Add common code for extensions event filtering.

chrome/common/extensions/event_filter.h

+// Copyright (c) 2012 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 CHROME_COMMON_EXTENSIONS_EVENT_FILTER_H_
+#define CHROME_COMMON_EXTENSIONS_EVENT_FILTER_H_
+#pragma once
+
+#include "base/memory/linked_ptr.h"
+#include "chrome/common/extensions/event_matcher.h"
+#include "chrome/common/extensions/event_filtering_info.h"
+#include "chrome/common/extensions/matcher/url_matcher.h"
+
+#include <map>
+#include <set>
+
+namespace extensions {
+
+// Matches incoming events against a collection of EventMatchers. Each added
+// EventMatcher is given an id which is returned by MatchEvent() when it is
+// passed a matching event.
+class EventFilter {
+ public:
+  typedef int MatcherID;
+  EventFilter();
+  ~EventFilter();
+
+  // Adds an event matcher that will be used in calls to MatchEvent(). Returns
+  // the id of the matcher, or -1 if there was an error.
+  MatcherID AddEventMatcher(const std::string& event_name,
+                            scoped_ptr<EventMatcher> matcher);
+  // Removes an event matcher, returning the name of the event that it was for.
+  std::string RemoveEventMatcher(MatcherID id);
+
+  // Match an event named |event_name| with filtering info |event_info| against
+  // our set of event matchers. Returns a set of ids that correspond to the
+  // event matchers that matched the event.
+  // TODO(koz): Add a std::string* parameter for retrieving error messages.
+  std::set<MatcherID> MatchEvent(const std::string& event_name,
+                                 const EventFilteringInfo& event_info);
+
+  int GetMatcherCountForEvent(const std::string& event_name);
+
+  // For testing.
+  bool IsURLMatcherEmpty() const {
+    return url_matcher_.IsEmpty();
+  }
+
+ private:
+  class EventMatcherEntry {
+   public:
+    // Adds |condition_sets| to |url_matcher| on construction and removes them
+    // again on destruction. |condition_sets| should be the
+    // URLMatcherConditionSets that match the URL constraints specified by
+    // |event_matcher|.
+    EventMatcherEntry(scoped_ptr<EventMatcher> event_matcher,
+                      URLMatcher* url_matcher,
+                      const URLMatcherConditionSet::Vector& condition_sets);
+    ~EventMatcherEntry();
+
+    // Prevents the removal of condition sets when this class is destroyed. We
+    // call this in EventFilter's destructor so that we don't do the costly
+    // removal of condition sets when the URLMatcher is going to be destroyed
+    // and clean them up anyway.
+    void DontRemoveConditionSetsInDestructor();
+
+    const EventMatcher& event_matcher() const {
+      return *event_matcher_;
+    }
+
+   private:
+    scoped_ptr<EventMatcher> event_matcher_;
+    // The id sets in url_matcher_ that this EventMatcher owns.
+    std::vector<URLMatcherConditionSet::ID> condition_set_ids_;
+    URLMatcher* url_matcher_;
+
+    DISALLOW_COPY_AND_ASSIGN(EventMatcherEntry);
+  };
+
+  // Maps from a matcher id to an event matcher entry.
+  typedef std::map<MatcherID, linked_ptr<EventMatcherEntry> > EventMatcherMap;
+
+  // Maps from event name to the map of matchers that are registered for it.
+  typedef std::map<std::string, EventMatcherMap> EventMatcherMultiMap;
+
+  // Adds the list of filters to the URL matcher, having matches for those URLs
+  // map to |id|.
+  bool CreateConditionSets(MatcherID id,
+                           base::ListValue* url_filters,
+                           URLMatcherConditionSet::Vector* condition_sets);
+
+  bool AddDictionaryAsConditionSet(
+      base::DictionaryValue* url_filter,
+      URLMatcherConditionSet::Vector* condition_sets);
+
+  URLMatcher url_matcher_;
+  EventMatcherMultiMap event_matchers_;
+
+  // The next id to assign to an EventMatcher.
+  MatcherID next_id_;
+
+  // The next id to assign to a condition set passed to URLMatcher.
+  URLMatcherConditionSet::ID next_condition_set_id_;
+
+  // Maps condition set ids, which URLMatcher operates in, to event matcher
+  // ids, which the interface to this class operates in. As each EventFilter
+  // can specify many condition sets this is a many to one relationship.
+  std::map<URLMatcherConditionSet::ID, MatcherID>
+      condition_set_id_to_event_matcher_id_;
+
+  // Maps from event matcher ids to the name of the event they match on.
+  std::map<MatcherID, std::string> id_to_event_name_;
+
+  DISALLOW_COPY_AND_ASSIGN(EventFilter);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_COMMON_EXTENSIONS_EVENT_FILTER_H_