| // 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. |
| |
| #ifndef RE2_FILTERED_RE2_H_ |
| #define RE2_FILTERED_RE2_H_ |
| |
| // The class FilteredRE2 is used as a wrapper to multiple RE2 regexps. |
| // It provides a prefilter mechanism that helps in cutting down the |
| // number of regexps that need to be actually searched. |
| // |
| // By design, it does not include a string matching engine. This is to |
| // allow the user of the class to use their favorite string match |
| // engine. The overall flow is: Add all the regexps using Add, then |
| // Compile the FilteredRE2. The compile returns strings that need to |
| // be matched. Note that all returned strings are lowercase. For |
| // applying regexps to a search text, the caller does the string |
| // matching using the strings returned. When doing the string match, |
| // note that the caller has to do that on lower cased version of the |
| // search text. Then call FirstMatch or AllMatches with a vector of |
| // indices of strings that were found in the text to get the actual |
| // regexp matches. |
| |
| #include <string> |
| #include <vector> |
| |
| #include "re2/re2.h" |
| |
| namespace re2 { |
| |
| class PrefilterTree; |
| |
| class FilteredRE2 { |
| public: |
| FilteredRE2(); |
| explicit FilteredRE2(int min_atom_len); |
| ~FilteredRE2(); |
| |
| // Uses RE2 constructor to create a RE2 object (re). Returns |
| // re->error_code(). If error_code is other than NoError, then re is |
| // deleted and not added to re2_vec_. |
| RE2::ErrorCode Add(const StringPiece& pattern, |
| const RE2::Options& options, |
| int *id); |
| |
| // Prepares the regexps added by Add for filtering. Returns a set |
| // of strings that the caller should check for in candidate texts. |
| // The returned strings are lowercased. When doing string matching, |
| // the search text should be lowercased first to find matching |
| // strings from the set of strings returned by Compile. Call after |
| // all Add calls are done. |
| void Compile(std::vector<string>* strings_to_match); |
| |
| // Returns the index of the first matching regexp. |
| // Returns -1 on no match. Can be called prior to Compile. |
| // Does not do any filtering: simply tries to Match the |
| // regexps in a loop. |
| int SlowFirstMatch(const StringPiece& text) const; |
| |
| // Returns the index of the first matching regexp. |
| // Returns -1 on no match. Compile has to be called before |
| // calling this. |
| int FirstMatch(const StringPiece& text, |
| const std::vector<int>& atoms) const; |
| |
| // Returns the indices of all matching regexps, after first clearing |
| // matched_regexps. |
| bool AllMatches(const StringPiece& text, |
| const std::vector<int>& atoms, |
| std::vector<int>* matching_regexps) const; |
| |
| // Returns the indices of all potentially matching regexps after first |
| // clearing potential_regexps. |
| // A regexp is potentially matching if it passes the filter. |
| // If a regexp passes the filter it may still not match. |
| // A regexp that does not pass the filter is guaranteed to not match. |
| void AllPotentials(const std::vector<int>& atoms, |
| std::vector<int>* potential_regexps) const; |
| |
| // The number of regexps added. |
| int NumRegexps() const { return static_cast<int>(re2_vec_.size()); } |
| |
| private: |
| |
| // Get the individual RE2 objects. Useful for testing. |
| RE2* GetRE2(int regexpid) const { return re2_vec_[regexpid]; } |
| |
| // Print prefilter. |
| void PrintPrefilter(int regexpid); |
| |
| // Useful for testing and debugging. |
| void RegexpsGivenStrings(const std::vector<int>& matched_atoms, |
| std::vector<int>* passed_regexps); |
| |
| // All the regexps in the FilteredRE2. |
| std::vector<RE2*> re2_vec_; |
| |
| // Has the FilteredRE2 been compiled using Compile() |
| bool compiled_; |
| |
| // An AND-OR tree of string atoms used for filtering regexps. |
| PrefilterTree* prefilter_tree_; |
| |
| FilteredRE2(const FilteredRE2&) = delete; |
| FilteredRE2& operator=(const FilteredRE2&) = delete; |
| }; |
| |
| } // namespace re2 |
| |
| #endif // RE2_FILTERED_RE2_H_ |