added parsing code for "for item in seq recursive" and improved parse…

…r interface a bit --HG-- branch : trunk
pallets · May 11, 2008 · fdf9530 · fdf9530
1 parent 27069d7
commit fdf9530
Show file tree

Hide file tree

Showing 10 changed files with 143 additions and 60 deletions.
diff --git a/docs/cache_extension.py b/docs/cache_extension.py
@@ -27,7 +27,7 @@ def parse(self, parser):
 
         # if there is a comma, the user provided a timeout.  If not use
         # None as second parameter.
-        if parser.skip_comma():
+        if parser.stream.skip_if('comma'):
             args.append(parser.parse_expression())
         else:
             args.append(nodes.Const(None))

diff --git a/docs/extensions.rst b/docs/extensions.rst
@@ -155,7 +155,7 @@ extensions:
 
 .. autoclass:: jinja2.parser.Parser
     :members: parse_expression, parse_tuple, parse_assign_target,
-              parse_statements, skip_colon, skip_comma, free_identifier
+              parse_statements, free_identifier
 
     .. attribute:: filename
 
@@ -169,7 +169,7 @@ extensions:
         The current :class:`~jinja2.lexer.TokenStream`
 
 .. autoclass:: jinja2.lexer.TokenStream
-   :members: push, look, eos, skip, next, expect
+   :members: push, look, eos, skip, next, next_if, skip_if, expect
 
    .. attribute:: current
 

diff --git a/docs/index.rst b/docs/index.rst
@@ -15,6 +15,7 @@ fast and secure.
    extensions
    integration
    switching
+   tricks
 
    changelog
 

diff --git a/docs/templates.rst b/docs/templates.rst
@@ -281,7 +281,8 @@ The ``{% extends %}`` tag is the key here. It tells the template engine that
 this template "extends" another template.  When the template system evaluates
 this template, first it locates the parent.  The extends tag should be the
 first tag in the template.  Everything before it is printed out normally and
-may cause confusion.
+may cause confusion.  For details about this behavior and how to take
+advantage of it, see :ref:`null-master-fallback`.
 
 The filename of the template depends on the template loader.  For example the
 :class:`FileSystemLoader` allows you to access other templates by giving the

diff --git a/docs/tricks.rst b/docs/tricks.rst
@@ -0,0 +1,81 @@
+Tipps and Tricks
+================
+
+.. highlight:: html+jinja
+
+This part of the documentation shows some tipps and tricks for Jinja2
+templates.
+
+
+.. _null-master-fallback:
+
+Null-Master Fallback
+--------------------
+
+Jinja2 supports dynamic inheritance and does not distinguish between parent
+and child template as long as no `extends` tag is visited.  While this leads
+to the surprising behavior that everything before the first `extends` tag
+including whitespace is printed out instead of being igored, it can be used
+for a neat trick.
+
+Usually child templates extend from one template that adds a basic HTML
+skeleton.  However it's possible put the `extends` tag into an `if` tag to
+only extend from the layout template if the `standalone` variable evaluates
+to false which it does per default if it's not defined.  Additionally a very
+basic skeleton is added to the file so that if it's indeed rendered with
+`standalone` set to `True` a very basic HTML skeleton is added::
+
+    {% if not standalone %}{% extends 'master.html' %}{% endif -%}
+    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+    <title>{% block title %}The Page Title{% endblock %}</title>
+    <link rel="stylesheet" href="style.css" type="text/css">
+    {% block body %}
+      <p>This is the page body.</p>
+    {% endblock %}
+
+
+Alternating Rows
+----------------
+
+If you want to have different styles for each row of a table or
+list you can use the `cycle` method on the `loop` object::
+
+    <ul>
+    {% for row in rows %}
+      <li class="{{ loop.cycle('odd', 'even') }}">{{ row }}</li>
+    {% endfor %}
+    </ul>
+
+`cycle` can take an unlimited amount of strings.  Each time this
+tag is encountered the next item from the list is rendered.
+
+
+Highlighting Active Menu Items
+------------------------------
+
+Often you want to have a navigation bar with an active navigation
+item.  This is really simple to achieve.  Because assignments outside
+of `block`\s in child templates are global and executed before the layout
+template is evaluated it's possible to define the active menu item in the
+child template::
+
+    {% extends "layout.html" %}
+    {% set active_page = "index" %}
+
+The layout template can then access `active_page`.  Additionally it makes
+sense to defined a default for that variable::
+
+    {% navigation_bar = [
+        ('/', 'index', 'Index'),
+        ('/downloads/', 'downloads', 'Downloads'),
+        ('/about/', 'about', 'About')
+    ] -%}
+    {% active_page = active_page|default('index') -%}
+    ...
+    <ul id="navigation">
+    {% for href, id, caption in navigation_bar %}
+      <li{% if id == active_page %} class="active"{% endif
+      %}><a href="{{ href|e }}">{{ caption|e }}</a>/li>
+    {% endfor %}
+    </ul>
+    ...
diff --git a/jinja2/compiler.py b/jinja2/compiler.py
@@ -1175,8 +1175,8 @@ def visitor(self, node, frame):
     del binop, uaop
 
     def visit_Concat(self, node, frame):
-        self.write('%s((' % self.environment.autoescape and
-                   'markup_join' or 'unicode_join')
+        self.write('%s((' % (self.environment.autoescape and
+                             'markup_join' or 'unicode_join'))
         for arg in node.nodes:
             self.visit(arg, frame)
             self.write(', ')

diff --git a/jinja2/ext.py b/jinja2/ext.py
@@ -145,7 +145,7 @@ def parse(self, parser):
                 parser.stream.expect('comma')
 
