home *** CD-ROM | disk | FTP | other *** search
- # Source Generated with Decompyle++
- # File: in.pyc (Python 2.4)
-
- from compiler import ast
-
- class ASTVisitor:
- """Performs a depth-first walk of the AST
-
- The ASTVisitor will walk the AST, performing either a preorder or
- postorder traversal depending on which method is called.
-
- methods:
- preorder(tree, visitor)
- postorder(tree, visitor)
- tree: an instance of ast.Node
- visitor: an instance with visitXXX methods
-
- The ASTVisitor is responsible for walking over the tree in the
- correct order. For each node, it checks the visitor argument for
- a method named 'visitNodeType' where NodeType is the name of the
- node's class, e.g. Class. If the method exists, it is called
- with the node as its sole argument.
-
- The visitor method for a particular node type can control how
- child nodes are visited during a preorder walk. (It can't control
- the order during a postorder walk, because it is called _after_
- the walk has occurred.) The ASTVisitor modifies the visitor
- argument by adding a visit method to the visitor; this method can
- be used to visit a child node of arbitrary type.
- """
- VERBOSE = 0
-
- def __init__(self):
- self.node = None
- self._cache = { }
-
-
- def default(self, node, *args):
- for child in node.getChildNodes():
- self.dispatch(child, *args)
-
-
-
- def dispatch(self, node, *args):
- self.node = node
- klass = node.__class__
- meth = self._cache.get(klass, None)
- if meth is None:
- className = klass.__name__
- meth = getattr(self.visitor, 'visit' + className, self.default)
- self._cache[klass] = meth
-
- return meth(node, *args)
-
-
- def preorder(self, tree, visitor, *args):
- '''Do preorder walk of tree using visitor'''
- self.visitor = visitor
- visitor.visit = self.dispatch
- self.dispatch(tree, *args)
-
-
-
- class ExampleASTVisitor(ASTVisitor):
- """Prints examples of the nodes that aren't visited
-
- This visitor-driver is only useful for development, when it's
- helpful to develop a visitor incrementally, and get feedback on what
- you still have to do.
- """
- examples = { }
-
- 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)
- self._cache[node.__class__] = meth
-
- if self.VERBOSE > 1:
- print 'dispatch', className,
- if not meth or meth.__name__:
- pass
- print ''
-
- if meth:
- meth(node, *args)
- elif self.VERBOSE > 0:
- klass = node.__class__
- 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)
- continue
-
- print
-
- return self.default(node, *args)
-
-
-
- _walker = ASTVisitor
-
- def walk(tree, visitor, walker = None, verbose = None):
- if walker is None:
- walker = _walker()
-
- if verbose is not None:
- walker.VERBOSE = verbose
-
- walker.preorder(tree, visitor)
- return walker.visitor
-
-
- def dumpNode(node):
- print node.__class__
- for attr in dir(node):
- if attr[0] != '_':
- print '\t', '%-10.10s' % attr, getattr(node, attr)
- continue
-
-
-