templater: comment that gettemplate() has different name resolution order

I've tried to unify gettemplate() with buildtemplate(), but it didn't go well
because gettemplate() have to bypass mapping dict.

For example, web templates have '{tags%changelogtag}' and 'changelogtag' is
defined in both mapping, the default, and context.cache, sourced from map file.
In general, mapping shadows context variables, but gettemplate() have to pick
it from context.cache.

mercurial/templater.py

@@ -1,861 +1,864
 # 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 os, re
 import util, config, templatefilters, templatekw, parser, error
 import revset as revsetmod
 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),
     "integer": (0, ("integer",), None),
     "symbol": (0, ("symbol",), None),
     "string": (0, ("template",), None),
     "rawstring": (0, ("rawstring",), 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 ('rawstring', program[s:pos], s)
                         break
                     yield ('string', program[s:pos], s)
                     break
                 pos += 1
             else:
                 raise error.ParseError(_("unterminated string"), s)
         elif c.isdigit() or c == '-':
             s = pos
             if c == '-': # simply take negate operator as part of integer
                 pos += 1
             if pos >= end or not program[pos].isdigit():
                 raise error.ParseError(_("integer literal without digits"), s)
             pos += 1
             while pos < end:
                 d = program[pos]
                 if not d.isdigit():
                     break
                 pos += 1
             yield ('integer', program[s:pos], s)
             pos -= 1
         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:]))
             break
         bs = (n - pos) - len(tmpl[pos:n].rstrip('\\'))
         if bs % 2 == 1:
             # escaped (e.g. '\{', '\\\{', but not '\\{')
             parsed.append(('string', (tmpl[pos:n - 1] + "{")))
             pos = n + 1
             continue
         if n > pos:
             parsed.append(('string', tmpl[pos:n]))
 
         pd = [tmpl, n + 1, stop]
         parseres, pos = p.parse(pd)
         parsed.append(parseres)
 
     return [compileexp(e, context, methods) for e in parsed]
 
 def compileexp(exp, context, curmethods):
     t = exp[0]
     if t in curmethods:
         return curmethods[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, got '%s'") % exp[0])
 
 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] == 'template':
         return compiletemplate(exp[1], context)
     if exp[0] == 'symbol':
+        # unlike runsymbol(), here 'symbol' is always taken as template name
+        # even if it exists in mapping. this allows us to override mapping
+        # by web templates, e.g. 'changelogtag' is redefined in map file.
         return context._load(exp[1])
     raise error.ParseError(_("expected template specifier"))
 
 def runinteger(context, mapping, data):
     return int(data)
 
 def runstring(context, mapping, data):
     return data.decode("string-escape")
 
 def runrawstring(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 callable(v):
         return v(**mapping)
     if isinstance(v, types.GeneratorType):
         v = list(v)
     return v
 
 def buildtemplate(exp, context):
     ctmpl = compiletemplate(exp[1], context)
     if len(ctmpl) == 1:
         return ctmpl[0]  # fast path for string with no template fragment
     return (runtemplate, ctmpl)
 
 def runtemplate(context, mapping, template):
     for func, data in template:
         yield func(context, mapping, data)
 
 def buildfilter(exp, context):
     func, data = compileexp(exp[1], context, methods)
     filt = getfilter(exp[2], context)
     return (runfilter, (func, data, filt))
 
 def runfilter(context, mapping, data):
     func, data, filt = data
     # func() may return string, generator of strings or arbitrary object such
     # as date tuple, but filter does not want generator.
     thing = func(context, mapping, data)
     if isinstance(thing, types.GeneratorType):
         thing = stringify(thing)
     try:
         return filt(thing)
     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, methods)
     ctmpl = gettemplate(exp[2], context)
     return (runmap, (func, data, ctmpl))
 
 def runmap(context, mapping, data):
     func, data, ctmpl = data
     d = func(context, mapping, data)
     if callable(d):
         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, exprmethods) 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))
     raise error.ParseError(_("unknown function '%s'") % n)
 
 def date(context, mapping, args):
     """:date(date[, fmt]): Format a date. See :hg:`help dates` for formatting
     strings."""
     if not (1 <= len(args) <= 2):
         # i18n: "date" is a keyword
         raise error.ParseError(_("date expects one or two arguments"))
 
