
 from common import paritygen, staticfile, get_contact, ErrorResponse
 from common import HTTP_OK, HTTP_FORBIDDEN, HTTP_NOT_FOUND
 from mercurial import graphmod, patch
 from mercurial import scmutil
 from mercurial.i18n import _
 from mercurial.error import ParseError, RepoLookupError, Abort
 from mercurial import revset
 
 __all__ = []
 commands = {}
 
 class webcommand(object):
     """Decorator used to register a web command handler.
 
     The decorator takes as its positional arguments the name/path the
     command should be accessible under.
 
     Usage:
 
     @webcommand('mycommand')
     def mycommand(web, req, tmpl):
         pass
     """
 
     def __init__(self, name):
         self.name = name
 
     def __call__(self, func):
         __all__.append(self.name)
         commands[self.name] = func
         return func
 
 @webcommand('log')
 def log(web, req, tmpl):
     """
     /log[/{revision}[/{path}]]
     --------------------------
 
     Show repository or file history.
 
     For URLs of the form ``/log/{revision}``, a list of changesets starting at
     the specified changeset identifier is shown. If ``{revision}`` is not
     defined, the default is ``tip``. This form is equivalent to the
     ``changelog`` handler.
 
     For URLs of the form ``/log/{revision}/{file}``, the history for a specific
     file will be shown. This form is equivalent to the ``filelog`` handler.
     """
 
     if 'file' in req.form and req.form['file'][0]:
         return filelog(web, req, tmpl)
     else:
         return changelog(web, req, tmpl)
 
 @webcommand('rawfile')
 def rawfile(web, req, tmpl):
     guessmime = web.configbool('web', 'guessmime', False)
 
     path = webutil.cleanpath(web.repo, req.form.get('file', [''])[0])
     if not path:
         content = manifest(web, req, tmpl)
         req.respond(HTTP_OK, web.ctype)
         return content
 
     try:
         fctx = webutil.filectx(web.repo, req)
     except error.LookupError, inst:
         try:
             content = manifest(web, req, tmpl)
             req.respond(HTTP_OK, web.ctype)
             return content
         except ErrorResponse:
             raise inst
 
     path = fctx.path()
     text = fctx.data()
     mt = 'application/binary'
     if guessmime:
         mt = mimetypes.guess_type(path)[0]
         if mt is None:
             mt = util.binary(text) and 'application/binary' or 'text/plain'
     if mt.startswith('text/'):
         mt += '; charset="%s"' % encoding.encoding
 
     req.respond(HTTP_OK, mt, path, body=text)
     return []
 
 def _filerevision(web, tmpl, fctx):
     f = fctx.path()
     text = fctx.data()
     parity = paritygen(web.stripecount)
 
     if util.binary(text):
         mt = mimetypes.guess_type(f)[0] or 'application/octet-stream'
         text = '(binary:%s)' % mt
 
     def lines():
         for lineno, t in enumerate(text.splitlines(True)):
             yield {"line": t,
                    "lineid": "l%d" % (lineno + 1),
                    "linenumber": "% 6d" % (lineno + 1),
                    "parity": parity.next()}
 
     return tmpl("filerevision",
                 file=f,
                 path=webutil.up(f),
                 text=lines(),
                 rev=fctx.rev(),
                 node=fctx.hex(),
                 author=fctx.user(),
                 date=fctx.date(),
                 desc=fctx.description(),
                 extra=fctx.extra(),
                 branch=webutil.nodebranchnodefault(fctx),
                 parent=webutil.parents(fctx),
                 child=webutil.children(fctx),
                 rename=webutil.renamelink(fctx),
                 permissions=fctx.manifest().flags(f))
 
 @webcommand('file')
 def file(web, req, tmpl):
     """
     /file/{revision}[/{path}]
     -------------------------
 
     Show information about a directory or file in the repository.
 
     Info about the ``path`` given as a URL parameter will be rendered.
 
     If ``path`` is a directory, information about the entries in that
     directory will be rendered. This form is equivalent to the ``manifest``
     handler.
 
     If ``path`` is a file, information about that file will be shown via
     the ``filerevision`` template.
 
     If ``path`` is not defined, information about the root directory will
     be rendered.
     """
     path = webutil.cleanpath(web.repo, req.form.get('file', [''])[0])
     if not path:
         return manifest(web, req, tmpl)
     try:
         return _filerevision(web, tmpl, webutil.filectx(web.repo, req))
     except error.LookupError, inst:
         try:
             return manifest(web, req, tmpl)
         except ErrorResponse:
             raise inst
 
 def _search(web, req, tmpl):
     MODE_REVISION = 'rev'
     MODE_KEYWORD = 'keyword'
     MODE_REVSET = 'revset'
 
     def revsearch(ctx):
         yield ctx
 
     def keywordsearch(query):
         lower = encoding.lower
         qw = lower(query).split()
 
         def revgen():
             cl = web.repo.changelog
             for i in xrange(len(web.repo) - 1, 0, -100):
                 l = []
                 for j in cl.revs(max(0, i - 99), i):
                     ctx = web.repo[j]
                     l.append(ctx)
                 l.reverse()
                 for e in l:
                     yield e
 
