templater: selecting a style with no templates does not crash (issue4140)

Running `hg log --style compact` (or any other style) raised a traceback when
no template directory was there. Now there is a message:

Abort: style 'compact' not found
(available styles: no templates found, try `hg debuginstall` for more info)


There is no test because this would require to rename the template directory.
But this would influence other tests running in parallel. And when the test
would be aborted the wrong named directory would remain, especially a problem
when running with -l.

mercurial/templater.py

@@ -1,587 +1,589 b''
 # templater.py - template expansion for output
 #
 # Copyright 2005, 2006 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 i18n import _
 import sys, os, re
 import util, config, templatefilters, parser, error
 import types
 import minirst
 
 # template parsing
 
 elements = {
     "(": (20, ("group", 1, ")"), ("func", 1, ")")),
     ",": (2, None, ("list", 2)),
     "|": (5, None, ("|", 5)),
     "%": (6, None, ("%", 6)),
     ")": (0, None, None),
     "symbol": (0, ("symbol",), None),
     "string": (0, ("string",), None),
     "end": (0, None, None),
 }
 
 def tokenizer(data):
     program, start, end = data
     pos = start
     while pos < end:
         c = program[pos]
         if c.isspace(): # skip inter-token whitespace
             pass
         elif c in "(,)%|": # handle simple operators
             yield (c, None, pos)
         elif (c in '"\'' or c == 'r' and
               program[pos:pos + 2] in ("r'", 'r"')): # handle quoted strings
             if c == 'r':
                 pos += 1
                 c = program[pos]
                 decode = False
             else:
                 decode = True
             pos += 1
             s = pos
             while pos < end: # find closing quote
                 d = program[pos]
                 if decode and d == '\\': # skip over escaped characters
                     pos += 2
                     continue
                 if d == c:
                     if not decode:
                         yield ('string', program[s:pos].replace('\\', r'\\'), s)
                         break
                     yield ('string', program[s:pos], s)
                     break
                 pos += 1
             else:
                 raise error.ParseError(_("unterminated string"), s)
         elif c.isalnum() or c in '_':
             s = pos
             pos += 1
             while pos < end: # find end of symbol
                 d = program[pos]
                 if not (d.isalnum() or d == "_"):
                     break
                 pos += 1
             sym = program[s:pos]
             yield ('symbol', sym, s)
             pos -= 1
         elif c == '}':
             pos += 1
             break
         else:
             raise error.ParseError(_("syntax error"), pos)
         pos += 1
     yield ('end', None, pos)
 
 def compiletemplate(tmpl, context):
     parsed = []
     pos, stop = 0, len(tmpl)
     p = parser.parser(tokenizer, elements)
     while pos < stop:
         n = tmpl.find('{', pos)
         if n < 0:
             parsed.append(("string", tmpl[pos:].decode("string-escape")))
             break
         if n > 0 and tmpl[n - 1] == '\\':
             # escaped
             parsed.append(("string",
                            (tmpl[pos:n - 1] + "{").decode("string-escape")))
             pos = n + 1
             continue
         if n > pos:
             parsed.append(("string", tmpl[pos:n].decode("string-escape")))
 
         pd = [tmpl, n + 1, stop]
         parseres, pos = p.parse(pd)
         parsed.append(parseres)
 
     return [compileexp(e, context) for e in parsed]
 
 def compileexp(exp, context):
     t = exp[0]
     if t in methods:
         return methods[t](exp, context)
     raise error.ParseError(_("unknown method '%s'") % t)
 
 # template evaluation
 
 def getsymbol(exp):
     if exp[0] == 'symbol':
         return exp[1]
     raise error.ParseError(_("expected a symbol"))
 
 def getlist(x):
     if not x:
         return []
     if x[0] == 'list':
         return getlist(x[1]) + [x[2]]
     return [x]
 
 def getfilter(exp, context):
     f = getsymbol(exp)
     if f not in context._filters:
         raise error.ParseError(_("unknown function '%s'") % f)
     return context._filters[f]
 
 def gettemplate(exp, context):
     if exp[0] == 'string':
         return compiletemplate(exp[1], context)
     if exp[0] == 'symbol':
         return context._load(exp[1])
     raise error.ParseError(_("expected template specifier"))
 
 def runstring(context, mapping, data):
     return data
 
 def runsymbol(context, mapping, key):
     v = mapping.get(key)
     if v is None:
         v = context._defaults.get(key)
     if v is None:
         try:
             v = context.process(key, mapping)
         except TemplateNotFound:
             v = ''
     if util.safehasattr(v, '__call__'):
         return v(**mapping)
     if isinstance(v, types.GeneratorType):
         v = list(v)
         mapping[key] = v
         return v
     return v
 