     date = args[0][0](context, mapping, args[0][1])
     fmt = None
     if len(args) == 2:
         fmt = stringify(args[1][0](context, mapping, args[1][1]))
     try:
         if fmt is None:
             return util.datestr(date)
         else:
             return util.datestr(date, fmt)
     except (TypeError, ValueError):
         # i18n: "date" is a keyword
         raise error.ParseError(_("date expects a date information"))
 
 def diff(context, mapping, args):
     """:diff([includepattern [, excludepattern]]): Show a diff, optionally
     specifying files to include or exclude."""
     if len(args) > 2:
         # i18n: "diff" is a keyword
         raise error.ParseError(_("diff expects one, two or no arguments"))
 
     def getpatterns(i):
         if i < len(args):
             s = stringify(args[i][0](context, mapping, args[i][1])).strip()
             if s:
                 return [s]
         return []
 
     ctx = mapping['ctx']
     chunks = ctx.diff(match=ctx.match([], getpatterns(0), getpatterns(1)))
 
     return ''.join(chunks)
 
 def fill(context, mapping, args):
     """:fill(text[, width[, initialident[, hangindent]]]): Fill many
     paragraphs with optional indentation. See the "fill" filter."""
     if not (1 <= len(args) <= 4):
         # i18n: "fill" is a keyword
         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:
             # i18n: "fill" is a keyword
             raise error.ParseError(_("fill expects an integer width"))
         try:
             initindent = stringify(args[2][0](context, mapping, args[2][1]))
             hangindent = stringify(args[3][0](context, mapping, args[3][1]))
         except IndexError:
             pass
 
     return templatefilters.fill(text, width, initindent, hangindent)
 
 def pad(context, mapping, args):
     """:pad(text, width[, fillchar=' '[, right=False]]): Pad text with a
     fill character."""
     if not (2 <= len(args) <= 4):
         # i18n: "pad" is a keyword
         raise error.ParseError(_("pad() expects two to four arguments"))
 
     width = int(args[1][1])
 
     text = stringify(args[0][0](context, mapping, args[0][1]))
 
     right = False
     fillchar = ' '
     if len(args) > 2:
         fillchar = stringify(args[2][0](context, mapping, args[2][1]))
     if len(args) > 3:
         right = util.parsebool(args[3][1])
 
     if right:
         return text.rjust(width, fillchar)
     else:
         return text.ljust(width, fillchar)
 
 def indent(context, mapping, args):
     """:indent(text, indentchars[, firstline]): Indents all non-empty lines
     with the characters given in the indentchars string. An optional
     third parameter will override the indent for the first line only
     if present."""
     if not (2 <= len(args) <= 3):
         # i18n: "indent" is a keyword
         raise error.ParseError(_("indent() expects two or three arguments"))
 
     text = stringify(args[0][0](context, mapping, args[0][1]))
     indent = stringify(args[1][0](context, mapping, args[1][1]))
 
     if len(args) == 3:
         firstline = stringify(args[2][0](context, mapping, args[2][1]))
     else:
         firstline = indent
 
     # the indent function doesn't indent the first line, so we do it here
     return templatefilters.indent(firstline + text, indent)
 
 def get(context, mapping, args):
     """:get(dict, key): Get an attribute/key from an object. Some keywords
     are complex types. This function allows you to obtain the value of an
     attribute on these type."""
     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 if_(context, mapping, args):
     """:if(expr, then[, else]): Conditionally execute based on the result of
     an expression."""
     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 args[1][0](context, mapping, args[1][1])
     elif len(args) == 3:
         yield args[2][0](context, mapping, args[2][1])
 
 def ifcontains(context, mapping, args):
     """:ifcontains(search, thing, then[, else]): Conditionally execute based
     on whether the item "search" is in "thing"."""
     if not (3 <= len(args) <= 4):
         # i18n: "ifcontains" is a keyword
         raise error.ParseError(_("ifcontains expects three or four arguments"))
 
     item = stringify(args[0][0](context, mapping, args[0][1]))
     items = args[1][0](context, mapping, args[1][1])
 
     if item in items:
         yield args[2][0](context, mapping, args[2][1])
     elif len(args) == 4:
         yield args[3][0](context, mapping, args[3][1])
 
