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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 CHROME_BROWSER_POLICY_POLICY_MAP_H_
      6 #define CHROME_BROWSER_POLICY_POLICY_MAP_H_
      7 
      8 #include <map>
      9 #include <set>
     10 #include <string>
     11 
     12 #include "base/memory/scoped_ptr.h"
     13 #include "base/values.h"
     14 #include "chrome/browser/policy/external_data_fetcher.h"
     15 #include "chrome/browser/policy/policy_types.h"
     16 
     17 namespace policy {
     18 
     19 // A mapping of policy names to policy values for a given policy namespace.
     20 class PolicyMap {
     21  public:
     22   // Each policy maps to an Entry which keeps the policy value as well as other
     23   // relevant data about the policy.
     24   struct Entry {
     25     PolicyLevel level;
     26     PolicyScope scope;
     27     base::Value* value;
     28     ExternalDataFetcher* external_data_fetcher;
     29 
     30     Entry()
     31         : level(POLICY_LEVEL_RECOMMENDED),
     32           scope(POLICY_SCOPE_USER),
     33           value(NULL),
     34           external_data_fetcher(NULL) {}
     35 
     36     // Returns true if |this| has higher priority than |other|.
     37     bool has_higher_priority_than(const Entry& other) const;
     38 
     39     // Returns true if |this| equals |other|.
     40     bool Equals(const Entry& other) const;
     41   };
     42 
     43   typedef std::map<std::string, Entry> PolicyMapType;
     44   typedef PolicyMapType::const_iterator const_iterator;
     45 
     46   PolicyMap();
     47   virtual ~PolicyMap();
     48 
     49   // Returns a weak reference to the entry currently stored for key |policy|,
     50   // or NULL if not found. Ownership is retained by the PolicyMap.
     51   const Entry* Get(const std::string& policy) const;
     52 
     53   // Returns a weak reference to the value currently stored for key |policy|,
     54   // or NULL if not found. Ownership is retained by the PolicyMap.
     55   // This is equivalent to Get(policy)->value, when it doesn't return NULL.
     56   const base::Value* GetValue(const std::string& policy) const;
     57 
     58   // Takes ownership of |value| and |external_data_fetcher|. Overwrites any
     59   // existing information stored in the map for the key |policy|.
     60   void Set(const std::string& policy,
     61            PolicyLevel level,
     62            PolicyScope scope,
     63            base::Value* value,
     64            ExternalDataFetcher* external_data_fetcher);
     65 
     66   // Erase the given |policy|, if it exists in this map.
     67   void Erase(const std::string& policy);
     68 
     69   // Swaps the internal representation of |this| with |other|.
     70   void Swap(PolicyMap* other);
     71 
     72   // |this| becomes a copy of |other|. Any existing policies are dropped.
     73   void CopyFrom(const PolicyMap& other);
     74 
     75   // Returns a copy of |this|.
     76   scoped_ptr<PolicyMap> DeepCopy() const;
     77 
     78   // Merges policies from |other| into |this|. Existing policies are only
     79   // overridden by those in |other| if they have a higher priority, as defined
     80   // by Entry::has_higher_priority_than(). If a policy is contained in both
     81   // maps with the same priority, the current value in |this| is preserved.
     82   void MergeFrom(const PolicyMap& other);
     83 
     84   // Loads the values in |policies| into this PolicyMap. All policies loaded
     85   // will have |level| and |scope| in their entries. Existing entries are
     86   // replaced.
     87   void LoadFrom(const base::DictionaryValue* policies,
     88                 PolicyLevel level,
     89                 PolicyScope scope);
     90 
     91   // Compares this value map against |other| and stores all key names that have
     92   // different values or reference different external data in |differing_keys|.
     93   // This includes keys that are present only in one of the maps.
     94   // |differing_keys| is not cleared before the keys are added.
     95   void GetDifferingKeys(const PolicyMap& other,
     96                         std::set<std::string>* differing_keys) const;
     97 
     98   // Removes all policies that don't have the specified |level|. This is a
     99   // temporary helper method, until mandatory and recommended levels are served
    100   // by a single provider.
    101   // TODO(joaodasilva): Remove this. http://crbug.com/108999
    102   void FilterLevel(PolicyLevel level);
    103 
    104   bool Equals(const PolicyMap& other) const;
    105   bool empty() const;
    106   size_t size() const;
    107 
    108   const_iterator begin() const;
    109   const_iterator end() const;
    110   void Clear();
    111 
    112  private:
    113   // Helper function for Equals().
    114   static bool MapEntryEquals(const PolicyMapType::value_type& a,
    115                              const PolicyMapType::value_type& b);
    116 
    117   PolicyMapType map_;
    118 
    119   DISALLOW_COPY_AND_ASSIGN(PolicyMap);
    120 };
    121 
    122 }  // namespace policy
    123 
    124 #endif  // CHROME_BROWSER_POLICY_POLICY_MAP_H_
    125