templater: clarify engine caching

mercurial/templater.py

@@ -1,390 +1,390 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
 import util, config, templatefilters, parser, error
 
 # 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 = lambda x: x
             else:
                 decode = lambda x: x.decode('string-escape')
             pos += 1
             s = pos
             while pos < end: # find closing quote
                 d = program[pos]
                 if d == '\\': # skip over escaped characters
                     pos += 2
                     continue
                 if d == c:
                     yield ('string', decode(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
     data[2] = pos
     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
         if n > 0 and tmpl[n - 1] == '\\':
             # escaped
             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]
         parsed.append(p.parse(pd))
         pos = pd[2]
 
     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 hasattr(v, '__call__'):
         return v(**mapping)
     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
     return filt(func(context, mapping, data))
 
 def buildmap(exp, context):
     func, data = compileexp(exp[1], context)
     ctmpl = gettemplate(exp[2], context)
     return (runmap, (func, data, ctmpl))
 
 def runmap(context, mapping, data):
     func, data, ctmpl = data
     d = func(context, mapping, data)
     lm = mapping.copy()
 
     for i in d:
         if isinstance(i, dict):
             lm.update(i)
             for f, d in ctmpl:
                 yield f(context, lm, d)
         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 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))
     elif n in context._funcs:
         f = context._funcs[n]
         return (f, args)
 
 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,
     }
 
 # 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 hasattr(thing, '__iter__'):
         if thing is not None:
             yield str(thing)
     else:
         for i in thing:
             if isinstance(i, str):
                 yield i
             elif not hasattr(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(func(self, mapping, data) for func, data in
                          self._load(t))
 
 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 = {}
+        self.ecache = {}
 
         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 KeyError, inst:
                 raise util.Abort(_('"%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'
-        proc = self.engines.get(ttype)
-        if proc is None:
-            proc = engines[ttype](self.load, self.filters, self.defaults)
-            self.engines[ttype] = proc
+        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 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(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)