third_party/re2/re2/prefilter.h

   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 // Prefilter is the class used to extract string guards from regexps.
   6 // Rather than using Prefilter class directly, use FilteredRE2.
   7 // See filtered_re2.h
   8
   9 #ifndef RE2_PREFILTER_H_
  10 #define RE2_PREFILTER_H_
  11
  12 #include "util/util.h"
  13
  14 namespace re2 {
  15
  16 class RE2;
  17
  18 class Regexp;
  19
  20 class Prefilter {
  21   // Instead of using Prefilter directly, use FilteredRE2; see filtered_re2.h
  22  public:
  23   enum Op {
  24     ALL = 0,  // Everything matches
  25     NONE,  // Nothing matches
  26     ATOM,  // The string atom() must match
  27     AND,   // All in subs() must match
  28     OR,   // One of subs() must match
  29   };
  30
  31   explicit Prefilter(Op op);
  32   ~Prefilter();
  33
  34   Op op() { return op_; }
  35   const string& atom() const { return atom_; }
  36   void set_unique_id(int id) { unique_id_ = id; }
  37   int unique_id() const { return unique_id_; }
  38
  39   // The children of the Prefilter node.
  40   vector<Prefilter*>* subs() {
  41     CHECK(op_ == AND || op_ == OR);
  42     return subs_;
  43   }
  44
  45   // Set the children vector. Prefilter takes ownership of subs and
  46   // subs_ will be deleted when Prefilter is deleted.
  47   void set_subs(vector<Prefilter*>* subs) { subs_ = subs; }
  48
  49   // Given a RE2, return a Prefilter. The caller takes ownership of
  50   // the Prefilter and should deallocate it. Returns NULL if Prefilter
  51   // cannot be formed.
  52   static Prefilter* FromRE2(const RE2* re2);
  53
  54   // Returns a readable debug string of the prefilter.
  55   string DebugString() const;
  56
  57  private:
  58   class Info;
  59
  60   // Combines two prefilters together to create an AND. The passed
  61   // Prefilters will be part of the returned Prefilter or deleted.
  62   static Prefilter* And(Prefilter* a, Prefilter* b);
  63
  64   // Combines two prefilters together to create an OR. The passed
  65   // Prefilters will be part of the returned Prefilter or deleted.
  66   static Prefilter* Or(Prefilter* a, Prefilter* b);
  67
  68   // Generalized And/Or
  69   static Prefilter* AndOr(Op op, Prefilter* a, Prefilter* b);
  70
  71   static Prefilter* FromRegexp(Regexp* a);
  72
  73   static Prefilter* FromString(const string& str);
  74
  75   static Prefilter* OrStrings(set<string>* ss);
  76
  77   static Info* BuildInfo(Regexp* re);
  78
  79   Prefilter* Simplify();
  80
  81   // Kind of Prefilter.
  82   Op op_;
  83
  84   // Sub-matches for AND or OR Prefilter.
  85   vector<Prefilter*>* subs_;
  86
  87   // Actual string to match in leaf node.
  88   string atom_;
  89
  90   // If different prefilters have the same string atom, or if they are
  91   // structurally the same (e.g., OR of same atom strings) they are
  92   // considered the same unique nodes. This is the id for each unique
  93   // node. This field is populated with a unique id for every node,
  94   // and -1 for duplicate nodes.
  95   int unique_id_;
  96
  97   // Used for debugging, helps in tracking memory leaks.
  98   int alloc_id_;
  99
 100   DISALLOW_EVIL_CONSTRUCTORS(Prefilter);
 101 };
 102
 103 }  // namespace re2
 104
 105 #endif  // RE2_PREFILTER_H_