idl_visitor.py revision 5821806d5e7f356e8fa4b058a389a808ea183019 
1# Copyright (c) 2012 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5""" Visitor Object for traversing AST """
6
7#
8# IDLVisitor
9#
10# The IDLVisitor class will traverse an AST truncating portions of the tree
11# when 'VisitFilter' returns false.  After the filter returns true, for each
12# node, the visitor will call the 'Arrive' member passing in the node and
13# and generic data object from the parent call.  The returned value is then
14# passed to all children who's results are aggregated into a list.  The child
15# results along with the original Arrive result are passed to the Depart
16# function which returns the final result of the Visit.  By default this is
17# the exact value that was return from the original arrive.
18#
19
20class IDLVisitor(object):
21  def __init__(self):
22    self.depth = 0
23
24  # Return TRUE if the node should be visited
25  def VisitFilter(self, node, data):
26    return True
27
28  # Return TRUE if data should be added to the childdata list
29  def AgrigateFilter(self, data):
30    return data is not None
31
32  def Visit(self, node, data):
33    self.depth += 1
34    if not self.VisitFilter(node, data): return None
35
36    childdata = []
37    newdata = self.Arrive(node, data)
38    for child in node.GetChildren():
39      ret = self.Visit(child, newdata)
40      if self.AgrigateFilter(ret):
41        childdata.append(ret)
42    out = self.Depart(node, newdata, childdata)
43
44    self.depth -= 1
45    return out
46
47  def Arrive(self, node, data):
48    __pychecker__ = 'unusednames=node'
49    return data
50
51  def Depart(self, node, data, childdata):
52    __pychecker__ = 'unusednames=node,childdata'
53    return data
54
55
56#
57# IDLVersionVisitor
58#
59# The IDLVersionVisitor will only visit nodes with intervals that include the
60# version.  It will also optionally filter based on a class list
61#
62class IDLVersionVisitor(object):
63  def __init__(self, version, classList):
64    self.version = version
65    self.classes = classes
66
67  def Filter(self, node, data):
68    if self.classList and node.cls not in self.classList: return False
69    if not node.IsVersion(self.version): return False
70    return True
71
72class IDLRangeVisitor(object):
73  def __init__(self, vmin, vmax, classList):
74    self.vmin = vmin
75    self.vmax = vmax
76    self.classList = classList
77
78  def Filter(self, node, data):
79    if self.classList and node.cls not in self.classList: return False
80    if not node.IsVersion(self.version): return False
81    return True
82