 def ifeq(context, mapping, args):
     """:ifeq(expr1, expr2, then[, else]): Conditionally execute based on
     whether 2 items are equivalent."""
     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 args[2][0](context, mapping, args[2][1])
     elif len(args) == 4:
         yield args[3][0](context, mapping, args[3][1])
 
 def join(context, mapping, args):
     """:join(list, sep): Join items in a list with a delimiter."""
     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 callable(joinset):
         jf = joinset.joinfmt
         joinset = [jf(x) for x in joinset()]
 
     joiner = " "
     if len(args) > 1:
         joiner = stringify(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):
     """:label(label, expr): Apply a label to generated content. Content with
     a label applied can result in additional post-processing, such as
     automatic colorization."""
     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 args[1][0](context, mapping, args[1][1])
 
 def revset(context, mapping, args):
     """:revset(query[, formatargs...]): Execute a revision set query. See
     :hg:`help revset`."""
     if not len(args) > 0:
         # i18n: "revset" is a keyword
         raise error.ParseError(_("revset expects one or more arguments"))
 
     raw = args[0][1]
     ctx = mapping['ctx']
     repo = ctx.repo()
 
     def query(expr):
         m = revsetmod.match(repo.ui, expr)
         return m(repo)
 
     if len(args) > 1:
         formatargs = list([a[0](context, mapping, a[1]) for a in args[1:]])
         revs = query(revsetmod.formatspec(raw, *formatargs))
         revs = list([str(r) for r in revs])
     else:
         revsetcache = mapping['cache'].setdefault("revsetcache", {})
         if raw in revsetcache:
             revs = revsetcache[raw]
         else:
             revs = query(raw)
             revs = list([str(r) for r in revs])
             revsetcache[raw] = revs
 
     return templatekw.showlist("revision", revs, **mapping)
 
 def rstdoc(context, mapping, args):
     """:rstdoc(text, style): Format ReStructuredText."""
     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 shortest(context, mapping, args):
     """:shortest(node, minlength=4): Obtain the shortest representation of
     a node."""
     if not (1 <= len(args) <= 2):
         # i18n: "shortest" is a keyword
         raise error.ParseError(_("shortest() expects one or two arguments"))
 
     node = stringify(args[0][0](context, mapping, args[0][1]))
 
     minlength = 4
     if len(args) > 1:
         minlength = int(args[1][1])
 
     cl = mapping['ctx']._repo.changelog
     def isvalid(test):
         try:
             try:
                 cl.index.partialmatch(test)
             except AttributeError:
                 # Pure mercurial doesn't support partialmatch on the index.
                 # Fallback to the slow way.
                 if cl._partialmatch(test) is None:
                     return False
 
             try:
                 i = int(test)
                 # if we are a pure int, then starting with zero will not be
                 # confused as a rev; or, obviously, if the int is larger than
                 # the value of the tip rev
                 if test[0] == '0' or i > len(cl):
                     return True
                 return False
             except ValueError:
                 return True
         except error.RevlogError:
             return False
 
     shortest = node
     startlength = max(6, minlength)
     length = startlength
     while True:
         test = node[:length]
         if isvalid(test):
             shortest = test
             if length == minlength or length > startlength:
                 return shortest
             length -= 1
         else:
             length += 1
             if len(shortest) <= length:
                 return shortest
 
 def strip(context, mapping, args):
     """:strip(text[, chars]): Strip characters from a string."""
     if not (1 <= len(args) <= 2):
         # i18n: "strip" is a keyword
         raise error.ParseError(_("strip expects one or two arguments"))
 
     text = stringify(args[0][0](context, mapping, args[0][1]))
     if len(args) == 2:
         chars = stringify(args[1][0](context, mapping, args[1][1]))
         return text.strip(chars)
     return text.strip()
 
 def sub(context, mapping, args):
     """:sub(pattern, replacement, expression): Perform text substitution
     using regular expressions."""
     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]))
     yield re.sub(pat, rpl, src)
 
 def startswith(context, mapping, args):
     """:startswith(pattern, text): Returns the value from the "text" argument
     if it begins with the content from the "pattern" argument."""
     if len(args) != 2:
         # i18n: "startswith" is a keyword
         raise error.ParseError(_("startswith expects two arguments"))
 
