Replace RE2 import with a dependency

third_party/re2/re2/prefilter_tree.h

-// Copyright 2009 The RE2 Authors.  All Rights Reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// The PrefilterTree class is used to form an AND-OR tree of strings
-// that would trigger each regexp. The 'prefilter' of each regexp is
-// added tp PrefilterTree, and then PrefilterTree is used to find all
-// the unique strings across the prefilters. During search, by using
-// matches from a string matching engine, PrefilterTree deduces the
-// set of regexps that are to be triggered. The 'string matching
-// engine' itself is outside of this class, and the caller can use any
-// favorite engine. PrefilterTree provides a set of strings (called
-// atoms) that the user of this class should use to do the string
-// matching.
-//
-#ifndef RE2_PREFILTER_TREE_H_
-#define RE2_PREFILTER_TREE_H_
-
-#include "util/util.h"
-#include "util/sparse_array.h"
-
-namespace re2 {
-
-typedef SparseArray<int> IntMap;
-typedef map<int, int> StdIntMap;
-
-class Prefilter;
-
-class PrefilterTree {
- public:
-  PrefilterTree();
-  ~PrefilterTree();
-
-  // Adds the prefilter for the next regexp. Note that we assume that
-  // Add called sequentially for all regexps. All Add calls
-  // must precede Compile.
-  void Add(Prefilter* prefilter);
-
-  // The Compile returns a vector of string in atom_vec.
-  // Call this after all the prefilters are added through Add.
-  // No calls to Add after Compile are allowed.
-  // The caller should use the returned set of strings to do string matching.
-  // Each time a string matches, the corresponding index then has to be
-  // and passed to RegexpsGivenStrings below.
-  void Compile(vector<string>* atom_vec);
-
-  // Given the indices of the atoms that matched, returns the indexes
-  // of regexps that should be searched.  The matched_atoms should
-  // contain all the ids of string atoms that were found to match the
-  // content. The caller can use any string match engine to perform
-  // this function. This function is thread safe.
-  void RegexpsGivenStrings(const vector<int>& matched_atoms,
-                           vector<int>* regexps) const;
-
-  // Print debug prefilter. Also prints unique ids associated with
-  // nodes of the prefilter of the regexp.
-  void PrintPrefilter(int regexpid);
-
-
-  // Each unique node has a corresponding Entry that helps in
-  // passing the matching trigger information along the tree.
-  struct Entry {
-   public:
-    // How many children should match before this node triggers the
-    // parent. For an atom and an OR node, this is 1 and for an AND
-    // node, it is the number of unique children.
-    int propagate_up_at_count;
-
-    // When this node is ready to trigger the parent, what are the indices
-    // of the parent nodes to trigger. The reason there may be more than
-    // one is because of sharing. For example (abc | def) and (xyz | def)
-    // are two different nodes, but they share the atom 'def'. So when
-    // 'def' matches, it triggers two parents, corresponding to the two
-    // different OR nodes.
-    StdIntMap* parents;
-
-    // When this node is ready to trigger the parent, what are the
-    // regexps that are triggered.
-    vector<int> regexps;
-  };
-
- private:
-  // This function assigns unique ids to various parts of the
-  // prefilter, by looking at if these nodes are already in the
-  // PrefilterTree.
-  void AssignUniqueIds(vector<string>* atom_vec);
-
-  // Given the matching atoms, find the regexps to be triggered.
-  void PropagateMatch(const vector<int>& atom_ids,
-                      IntMap* regexps) const;
-
-  // Returns the prefilter node that has the same NodeString as this
-  // node. For the canonical node, returns node.
-  Prefilter* CanonicalNode(Prefilter* node);
-
-  // A string that uniquely identifies the node. Assumes that the
-  // children of node has already been assigned unique ids.
-  string NodeString(Prefilter* node) const;
-
-  // Recursively constructs a readable prefilter string.
-  string DebugNodeString(Prefilter* node) const;
-
-  // Used for debugging.
-  void PrintDebugInfo();
-
-  // These are all the nodes formed by Compile. Essentially, there is
-  // one node for each unique atom and each unique AND/OR node.
-  vector<Entry> entries_;
-
-  // Map node string to canonical Prefilter node.
-  map<string, Prefilter*> node_map_;
-
-  // indices of regexps that always pass through the filter (since we
-  // found no required literals in these regexps).
-  vector<int> unfiltered_;
-
-  // vector of Prefilter for all regexps.
-  vector<Prefilter*> prefilter_vec_;
-
-  // Atom index in returned strings to entry id mapping.
-  vector<int> atom_index_to_id_;
-
-  // Has the prefilter tree been compiled.
-  bool compiled_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrefilterTree);
-};
-
-}  // namespace
-
-#endif  // RE2_PREFILTER_TREE_H_