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