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76727919 TT |
1 | /* Observers |
2 | ||
42a4f53d | 3 | Copyright (C) 2016-2019 Free Software Foundation, Inc. |
76727919 TT |
4 | |
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
19 | ||
20 | #if !defined (GDB_COMMON_OBSERVABLE_H) | |
21 | #define GDB_COMMON_OBSERVABLE_H | |
22 | ||
23 | #include <algorithm> | |
24 | #include <functional> | |
25 | #include <vector> | |
26 | ||
27 | namespace gdb | |
28 | { | |
29 | ||
30 | namespace observers | |
31 | { | |
32 | ||
33 | extern unsigned int observer_debug; | |
34 | ||
35 | /* An observer is an entity which is interested in being notified | |
36 | when GDB reaches certain states, or certain events occur in GDB. | |
37 | The entity being observed is called the observable. To receive | |
38 | notifications, the observer attaches a callback to the observable. | |
39 | One observable can have several observers. | |
40 | ||
41 | The observer implementation is also currently not reentrant. In | |
42 | particular, it is therefore not possible to call the attach or | |
43 | detach routines during a notification. */ | |
44 | ||
45 | /* The type of a key that can be passed to attach, which can be passed | |
46 | to detach to remove associated observers. Tokens have address | |
47 | identity, and are thus usually const globals. */ | |
48 | struct token | |
49 | { | |
50 | token () = default; | |
51 | ||
52 | DISABLE_COPY_AND_ASSIGN (token); | |
53 | }; | |
54 | ||
55 | template<typename... T> | |
56 | class observable | |
57 | { | |
58 | public: | |
59 | ||
60 | typedef std::function<void (T...)> func_type; | |
61 | ||
62 | explicit observable (const char *name) | |
63 | : m_name (name) | |
64 | { | |
65 | } | |
66 | ||
67 | DISABLE_COPY_AND_ASSIGN (observable); | |
68 | ||
69 | /* Attach F as an observer to this observable. F cannot be | |
70 | detached. */ | |
71 | void attach (const func_type &f) | |
72 | { | |
73 | m_observers.emplace_back (nullptr, f); | |
74 | } | |
75 | ||
76 | /* Attach F as an observer to this observable. T is a reference to | |
77 | a token that can be used to later remove F. */ | |
78 | void attach (const func_type &f, const token &t) | |
79 | { | |
80 | m_observers.emplace_back (&t, f); | |
81 | } | |
82 | ||
83 | /* Remove observers associated with T from this observable. T is | |
84 | the token that was previously passed to any number of "attach" | |
85 | calls. */ | |
86 | void detach (const token &t) | |
87 | { | |
88 | auto iter = std::remove_if (m_observers.begin (), | |
89 | m_observers.end (), | |
90 | [&] (const std::pair<const token *, | |
91 | func_type> &e) | |
92 | { | |
93 | return e.first == &t; | |
94 | }); | |
95 | ||
96 | m_observers.erase (iter, m_observers.end ()); | |
97 | } | |
98 | ||
99 | /* Notify all observers that are attached to this observable. */ | |
100 | void notify (T... args) const | |
101 | { | |
102 | if (observer_debug) | |
103 | fprintf_unfiltered (gdb_stdlog, "observable %s notify() called\n", | |
104 | m_name); | |
105 | for (auto &&e : m_observers) | |
106 | e.second (args...); | |
107 | } | |
108 | ||
109 | private: | |
110 | ||
111 | std::vector<std::pair<const token *, func_type>> m_observers; | |
112 | const char *m_name; | |
113 | }; | |
114 | ||
115 | } /* namespace observers */ | |
116 | ||
117 | } /* namespace gdb */ | |
118 | ||
119 | #endif /* GDB_COMMON_OBSERVABLE_H */ |