ScopeGuard.h

/* -*- mode: c++; indent-tabs-mode: nil -*- */

/* The Loki Library
   Copyright (c) 2000 Andrei Alexandrescu
   Copyright (c) 2000 Petru Marginean
   Copyright (c) 2005 Joshua Lehrer
  
   Permission to use, copy, modify, distribute and sell this software for any 
       purpose is hereby granted without fee, provided that the above copyright 
       notice appear in all copies and that both that copyright notice and this 
       permission notice appear in supporting documentation.
   The author makes no representations about the 
       suitability of this software for any purpose. It is provided "as is" 
       without express or implied warranty.
*/

#ifndef SCOPEGUARD_H_
#define SCOPEGUARD_H_

template <class T>
class RefHolder
{
    T& ref_;
public:
    RefHolder(T& ref) : ref_(ref) {}
    operator T& () const 
    {
        return ref_;
    }
private:
    // Disable assignment - not implemented
    RefHolder& operator=(const RefHolder&);
};

template <class T>
inline RefHolder<T> ByRef(T& t)
{
    return RefHolder<T>(t);
}

class ScopeGuardImplBase
{
    ScopeGuardImplBase& operator =(const ScopeGuardImplBase&);
protected:
    ~ScopeGuardImplBase()
    {
    }
public:
    ScopeGuardImplBase(const ScopeGuardImplBase& other) throw() 
        : dismissed_(other.dismissed_)
    {
        other.Dismiss();
    }
protected:
    template <typename J>
    static void SafeExecute(J& j) throw() 
    {
        if (!j.dismissed_)
            try
            {
                j.Execute();
            }
            catch(...)
            {
            }
    }
    
    mutable bool dismissed_;
public:
    ScopeGuardImplBase() throw() : dismissed_(false) 
    {
    }
    void Dismiss() const throw() 
    {
        dismissed_ = true;
    }
};

typedef const ScopeGuardImplBase& ScopeGuard;

template <typename F>
class ScopeGuardImpl0 : public ScopeGuardImplBase
{
public:
    static ScopeGuardImpl0<F> MakeGuard(F fun)
    {
        return ScopeGuardImpl0<F>(fun);
    }
    ~ScopeGuardImpl0() throw() 
    {
        SafeExecute(*this);
    }
    void Execute() 
    {
        fun_();
    }
protected:
    ScopeGuardImpl0(F fun) : fun_(fun) 
    {
    }
    F fun_;
};

template <typename F> 
inline ScopeGuardImpl0<F> MakeGuard(F fun)
{
    return ScopeGuardImpl0<F>::MakeGuard(fun);
}

template <typename F, typename P1>
class ScopeGuardImpl1 : public ScopeGuardImplBase
{
public:
    static ScopeGuardImpl1<F, P1> MakeGuard(F fun, P1 p1)
    {
        return ScopeGuardImpl1<F, P1>(fun, p1);
    }
    ~ScopeGuardImpl1() throw() 
    {
        SafeExecute(*this);
    }
    void Execute()
    {
        fun_(p1_);
    }
protected:
    ScopeGuardImpl1(F fun, P1 p1) : fun_(fun), p1_(p1) 
    {
    }
    F fun_;
    const P1 p1_;
};

template <typename F, typename P1> 
inline ScopeGuardImpl1<F, P1> MakeGuard(F fun, P1 p1)
{
    return ScopeGuardImpl1<F, P1>::MakeGuard(fun, p1);
}

template <typename F, typename P1, typename P2>
class ScopeGuardImpl2: public ScopeGuardImplBase
{
public:
    static ScopeGuardImpl2<F, P1, P2> MakeGuard(F fun, P1 p1, P2 p2)
    {
        return ScopeGuardImpl2<F, P1, P2>(fun, p1, p2);
    }
    ~ScopeGuardImpl2() throw() 
    {
        SafeExecute(*this);
    }
    void Execute()
    {
        fun_(p1_, p2_);
    }
protected:
    ScopeGuardImpl2(F fun, P1 p1, P2 p2) : fun_(fun), p1_(p1), p2_(p2) 
    {
    }
    F fun_;
    const P1 p1_;
    const P2 p2_;
};