         for ctx in revgen():
             miss = 0
             for q in qw:
                 if not (q in lower(ctx.user()) or
                         q in lower(ctx.description()) or
                         q in lower(" ".join(ctx.files()))):
                     miss = 1
                     break
             if miss:
                 continue
 
             yield ctx
 
     def revsetsearch(revs):
         for r in revs:
             yield web.repo[r]
 
     searchfuncs = {
         MODE_REVISION: (revsearch, 'exact revision search'),
         MODE_KEYWORD: (keywordsearch, 'literal keyword search'),
         MODE_REVSET: (revsetsearch, 'revset expression search'),
     }
 
     def getsearchmode(query):
         try:
             ctx = web.repo[query]
         except (error.RepoError, error.LookupError):
             # query is not an exact revision pointer, need to
             # decide if it's a revset expression or keywords
             pass
         else:
             return MODE_REVISION, ctx
 
         revdef = 'reverse(%s)' % query
         try:
             tree, pos = revset.parse(revdef)
         except ParseError:
             # can't parse to a revset tree
             return MODE_KEYWORD, query
 
         if revset.depth(tree) <= 2:
             # no revset syntax used
             return MODE_KEYWORD, query
 
         if util.any((token, (value or '')[:3]) == ('string', 're:')
                     for token, value, pos in revset.tokenize(revdef)):
             return MODE_KEYWORD, query
 
         funcsused = revset.funcsused(tree)
         if not funcsused.issubset(revset.safesymbols):
             return MODE_KEYWORD, query
 
         mfunc = revset.match(web.repo.ui, revdef)
         try:
             revs = mfunc(web.repo, revset.spanset(web.repo))
             return MODE_REVSET, revs
             # ParseError: wrongly placed tokens, wrongs arguments, etc
             # RepoLookupError: no such revision, e.g. in 'revision:'
             # Abort: bookmark/tag not exists
             # LookupError: ambiguous identifier, e.g. in '(bc)' on a large repo
         except (ParseError, RepoLookupError, Abort, LookupError):
             return MODE_KEYWORD, query
 
     def changelist(**map):
         count = 0
 
         for ctx in searchfunc[0](funcarg):
             count += 1
             n = ctx.node()
             showtags = webutil.showtag(web.repo, tmpl, 'changelogtag', n)
             files = webutil.listfilediffs(tmpl, ctx.files(), n, web.maxfiles)
 
             yield tmpl('searchentry',
                        parity=parity.next(),
                        author=ctx.user(),
                        parent=webutil.parents(ctx),
                        child=webutil.children(ctx),
                        changelogtag=showtags,
                        desc=ctx.description(),
                        extra=ctx.extra(),
                        date=ctx.date(),
                        files=files,
                        rev=ctx.rev(),
                        node=hex(n),
                        tags=webutil.nodetagsdict(web.repo, n),
                        bookmarks=webutil.nodebookmarksdict(web.repo, n),
                        inbranch=webutil.nodeinbranch(web.repo, ctx),
                        branches=webutil.nodebranchdict(web.repo, ctx))
 
             if count >= revcount:
                 break
 
     query = req.form['rev'][0]
     revcount = web.maxchanges
     if 'revcount' in req.form:
         try:
             revcount = int(req.form.get('revcount', [revcount])[0])
             revcount = max(revcount, 1)
             tmpl.defaults['sessionvars']['revcount'] = revcount
         except ValueError:
             pass
 
     lessvars = copy.copy(tmpl.defaults['sessionvars'])
     lessvars['revcount'] = max(revcount / 2, 1)
     lessvars['rev'] = query
     morevars = copy.copy(tmpl.defaults['sessionvars'])
     morevars['revcount'] = revcount * 2
     morevars['rev'] = query
 
     mode, funcarg = getsearchmode(query)
 
     if 'forcekw' in req.form:
         showforcekw = ''
         showunforcekw = searchfuncs[mode][1]
         mode = MODE_KEYWORD
         funcarg = query
     else:
         if mode != MODE_KEYWORD:
             showforcekw = searchfuncs[MODE_KEYWORD][1]
         else:
             showforcekw = ''
         showunforcekw = ''
 
     searchfunc = searchfuncs[mode]
 
     tip = web.repo['tip']
     parity = paritygen(web.stripecount)
 
     return tmpl('search', query=query, node=tip.hex(),
                 entries=changelist, archives=web.archivelist("tip"),
                 morevars=morevars, lessvars=lessvars,
                 modedesc=searchfunc[1],
                 showforcekw=showforcekw, showunforcekw=showunforcekw)
 
 @webcommand('changelog')
 def changelog(web, req, tmpl, shortlog=False):
     """
     /changelog[/{revision}]
     -----------------------
 
     Show information about multiple changesets.
 
     If the optional ``revision`` URL argument is absent, information about
     all changesets starting at ``tip`` will be rendered. If the ``revision``
     argument is present, changesets will be shown starting from the specified
     revision.
 
     If ``revision`` is absent, the ``rev`` query string argument may be
     defined. This will perform a search for changesets.
 
     The argument for ``rev`` can be a single revision, a revision set,
     or a literal keyword to search for in changeset data (equivalent to
     :hg:`log -k`.
 
     The ``revcount`` query string argument defines the maximum numbers of
     changesets to render.
 