 def buildfilter(exp, context):
     func, data = compileexp(exp[1], context)
     filt = getfilter(exp[2], context)
     return (runfilter, (func, data, filt))
 
 def runfilter(context, mapping, data):
     func, data, filt = data
     try:
         return filt(func(context, mapping, data))
     except (ValueError, AttributeError, TypeError):
         if isinstance(data, tuple):
             dt = data[1]
         else:
             dt = data
         raise util.Abort(_("template filter '%s' is not compatible with "
                            "keyword '%s'") % (filt.func_name, dt))
 
 def buildmap(exp, context):
     func, data = compileexp(exp[1], context)
     ctmpl = gettemplate(exp[2], context)
     return (runmap, (func, data, ctmpl))
 
 def runtemplate(context, mapping, template):
     for func, data in template:
         yield func(context, mapping, data)
 
 def runmap(context, mapping, data):
     func, data, ctmpl = data
     d = func(context, mapping, data)
     if util.safehasattr(d, '__call__'):
         d = d()
 
     lm = mapping.copy()
 
     for i in d:
         if isinstance(i, dict):
             lm.update(i)
             lm['originalnode'] = mapping.get('node')
             yield runtemplate(context, lm, ctmpl)
         else:
             # v is not an iterable of dicts, this happen when 'key'
             # has been fully expanded already and format is useless.
             # If so, return the expanded value.
             yield i
 
 def buildfunc(exp, context):
     n = getsymbol(exp[1])
     args = [compileexp(x, context) for x in getlist(exp[2])]
     if n in funcs:
         f = funcs[n]
         return (f, args)
     if n in context._filters:
         if len(args) != 1:
             raise error.ParseError(_("filter %s expects one argument") % n)
         f = context._filters[n]
         return (runfilter, (args[0][0], args[0][1], f))
 
 def date(context, mapping, args):
     if not (1 <= len(args) <= 2):
         raise error.ParseError(_("date expects one or two arguments"))
 
     date = args[0][0](context, mapping, args[0][1])
     if len(args) == 2:
         fmt = stringify(args[1][0](context, mapping, args[1][1]))
         return util.datestr(date, fmt)
     return util.datestr(date)
 
 def fill(context, mapping, args):
     if not (1 <= len(args) <= 4):
         raise error.ParseError(_("fill expects one to four arguments"))
 
     text = stringify(args[0][0](context, mapping, args[0][1]))
     width = 76
     initindent = ''
     hangindent = ''
     if 2 <= len(args) <= 4:
         try:
             width = int(stringify(args[1][0](context, mapping, args[1][1])))
         except ValueError:
             raise error.ParseError(_("fill expects an integer width"))
         try:
             initindent = stringify(args[2][0](context, mapping, args[2][1]))
             initindent = stringify(runtemplate(context, mapping,
                                      compiletemplate(initindent, context)))
             hangindent = stringify(args[3][0](context, mapping, args[3][1]))
             hangindent = stringify(runtemplate(context, mapping,
                                      compiletemplate(hangindent, context)))
         except IndexError:
             pass
 
     return templatefilters.fill(text, width, initindent, hangindent)
 
 def get(context, mapping, args):
     if len(args) != 2:
         # i18n: "get" is a keyword
         raise error.ParseError(_("get() expects two arguments"))
 
     dictarg = args[0][0](context, mapping, args[0][1])
     if not util.safehasattr(dictarg, 'get'):
         # i18n: "get" is a keyword
         raise error.ParseError(_("get() expects a dict as first argument"))
 
     key = args[1][0](context, mapping, args[1][1])
     yield dictarg.get(key)
 
 def _evalifliteral(arg, context, mapping):
     t = stringify(arg[0](context, mapping, arg[1]))
     if arg[0] == runstring:
         yield runtemplate(context, mapping, compiletemplate(t, context))
     else:
         yield t
 
 def if_(context, mapping, args):
     if not (2 <= len(args) <= 3):
         # i18n: "if" is a keyword
         raise error.ParseError(_("if expects two or three arguments"))
 
     test = stringify(args[0][0](context, mapping, args[0][1]))
     if test:
         yield _evalifliteral(args[1], context, mapping)
     elif len(args) == 3:
         yield _evalifliteral(args[2], context, mapping)
 
 def ifeq(context, mapping, args):
     if not (3 <= len(args) <= 4):
         # i18n: "ifeq" is a keyword
         raise error.ParseError(_("ifeq expects three or four arguments"))
 
     test = stringify(args[0][0](context, mapping, args[0][1]))
     match = stringify(args[1][0](context, mapping, args[1][1]))
     if test == match:
         yield _evalifliteral(args[2], context, mapping)
     elif len(args) == 4:
         yield _evalifliteral(args[3], context, mapping)
 
