templater: make a template a string-only iterator

mercurial/templater.py

@@ -1,150 +1,171 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, incorporated herein by reference.
 
 from i18n import _
 import re, sys, os
 from mercurial import util
 
 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 templater(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\|%]+})))"
                              r"(\w+)(?:(?:%(\w+))|((?:\|\w+)*))[#}]")
 
     def __init__(self, mapfile, filters={}, defaults={}, cache={}):
         '''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 = filters
         self.defaults = defaults
 
         if not mapfile:
             return
         if not os.path.exists(mapfile):
             raise util.Abort(_('style not found: %s') % mapfile)
 
         i = 0
         for l in file(mapfile):
             l = l.strip()
             i += 1
             if not l or l[0] in '#;': continue
             m = re.match(r'([a-zA-Z_][a-zA-Z0-9_]*)\s*=\s*(.+)$', l)
             if m:
                 key, val = m.groups()
                 if val[0] in "'\"":
                     try:
                         self.cache[key] = parsestring(val)
                     except SyntaxError, inst:
                         raise SyntaxError('%s:%s: %s' %
                                           (mapfile, i, inst.args[0]))
                 else:
                     self.map[key] = os.path.join(self.base, val)
             else:
                 raise SyntaxError(_("%s:%s: parse error") % (mapfile, i))
 
     def __contains__(self, key):
         return key in self.cache or key in self.map
 
-    def __call__(self, t, **map):
-        '''perform expansion.
-        t is name of map element to expand.
-        map is added elements to use during expansion.'''
+    def _template(self, t):
+        '''Get the template for the given template name. Use a local cache.'''
         if not t in self.cache:
             try:
                 self.cache[t] = file(self.map[t]).read()
             except IOError, inst:
                 raise IOError(inst.args[0], _('template file %s: %s') %
                               (self.map[t], inst.args[1]))
-        tmpl = self.cache[t]
+        return self.cache[t]
 
+    def _process(self, tmpl, map):
+        '''Render a template. Returns a generator.'''
         while tmpl:
             m = self.template_re.search(tmpl)
             if not m:
                 yield tmpl
                 break
 
             start, end = m.span(0)
             key, format, fl = m.groups()
 
             if start:
                 yield tmpl[:start]
             tmpl = tmpl[end:]
 
             if key in map:
                 v = map[key]
             else:
                 v = self.defaults.get(key, "")
             if callable(v):
                 v = v(**map)
             if format:
                 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(format, **lm)
+                    t = self._template(format)
+                    yield self._process(t, lm)
             else:
                 if fl:
                     for f in fl.split("|")[1:]:
                         v = self.filters[f](v)
                 yield v
 
+    def __call__(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._template(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 templatepath(name=None):
     '''return location of template file or directory (if no name).
     returns None if not found.'''
 
     # executable version (py2exe) doesn't support __file__
     if hasattr(sys, 'frozen'):
         module = sys.executable
     else:
         module = __file__
     for f in 'templates', '../templates':
         fl = f.split('/')
         if name: fl.append(name)
         p = os.path.join(os.path.dirname(module), *fl)
         if (name and os.path.exists(p)) or os.path.isdir(p):
             return os.path.normpath(p)
 
 def stringify(thing):
     '''turn nested template iterator into string.'''
     if hasattr(thing, '__iter__'):
         return "".join([stringify(t) for t in thing if t is not None])
     return str(thing)