     For non-searches, the ``changelog`` template will be rendered.
     """
 
     query = ''
     if 'node' in req.form:
         ctx = webutil.changectx(web.repo, req)
     elif 'rev' in req.form:
         return _search(web, req, tmpl)
     else:
         ctx = web.repo['tip']
 
     def changelist():
         revs = []
         if pos != -1:
             revs = web.repo.changelog.revs(pos, 0)
         curcount = 0
         for rev in revs:
             curcount += 1
             if curcount > revcount + 1:
                 break
 
             entry = webutil.changelistentry(web, web.repo[rev], tmpl)
             entry['parity'] = parity.next()
             yield entry
 
     revcount = shortlog and web.maxshortchanges or web.maxchanges
     if 'revcount' in req.form:
         try:
             revcount = int(req.form.get('revcount', [revcount])[0])
             revcount = max(revcount, 1)
             tmpl.defaults['sessionvars']['revcount'] = revcount
         except ValueError:
             pass
 
     lessvars = copy.copy(tmpl.defaults['sessionvars'])
     lessvars['revcount'] = max(revcount / 2, 1)
     morevars = copy.copy(tmpl.defaults['sessionvars'])
     morevars['revcount'] = revcount * 2
 
     count = len(web.repo)
     pos = ctx.rev()
     parity = paritygen(web.stripecount)
 
     changenav = webutil.revnav(web.repo).gen(pos, revcount, count)
 
     entries = list(changelist())
     latestentry = entries[:1]
     if len(entries) > revcount:
         nextentry = entries[-1:]
         entries = entries[:-1]
     else:
         nextentry = []
 
     return tmpl(shortlog and 'shortlog' or 'changelog', changenav=changenav,
                 node=ctx.hex(), rev=pos, changesets=count,
                 entries=entries,
                 latestentry=latestentry, nextentry=nextentry,
                 archives=web.archivelist("tip"), revcount=revcount,
                 morevars=morevars, lessvars=lessvars, query=query)
 
 @webcommand('shortlog')
 def shortlog(web, req, tmpl):
     """
     /shortlog
     ---------
 
     Show basic information about a set of changesets.
 
     This accepts the same parameters as the ``changelog`` handler. The only
     difference is the ``shortlog`` template will be rendered instead of the
     ``changelog`` template.
     """
     return changelog(web, req, tmpl, shortlog=True)
 
 @webcommand('changeset')
 def changeset(web, req, tmpl):
     """
     /changeset[/{revision}]
     -----------------------
 
     Show information about a single changeset.
 
     A URL path argument is the changeset identifier to show. See ``hg help
     revisions`` for possible values. If not defined, the ``tip`` changeset
     will be shown.
 
     The ``changeset`` template is rendered. Contents of the ``changesettag``,
     ``changesetbookmark``, ``filenodelink``, ``filenolink``, and the many
     templates related to diffs may all be used to produce the output.
     """
     ctx = webutil.changectx(web.repo, req)
     basectx = webutil.basechangectx(web.repo, req)
     if basectx is None:
         basectx = ctx.p1()
     showtags = webutil.showtag(web.repo, tmpl, 'changesettag', ctx.node())
     showbookmarks = webutil.showbookmark(web.repo, tmpl, 'changesetbookmark',
                                          ctx.node())
     showbranch = webutil.nodebranchnodefault(ctx)
 
     files = []
     parity = paritygen(web.stripecount)
     for blockno, f in enumerate(ctx.files()):
         template = f in ctx and 'filenodelink' or 'filenolink'
         files.append(tmpl(template,
                           node=ctx.hex(), file=f, blockno=blockno + 1,
                           parity=parity.next()))
 
     style = web.config('web', 'style', 'paper')
     if 'style' in req.form:
         style = req.form['style'][0]
 
     parity = paritygen(web.stripecount)
     diffs = webutil.diffs(web.repo, tmpl, ctx, basectx, None, parity, style)
 
     parity = paritygen(web.stripecount)
     diffstatgen = webutil.diffstatgen(ctx, basectx)
     diffstat = webutil.diffstat(tmpl, ctx, diffstatgen, parity)
 
     return tmpl('changeset',
                 diff=diffs,
                 rev=ctx.rev(),
                 node=ctx.hex(),
                 parent=tuple(webutil.parents(ctx)),
                 child=webutil.children(ctx),
                 basenode=basectx.hex(),
                 changesettag=showtags,
                 changesetbookmark=showbookmarks,
                 changesetbranch=showbranch,
                 author=ctx.user(),
                 desc=ctx.description(),
                 extra=ctx.extra(),
                 date=ctx.date(),
                 files=files,
                 diffsummary=lambda **x: webutil.diffsummary(diffstatgen),
                 diffstat=diffstat,
                 archives=web.archivelist(ctx.hex()),
                 tags=webutil.nodetagsdict(web.repo, ctx.node()),
                 bookmarks=webutil.nodebookmarksdict(web.repo, ctx.node()),
                 branch=webutil.nodebranchnodefault(ctx),
                 inbranch=webutil.nodeinbranch(web.repo, ctx),
                 branches=webutil.nodebranchdict(web.repo, ctx))
 
 rev = webcommand('rev')(changeset)
 
 def decodepath(path):
     """Hook for mapping a path in the repository to a path in the
     working copy.
 