 def join(context, mapping, args):
     if not (1 <= len(args) <= 2):
         # i18n: "join" is a keyword
         raise error.ParseError(_("join expects one or two arguments"))
 
     joinset = args[0][0](context, mapping, args[0][1])
     if util.safehasattr(joinset, '__call__'):
         jf = joinset.joinfmt
         joinset = [jf(x) for x in joinset()]
 
     joiner = " "
     if len(args) > 1:
         joiner = args[1][0](context, mapping, args[1][1])
 
     first = True
     for x in joinset:
         if first:
             first = False
         else:
             yield joiner
         yield x
 
 def label(context, mapping, args):
     if len(args) != 2:
         # i18n: "label" is a keyword
         raise error.ParseError(_("label expects two arguments"))
 
     # ignore args[0] (the label string) since this is supposed to be a a no-op
     yield _evalifliteral(args[1], context, mapping)
 
 def rstdoc(context, mapping, args):
     if len(args) != 2:
         # i18n: "rstdoc" is a keyword
         raise error.ParseError(_("rstdoc expects two arguments"))
 
     text = stringify(args[0][0](context, mapping, args[0][1]))
     style = stringify(args[1][0](context, mapping, args[1][1]))
 
     return minirst.format(text, style=style, keep=['verbose'])
 
 def strip(context, mapping, args):
     if not (1 <= len(args) <= 2):
         raise error.ParseError(_("strip expects one or two arguments"))
 
     text = args[0][0](context, mapping, args[0][1])
     if len(args) == 2:
         chars = args[1][0](context, mapping, args[1][1])
         return text.strip(chars)
     return text.strip()
 
 def sub(context, mapping, args):
     if len(args) != 3:
         # i18n: "sub" is a keyword
         raise error.ParseError(_("sub expects three arguments"))
 
     pat = stringify(args[0][0](context, mapping, args[0][1]))
     rpl = stringify(args[1][0](context, mapping, args[1][1]))
     src = stringify(args[2][0](context, mapping, args[2][1]))
     src = stringify(runtemplate(context, mapping,
                                 compiletemplate(src, context)))
     yield re.sub(pat, rpl, src)
 
 methods = {
     "string": lambda e, c: (runstring, e[1]),
     "symbol": lambda e, c: (runsymbol, e[1]),
     "group": lambda e, c: compileexp(e[1], c),
 #    ".": buildmember,
     "|": buildfilter,
     "%": buildmap,
     "func": buildfunc,
     }
 
 funcs = {
     "date": date,
     "fill": fill,
     "get": get,
     "if": if_,
     "ifeq": ifeq,
     "join": join,
     "label": label,
     "rstdoc": rstdoc,
     "strip": strip,
     "sub": sub,
 }
 
 # template engine
 
 path = ['templates', '../templates']
 stringify = templatefilters.stringify
 
 def _flatten(thing):
     '''yield a single stream from a possibly nested set of iterators'''
     if isinstance(thing, str):
         yield thing
     elif not util.safehasattr(thing, '__iter__'):
         if thing is not None:
             yield str(thing)
     else:
         for i in thing:
             if isinstance(i, str):
                 yield i
             elif not util.safehasattr(i, '__iter__'):
                 if i is not None:
                     yield str(i)
             elif i is not None:
                 for j in _flatten(i):
                     yield j
 
 def parsestring(s, quoted=True):
     '''parse a string using simple c-like syntax.
     string must be in quotes if quoted is True.'''
     if quoted:
         if len(s) < 2 or s[0] != s[-1]:
             raise SyntaxError(_('unmatched quotes'))
         return s[1:-1].decode('string_escape')
 
     return s.decode('string_escape')
 
 class engine(object):
     '''template expansion engine.
 
     template expansion works like this. a map file contains key=value
     pairs. if value is quoted, it is treated as string. otherwise, it
     is treated as name of template file.
 
     templater is asked to expand a key in map. it looks up key, and
     looks for strings like this: {foo}. it expands {foo} by looking up
     foo in map, and substituting it. expansion is recursive: it stops
     when there is no more {foo} to replace.
 
     expansion also allows formatting and filtering.
 
     format uses key to expand each item in list. syntax is
     {key%format}.
 
     filter uses function to transform value. syntax is
     {key|filter1|filter2|...}.'''
 
