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simplify visitor walker class

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- remove postorder
- remove protocol for automatically walking children based on visitor
  method return value; now only walks if there is no method
This commit is contained in:
Jeremy Hylton 2000-03-16 20:04:16 +00:00
parent b631b8ede5
commit f635abee3a
2 changed files with 46 additions and 66 deletions
Download patch file Download diff file Expand all files Collapse all files

34
Lib/compiler/visitor.py
View file

@ -47,31 +47,19 @@ class ASTVisitor:
self._preorder(tree) self._preorder(tree)
def _preorder(self, node, *args): def _preorder(self, node, *args):
stop = apply(self.dispatch, (node,) + args) return apply(self.dispatch, (node,) + args)
if stop:
return def default(self, node, *args):
for child in node.getChildren(): for child in node.getChildren():
if isinstance(child, ast.Node): if isinstance(child, ast.Node):
self._preorder(child) apply(self._preorder, (child,) + args)
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)
def dispatch(self, node, *args): def dispatch(self, node, *args):
self.node = node self.node = node
meth = self._cache.get(node.__class__, None) meth = self._cache.get(node.__class__, None)
className = node.__class__.__name__ className = node.__class__.__name__
if meth is None: if meth is None:
meth = getattr(self.visitor, 'visit' + className, 0) meth = getattr(self.visitor, 'visit' + className, self.default)
self._cache[node.__class__] = meth self._cache[node.__class__] = meth
if self.VERBOSE > 0: if self.VERBOSE > 0:
if self.VERBOSE == 1: if self.VERBOSE == 1:
@ -79,7 +67,6 @@ class ASTVisitor:
print "dispatch", className print "dispatch", className
else: else:
print "dispatch", className, (meth and meth.__name__ or '') print "dispatch", className, (meth and meth.__name__ or '')
if meth:
return apply(meth, (node,) + args) return apply(meth, (node,) + args)
class ExampleASTVisitor(ASTVisitor): class ExampleASTVisitor(ASTVisitor):
@ -93,24 +80,27 @@ class ExampleASTVisitor(ASTVisitor):
def dispatch(self, node, *args): def dispatch(self, node, *args):
self.node = node self.node = node
meth = self._cache.get(node.__class__, None)
className = node.__class__.__name__ className = node.__class__.__name__
meth = getattr(self.visitor, 'visit' + className, None) if meth is None:
if self.VERBOSE > 0: meth = getattr(self.visitor, 'visit' + className, 0)
self._cache[node.__class__] = meth
if self.VERBOSE > 1: if self.VERBOSE > 1:
print "dispatch", className, (meth and meth.__name__ or '') print "dispatch", className, (meth and meth.__name__ or '')
if meth: if meth:
return apply(meth, (node,) + args) return apply(meth, (node,) + args)
elif self.VERBOSE > 0: elif self.VERBOSE > 0:
klass = node.__class__ klass = node.__class__
if self.examples.has_key(klass): if not self.examples.has_key(klass):
return
self.examples[klass] = klass self.examples[klass] = klass
print print
print self.visitor
print klass print klass
for attr in dir(node): for attr in dir(node):
if attr[0] != '_': if attr[0] != '_':
print "\t", "%-12.12s" % attr, getattr(node, attr) print "\t", "%-12.12s" % attr, getattr(node, attr)
print print
return apply(self.default, (node,) + args)
_walker = ASTVisitor _walker = ASTVisitor
def walk(tree, visitor, verbose=None): def walk(tree, visitor, verbose=None):

34
Tools/compiler/compiler/visitor.py
View file

@ -47,31 +47,19 @@ class ASTVisitor:
self._preorder(tree) self._preorder(tree)
def _preorder(self, node, *args): def _preorder(self, node, *args):
stop = apply(self.dispatch, (node,) + args) return apply(self.dispatch, (node,) + args)
if stop:
return def default(self, node, *args):
for child in node.getChildren(): for child in node.getChildren():
if isinstance(child, ast.Node): if isinstance(child, ast.Node):
self._preorder(child) apply(self._preorder, (child,) + args)
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)
def dispatch(self, node, *args): def dispatch(self, node, *args):
self.node = node self.node = node
meth = self._cache.get(node.__class__, None) meth = self._cache.get(node.__class__, None)
className = node.__class__.__name__ className = node.__class__.__name__
if meth is None: if meth is None:
meth = getattr(self.visitor, 'visit' + className, 0) meth = getattr(self.visitor, 'visit' + className, self.default)
self._cache[node.__class__] = meth self._cache[node.__class__] = meth
if self.VERBOSE > 0: if self.VERBOSE > 0:
if self.VERBOSE == 1: if self.VERBOSE == 1:
@ -79,7 +67,6 @@ class ASTVisitor:
print "dispatch", className print "dispatch", className
else: else:
print "dispatch", className, (meth and meth.__name__ or '') print "dispatch", className, (meth and meth.__name__ or '')
if meth:
return apply(meth, (node,) + args) return apply(meth, (node,) + args)
class ExampleASTVisitor(ASTVisitor): class ExampleASTVisitor(ASTVisitor):
@ -93,24 +80,27 @@ class ExampleASTVisitor(ASTVisitor):
def dispatch(self, node, *args): def dispatch(self, node, *args):
self.node = node self.node = node
meth = self._cache.get(node.__class__, None)
className = node.__class__.__name__ className = node.__class__.__name__
meth = getattr(self.visitor, 'visit' + className, None) if meth is None:
if self.VERBOSE > 0: meth = getattr(self.visitor, 'visit' + className, 0)
self._cache[node.__class__] = meth
if self.VERBOSE > 1: if self.VERBOSE > 1:
print "dispatch", className, (meth and meth.__name__ or '') print "dispatch", className, (meth and meth.__name__ or '')
if meth: if meth:
return apply(meth, (node,) + args) return apply(meth, (node,) + args)
elif self.VERBOSE > 0: elif self.VERBOSE > 0:
klass = node.__class__ klass = node.__class__
if self.examples.has_key(klass): if not self.examples.has_key(klass):
return
self.examples[klass] = klass self.examples[klass] = klass
print print
print self.visitor
print klass print klass
for attr in dir(node): for attr in dir(node):
if attr[0] != '_': if attr[0] != '_':
print "\t", "%-12.12s" % attr, getattr(node, attr) print "\t", "%-12.12s" % attr, getattr(node, attr)
print print
return apply(self.default, (node,) + args)
_walker = ASTVisitor _walker = ASTVisitor
def walk(tree, visitor, verbose=None): def walk(tree, visitor, verbose=None):