| # Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| """ Visitor Object for traversing AST """ |
| |
| # |
| # IDLVisitor |
| # |
| # The IDLVisitor class will traverse an AST truncating portions of the tree |
| # when 'VisitFilter' returns false. After the filter returns true, for each |
| # node, the visitor will call the 'Arrive' member passing in the node and |
| # and generic data object from the parent call. The returned value is then |
| # passed to all children who's results are aggregated into a list. The child |
| # results along with the original Arrive result are passed to the Depart |
| # function which returns the final result of the Visit. By default this is |
| # the exact value that was return from the original arrive. |
| # |
| |
| class IDLVisitor(object): |
| def __init__(self): |
| pass |
| |
| # Return TRUE if the node should be visited |
| def VisitFilter(self, node, data): |
| return True |
| |
| def Visit(self, node, data): |
| if not self.VisitFilter(node, data): return None |
| |
| childdata = [] |
| newdata = self.Arrive(node, data) |
| for child in node.GetChildren(): |
| ret = self.Visit(child, newdata) |
| if ret is not None: |
| childdata.append(ret) |
| return self.Depart(node, newdata, childdata) |
| |
| def Arrive(self, node, data): |
| __pychecker__ = 'unusednames=node' |
| return data |
| |
| def Depart(self, node, data, childdata): |
| __pychecker__ = 'unusednames=node,childdata' |
| return data |