     def __init__(self, loader, filters={}, defaults={}):
         self._loader = loader
         self._filters = filters
         self._defaults = defaults
         self._cache = {}
 
     def _load(self, t):
         '''load, parse, and cache a template'''
         if t not in self._cache:
             self._cache[t] = compiletemplate(self._loader(t), self)
         return self._cache[t]
 
     def process(self, t, mapping):
         '''Perform expansion. t is name of map element to expand.
         mapping contains added elements for use during expansion. Is a
         generator.'''
         return _flatten(runtemplate(self, mapping, self._load(t)))
 
 engines = {'default': engine}
 
 def stylelist():
-    path = templatepath()[0]
-    dirlist =  os.listdir(path)
+    paths = templatepath()
+    if not paths:
+        return _('no templates found, try `hg debuginstall` for more info')
+    dirlist =  os.listdir(paths[0])
     stylelist = []
     for file in dirlist:
         split = file.split(".")
         if split[0] == "map-cmdline":
             stylelist.append(split[1])
     return ", ".join(sorted(stylelist))
 
 class TemplateNotFound(util.Abort):
     pass
 
 class templater(object):
 
     def __init__(self, mapfile, filters={}, defaults={}, cache={},
                  minchunk=1024, maxchunk=65536):
         '''set up template engine.
         mapfile is name of file to read map definitions from.
         filters is dict of functions. each transforms a value into another.
         defaults is dict of default map definitions.'''
         self.mapfile = mapfile or 'template'
         self.cache = cache.copy()
         self.map = {}
         self.base = (mapfile and os.path.dirname(mapfile)) or ''
         self.filters = templatefilters.filters.copy()
         self.filters.update(filters)
         self.defaults = defaults
         self.minchunk, self.maxchunk = minchunk, maxchunk
         self.ecache = {}
 
         if not mapfile:
             return
         if not os.path.exists(mapfile):
             raise util.Abort(_("style '%s' not found") % mapfile,
                              hint=_("available styles: %s") % stylelist())
 
         conf = config.config()
         conf.read(mapfile)
 
         for key, val in conf[''].items():
             if not val:
                 raise SyntaxError(_('%s: missing value') % conf.source('', key))
             if val[0] in "'\"":
                 try:
                     self.cache[key] = parsestring(val)
                 except SyntaxError, inst:
                     raise SyntaxError('%s: %s' %
                                       (conf.source('', key), inst.args[0]))
             else:
                 val = 'default', val
                 if ':' in val[1]:
                     val = val[1].split(':', 1)
                 self.map[key] = val[0], os.path.join(self.base, val[1])
 
     def __contains__(self, key):
         return key in self.cache or key in self.map
 
     def load(self, t):
         '''Get the template for the given template name. Use a local cache.'''
         if t not in self.cache:
             try:
                 self.cache[t] = util.readfile(self.map[t][1])
             except KeyError, inst:
                 raise TemplateNotFound(_('"%s" not in template map') %
                                        inst.args[0])
             except IOError, inst:
                 raise IOError(inst.args[0], _('template file %s: %s') %
                               (self.map[t][1], inst.args[1]))
         return self.cache[t]
 
     def __call__(self, t, **mapping):
         ttype = t in self.map and self.map[t][0] or 'default'
         if ttype not in self.ecache:
             self.ecache[ttype] = engines[ttype](self.load,
                                                  self.filters, self.defaults)
         proc = self.ecache[ttype]
 
         stream = proc.process(t, mapping)
         if self.minchunk:
             stream = util.increasingchunks(stream, min=self.minchunk,
                                            max=self.maxchunk)
         return stream
 
 def templatepath(name=None):
     '''return location of template file or directory (if no name).
     returns None if not found.'''
     normpaths = []
 
     # executable version (py2exe) doesn't support __file__
     if util.mainfrozen():
         module = sys.executable
     else:
         module = __file__
     for f in path:
         if f.startswith('/'):
             p = f
         else:
             fl = f.split('/')
             p = os.path.join(os.path.dirname(module), *fl)
         if name:
             p = os.path.join(p, name)
         if name and os.path.exists(p):
             return os.path.normpath(p)
         elif os.path.isdir(p):
             normpaths.append(os.path.normpath(p))
 
     return normpaths
 
 def stylemap(styles, paths=None):
     """Return path to mapfile for a given style.
 
     Searches mapfile in the following locations:
     1. templatepath/style/map
     2. templatepath/map-style
     3. templatepath/map
     """
 
     if paths is None:
         paths = templatepath()
     elif isinstance(paths, str):
         paths = [paths]
 
     if isinstance(styles, str):
         styles = [styles]
 
     for style in styles:
         if not style:
             continue
         locations = [os.path.join(style, 'map'), 'map-' + style]
         locations.append('map')
 
         for path in paths:
             for location in locations:
                 mapfile = os.path.join(path, location)
                 if os.path.isfile(mapfile):
                     return style, mapfile
 
     raise RuntimeError("No hgweb templates found in %r" % paths)