hgweb: `limit` argument is actually `latestonly` renames and enforce

The `limit` argument of several generator have only two possible values in
practice: 0 and 1. We rename this parameter to `latestonly` and simplify it's
handling.

The simplification allows us to save fetching of data that we are sure to not
consume.

Having a function minimal function perimeter will helps future refactoring.

mercurial/hgweb/webcommands.py

@@ -1,981 +1,981 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, nullid
 from mercurial.util import binary
 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 help as helpmod
 from mercurial import scmutil
 from mercurial.i18n import _
 
 # __all__ is populated with the allowed commands. Be sure to add to it if
 # you're adding a new command, or the new command won't work.
 
 __all__ = [
    'log', 'rawfile', 'file', 'changelog', 'shortlog', 'changeset', 'rev',
    'manifest', 'tags', 'bookmarks', 'branches', 'summary', 'filediff', 'diff',
    'comparison', 'annotate', 'filelog', 'archive', 'static', 'graph', 'help',
 ]
 
 def log(web, req, tmpl):
     if 'file' in req.form and req.form['file'][0]:
         return filelog(web, req, tmpl)
     else:
         return changelog(web, req, tmpl)
 
 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 = 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 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(),
                 branch=webutil.nodebranchnodefault(fctx),
                 parent=webutil.parents(fctx),
                 child=webutil.children(fctx),
                 rename=webutil.renamelink(fctx),
                 permissions=fctx.manifest().flags(f))
 
 def file(web, req, tmpl):
     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):
 
     query = req.form['rev'][0]
     revcount = web.maxchanges
     if 'revcount' in req.form:
         revcount = int(req.form.get('revcount', [revcount])[0])
         revcount = max(revcount, 1)
         tmpl.defaults['sessionvars']['revcount'] = revcount
 
     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
 
     def changelist(**map):
         count = 0
         lower = encoding.lower
         qw = lower(query).split()
 
         def revgen():
             for i in xrange(len(web.repo) - 1, 0, -100):
                 l = []
                 for j in xrange(max(0, i - 100), i + 1):
                     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
 
             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(),
                        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
 
     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)
 
 def changelog(web, req, tmpl, shortlog=False):
 
     if 'node' in req.form:
         ctx = webutil.changectx(web.repo, req)
     else:
         if 'rev' in req.form:
             hi = req.form['rev'][0]
         else:
             hi = len(web.repo) - 1
         try:
             ctx = web.repo[hi]
         except error.RepoError:
             return _search(web, req, tmpl) # XXX redirect to 404 page?
 
-    def changelist(limit=0, **map):
+    def changelist(latestonly, **map):
         l = [] # build a list in forward order for efficiency
-        for i in xrange(start, end):
+        if latestonly:
+            revs = (end - 1,)
+        else:
+            revs = xrange(start, end)
+        for i in revs:
             ctx = web.repo[i]
             n = ctx.node()
             showtags = webutil.showtag(web.repo, tmpl, 'changelogtag', n)
             files = webutil.listfilediffs(tmpl, ctx.files(), n, web.maxfiles)
 
             l.append({"parity": parity.next(),
                       "author": ctx.user(),
                       "parent": webutil.parents(ctx, i - 1),
                       "child": webutil.children(ctx, i + 1),
                       "changelogtag": showtags,
                       "desc": ctx.description(),
                       "date": ctx.date(),
                       "files": files,
                       "rev": i,
                       "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 limit > 0:
-            l = l[-limit:]
-
         for e in reversed(l):
             yield e
 
     revcount = shortlog and web.maxshortchanges or web.maxchanges
     if 'revcount' in req.form:
         revcount = int(req.form.get('revcount', [revcount])[0])
         revcount = max(revcount, 1)
         tmpl.defaults['sessionvars']['revcount'] = revcount
 
