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// Copyright 2013 The Chromium 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 COMPONENTS_URL_MATCHER_REGEX_SET_MATCHER_H_
#define COMPONENTS_URL_MATCHER_REGEX_SET_MATCHER_H_
#include <map>
#include <set>
#include <string>
#include <vector>
#include "base/memory/scoped_ptr.h"
#include "components/url_matcher/string_pattern.h"
#include "components/url_matcher/substring_set_matcher.h"
#include "components/url_matcher/url_matcher_export.h"
namespace re2 {
class FilteredRE2;
}
namespace url_matcher {
// Efficiently matches URLs against a collection of regular expressions,
// using FilteredRE2 to reduce the number of regexes that must be matched
// by pre-filtering with substring matching. See:
// http://swtch.com/~rsc/regexp/regexp3.html#analysis
class URL_MATCHER_EXPORT RegexSetMatcher {
public:
RegexSetMatcher();
virtual ~RegexSetMatcher();
// Adds the regex patterns in |regex_list| to the matcher. Also rebuilds
// the FilteredRE2 matcher; thus, for efficiency, prefer adding multiple
// patterns at once.
// Ownership of the patterns remains with the caller.
void AddPatterns(const std::vector<const StringPattern*>& regex_list);
// Removes all regex patterns.
void ClearPatterns();
// Appends the IDs of regular expressions in our set that match the |text|
// to |matches|.
bool Match(const std::string& text,
std::set<StringPattern::ID>* matches) const;
bool IsEmpty() const;
private:
typedef int RE2ID;
typedef std::map<StringPattern::ID, const StringPattern*> RegexMap;
typedef std::vector<StringPattern::ID> RE2IDMap;
// Use Aho-Corasick SubstringSetMatcher to find which literal patterns
// match the |text|.
std::vector<RE2ID> FindSubstringMatches(const std::string& text) const;
// Rebuild FilteredRE2 from scratch. Needs to be called whenever
// our set of regexes changes.
// TODO(yoz): investigate if it could be done incrementally;
// apparently not supported by FilteredRE2.
void RebuildMatcher();
// Clean up StringPatterns in |substring_patterns_|.
void DeleteSubstringPatterns();
// Mapping of regex StringPattern::IDs to regexes.
RegexMap regexes_;
// Mapping of RE2IDs from FilteredRE2 (which are assigned in order)
// to regex StringPattern::IDs.
RE2IDMap re2_id_map_;
scoped_ptr<re2::FilteredRE2> filtered_re2_;
scoped_ptr<SubstringSetMatcher> substring_matcher_;
// The substring patterns from FilteredRE2, which are used in
// |substring_matcher_| but whose lifetime is managed here.
std::vector<const StringPattern*> substring_patterns_;
};
} // namespace url_matcher
#endif // COMPONENTS_URL_MATCHER_REGEX_SET_MATCHER_H_
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