# templater.py - template expansion for output
#
# Copyright 2005, 2006 Matt Mackall <[email protected]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2, incorporated herein by reference.

from i18n import _
import re, sys, os
import util, config, templatefilters

path = ['templates', '../templates']
stringify = templatefilters.stringify

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|...}.'''

   template_re = re.compile(r'{([\w\|%]+)}|#([\w\|%]+)#')

   def __init__(self, loader, filters={}, defaults={}):
       self.loader = loader
       self.filters = filters
       self.defaults = defaults
       self.cache = {}

   def process(self, t, map):
       '''Perform expansion. t is name of map element to expand. map contains
       added elements for use during expansion. Is a generator.'''
       tmpl = self.loader(t)
       iters = [self._process(tmpl, map)]
       while iters:
           try:
               item = iters[0].next()
           except StopIteration:
               iters.pop(0)
               continue
           if isinstance(item, str):
               yield item
           elif item is None:
               yield ''
           elif hasattr(item, '__iter__'):
               iters.insert(0, iter(item))
           else:
               yield str(item)

   def _format(self, expr, get, map):
       key, format = expr.split('%')
       v = get(key)
       if not hasattr(v, '__iter__'):
           raise SyntaxError(_("error expanding '%s%%%s'") % (key, format))
       lm = map.copy()
       for i in v:
           lm.update(i)
           yield self.process(format, lm)

   def _filter(self, expr, get, map):
       if expr not in self.cache:
           parts = expr.split('|')
           val = parts[0]
           try:
               filters = [self.filters[f] for f in parts[1:]]
           except KeyError, i:
               raise SyntaxError(_("unknown filter '%s'") % i[0])
           def apply(get):
                   x = get(val)
                   for f in filters:
                       x = f(x)
                   return x
           self.cache[expr] = apply
       return self.cache[expr](get)

   def _process(self, tmpl, map):
       '''Render a template. Returns a generator.'''

       def get(key):
           v = map.get(key)
           if v is None:
               v = self.defaults.get(key, '')
           if hasattr(v, '__call__'):
               v = v(**map)
           return v

       while tmpl:
           m = self.template_re.search(tmpl)
           if not m:
               yield tmpl
               break

           start, end = m.span(0)
           variants = m.groups()
           expr = variants[0] or variants[1]

           if start:
               yield tmpl[:start]
           tmpl = tmpl[end:]

           if '%' in expr:
               yield self._format(expr, get, map)
           elif '|' in expr:
               yield self._filter(expr, get, map)
           else:
               yield get(expr)

engines = {'default': engine}

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.engines = {}

       if not mapfile:
           return
       if not os.path.exists(mapfile):
           raise util.Abort(_('style not found: %s') % mapfile)

       conf = config.config()
       conf.read(mapfile)

       for key, val in conf[''].items():
           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 not t in self.cache:
           try:
               self.cache[t] = open(self.map[t][1]).read()
           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, **map):
       ttype = t in self.map and self.map[t][0] or 'default'
       proc = self.engines.get(ttype)
       if proc is None:
           proc = engines[ttype](self.load, self.filters, self.defaults)
           self.engines[ttype] = proc

       stream = proc.process(t, map)
       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 hasattr(sys, 'frozen'):
       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(style, 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]

   locations = style and [os.path.join(style, "map"), "map-" + style] or []
   locations.append("map")
   for path in paths:
       for location in locations:
           mapfile = os.path.join(path, location)
           if os.path.isfile(mapfile):
               return mapfile

   raise RuntimeError("No hgweb templates found in %r" % paths)

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