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      1 // Copyright 2013 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 COMPONENTS_POLICY_CORE_COMMON_POLICY_MAP_H_
      6 #define COMPONENTS_POLICY_CORE_COMMON_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 "components/policy/core/common/external_data_fetcher.h"
     15 #include "components/policy/core/common/policy_types.h"
     16 #include "components/policy/policy_export.h"
     17 
     18 namespace policy {
     19 
     20 // A mapping of policy names to policy values for a given policy namespace.
     21 class POLICY_EXPORT PolicyMap {
     22  public:
     23   // Each policy maps to an Entry which keeps the policy value as well as other
     24   // relevant data about the policy.
     25   struct POLICY_EXPORT Entry {
     26     PolicyLevel level;
     27     PolicyScope scope;
     28     base::Value* value;
     29     ExternalDataFetcher* external_data_fetcher;
     30 
     31     Entry();
     32 
     33     // Deletes all members owned by |this|.
     34     void DeleteOwnedMembers();
     35 
     36     // Returns a copy of |this|.
     37     scoped_ptr<Entry> DeepCopy() const;
     38 
     39     // Returns true if |this| has higher priority than |other|.
     40     bool has_higher_priority_than(const Entry& other) const;
     41 
     42     // Returns true if |this| equals |other|.
     43     bool Equals(const Entry& other) const;
     44   };
     45 
     46   typedef std::map<std::string, Entry> PolicyMapType;
     47   typedef PolicyMapType::const_iterator const_iterator;
     48 
     49   PolicyMap();
     50   virtual ~PolicyMap();
     51 
     52   // Returns a weak reference to the entry currently stored for key |policy|,
     53   // or NULL if not found. Ownership is retained by the PolicyMap.
     54   const Entry* Get(const std::string& policy) const;
     55 
     56   // Returns a weak reference to the value currently stored for key |policy|,
     57   // or NULL if not found. Ownership is retained by the PolicyMap.
     58   // This is equivalent to Get(policy)->value, when it doesn't return NULL.
     59   const base::Value* GetValue(const std::string& policy) const;
     60 
     61   // Takes ownership of |value| and |external_data_fetcher|. Overwrites any
     62   // existing information stored in the map for the key |policy|.
     63   void Set(const std::string& policy,
     64            PolicyLevel level,
     65            PolicyScope scope,
     66            base::Value* value,
     67            ExternalDataFetcher* external_data_fetcher);
     68 
     69   // Erase the given |policy|, if it exists in this map.
     70   void Erase(const std::string& policy);
     71 
     72   // Swaps the internal representation of |this| with |other|.
     73   void Swap(PolicyMap* other);
     74 
     75   // |this| becomes a copy of |other|. Any existing policies are dropped.
     76   void CopyFrom(const PolicyMap& other);
     77 
     78   // Returns a copy of |this|.
     79   scoped_ptr<PolicyMap> DeepCopy() const;
     80 
     81   // Merges policies from |other| into |this|. Existing policies are only
     82   // overridden by those in |other| if they have a higher priority, as defined
     83   // by Entry::has_higher_priority_than(). If a policy is contained in both
     84   // maps with the same priority, the current value in |this| is preserved.
     85   void MergeFrom(const PolicyMap& other);
     86 
     87   // Loads the values in |policies| into this PolicyMap. All policies loaded
     88   // will have |level| and |scope| in their entries. Existing entries are
     89   // replaced.
     90   void LoadFrom(const base::DictionaryValue* policies,
     91                 PolicyLevel level,
     92                 PolicyScope scope);
     93 
     94   // Compares this value map against |other| and stores all key names that have
     95   // different values or reference different external data in |differing_keys|.
     96   // This includes keys that are present only in one of the maps.
     97   // |differing_keys| is not cleared before the keys are added.
     98   void GetDifferingKeys(const PolicyMap& other,
     99                         std::set<std::string>* differing_keys) const;
    100 
    101   // Removes all policies that don't have the specified |level|. This is a
    102   // temporary helper method, until mandatory and recommended levels are served
    103   // by a single provider.
    104   // TODO(joaodasilva): Remove this. http://crbug.com/108999
    105   void FilterLevel(PolicyLevel level);
    106 
    107   bool Equals(const PolicyMap& other) const;
    108   bool empty() const;
    109   size_t size() const;
    110 
    111   const_iterator begin() const;
    112   const_iterator end() const;
    113   void Clear();
    114 
    115  private:
    116   // Helper function for Equals().
    117   static bool MapEntryEquals(const PolicyMapType::value_type& a,
    118                              const PolicyMapType::value_type& b);
    119 
    120   PolicyMapType map_;
    121 
    122   DISALLOW_COPY_AND_ASSIGN(PolicyMap);
    123 };
    124 
    125 }  // namespace policy
    126 
    127 #endif  // COMPONENTS_POLICY_CORE_COMMON_POLICY_MAP_H_
    128