     Extensions (e.g., largefiles) can override this to remap files in
     the virtual file system presented by the manifest command below."""
     return path
 
 @webcommand('manifest')
 def manifest(web, req, tmpl):
     """
     /manifest[/{revision}[/{path}]]
     -------------------------------
 
     Show information about a directory.
 
     If the URL path arguments are defined, information about the root
     directory for the ``tip`` changeset will be shown.
 
     Because this handler can only show information for directories, it
     is recommended to use the ``file`` handler instead, as it can handle both
     directories and files.
 
     The ``manifest`` template will be rendered for this handler.
     """
     ctx = webutil.changectx(web.repo, req)
     path = webutil.cleanpath(web.repo, req.form.get('file', [''])[0])
     mf = ctx.manifest()
     node = ctx.node()
 
     files = {}
     dirs = {}
     parity = paritygen(web.stripecount)
 
     if path and path[-1] != "/":
         path += "/"
     l = len(path)
     abspath = "/" + path
 
     for full, n in mf.iteritems():
         # the virtual path (working copy path) used for the full
         # (repository) path
         f = decodepath(full)
 
         if f[:l] != path:
             continue
         remain = f[l:]
         elements = remain.split('/')
         if len(elements) == 1:
             files[remain] = full
         else:
             h = dirs # need to retain ref to dirs (root)
             for elem in elements[0:-1]:
                 if elem not in h:
                     h[elem] = {}
                 h = h[elem]
                 if len(h) > 1:
                     break
             h[None] = None # denotes files present
 
     if mf and not files and not dirs:
         raise ErrorResponse(HTTP_NOT_FOUND, 'path not found: ' + path)
 
     def filelist(**map):
         for f in sorted(files):
             full = files[f]
 
             fctx = ctx.filectx(full)
             yield {"file": full,
                    "parity": parity.next(),
                    "basename": f,
                    "date": fctx.date(),
                    "size": fctx.size(),
                    "permissions": mf.flags(full)}
 
     def dirlist(**map):
         for d in sorted(dirs):
 
             emptydirs = []
             h = dirs[d]
             while isinstance(h, dict) and len(h) == 1:
                 k, v = h.items()[0]
                 if v:
                     emptydirs.append(k)
                 h = v
 
             path = "%s%s" % (abspath, d)
             yield {"parity": parity.next(),
                    "path": path,
                    "emptydirs": "/".join(emptydirs),
                    "basename": d}
 
     return tmpl("manifest",
                 rev=ctx.rev(),
                 node=hex(node),
                 path=abspath,
                 up=webutil.up(abspath),
                 upparity=parity.next(),
                 fentries=filelist,
                 dentries=dirlist,
                 archives=web.archivelist(hex(node)),
                 tags=webutil.nodetagsdict(web.repo, node),
                 bookmarks=webutil.nodebookmarksdict(web.repo, node),
                 inbranch=webutil.nodeinbranch(web.repo, ctx),
                 branches=webutil.nodebranchdict(web.repo, ctx))
 
 @webcommand('tags')
 def tags(web, req, tmpl):
     """
     /tags
     -----
 
     Show information about tags.
 
     No arguments are accepted.
 
     The ``tags`` template is rendered.
     """
     i = list(reversed(web.repo.tagslist()))
     parity = paritygen(web.stripecount)
 
     def entries(notip, latestonly, **map):
         t = i
         if notip:
             t = [(k, n) for k, n in i if k != "tip"]
         if latestonly:
             t = t[:1]
         for k, n in t:
             yield {"parity": parity.next(),
                    "tag": k,
                    "date": web.repo[n].date(),
                    "node": hex(n)}
 
     return tmpl("tags",
                 node=hex(web.repo.changelog.tip()),
                 entries=lambda **x: entries(False, False, **x),
                 entriesnotip=lambda **x: entries(True, False, **x),
                 latestentry=lambda **x: entries(True, True, **x))
 
 @webcommand('bookmarks')
 def bookmarks(web, req, tmpl):
     """
     /bookmarks
     ----------
 
     Show information about bookmarks.
 
     No arguments are accepted.
 
     The ``bookmarks`` template is rendered.
     """
     i = [b for b in web.repo._bookmarks.items() if b[1] in web.repo]
     parity = paritygen(web.stripecount)
 
     def entries(latestonly, **map):
         if latestonly:
             t = [min(i)]
         else:
             t = sorted(i)
         for k, n in t:
             yield {"parity": parity.next(),
                    "bookmark": k,
                    "date": web.repo[n].date(),
                    "node": hex(n)}
 
     return tmpl("bookmarks",
                 node=hex(web.repo.changelog.tip()),
                 entries=lambda **x: entries(latestonly=False, **x),
                 latestentry=lambda **x: entries(latestonly=True, **x))
 
 @webcommand('branches')
 def branches(web, req, tmpl):
     """
     /branches
     ---------
 
     Show information about branches.
 
     All known branches are contained in the output, even closed branches.
 
     No arguments are accepted.
 
