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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef EXTENSIONS_COMMON_EVENT_FILTER_H_
      6 #define EXTENSIONS_COMMON_EVENT_FILTER_H_
      7 
      8 #include <map>
      9 #include <set>
     10 
     11 #include "base/memory/linked_ptr.h"
     12 #include "extensions/common/event_filtering_info.h"
     13 #include "extensions/common/event_matcher.h"
     14 #include "extensions/common/matcher/url_matcher.h"
     15 
     16 namespace extensions {
     17 
     18 // Matches incoming events against a collection of EventMatchers. Each added
     19 // EventMatcher is given an id which is returned by MatchEvent() when it is
     20 // passed a matching event.
     21 class EventFilter {
     22  public:
     23   typedef int MatcherID;
     24   EventFilter();
     25   ~EventFilter();
     26 
     27   // Adds an event matcher that will be used in calls to MatchEvent(). Returns
     28   // the id of the matcher, or -1 if there was an error.
     29   MatcherID AddEventMatcher(const std::string& event_name,
     30                             scoped_ptr<EventMatcher> matcher);
     31 
     32   // Retrieve the EventMatcher with the given id.
     33   EventMatcher* GetEventMatcher(MatcherID id);
     34 
     35   // Retrieve the name of the event that the EventMatcher specified by |id| is
     36   // referring to.
     37   const std::string& GetEventName(MatcherID id);
     38 
     39   // Removes an event matcher, returning the name of the event that it was for.
     40   std::string RemoveEventMatcher(MatcherID id);
     41 
     42   // Match an event named |event_name| with filtering info |event_info| against
     43   // our set of event matchers. Returns a set of ids that correspond to the
     44   // event matchers that matched the event.
     45   // TODO(koz): Add a std::string* parameter for retrieving error messages.
     46   std::set<MatcherID> MatchEvent(const std::string& event_name,
     47                                  const EventFilteringInfo& event_info,
     48                                  int routing_id);
     49 
     50   int GetMatcherCountForEvent(const std::string& event_name);
     51 
     52   // For testing.
     53   bool IsURLMatcherEmpty() const {
     54     return url_matcher_.IsEmpty();
     55   }
     56 
     57  private:
     58   class EventMatcherEntry {
     59    public:
     60     // Adds |condition_sets| to |url_matcher| on construction and removes them
     61     // again on destruction. |condition_sets| should be the
     62     // URLMatcherConditionSets that match the URL constraints specified by
     63     // |event_matcher|.
     64     EventMatcherEntry(scoped_ptr<EventMatcher> event_matcher,
     65                       URLMatcher* url_matcher,
     66                       const URLMatcherConditionSet::Vector& condition_sets);
     67     ~EventMatcherEntry();
     68 
     69     // Prevents the removal of condition sets when this class is destroyed. We
     70     // call this in EventFilter's destructor so that we don't do the costly
     71     // removal of condition sets when the URLMatcher is going to be destroyed
     72     // and clean them up anyway.
     73     void DontRemoveConditionSetsInDestructor();
     74 
     75     EventMatcher* event_matcher() {
     76       return event_matcher_.get();
     77     }
     78 
     79    private:
     80     scoped_ptr<EventMatcher> event_matcher_;
     81     // The id sets in url_matcher_ that this EventMatcher owns.
     82     std::vector<URLMatcherConditionSet::ID> condition_set_ids_;
     83     URLMatcher* url_matcher_;
     84 
     85     DISALLOW_COPY_AND_ASSIGN(EventMatcherEntry);
     86   };
     87 
     88   // Maps from a matcher id to an event matcher entry.
     89   typedef std::map<MatcherID, linked_ptr<EventMatcherEntry> > EventMatcherMap;
     90 
     91   // Maps from event name to the map of matchers that are registered for it.
     92   typedef std::map<std::string, EventMatcherMap> EventMatcherMultiMap;
     93 
     94   // Adds the list of URL filters in |matcher| to the URL matcher, having
     95   // matches for those URLs map to |id|.
     96   bool CreateConditionSets(MatcherID id,
     97                            EventMatcher* matcher,
     98                            URLMatcherConditionSet::Vector* condition_sets);
     99 
    100   bool AddDictionaryAsConditionSet(
    101       base::DictionaryValue* url_filter,
    102       URLMatcherConditionSet::Vector* condition_sets);
    103 
    104   URLMatcher url_matcher_;
    105   EventMatcherMultiMap event_matchers_;
    106 
    107   // The next id to assign to an EventMatcher.
    108   MatcherID next_id_;
    109 
    110   // The next id to assign to a condition set passed to URLMatcher.
    111   URLMatcherConditionSet::ID next_condition_set_id_;
    112 
    113   // Maps condition set ids, which URLMatcher operates in, to event matcher
    114   // ids, which the interface to this class operates in. As each EventFilter
    115   // can specify many condition sets this is a many to one relationship.
    116   std::map<URLMatcherConditionSet::ID, MatcherID>
    117       condition_set_id_to_event_matcher_id_;
    118 
    119   // Maps from event matcher ids to the name of the event they match on.
    120   std::map<MatcherID, std::string> id_to_event_name_;
    121 
    122   DISALLOW_COPY_AND_ASSIGN(EventFilter);
    123 };
    124 
    125 }  // namespace extensions
    126 
    127 #endif  // EXTENSIONS_COMMON_EVENT_FILTER_H_
    128