added support for local aliasing of some attributes. the technique used is not very good but covers at least some of the more common use cases
--HG--
branch : trunk
diff --git a/jinja2/compiler.py b/jinja2/compiler.py
index f835835..cbac003 100644
--- a/jinja2/compiler.py
+++ b/jinja2/compiler.py
@@ -107,6 +107,9 @@
# names that are declared by parameters
self.declared_parameter = set()
+ # static subscribes
+ self.static_subscribes = {}
+
def add_special(self, name):
"""Register a special name like `loop`."""
self.undeclared.discard(name)
@@ -149,6 +152,9 @@
# the name of the block we're in, otherwise None.
self.block = parent and parent.block or None
+ # node overlays. see `CodeGenerator.overlay` for more details
+ self.overlays = {}
+
# the parent of this frame
self.parent = parent
@@ -156,7 +162,8 @@
self.identifiers.declared.update(
parent.identifiers.declared |
parent.identifiers.declared_locally |
- parent.identifiers.declared_parameter
+ parent.identifiers.declared_parameter |
+ parent.identifiers.undeclared
)
self.identifiers.outer_undeclared.update(
parent.identifiers.undeclared -
@@ -253,6 +260,25 @@
self.identifiers.is_declared(node.name, self.hard_scope):
self.identifiers.undeclared.add(node.name)
+ def visit_Subscript(self, node):
+ """Under some circumstances subscripts are aliased with local names:
+
+ - the subscript node is either already aliased or a name that was not
+ reassigned.
+ - and the subscription argument is a constant string.
+ """
+ self.generic_visit(node)
+ if isinstance(node.arg, nodes.Const) and \
+ isinstance(node.arg.value, basestring) and \
+ (isinstance(node.node, nodes.Name) and
+ node.node.name not in (self.identifiers.declared_locally |
+ self.identifiers.declared_parameter)) or \
+ node.node in self.identifiers.static_subscribes:
+ if node in self.identifiers.static_subscribes:
+ self.identifiers.static_subscribes[node] += 1
+ else:
+ self.identifiers.static_subscribes[node] = 1
+
def visit_Macro(self, node):
self.generic_visit(node)
self.identifiers.declared_locally.add(node.name)
@@ -468,11 +494,47 @@
self.write('**')
self.visit(node.dyn_kwargs, frame)
+ def overlay(self, node, frame):
+ """Visit an overlay and return `True` or `False` if the overlay
+ does not exist or is exhausted. An overlay is used to replace a
+ node with another one (or an identifier) N times. This is for
+ example used to replace static subscribes before reassignments
+ of a name that occour more than one time. If a node has overlays
+ it's important that this method is called, otherwise the count
+ will be out of sync and the generated code is broken.
+ """
+ if node not in frame.overlays:
+ return False
+ overlay, count = frame.overlays[node]
+ if count is not None and count <= 0:
+ return False
+ if isinstance(overlay, basestring):
+ self.write(overlay)
+ else:
+ self.visit(overlay, frame)
+ frame.overlays[node] = (overlay, count - 1)
+ return True
+
def pull_locals(self, frame):
"""Pull all the references identifiers into the local scope."""
for name in frame.identifiers.undeclared:
self.writeline('l_%s = context.resolve(%r)' % (name, name))
+ # find all the static subscribes with a count > 2 and
+ # order them properly so that subscribes depending on other
+ # subscribes are handled later.
+ static_subscribes = [(node, count) for node, count in
+ frame.identifiers.static_subscribes.items() if
+ count >= 2]
+ if static_subscribes:
+ static_subscribes.sort(key=lambda x: type(x[0].node)
+ is nodes.Subscript)
+ for node, count in static_subscribes:
+ ident = self.temporary_identifier()
+ self.writeline(ident + ' = ')
+ self.visit(node, frame)
+ frame.overlays[node] = (ident, count)
+
def pull_dependencies(self, nodes):
"""Pull all the dependencies."""
visitor = DependencyFinderVisitor()
@@ -1264,6 +1326,10 @@
self.visit(node.expr, frame)
def visit_Subscript(self, node, frame):
+ # subscripts can have overlays
+ if self.overlay(node, frame):
+ return
+
# slices or integer subscriptions bypass the subscribe
# method if we can determine that at compile time.
if isinstance(node.arg, nodes.Slice) or \