jinja2: support custom delimiters

slapos/recipe/template/README.jinja2.txt

@@ -58,6 +58,66 @@ And the template has been rendered::
     parameters from section: [('bar', 'bar'), ('foo', '1')]
     Rendered with slapos.recipe.template:jinja2
 
+Custom environment
+------------------
+
+We might want to embed jinja inline templates inside jinja template files.
+To this purpose, we can use two sets of delimiters, by defining our owns
+instead of the default ones - {% %} {{ }} {# and #}.
+Other options for controlling whitespace handling are supported as well, see
+http://jinja.pocoo.org/docs/dev/api/
+
+    >>> write('buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... parts = template
+    ...
+    ... [template]
+    ... recipe = slapos.recipe.template:jinja2
+    ... template = foo.in
+    ... rendered = foo
+    ... block-start-string = [%
+    ... block-end-string = %]
+    ... variable-start-string = [[
+    ... variable-end-string = ]]
+    ... comment-start-string = /*
+    ... comment-end-string = */
+    ... line-statement-prefix = @@
+    ... line-comment-prefix = //
+    ... lstrip-blocks = True
+    ... trim-blocks = True
+    ... context =
+    ...     raw     knight       Ni!
+    ... ''')
+
+The template can now use [ instead of {
+
+    >>> write('foo.in',
+    ...     'Knights who say "[[knight]]"\n'
+    ...     'Say it again: /* embedded comment */\n'
+    ...     '   [% for i in range(5) -%][[knight]] [% endfor -%]\n'
+    ...     '// full line comment\n'
+    ...     '@@ for i in range(3)\n'
+    ...     '[[knight]]\n'
+    ...     '@@ endfor\n'
+    ... )
+
+We run buildout::
+
+    >>> print system(join('bin', 'buildout')),
+    Uninstalling template.
+    Installing template.
+
+And the template has been rendered::
+
+    >>> cat('foo')
+    Knights who say "Ni!"
+    Say it again: Ni! Ni! Ni! Ni! Ni! 
+    Ni!
+    Ni!
+    Ni!
+
+
 Parameters
 ----------
 

slapos/recipe/template/jinja2_template.py

@@ -186,6 +186,37 @@ class Recipe(object):
         if umask_value:
             self.umask = int(umask_value, 8)
 
+        self.extra_environment = dict((key, value)
+                for key, value in self.iter_extra_environment(options))
+
+    def iter_extra_environment(self, options):
+        for is_boolean, okey in [
+                (0, 'block-start-string'),
+                (0, 'block-end-string'),
+                (0, 'variable-start-string'),
+                (0, 'variable-end-string'),
+                (0, 'comment-start-string'),
+                (0, 'comment-end-string'),
+                (0, 'line-statement-prefix'),
+                (0, 'line-comment-prefix'),
+                (1, 'trim-blocks'),
+                (1, 'lstrip-blocks')]:
+            jkey = okey.replace('-', '_')
+            if jkey in options:
+                raise ValueError('Invalid Jinja2 environment key %s: use %s' % (jkey, okey))
+
+            if okey in options:
+                if is_boolean:
+                    if options[okey].strip().lower() == 'true':
+                        yield jkey, True
+                    elif options[okey].strip().lower() == 'false':
+                        yield jkey, False
+                    else:
+                        raise ValueError('Invalid value for boolean key %s, should be True or False' % okey)
+                else:
+                    yield jkey, options[okey]
+
+
     def install(self):
         # Unlink any existing file, so umask is always applied.
         try:
@@ -197,6 +228,7 @@ class Recipe(object):
             outdir = os.path.dirname(self.rendered)
             if outdir and not os.path.exists(outdir):
                 os.makedirs(outdir)
+
             # XXX: open doesn't allow providing a filesystem mode, so use
             # os.open and os.fdopen instead.
             with os.fdopen(os.open(self.rendered,
@@ -207,6 +239,7 @@ class Recipe(object):
                         extensions=self.extension_list,
                         undefined=StrictUndefined,
                         loader=self.loader,
+                        **self.extra_environment
                     ).from_string(
                         self.get_template(),
                     ).render(