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source: code/trunk/src/libraries/util/Scope.h @ 8324

Last change on this file since 8324 was 7401, checked in by landauf, 14 years ago

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1/*
2 *   ORXONOX - the hottest 3D action shooter ever to exist
3 *                    > www.orxonox.net <
4 *
5 *
6 *   License notice:
7 *
8 *   This program is free software; you can redistribute it and/or
9 *   modify it under the terms of the GNU General Public License
10 *   as published by the Free Software Foundation; either version 2
11 *   of the License, or (at your option) any later version.
12 *
13 *   This program is distributed in the hope that it will be useful,
14 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 *   GNU General Public License for more details.
17 *
18 *   You should have received a copy of the GNU General Public License
19 *   along with this program; if not, write to the Free Software
20 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
21 *
22 *   Author:
23 *      Fabian 'x3n' Landau
24 *   Co-authors:
25 *      ...
26 *
27 */
28
29/**
30@file
31@ingroup SingletonScope
32@brief Declaration of the classes that are needed to use Scopes:
33orxonox::Scope, orxonox::ScopeListener, and orxonox::ScopeManager.
34
35@anchor Scope
36
37A virtual scope can be represented by an instance of class orxonox::Scope. orxonox::Scope<@a scope> is a template
38an its template argument defines the name of the virtual scope. See orxonox::ScopeID for an enumeration of the
39available values for @a scope. The orxonox::Scope object for a given @a scope can be activated or deactivated.
40Instances of orxonox::ScopeListener can register for a given @a scope and will get a notification if the
41corresponding orxonox::Scope object changes its state.
42
43To avoid multiple instances of orxonox::Scope<@a scope> in different libraries, each instance of orxonox::Scope
44registers in orxonox::ScopeManager, where they are linked statically in the util library.
45
46Scopes are usually used to control the creation and destruction of Singletons.
47
48@see orxonox::ScopedSingletonManager
49@see orxonox::Singleton
50*/
51
52#ifndef __Util_Scope_H__
53#define __Util_Scope_H__
54
55#include "UtilPrereqs.h"
56
57#include <cassert>
58#include <map>
59#include <set>
60#include <loki/ScopeGuard.h>
61
62#include "Debug.h"
63
64namespace orxonox
65{
66    /**
67        @brief The ScopeManager stores the variables of the Scope templates in a statically linked context.
68
69        If all Scope objects are managed by this class, they are statically linked in the util library.
70        Without this, a new instance of Scope<T> for each T would be created in every library of Orxonox,
71        which is of course not the desired behavior.
72
73        @see See @ref Scope "this description" for details about the interrelationship of Scope, ScopeListener, and ScopeManager.
74    */
75    class _UtilExport ScopeManager
76    {
77        template <ScopeID::Value scope>
78        friend class Scope;
79        friend class ScopeListener;
80
81        private:
82            static std::map<ScopeID::Value, int> instanceCounts_s;                  //!< Counts the number of active instances (>0 means active) for a scope
83            static std::map<ScopeID::Value, std::set<ScopeListener*> > listeners_s; //!< Stores all listeners for a scope
84    };
85
86    /**
87        @brief ScopeListeners register themselves in the corresponding Scope and wait for notifications.
88        Notifications are sent if a Scope is activated or deactivated.
89
90        @see See @ref Scope "this description" for details about the interrelationship of Scope, ScopeListener, and ScopeManager.
91    */
92    class _UtilExport ScopeListener
93    {
94        template <ScopeID::Value scope>
95        friend class Scope;
96
97        protected:
98            //! Constructor: Registers the instance.
99            ScopeListener(ScopeID::Value scope) : scope_(scope), bActivated_(false)
100                { ScopeManager::listeners_s[this->scope_].insert(this); }
101            //! Destructor: Unregisters the instance.
102            virtual ~ScopeListener()
103                { ScopeManager::listeners_s[this->scope_].erase(this); }
104
105            //! Gets called if the scope is activated
106            virtual void activated() = 0;
107            //! Gets called if the scope is deactivated
108            virtual void deactivated() = 0;
109
110        private:
111            ScopeID::Value scope_; //!< Store the scope to unregister on destruction
112            bool bActivated_;
113    };
114
115    /**
116        @brief A scope for a given template argument is either active or not.
117
118        Objects inheriting from a ScopeListener are registered in a list (different for each scope).
119        If the scope gets activated or deactivated, all objects in this list are notified.
120
121        @see See @ref Scope "this description" for details about the interrelationship of Scope, ScopeListener, and ScopeManager.
122    */
123    template <ScopeID::Value scope>
124    class Scope
125    {
126        public:
127            //! Constructor: Increases the instance counter and activates the scope if the count went from 0 to 1. Counts >1 don't change anything.
128            Scope()
129            {
130                try
131                {
132                    ScopeManager::instanceCounts_s[scope]++;
133                    assert(ScopeManager::instanceCounts_s[scope] > 0);
134                    if (ScopeManager::instanceCounts_s[scope] == 1)
135                    {
136                        Loki::ScopeGuard deactivator = Loki::MakeObjGuard(*this, &Scope::deactivateListeners);
137                        for (typename std::set<ScopeListener*>::iterator it = ScopeManager::listeners_s[scope].begin(); it != ScopeManager::listeners_s[scope].end(); )
138                        {
139                            (*it)->activated();
140                            (*(it++))->bActivated_ = true;
141                        }
142                        deactivator.Dismiss();
143                    }
144                }
145                catch (...)
146                {
147                    ScopeManager::instanceCounts_s[scope]--;
148                    throw;
149                }
150            }
151
152            //! Destructor: Decreases the instance counter and deactivates the scope if the count went from 1 to 0. Counts >0 don't change anything.
153            ~Scope()
154            {
155                ScopeManager::instanceCounts_s[scope]--;
156
157                // This shouldn't happen but just to be sure: check if the count is positive
158                assert(ScopeManager::instanceCounts_s[scope] >= 0);
159                if (ScopeManager::instanceCounts_s[scope] < 0)
160                    ScopeManager::instanceCounts_s[scope] = 0;
161
162                if (ScopeManager::instanceCounts_s[scope] == 0)
163                    this->deactivateListeners();
164            }
165
166            //! Deactivates the listeners of this scope in case the scope is destroyed or the construction fails.
167            void deactivateListeners()
168            {
169                for (typename std::set<ScopeListener*>::iterator it = ScopeManager::listeners_s[scope].begin(); it != ScopeManager::listeners_s[scope].end(); )
170                {
171                    if ((*it)->bActivated_)
172                    {
173                        try
174                            { (*it)->deactivated(); }
175                        catch (...)
176                            { COUT(0) << "ScopeListener::deactivated() failed! This MUST NOT happen, fix it!" << std::endl; }
177                        (*(it++))->bActivated_ = false;
178                    }
179                    else
180                        ++it;
181                }
182            }
183
184            //! Returns true if the scope is active.
185            static bool isActive()
186            {
187                return (ScopeManager::instanceCounts_s[scope] > 0);
188            }
189    };
190}
191
192#endif /* __Util_Scope_H__ */
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