screen_context.h revision 1320f92c476a1ad9d19dba2a48c72b75566198e9 
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  bool SetStringList(const KeyType& key, const StringList& value);
49  bool SetString16List(const KeyType& key, const String16List& value);
50
51  bool GetBoolean(const KeyType& key) const;
52  bool GetBoolean(const KeyType& key, bool default_value) const;
53  int GetInteger(const KeyType& key) const;
54  int GetInteger(const KeyType& key, int default_value) const;
55  double GetDouble(const KeyType& key) const;
56  double GetDouble(const KeyType& key, double default_value) const;
57  std::string GetString(const KeyType& key) const;
58  std::string GetString(const KeyType& key,
59                        const std::string& default_value) const;
60  base::string16 GetString16(const KeyType& key) const;
61  base::string16 GetString16(const KeyType& key,
62                             const base::string16& default_value) const;
63  StringList GetStringList(const KeyType& key) const;
64  StringList GetStringList(const KeyType& key,
65                           const StringList& default_value) const;
66  String16List GetString16List(const KeyType& key) const;
67  String16List GetString16List(const KeyType& key,
68                               const String16List& default_value) const;
69
70  // Returns true if context has |key|.
71  bool HasKey(const KeyType& key) const;
72
73  // Returns true if there was changes since last call to
74  // GetChangesAndReset().
75  bool HasChanges() const;
76
77  // Stores all changes since the last call to the
78  // GetChangesAndReset() in |diff|.  All previous contents of |diff|
79  // will be thrown away.
80  void GetChangesAndReset(base::DictionaryValue* diff);
81
82  // Applies changes from |diff| to the context. All keys from |diff|
83  // are stored in |keys|. |keys| argument is optional and can be NULL.
84  void ApplyChanges(const base::DictionaryValue& diff,
85                    std::vector<std::string>* keys);
86
87  // Returns underlying dictionary containing all the stored data.
88  const base::DictionaryValue& storage() const { return storage_; }
89
90 private:
91  bool Set(const KeyType& key, base::Value* value);
92
93  template <typename T>
94  T Get(const KeyType& key) const {
95    DCHECK(CalledOnValidThread());
96    const base::Value* value;
97    bool has_key = storage_.Get(key, &value);
98    DCHECK(has_key);
99    T result;
100    if (!ParseValue(value, &result)) {
101      NOTREACHED();
102      return T();
103    }
104    return result;
105  }
106
107  template <typename T>
108  T Get(const KeyType& key, const T& default_value) const {
109    DCHECK(CalledOnValidThread());
110    if (!HasKey(key))
111      return default_value;
112    return Get<T>(key);
113  }
114
115  // Contains current state of <key, value> map.
116  base::DictionaryValue storage_;
117
118  // Contains all pending changes.
119  base::DictionaryValue changes_;
120
121  DISALLOW_COPY_AND_ASSIGN(ScreenContext);
122};
123
124}  // namespace chromeos
125
126#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_SCREEN_CONTEXT_H_
127