screen_context.h revision 7d4cd473f85ac64c3747c96c277f9e506a0d2246 
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
20namespace 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.
35class 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(DictionaryValue* diff);
72
73  // Applies changes from |diff| to the context. All keys from |diff|
74  // are stored in |keys|.
75  void ApplyChanges(const DictionaryValue& diff,
76                    std::vector<std::string>* keys);
77
78 private:
79  bool Set(const KeyType& key, Value* value);
80
81  template<typename T>
82  T Get(const KeyType& key) {
83    DCHECK(CalledOnValidThread());
84    const 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  DictionaryValue storage_;
105
106  // Contains all pending changes.
107  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_
115