     The ``branches`` template is rendered.
     """
     tips = []
     heads = web.repo.heads()
     parity = paritygen(web.stripecount)
     sortkey = lambda item: (not item[1], item[0].rev())
 
     def entries(limit, **map):
         count = 0
         if not tips:
             for tag, hs, tip, closed in web.repo.branchmap().iterbranches():
                 tips.append((web.repo[tip], closed))
         for ctx, closed in sorted(tips, key=sortkey, reverse=True):
             if limit > 0 and count >= limit:
                 return
             count += 1
             if closed:
                 status = 'closed'
             elif ctx.node() not in heads:
                 status = 'inactive'
             else:
                 status = 'open'
             yield {'parity': parity.next(),
                    'branch': ctx.branch(),
                    'status': status,
                    'node': ctx.hex(),
                    'date': ctx.date()}
 
     return tmpl('branches', node=hex(web.repo.changelog.tip()),
                 entries=lambda **x: entries(0, **x),
                 latestentry=lambda **x: entries(1, **x))
 
 @webcommand('summary')
 def summary(web, req, tmpl):
     """
     /summary
     --------
 
     Show a summary of repository state.
 
     Information about the latest changesets, bookmarks, tags, and branches
     is captured by this handler.
 
     The ``summary`` template is rendered.
     """
     i = reversed(web.repo.tagslist())
 
     def tagentries(**map):
         parity = paritygen(web.stripecount)
         count = 0
         for k, n in i:
             if k == "tip": # skip tip
                 continue
 
             count += 1
             if count > 10: # limit to 10 tags
                 break
 
             yield tmpl("tagentry",
                        parity=parity.next(),
                        tag=k,
                        node=hex(n),
                        date=web.repo[n].date())
 
     def bookmarks(**map):
         parity = paritygen(web.stripecount)
         marks = [b for b in web.repo._bookmarks.items() if b[1] in web.repo]
         for k, n in sorted(marks)[:10]:  # limit to 10 bookmarks
             yield {'parity': parity.next(),
                    'bookmark': k,
                    'date': web.repo[n].date(),
                    'node': hex(n)}
 
     def branches(**map):
         parity = paritygen(web.stripecount)
 
         b = web.repo.branchmap()
         l = [(-web.repo.changelog.rev(tip), tip, tag)
              for tag, heads, tip, closed in b.iterbranches()]
         for r, n, t in sorted(l):
             yield {'parity': parity.next(),
                    'branch': t,
                    'node': hex(n),
                    'date': web.repo[n].date()}
 
     def changelist(**map):
         parity = paritygen(web.stripecount, offset=start - end)
         l = [] # build a list in forward order for efficiency
         revs = []
         if start < end:
             revs = web.repo.changelog.revs(start, end - 1)
         for i in revs:
             ctx = web.repo[i]
             n = ctx.node()
             hn = hex(n)
 
             l.append(tmpl(
                'shortlogentry',
                 parity=parity.next(),
                 author=ctx.user(),
                 desc=ctx.description(),
                 extra=ctx.extra(),
                 date=ctx.date(),
                 rev=i,
                 node=hn,
                 tags=webutil.nodetagsdict(web.repo, n),
                 bookmarks=webutil.nodebookmarksdict(web.repo, n),
                 inbranch=webutil.nodeinbranch(web.repo, ctx),
                 branches=webutil.nodebranchdict(web.repo, ctx)))
 
         l.reverse()
         yield l
 
     tip = web.repo['tip']
     count = len(web.repo)
     start = max(0, count - web.maxchanges)
     end = min(count, start + web.maxchanges)
 
     return tmpl("summary",
                 desc=web.config("web", "description", "unknown"),
                 owner=get_contact(web.config) or "unknown",
                 lastchange=tip.date(),
                 tags=tagentries,
                 bookmarks=bookmarks,
                 branches=branches,
                 shortlog=changelist,
                 node=tip.hex(),
                 archives=web.archivelist("tip"))
 
 @webcommand('filediff')
 def filediff(web, req, tmpl):
     """
     /diff/{revision}/{path}
     -----------------------
 
     Show how a file changed in a particular commit.
 
     The ``filediff`` template is rendered.
 
     This hander is registered under both the ``/diff`` and ``/filediff``
     paths. ``/diff`` is used in modern code.
     """
     fctx, ctx = None, None
     try:
         fctx = webutil.filectx(web.repo, req)
     except LookupError:
         ctx = webutil.changectx(web.repo, req)
         path = webutil.cleanpath(web.repo, req.form['file'][0])
         if path not in ctx.files():
             raise
 
     if fctx is not None:
         n = fctx.node()
         path = fctx.path()
         ctx = fctx.changectx()
     else:
         n = ctx.node()
         # path already defined in except clause
 
     parity = paritygen(web.stripecount)
     style = web.config('web', 'style', 'paper')
     if 'style' in req.form:
         style = req.form['style'][0]
 
     diffs = webutil.diffs(web.repo, tmpl, ctx, None, [path], parity, style)
     rename = fctx and webutil.renamelink(fctx) or []
     ctx = fctx and fctx or ctx
     return tmpl("filediff",
                 file=path,
                 node=hex(n),
                 rev=ctx.rev(),
                 date=ctx.date(),
                 desc=ctx.description(),
                 extra=ctx.extra(),
                 author=ctx.user(),
                 rename=rename,
                 branch=webutil.nodebranchnodefault(ctx),
                 parent=webutil.parents(ctx),
                 child=webutil.children(ctx),
                 diff=diffs)
 
 diff = webcommand('diff')(filediff)
 