     patn = stringify(args[0][0](context, mapping, args[0][1]))
     text = stringify(args[1][0](context, mapping, args[1][1]))
     if text.startswith(patn):
         return text
     return ''
 
 
 def word(context, mapping, args):
     """:word(number, text[, separator]): Return the nth word from a string."""
     if not (2 <= len(args) <= 3):
         # i18n: "word" is a keyword
         raise error.ParseError(_("word expects two or three arguments, got %d")
                                % len(args))
 
     try:
         num = int(stringify(args[0][0](context, mapping, args[0][1])))
     except ValueError:
         # i18n: "word" is a keyword
         raise error.ParseError(_("word expects an integer index"))
     text = stringify(args[1][0](context, mapping, args[1][1]))
     if len(args) == 3:
         splitter = stringify(args[2][0](context, mapping, args[2][1]))
     else:
         splitter = None
 
     tokens = text.split(splitter)
     if num >= len(tokens):
         return ''
     else:
         return tokens[num]
 
 # methods to interpret function arguments or inner expressions (e.g. {_(x)})
 exprmethods = {
     "integer": lambda e, c: (runinteger, e[1]),
     "string": lambda e, c: (runstring, e[1]),
     "rawstring": lambda e, c: (runrawstring, e[1]),
     "symbol": lambda e, c: (runsymbol, e[1]),
     "template": buildtemplate,
     "group": lambda e, c: compileexp(e[1], c, exprmethods),
 #    ".": buildmember,
     "|": buildfilter,
     "%": buildmap,
     "func": buildfunc,
     }
 
 # methods to interpret top-level template (e.g. {x}, {x|_}, {x % "y"})
 methods = exprmethods.copy()
 methods["integer"] = exprmethods["symbol"]  # '{1}' as variable
 
 funcs = {
     "date": date,
     "diff": diff,
     "fill": fill,
     "get": get,
     "if": if_,
     "ifcontains": ifcontains,
     "ifeq": ifeq,
     "indent": indent,
     "join": join,
     "label": label,
     "pad": pad,
     "revset": revset,
     "rstdoc": rstdoc,
     "shortest": shortest,
     "startswith": startswith,
     "strip": strip,
     "sub": sub,
     "word": word,
 }
 
 # template engine
 
 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 unquotestring(s):
     '''unwrap quotes'''
     if len(s) < 2 or s[0] != s[-1]:
         raise SyntaxError(_('unmatched quotes'))
     # de-backslash-ify only <\">. it is invalid syntax in non-string part of
     # template, but we are likely to escape <"> in quoted string and it was
     # accepted before, thanks to issue4290. <\\"> is unmodified because it
     # is ambiguous and it was processed as such before 2.8.1.
     #
     #  template  result
     #  --------- ------------------------
     #  {\"\"}    parse error
     #  "{""}"    {""} -> <>
     #  "{\"\"}"  {""} -> <>
     #  {"\""}    {"\""} -> <">
     #  '{"\""}'  {"\""} -> <">
     #  "{"\""}"  parse error (don't care)
     q = s[0]
     return s[1:-1].replace('\\\\' + q, '\\\\\\' + q).replace('\\' + q, q)
 
 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():
     paths = templatepaths()
     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 = {}
         if mapfile:
             self.base = os.path.dirname(mapfile)
         else:
             self.base = ''
         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(includepaths=templatepaths())
         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] = unquotestring(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 templatepaths():
     '''return locations used for template files.'''
     pathsrel = ['templates']
     paths = [os.path.normpath(os.path.join(util.datapath, f))
              for f in pathsrel]
     return [p for p in paths if os.path.isdir(p)]
 
 def templatepath(name):
     '''return location of template file. returns None if not found.'''
     for p in templatepaths():
         f = os.path.join(p, name)
         if os.path.exists(f):
             return f
     return None
 
 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 = templatepaths()
     elif isinstance(paths, str):
         paths = [paths]
 
     if isinstance(styles, str):
         styles = [styles]
 
     for style in styles:
         # only plain name is allowed to honor template paths
         if (not style
             or style in (os.curdir, os.pardir)
             or os.sep in style
             or os.altsep and os.altsep in 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)
 
 # tell hggettext to extract docstrings from these functions:
 i18nfunctions = funcs.values()