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: 15 NullWalker() { } 16 bool PostVisit(Regexp* re, bool parent_arg, bool pre_arg, 17 bool* child_args, int nchild_args); 18 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. 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. 39 void Regexp::NullWalk() { 40 NullWalker w; 41 w.Walk(this, false); 42 } 43 44 } // namespace re2 45