             # skip colon for python compatibility
-            if parser.skip_colon():
+            if parser.stream.skip_if('colon'):
                 break
 
             name = parser.stream.expect('name')

diff --git a/jinja2/lexer.py b/jinja2/lexer.py
@@ -219,19 +219,27 @@ def skip(self, n=1):
         for x in xrange(n):
             self.next()
 
-    def next(self, skip_eol=True):
+    def next_if(self, expr):
+        """Perform the token test and return the token if it matched.
+        Otherwise the return value is `None`.
+        """
+        if self.current.test(expr):
+            return self.next()
+
+    def skip_if(self, expr):
+        """Like `next_if` but only returns `True` or `False`."""
+        return self.next_if(expr) is not None
+
+    def next(self):
         """Go one token ahead and return the old one"""
         rv = self.current
-        while 1:
-            if self._pushed:
-                self.current = self._pushed.popleft()
-            elif self.current.type is not 'eof':
-                try:
-                    self.current = self._next()
-                except StopIteration:
-                    self.close()
-            if not skip_eol or self.current.type is not 'eol':
-                break
+        if self._pushed:
+            self.current = self._pushed.popleft()
+        elif self.current.type is not 'eof':
+            try:
+                self.current = self._next()
+            except StopIteration:
+                self.close()
         return rv
 
     def close(self):

diff --git a/jinja2/nodes.py b/jinja2/nodes.py
@@ -273,7 +273,7 @@ class For(Stmt):
 
     For filtered nodes an expression can be stored as `test`, otherwise `None`.
     """
-    fields = ('target', 'iter', 'body', 'else_', 'test')
+    fields = ('target', 'iter', 'body', 'else_', 'test', 'recursive')
 
 
 class If(Stmt):

diff --git a/jinja2/parser.py b/jinja2/parser.py
@@ -36,24 +36,12 @@ def __init__(self, environment, source, filename=None):
                 self.extensions[tag] = extension.parse
         self._last_identifier = 0
 
-    def is_tuple_end(self):
+    def is_tuple_end(self, extra_end_rules=None):
         """Are we at the end of a tuple?"""
-        return self.stream.current.type in ('variable_end', 'block_end',
-                                            'rparen') or \
-               self.stream.current.test('name:in')
-
-    def skip_colon(self):
-        """If there is a colon, skip it and return `True`, else `False`."""
-        if self.stream.current.type is 'colon':
-            self.stream.next()
-            return True
-        return False
-
-    def skip_comma(self):
-        """If there is a comma, skip it and return `True`, else `False`."""
-        if self.stream.current.type is 'comma':
-            self.stream.next()
+        if self.stream.current.type in ('variable_end', 'block_end', 'rparen'):
             return True
+        elif extra_end_rules is not None:
+            return self.stream.current.test_any(extra_end_rules)
         return False
 
     def free_identifier(self, lineno=None):
@@ -107,7 +95,7 @@ def parse_statements(self, end_tokens, drop_needle=False):
         can be set to `True` and the end token is removed.
         """
         # the first token may be a colon for python compatibility
-        self.skip_colon()
+        self.stream.skip_if('colon')
 
         # in the future it would be possible to add whole code sections
         # by adding some sort of end of statement token and parsing those here.
@@ -121,19 +109,21 @@ def parse_statements(self, end_tokens, drop_needle=False):
     def parse_for(self):
         """Parse a for loop."""
         lineno = self.stream.expect('name:for').lineno
-        target = self.parse_assign_target()
+        target = self.parse_assign_target(extra_end_rules=('name:in',))
         self.stream.expect('name:in')
-        iter = self.parse_tuple(with_condexpr=False)
+        iter = self.parse_tuple(with_condexpr=False,
+                                extra_end_rules=('name:recursive',))
         test = None
-        if self.stream.current.test('name:if'):
-            self.stream.next()
+        if self.stream.skip_if('name:if'):
             test = self.parse_expression()
+        recursive = self.stream.skip_if('name:recursive')
         body = self.parse_statements(('name:endfor', 'name:else'))
         if self.stream.next().value == 'endfor':
             else_ = []
         else:
             else_ = self.parse_statements(('name:endfor',), drop_needle=True)
-        return nodes.For(target, iter, body, else_, test, lineno=lineno)
+        return nodes.For(target, iter, body, else_, test,
+                         recursive, lineno=lineno)
 
