120 lines
3.1 KiB
C++
120 lines
3.1 KiB
C++
/* Observers
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Copyright (C) 2016-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#if !defined (GDB_COMMON_OBSERVABLE_H)
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#define GDB_COMMON_OBSERVABLE_H
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#include <algorithm>
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#include <functional>
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#include <vector>
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namespace gdb
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{
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namespace observers
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{
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extern unsigned int observer_debug;
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/* An observer is an entity which is interested in being notified
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when GDB reaches certain states, or certain events occur in GDB.
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The entity being observed is called the observable. To receive
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notifications, the observer attaches a callback to the observable.
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One observable can have several observers.
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The observer implementation is also currently not reentrant. In
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particular, it is therefore not possible to call the attach or
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detach routines during a notification. */
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/* The type of a key that can be passed to attach, which can be passed
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to detach to remove associated observers. Tokens have address
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identity, and are thus usually const globals. */
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struct token
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{
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token () = default;
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DISABLE_COPY_AND_ASSIGN (token);
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};
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template<typename... T>
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class observable
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{
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public:
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typedef std::function<void (T...)> func_type;
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explicit observable (const char *name)
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: m_name (name)
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{
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}
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DISABLE_COPY_AND_ASSIGN (observable);
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/* Attach F as an observer to this observable. F cannot be
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detached. */
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void attach (const func_type &f)
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{
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m_observers.emplace_back (nullptr, f);
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}
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/* Attach F as an observer to this observable. T is a reference to
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a token that can be used to later remove F. */
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void attach (const func_type &f, const token &t)
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{
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m_observers.emplace_back (&t, f);
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}
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/* Remove observers associated with T from this observable. T is
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the token that was previously passed to any number of "attach"
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calls. */
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void detach (const token &t)
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{
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auto iter = std::remove_if (m_observers.begin (),
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m_observers.end (),
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[&] (const std::pair<const token *,
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func_type> &e)
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{
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return e.first == &t;
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});
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m_observers.erase (iter, m_observers.end ());
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}
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/* Notify all observers that are attached to this observable. */
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void notify (T... args) const
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{
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if (observer_debug)
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fprintf_unfiltered (gdb_stdlog, "observable %s notify() called\n",
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m_name);
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for (auto &&e : m_observers)
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e.second (args...);
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}
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private:
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std::vector<std::pair<const token *, func_type>> m_observers;
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const char *m_name;
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};
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} /* namespace observers */
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} /* namespace gdb */
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#endif /* GDB_COMMON_OBSERVABLE_H */
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