 @webcommand('comparison')
 def comparison(web, req, tmpl):
+    """
+    /comparison/{revision}/{path}
+    -----------------------------
+
+    Show a comparison between the old and new versions of a file from changes
+    made on a particular revision.
+
+    This is similar to the ``diff`` handler. However, this form features
+    a split or side-by-side diff rather than a unified diff.
+
+    The ``context`` query string argument can be used to control the lines of
+    context in the diff.
+
+    The ``filecomparison`` template is rendered.
+    """
     ctx = webutil.changectx(web.repo, req)
     if 'file' not in req.form:
         raise ErrorResponse(HTTP_NOT_FOUND, 'file not given')
     path = webutil.cleanpath(web.repo, req.form['file'][0])
     rename = path in ctx and webutil.renamelink(ctx[path]) or []
 
     parsecontext = lambda v: v == 'full' and -1 or int(v)
     if 'context' in req.form:
         context = parsecontext(req.form['context'][0])
     else:
         context = parsecontext(web.config('web', 'comparisoncontext', '5'))
 
     def filelines(f):
         if util.binary(f.data()):
             mt = mimetypes.guess_type(f.path())[0]
             if not mt:
                 mt = 'application/octet-stream'
             return [_('(binary file %s, hash: %s)') % (mt, hex(f.filenode()))]
         return f.data().splitlines()
 
     parent = ctx.p1()
     leftrev = parent.rev()
     leftnode = parent.node()
     rightrev = ctx.rev()
     rightnode = ctx.node()
     if path in ctx:
         fctx = ctx[path]
         rightlines = filelines(fctx)
         if path not in parent:
             leftlines = ()
         else:
             pfctx = parent[path]
             leftlines = filelines(pfctx)
     else:
         rightlines = ()
         fctx = ctx.parents()[0][path]
         leftlines = filelines(fctx)
 
     comparison = webutil.compare(tmpl, context, leftlines, rightlines)
     return tmpl('filecomparison',
                 file=path,
                 node=hex(ctx.node()),
                 rev=ctx.rev(),
                 date=ctx.date(),
                 desc=ctx.description(),
                 extra=ctx.extra(),
                 author=ctx.user(),
                 rename=rename,
                 branch=webutil.nodebranchnodefault(ctx),
                 parent=webutil.parents(fctx),
                 child=webutil.children(fctx),
                 leftrev=leftrev,
                 leftnode=hex(leftnode),
                 rightrev=rightrev,
                 rightnode=hex(rightnode),
                 comparison=comparison)
 
 @webcommand('annotate')
 def annotate(web, req, tmpl):
     fctx = webutil.filectx(web.repo, req)
     f = fctx.path()
     parity = paritygen(web.stripecount)
     diffopts = patch.difffeatureopts(web.repo.ui, untrusted=True,
                                      section='annotate', whitespace=True)
 
     def annotate(**map):
         last = None
         if util.binary(fctx.data()):
             mt = (mimetypes.guess_type(fctx.path())[0]
                   or 'application/octet-stream')
             lines = enumerate([((fctx.filectx(fctx.filerev()), 1),
                                 '(binary:%s)' % mt)])
         else:
             lines = enumerate(fctx.annotate(follow=True, linenumber=True,
                                             diffopts=diffopts))
         for lineno, ((f, targetline), l) in lines:
             fnode = f.filenode()
 
             if last != fnode:
                 last = fnode
 
             yield {"parity": parity.next(),
                    "node": f.hex(),
                    "rev": f.rev(),
                    "author": f.user(),
                    "desc": f.description(),
                    "extra": f.extra(),
                    "file": f.path(),
                    "targetline": targetline,
                    "line": l,
                    "lineid": "l%d" % (lineno + 1),
                    "linenumber": "% 6d" % (lineno + 1),
                    "revdate": f.date()}
 
     return tmpl("fileannotate",
                 file=f,
                 annotate=annotate,
                 path=webutil.up(f),
                 rev=fctx.rev(),
                 node=fctx.hex(),
                 author=fctx.user(),
                 date=fctx.date(),
                 desc=fctx.description(),
                 extra=fctx.extra(),
                 rename=webutil.renamelink(fctx),
                 branch=webutil.nodebranchnodefault(fctx),
                 parent=webutil.parents(fctx),
                 child=webutil.children(fctx),
                 permissions=fctx.manifest().flags(f))
 
 @webcommand('filelog')
 def filelog(web, req, tmpl):
 
     try:
         fctx = webutil.filectx(web.repo, req)
         f = fctx.path()
         fl = fctx.filelog()
     except error.LookupError:
         f = webutil.cleanpath(web.repo, req.form['file'][0])
         fl = web.repo.file(f)
         numrevs = len(fl)
         if not numrevs: # file doesn't exist at all
             raise
         rev = webutil.changectx(web.repo, req).rev()
         first = fl.linkrev(0)
         if rev < first: # current rev is from before file existed
             raise
         frev = numrevs - 1
         while fl.linkrev(frev) > rev:
             frev -= 1
         fctx = web.repo.filectx(f, fl.linkrev(frev))
 
     revcount = web.maxshortchanges
     if 'revcount' in req.form:
         try:
             revcount = int(req.form.get('revcount', [revcount])[0])
             revcount = max(revcount, 1)
             tmpl.defaults['sessionvars']['revcount'] = revcount
         except ValueError:
             pass
 