     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()
     start = max(0, pos - revcount + 1)
     end = min(count, start + revcount)
     pos = end - 1
     parity = paritygen(web.stripecount, offset=start - end)
 
     changenav = webutil.revnavgen(pos, revcount, count, web.repo.changectx)
 
     return tmpl(shortlog and 'shortlog' or 'changelog', changenav=changenav,
                 node=ctx.hex(), rev=pos, changesets=count,
-                entries=lambda **x: changelist(limit=0,**x),
-                latestentry=lambda **x: changelist(limit=1,**x),
+                entries=lambda **x: changelist(latestonly=False, **x),
+                latestentry=lambda **x: changelist(latestonly=True, **x),
                 archives=web.archivelist("tip"), revcount=revcount,
                 morevars=morevars, lessvars=lessvars)
 
 def shortlog(web, req, tmpl):
     return changelog(web, req, tmpl, shortlog = True)
 
 def changeset(web, req, tmpl):
     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=webutil.parents(ctx),
                 child=webutil.children(ctx),
                 currentbaseline=basectx.hex(),
                 changesettag=showtags,
                 changesetbookmark=showbookmarks,
                 changesetbranch=showbranch,
                 author=ctx.user(),
                 desc=ctx.description(),
                 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 = 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
 
 def manifest(web, req, tmpl):
     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))
 
 def tags(web, req, tmpl):
     i = list(reversed(web.repo.tagslist()))
     parity = paritygen(web.stripecount)
 
-    def entries(notip=False, limit=0, **map):
-        count = 0
-        for k, n in i:
-            if notip and k == "tip":
-                continue
-            if limit > 0 and count >= limit:
-                continue
-            count = count + 1
+    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, 0, **x),
-                entriesnotip=lambda **x: entries(True, 0, **x),
-                latestentry=lambda **x: entries(True, 1, **x))
+                entries=lambda **x: entries(False, False, **x),
+                entriesnotip=lambda **x: entries(True, False, **x),
+                latestentry=lambda **x: entries(True, True, **x))
 
 def bookmarks(web, req, tmpl):
     i = web.repo._bookmarks.items()
     parity = paritygen(web.stripecount)
 
-    def entries(limit=0, **map):
-        count = 0
-        for k, n in sorted(i):
-            if limit > 0 and count >= limit:
-                continue
-            count = count + 1
+    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(0, **x),
-                latestentry=lambda **x: entries(1, **x))
+                entries=lambda **x: entries(latestonly=False, **x),
+                latestentry=lambda **x: entries(latestonly=True, **x))
 
 def branches(web, req, tmpl):
     tips = []
     heads = web.repo.heads()
     parity = paritygen(web.stripecount)
     sortkey = lambda ctx: (not ctx.closesbranch(), ctx.rev())
 
     def entries(limit, **map):
         count = 0
         if not tips:
             for t, n in web.repo.branchtags().iteritems():
                 tips.append(web.repo[n])
         for ctx in sorted(tips, key=sortkey, reverse=True):
             if limit > 0 and count >= limit:
                 return
             count += 1
             if not web.repo.branchheads(ctx.branch()):
                 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))
 
 def summary(web, req, tmpl):
     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)
         b = web.repo._bookmarks.items()
         for k, n in sorted(b)[: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.branchtags()
         l = [(-web.repo.changelog.rev(n), n, t) for t, n in b.iteritems()]
         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
         for i in xrange(start, end):
             ctx = web.repo[i]
             n = ctx.node()
             hn = hex(n)
 
             l.append(tmpl(
                'shortlogentry',
                 parity=parity.next(),
                 author=ctx.user(),
                 desc=ctx.description(),
                 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"))
 
 def filediff(web, req, tmpl):
     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(),
                 author=ctx.user(),
                 rename=rename,
                 branch=webutil.nodebranchnodefault(ctx),
                 parent=webutil.parents(ctx),
                 child=webutil.children(ctx),
                 diff=diffs)
 
 diff = filediff
 
 def comparison(web, req, tmpl):
     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 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()
 