     def parse_if(self):
         """Parse an if construct."""
@@ -214,8 +204,7 @@ def parse_context():
                                                  'underscores can not be '
                                                  'imported', target.lineno,
                                                  self.filename)
-                if self.stream.current.test('name:as'):
-                    self.stream.next()
+                if self.stream.skip_if('name:as'):
                     alias = self.parse_assign_target(name_only=True)
                     node.names.append((target.name, alias.name))
                 else:
@@ -226,8 +215,7 @@ def parse_context():
                 break
         if not hasattr(node, 'with_context'):
             node.with_context = False
-            if self.stream.current.type is 'comma':
-                self.stream.next()
+            self.stream.skip_if('comma')
         return node
 
     def parse_signature(self, node):
@@ -238,8 +226,7 @@ def parse_signature(self, node):
             if args:
                 self.stream.expect('comma')
             arg = self.parse_assign_target(name_only=True)
-            if self.stream.current.type is 'assign':
-                self.stream.next()
+            if self.stream.skip_if('assign'):
                 defaults.append(self.parse_expression())
             args.append(arg)
         self.stream.expect('rparen')
@@ -283,19 +270,22 @@ def parse_print(self):
             node.nodes.append(self.parse_expression())
         return node
 
-    def parse_assign_target(self, with_tuple=True, name_only=False):
+    def parse_assign_target(self, with_tuple=True, name_only=False,
+                            extra_end_rules=None):
         """Parse an assignment target.  As Jinja2 allows assignments to
         tuples, this function can parse all allowed assignment targets.  Per
         default assignments to tuples are parsed, that can be disable however
         by setting `with_tuple` to `False`.  If only assignments to names are
-        wanted `name_only` can be set to `True`.
+        wanted `name_only` can be set to `True`.  The `extra_end_rules`
+        parameter is forwarded to the tuple parsing function.
         """
         if name_only:
             token = self.stream.expect('name')
             target = nodes.Name(token.value, 'store', lineno=token.lineno)
         else:
             if with_tuple:
-                target = self.parse_tuple(simplified=True)
+                target = self.parse_tuple(simplified=True,
+                                          extra_end_rules=extra_end_rules)
             else:
                 target = self.parse_primary(with_postfix=False)
             target.set_ctx('store')
@@ -317,8 +307,7 @@ def parse_expression(self, with_condexpr=True):
     def parse_condexpr(self):
         lineno = self.stream.current.lineno
         expr1 = self.parse_or()
-        while self.stream.current.test('name:if'):
-            self.stream.next()
+        while self.stream.skip_if('name:if'):
             expr2 = self.parse_or()
             self.stream.expect('name:else')
             expr3 = self.parse_condexpr()
@@ -329,8 +318,7 @@ def parse_condexpr(self):
     def parse_or(self):
         lineno = self.stream.current.lineno
         left = self.parse_and()
-        while self.stream.current.test('name:or'):
-            self.stream.next()
+        while self.stream.skip_if('name:or'):
             right = self.parse_and()
             left = nodes.Or(left, right, lineno=lineno)
             lineno = self.stream.current.lineno
@@ -339,8 +327,7 @@ def parse_or(self):
     def parse_and(self):
         lineno = self.stream.current.lineno
         left = self.parse_compare()
-        while self.stream.current.test('name:and'):
-            self.stream.next()
+        while self.stream.skip_if('name:and'):
             right = self.parse_compare()
             left = nodes.And(left, right, lineno=lineno)
             lineno = self.stream.current.lineno
@@ -355,8 +342,7 @@ def parse_compare(self):
             if token_type in _compare_operators:
                 self.stream.next()
                 ops.append(nodes.Operand(token_type, self.parse_add()))
-            elif self.stream.current.test('name:in'):
-                self.stream.next()
+            elif self.stream.skip_if('name:in'):
                 ops.append(nodes.Operand('in', self.parse_add()))
             elif self.stream.current.test('name:not') and \
                  self.stream.look().test('name:in'):
@@ -495,7 +481,8 @@ def parse_primary(self, with_postfix=True):
             node = self.parse_postfix(node)
         return node
 
-    def parse_tuple(self, simplified=False, with_condexpr=True):
+    def parse_tuple(self, simplified=False, with_condexpr=True,
+                    extra_end_rules=None):
         """Works like `parse_expression` but if multiple expressions are
         delimited by a comma a :class:`~jinja2.nodes.Tuple` node is created.
         This method could also return a regular expression instead of a tuple
@@ -504,6 +491,11 @@ def parse_tuple(self, simplified=False, with_condexpr=True):
         The default parsing mode is a full tuple.  If `simplified` is `True`
         only names and literals are parsed.  The `no_condexpr` parameter is
         forwarded to :meth:`parse_expression`.
+
+        Because tuples do not require delimiters and may end in a bogus comma
+        an extra hint is needed that marks the end of a tuple.  For example
+        for loops support tuples between `for` and `in`.  In that case the
+        `extra_end_rules` is set to ``['name:in']``.
         """
         lineno = self.stream.current.lineno
         if simplified:
@@ -517,7 +509,7 @@ def parse_tuple(self, simplified=False, with_condexpr=True):
         while 1:
             if args:
                 self.stream.expect('comma')
-            if self.is_tuple_end():
+            if self.is_tuple_end(extra_end_rules):
                 break
             args.append(parse())
             if self.stream.current.type is 'comma':