simplify visitor walker class
- remove postorder
- remove protocol for automatically walking children based on visitor
method return value; now only walks if there is no method
diff --git a/Lib/compiler/visitor.py b/Lib/compiler/visitor.py
index 7392662..d0e5223 100644
--- a/Lib/compiler/visitor.py
+++ b/Lib/compiler/visitor.py
@@ -47,31 +47,19 @@
self._preorder(tree)
def _preorder(self, node, *args):
- stop = apply(self.dispatch, (node,) + args)
- if stop:
- return
+ return apply(self.dispatch, (node,) + args)
+
+ def default(self, node, *args):
for child in node.getChildren():
if isinstance(child, ast.Node):
- self._preorder(child)
-
- def postorder(self, tree, visitor):
- """Do preorder walk of tree using visitor"""
- self.visitor = visitor
- visitor.visit = self._postorder
- self._postorder(tree)
-
- def _postorder(self, tree, *args):
- for child in node.getChildren():
- if isinstance(child, ast.Node):
- self._postorder(child)
- apply(self.dispatch, (node,) + args)
+ apply(self._preorder, (child,) + args)
def dispatch(self, node, *args):
self.node = node
meth = self._cache.get(node.__class__, None)
className = node.__class__.__name__
if meth is None:
- meth = getattr(self.visitor, 'visit' + className, 0)
+ meth = getattr(self.visitor, 'visit' + className, self.default)
self._cache[node.__class__] = meth
if self.VERBOSE > 0:
if self.VERBOSE == 1:
@@ -79,8 +67,7 @@
print "dispatch", className
else:
print "dispatch", className, (meth and meth.__name__ or '')
- if meth:
- return apply(meth, (node,) + args)
+ return apply(meth, (node,) + args)
class ExampleASTVisitor(ASTVisitor):
"""Prints examples of the nodes that aren't visited
@@ -93,24 +80,27 @@
def dispatch(self, node, *args):
self.node = node
- className = node.__class__.__name__
- meth = getattr(self.visitor, 'visit' + className, None)
- if self.VERBOSE > 0:
- if self.VERBOSE > 1:
- print "dispatch", className, (meth and meth.__name__ or '')
+ meth = self._cache.get(node.__class__, None)
+ className = node.__class__.__name__
+ if meth is None:
+ meth = getattr(self.visitor, 'visit' + className, 0)
+ self._cache[node.__class__] = meth
+ if self.VERBOSE > 1:
+ print "dispatch", className, (meth and meth.__name__ or '')
if meth:
return apply(meth, (node,) + args)
elif self.VERBOSE > 0:
klass = node.__class__
- if self.examples.has_key(klass):
- return
- self.examples[klass] = klass
- print
- print klass
- for attr in dir(node):
- if attr[0] != '_':
- print "\t", "%-12.12s" % attr, getattr(node, attr)
- print
+ if not self.examples.has_key(klass):
+ self.examples[klass] = klass
+ print
+ print self.visitor
+ print klass
+ for attr in dir(node):
+ if attr[0] != '_':
+ print "\t", "%-12.12s" % attr, getattr(node, attr)
+ print
+ return apply(self.default, (node,) + args)
_walker = ASTVisitor
def walk(tree, visitor, verbose=None):