     if path in ctx:
         fctx = ctx[path]
         rightrev = fctx.filerev()
         rightnode = fctx.filenode()
         rightlines = filelines(fctx)
         parents = fctx.parents()
         if not parents:
             leftrev = -1
             leftnode = nullid
             leftlines = ()
         else:
             pfctx = parents[0]
             leftrev = pfctx.filerev()
             leftnode = pfctx.filenode()
             leftlines = filelines(pfctx)
     else:
         rightrev = -1
         rightnode = nullid
         rightlines = ()
         fctx = ctx.parents()[0][path]
         leftrev = fctx.filerev()
         leftnode = fctx.filenode()
         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(),
                 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)
 
 def annotate(web, req, tmpl):
     fctx = webutil.filectx(web.repo, req)
     f = fctx.path()
     parity = paritygen(web.stripecount)
     diffopts = patch.diffopts(web.repo.ui, untrusted=True, section='annotate')
 
     def annotate(**map):
         last = None
         if 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(),
                    "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(),
                 rename=webutil.renamelink(fctx),
                 branch=webutil.nodebranchnodefault(fctx),
                 parent=webutil.parents(fctx),
                 child=webutil.children(fctx),
                 permissions=fctx.manifest().flags(f))
 
 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:
         revcount = int(req.form.get('revcount', [revcount])[0])
         revcount = max(revcount, 1)
         tmpl.defaults['sessionvars']['revcount'] = revcount
 
     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(limit=0, **map):
+    def entries(latestonly, **map):
         l = []
 
         repo = web.repo
-        for i in xrange(start, end):
+        if latestonly:
+            revs = (end - 1,)
+        else:
+            revs = xrange(start, end)
+        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(),
                       "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)})
-
-        if limit > 0:
-            l = l[-limit:]
-
         for e in reversed(l):
             yield e
 
     nodefunc = lambda x: fctx.filectx(fileid=x)
     nav = webutil.revnavgen(end - 1, revcount, count, nodefunc)
     return tmpl("filelog", file=f, node=fctx.hex(), nav=nav,
-                entries=lambda **x: entries(limit=0, **x),
-                latestentry=lambda **x: entries(limit=1, **x),
+                entries=lambda **x: entries(latestonly=False, **x),
+                latestentry=lambda **x: entries(latestonly=True, **x),
                 revcount=revcount, morevars=morevars, lessvars=lessvars)
 
 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)
     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)
 
     ctx = webutil.changectx(web.repo, req)
     archival.archive(web.repo, req, cnode, artype, prefix=name,
                      matchfn=scmutil.match(ctx, []),
                      subrepos=web.configbool("web", "archivesubrepos"))
     return []
 
 
 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.templatepath()
         if isinstance(tp, str):
             tp = [tp]
         static = [os.path.join(p, 'static') for p in tp]
     return [staticfile(static, fname, req)]
 
 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:
         revcount = int(req.form.get('revcount', [revcount])[0])
         revcount = max(revcount, 1)
         tmpl.defaults['sessionvars']['revcount'] = revcount
 
     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
     start = max(0, pos - revcount + 1)
     end = min(count, start + revcount)
     pos = end - 1
 
     uprev = min(max(0, count - 1), rev + revcount)
     downrev = max(0, rev - revcount)
     changenav = webutil.revnavgen(pos, revcount, count, web.repo.changectx)
 
     dag = graphmod.dagwalker(web.repo, range(start, end)[::-1])
     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 = 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,
                              ctx.tags(), ctx.bookmarks()))
             else:
                 edgedata = [dict(col=edge[0], nextcol=edge[1],
                                  color=(edge[2] - 1) % 6 + 1,
                                  width=edge[3], bcolor=edge[4])
                             for edge in edges]
 
                 data.append(
                     dict(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
 
 def help(web, req, tmpl):
     from mercurial import commands # avoid cycle
 
     topicname = req.form.get('node', [None])[0]
     if not topicname:
         def topics(**map):
             for entries, summary, _ 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.pushbuffer()
     u.verbose = True
     try:
         commands.help_(u, topicname)
     except error.UnknownCommand:
         raise ErrorResponse(HTTP_NOT_FOUND)
     doc = u.popbuffer()
     return tmpl('help', topic=topicname, doc=doc)