components/login/screens/screen_context.h

   1 // Copyright (c) 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_LOGIN_SCREENS_SCREEN_CONTEXT_H_
   6 #define COMPONENTS_LOGIN_SCREENS_SCREEN_CONTEXT_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/logging.h"
  13 #include "base/memory/linked_ptr.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "base/strings/string16.h"
  16 #include "base/threading/non_thread_safe.h"
  17 #include "base/values.h"
  18 #include "components/login/base_screen_handler_utils.h"
  19 #include "components/login/login_export.h"
  20
  21 namespace login {
  22
  23 // ScreenContext is a key-value storage for values that are shared
  24 // between C++ and JS sides. Objects of this class should be used in
  25 // the following way:
  26 //
  27 // context.SetString("user", "john");
  28 // context.SetInteger("image-index", 0);
  29 // context.SetDouble("zoom", 1.25);
  30 // context.GetChangesAndReset(&dictionary);
  31 // CallJS("onContextChanged", dictionary);
  32 //
  33 // ScreenContext memorizes changed key-value pairs and returns them
  34 // via GetChangesAndReset() method. After call to this method an
  35 // internal buffer of changes will be cleared.
  36 class LOGIN_EXPORT ScreenContext : public base::NonThreadSafe {
  37  public:
  38   typedef std::string KeyType;
  39   typedef base::Value ValueType;
  40
  41   ScreenContext();
  42   ~ScreenContext();
  43
  44   bool SetBoolean(const KeyType& key, bool value);
  45   bool SetInteger(const KeyType& key, int value);
  46   bool SetDouble(const KeyType& key, double value);
  47   bool SetString(const KeyType& key, const std::string& value);
  48   bool SetString(const KeyType& key, const base::string16& value);
  49   bool SetStringList(const KeyType& key, const StringList& value);
  50   bool SetString16List(const KeyType& key, const String16List& value);
  51
  52   bool GetBoolean(const KeyType& key) const;
  53   bool GetBoolean(const KeyType& key, bool default_value) const;
  54   int GetInteger(const KeyType& key) const;
  55   int GetInteger(const KeyType& key, int default_value) const;
  56   double GetDouble(const KeyType& key) const;
  57   double GetDouble(const KeyType& key, double default_value) const;
  58   std::string GetString(const KeyType& key) const;
  59   std::string GetString(const KeyType& key,
  60                         const std::string& default_value) const;
  61   base::string16 GetString16(const KeyType& key) const;
  62   base::string16 GetString16(const KeyType& key,
  63                              const base::string16& default_value) const;
  64   StringList GetStringList(const KeyType& key) const;
  65   StringList GetStringList(const KeyType& key,
  66                            const StringList& default_value) const;
  67   String16List GetString16List(const KeyType& key) const;
  68   String16List GetString16List(const KeyType& key,
  69                                const String16List& default_value) const;
  70
  71   // Copies internal state of |context|.
  72   void CopyFrom(ScreenContext& context);
  73
  74   // Returns true if context has |key|.
  75   bool HasKey(const KeyType& key) const;
  76
  77   // Returns true if there was changes since last call to
  78   // GetChangesAndReset().
  79   bool HasChanges() const;
  80
  81   // Stores all changes since the last call to the
  82   // GetChangesAndReset() in |diff|.  All previous contents of |diff|
  83   // will be thrown away.
  84   void GetChangesAndReset(base::DictionaryValue* diff);
  85
  86   // Applies changes from |diff| to the context. All keys from |diff|
  87   // are stored in |keys|. |keys| argument is optional and can be NULL.
  88   void ApplyChanges(const base::DictionaryValue& diff,
  89                     std::vector<std::string>* keys);
  90
  91   // Returns underlying dictionary containing all the stored data.
  92   const base::DictionaryValue& storage() const { return storage_; }
  93
  94  private:
  95   bool Set(const KeyType& key, base::Value* value);
  96
  97   template <typename T>
  98   T Get(const KeyType& key) const {
  99     DCHECK(CalledOnValidThread());
 100     const base::Value* value;
 101     bool has_key = storage_.Get(key, &value);
 102     DCHECK(has_key);
 103     T result;
 104     if (!ParseValue(value, &result)) {
 105       NOTREACHED();
 106       return T();
 107     }
 108     return result;
 109   }
 110
 111   template <typename T>
 112   T Get(const KeyType& key, const T& default_value) const {
 113     DCHECK(CalledOnValidThread());
 114     if (!HasKey(key))
 115       return default_value;
 116     return Get<T>(key);
 117   }
 118
 119   // Contains current state of <key, value> map.
 120   base::DictionaryValue storage_;
 121
 122   // Contains all pending changes.
 123   base::DictionaryValue changes_;
 124
 125   DISALLOW_COPY_AND_ASSIGN(ScreenContext);
 126 };
 127
 128 }  // namespace login
 129
 130 #endif  // COMPONENTS_LOGIN_SCREENS_SCREEN_CONTEXT_H_