     lessvars = copy.copy(tmpl.defaults['sessionvars'])
     lessvars['revcount'] = max(revcount / 2, 1)
     morevars = copy.copy(tmpl.defaults['sessionvars'])
     morevars['revcount'] = revcount * 2
 
     count = fctx.filerev() + 1
     start = max(0, fctx.filerev() - revcount + 1) # first rev on this page
     end = min(count, start + revcount) # last rev on this page
     parity = paritygen(web.stripecount, offset=start - end)
 
     def entries():
         l = []
 
         repo = web.repo
         revs = fctx.filelog().revs(start, end - 1)
         for i in revs:
             iterfctx = fctx.filectx(i)
 
             l.append({"parity": parity.next(),
                       "filerev": i,
                       "file": f,
                       "node": iterfctx.hex(),
                       "author": iterfctx.user(),
                       "date": iterfctx.date(),
                       "rename": webutil.renamelink(iterfctx),
                       "parent": webutil.parents(iterfctx),
                       "child": webutil.children(iterfctx),
                       "desc": iterfctx.description(),
                       "extra": iterfctx.extra(),
                       "tags": webutil.nodetagsdict(repo, iterfctx.node()),
                       "bookmarks": webutil.nodebookmarksdict(
                           repo, iterfctx.node()),
                       "branch": webutil.nodebranchnodefault(iterfctx),
                       "inbranch": webutil.nodeinbranch(repo, iterfctx),
                       "branches": webutil.nodebranchdict(repo, iterfctx)})
         for e in reversed(l):
             yield e
 
     entries = list(entries())
     latestentry = entries[:1]
 
     revnav = webutil.filerevnav(web.repo, fctx.path())
     nav = revnav.gen(end - 1, revcount, count)
     return tmpl("filelog", file=f, node=fctx.hex(), nav=nav,
                 entries=entries,
                 latestentry=latestentry,
                 revcount=revcount, morevars=morevars, lessvars=lessvars)
 
 @webcommand('archive')
 def archive(web, req, tmpl):
     type_ = req.form.get('type', [None])[0]
     allowed = web.configlist("web", "allow_archive")
     key = req.form['node'][0]
 
     if type_ not in web.archives:
         msg = 'Unsupported archive type: %s' % type_
         raise ErrorResponse(HTTP_NOT_FOUND, msg)
 
     if not ((type_ in allowed or
         web.configbool("web", "allow" + type_, False))):
         msg = 'Archive type not allowed: %s' % type_
         raise ErrorResponse(HTTP_FORBIDDEN, msg)
 
     reponame = re.sub(r"\W+", "-", os.path.basename(web.reponame))
     cnode = web.repo.lookup(key)
     arch_version = key
     if cnode == key or key == 'tip':
         arch_version = short(cnode)
     name = "%s-%s" % (reponame, arch_version)
 
     ctx = webutil.changectx(web.repo, req)
     pats = []
     matchfn = scmutil.match(ctx, [])
     file = req.form.get('file', None)
     if file:
         pats = ['path:' + file[0]]
         matchfn = scmutil.match(ctx, pats, default='path')
         if pats:
             files = [f for f in ctx.manifest().keys() if matchfn(f)]
             if not files:
                 raise ErrorResponse(HTTP_NOT_FOUND,
                     'file(s) not found: %s' % file[0])
 
     mimetype, artype, extension, encoding = web.archive_specs[type_]
     headers = [
         ('Content-Disposition', 'attachment; filename=%s%s' % (name, extension))
         ]
     if encoding:
         headers.append(('Content-Encoding', encoding))
     req.headers.extend(headers)
     req.respond(HTTP_OK, mimetype)
 
     archival.archive(web.repo, req, cnode, artype, prefix=name,
                      matchfn=matchfn,
                      subrepos=web.configbool("web", "archivesubrepos"))
     return []
 
 
 @webcommand('static')
 def static(web, req, tmpl):
     fname = req.form['file'][0]
     # a repo owner may set web.static in .hg/hgrc to get any file
     # readable by the user running the CGI script
     static = web.config("web", "static", None, untrusted=False)
     if not static:
         tp = web.templatepath or templater.templatepaths()
         if isinstance(tp, str):
             tp = [tp]
         static = [os.path.join(p, 'static') for p in tp]
     staticfile(static, fname, req)
     return []
 
 @webcommand('graph')
 def graph(web, req, tmpl):
 
     ctx = webutil.changectx(web.repo, req)
     rev = ctx.rev()
 
     bg_height = 39
     revcount = web.maxshortchanges
     if 'revcount' in req.form:
         try:
             revcount = int(req.form.get('revcount', [revcount])[0])
             revcount = max(revcount, 1)
             tmpl.defaults['sessionvars']['revcount'] = revcount
         except ValueError:
             pass
 
     lessvars = copy.copy(tmpl.defaults['sessionvars'])
     lessvars['revcount'] = max(revcount / 2, 1)
     morevars = copy.copy(tmpl.defaults['sessionvars'])
     morevars['revcount'] = revcount * 2
 
     count = len(web.repo)
     pos = rev
 
     uprev = min(max(0, count - 1), rev + revcount)
     downrev = max(0, rev - revcount)
     changenav = webutil.revnav(web.repo).gen(pos, revcount, count)
 
     tree = []
     if pos != -1:
         allrevs = web.repo.changelog.revs(pos, 0)
         revs = []
         for i in allrevs:
             revs.append(i)
             if len(revs) >= revcount:
                 break
 
