1 // Copyright 2009 The RE2 Authors. All Rights Reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 #include "util/test.h"
6 #include "re2/regexp.h"
7 #include "re2/walker-inl.h"
8
9 namespace re2 {
10
11 // Null walker. For benchmarking the walker itself.
12
13 class NullWalker : public Regexp::Walker<bool> {
14 public:
NullWalker()15 NullWalker() { }
16 bool PostVisit(Regexp* re, bool parent_arg, bool pre_arg,
17 bool* child_args, int nchild_args);
18
ShortVisit(Regexp * re,bool a)19 bool ShortVisit(Regexp* re, bool a) {
20 // Should never be called: we use Walk not WalkExponential.
21 LOG(DFATAL) << "NullWalker::ShortVisit called";
22 return a;
23 }
24
25 private:
26 DISALLOW_EVIL_CONSTRUCTORS(NullWalker);
27 };
28
29 // Called after visiting re's children. child_args contains the return
30 // value from each of the children's PostVisits (i.e., whether each child
31 // can match an empty string). Returns whether this clause can match an
32 // empty string.
PostVisit(Regexp * re,bool parent_arg,bool pre_arg,bool * child_args,int nchild_args)33 bool NullWalker::PostVisit(Regexp* re, bool parent_arg, bool pre_arg,
34 bool* child_args, int nchild_args) {
35 return false;
36 }
37
38 // Returns whether re can match an empty string.
NullWalk()39 void Regexp::NullWalk() {
40 NullWalker w;
41 w.Walk(this, false);
42 }
43
44 } // namespace re2
45