         # We have to feed a baseset to dagwalker as it is expecting smartset
         # object. This does not have a big impact on hgweb performance itself
         # since hgweb graphing code is not itself lazy yet.
         dag = graphmod.dagwalker(web.repo, revset.baseset(revs))
         # As we said one line above... not lazy.
         tree = list(graphmod.colored(dag, web.repo))
 
     def getcolumns(tree):
         cols = 0
         for (id, type, ctx, vtx, edges) in tree:
             if type != graphmod.CHANGESET:
                 continue
             cols = max(cols, max([edge[0] for edge in edges] or [0]),
                              max([edge[1] for edge in edges] or [0]))
         return cols
 
     def graphdata(usetuples, **map):
         data = []
 
         row = 0
         for (id, type, ctx, vtx, edges) in tree:
             if type != graphmod.CHANGESET:
                 continue
             node = str(ctx)
             age = templatefilters.age(ctx.date())
             desc = templatefilters.firstline(ctx.description())
             desc = cgi.escape(templatefilters.nonempty(desc))
             user = cgi.escape(templatefilters.person(ctx.user()))
             branch = cgi.escape(ctx.branch())
             try:
                 branchnode = web.repo.branchtip(branch)
             except error.RepoLookupError:
                 branchnode = None
             branch = branch, branchnode == ctx.node()
 
             if usetuples:
                 data.append((node, vtx, edges, desc, user, age, branch,
                              [cgi.escape(x) for x in ctx.tags()],
                              [cgi.escape(x) for x in ctx.bookmarks()]))
             else:
                 edgedata = [{'col': edge[0], 'nextcol': edge[1],
                              'color': (edge[2] - 1) % 6 + 1,
                              'width': edge[3], 'bcolor': edge[4]}
                             for edge in edges]
 
                 data.append(
                     {'node': node,
                      'col': vtx[0],
                      'color': (vtx[1] - 1) % 6 + 1,
                      'edges': edgedata,
                      'row': row,
                      'nextrow': row + 1,
                      'desc': desc,
                      'user': user,
                      'age': age,
                      'bookmarks': webutil.nodebookmarksdict(
                          web.repo, ctx.node()),
                      'branches': webutil.nodebranchdict(web.repo, ctx),
                      'inbranch': webutil.nodeinbranch(web.repo, ctx),
                      'tags': webutil.nodetagsdict(web.repo, ctx.node())})
 
             row += 1
 
         return data
 
     cols = getcolumns(tree)
     rows = len(tree)
     canvasheight = (rows + 1) * bg_height - 27
 
     return tmpl('graph', rev=rev, revcount=revcount, uprev=uprev,
                 lessvars=lessvars, morevars=morevars, downrev=downrev,
                 cols=cols, rows=rows,
                 canvaswidth=(cols + 1) * bg_height,
                 truecanvasheight=rows * bg_height,
                 canvasheight=canvasheight, bg_height=bg_height,
                 jsdata=lambda **x: graphdata(True, **x),
                 nodes=lambda **x: graphdata(False, **x),
                 node=ctx.hex(), changenav=changenav)
 
 def _getdoc(e):
     doc = e[0].__doc__
     if doc:
         doc = _(doc).split('\n')[0]
     else:
         doc = _('(no help text available)')
     return doc
 
 @webcommand('help')
 def help(web, req, tmpl):
     """
     /help[/{topic}]
     ---------------
 
     Render help documentation.
 
     This web command is roughly equivalent to :hg:`help`. If a ``topic``
     is defined, that help topic will be rendered. If not, an index of
     available help topics will be rendered.
 
     The ``help`` template will be rendered when requesting help for a topic.
     ``helptopics`` will be rendered for the index of help topics.
     """
     from mercurial import commands # avoid cycle
     from mercurial import help as helpmod # avoid cycle
 
     topicname = req.form.get('node', [None])[0]
     if not topicname:
         def topics(**map):
             for entries, summary, _doc in helpmod.helptable:
                 yield {'topic': entries[0], 'summary': summary}
 
         early, other = [], []
         primary = lambda s: s.split('|')[0]
         for c, e in commands.table.iteritems():
             doc = _getdoc(e)
             if 'DEPRECATED' in doc or c.startswith('debug'):
                 continue
             cmd = primary(c)
             if cmd.startswith('^'):
                 early.append((cmd[1:], doc))
             else:
                 other.append((cmd, doc))
 
         early.sort()
         other.sort()
 
         def earlycommands(**map):
             for c, doc in early:
                 yield {'topic': c, 'summary': doc}
 
         def othercommands(**map):
             for c, doc in other:
                 yield {'topic': c, 'summary': doc}
 
         return tmpl('helptopics', topics=topics, earlycommands=earlycommands,
                     othercommands=othercommands, title='Index')
 
     u = webutil.wsgiui()
     u.verbose = True
     try:
         doc = helpmod.help_(u, topicname)
     except error.UnknownCommand:
         raise ErrorResponse(HTTP_NOT_FOUND)
     return tmpl('help', topic=topicname, doc=doc)