template <typename F, typename P1, typename P2>
inline ScopeGuardImpl2<F, P1, P2> MakeGuard(F fun, P1 p1, P2 p2)
{
    return ScopeGuardImpl2<F, P1, P2>::MakeGuard(fun, p1, p2);
}

template <typename F, typename P1, typename P2, typename P3>
class ScopeGuardImpl3 : public ScopeGuardImplBase
{
public:
    static ScopeGuardImpl3<F, P1, P2, P3> MakeGuard(F fun, P1 p1, P2 p2, P3 p3)
    {
        return ScopeGuardImpl3<F, P1, P2, P3>(fun, p1, p2, p3);
    }
    ~ScopeGuardImpl3() throw() 
    {
        SafeExecute(*this);
    }
    void Execute()
    {
        fun_(p1_, p2_, p3_);
    }
protected:
    ScopeGuardImpl3(F fun, P1 p1, P2 p2, P3 p3) : fun_(fun), p1_(p1), p2_(p2), p3_(p3) 
    {
    }
    F fun_;
    const P1 p1_;
    const P2 p2_;
    const P3 p3_;
};

template <typename F, typename P1, typename P2, typename P3>
inline ScopeGuardImpl3<F, P1, P2, P3> MakeGuard(F fun, P1 p1, P2 p2, P3 p3)
{
    return ScopeGuardImpl3<F, P1, P2, P3>::MakeGuard(fun, p1, p2, p3);
}

//************************************************************

template <class Obj, typename MemFun>
class ObjScopeGuardImpl0 : public ScopeGuardImplBase
{
public:
    static ObjScopeGuardImpl0<Obj, MemFun> MakeObjGuard(Obj& obj, MemFun memFun)
    {
        return ObjScopeGuardImpl0<Obj, MemFun>(obj, memFun);
    }
    ~ObjScopeGuardImpl0() throw() 
    {
        SafeExecute(*this);
    }
    void Execute() 
    {
        (obj_.*memFun_)();
    }
protected:
    ObjScopeGuardImpl0(Obj& obj, MemFun memFun) 
        : obj_(obj), memFun_(memFun) {}
    Obj& obj_;
    MemFun memFun_;
};

template <class Obj, typename MemFun>
inline ObjScopeGuardImpl0<Obj, MemFun> MakeObjGuard(Obj& obj, MemFun memFun)
{
    return ObjScopeGuardImpl0<Obj, MemFun>::MakeObjGuard(obj, memFun);
}

template <class Obj, typename MemFun, typename P1>
class ObjScopeGuardImpl1 : public ScopeGuardImplBase
{
public:
    static ObjScopeGuardImpl1<Obj, MemFun, P1> MakeObjGuard(Obj& obj, MemFun memFun, P1 p1)
    {
        return ObjScopeGuardImpl1<Obj, MemFun, P1>(obj, memFun, p1);
    }
    ~ObjScopeGuardImpl1() throw() 
    {
        SafeExecute(*this);
    }
    void Execute() 
    {
        (obj_.*memFun_)(p1_);
    }
protected:
    ObjScopeGuardImpl1(Obj& obj, MemFun memFun, P1 p1) 
        : obj_(obj), memFun_(memFun), p1_(p1) {}
    Obj& obj_;
    MemFun memFun_;
    const P1 p1_;
};

template <class Obj, typename MemFun, typename P1>
inline ObjScopeGuardImpl1<Obj, MemFun, P1> MakeObjGuard(Obj& obj, MemFun memFun, P1 p1)
{
    return ObjScopeGuardImpl1<Obj, MemFun, P1>::MakeObjGuard(obj, memFun, p1);
}

template <class Obj, typename MemFun, typename P1, typename P2>
class ObjScopeGuardImpl2 : public ScopeGuardImplBase
{
public:
    static ObjScopeGuardImpl2<Obj, MemFun, P1, P2> MakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2)
    {
        return ObjScopeGuardImpl2<Obj, MemFun, P1, P2>(obj, memFun, p1, p2);
    }
    ~ObjScopeGuardImpl2() throw() 
    {
        SafeExecute(*this);
    }
    void Execute() 
    {
        (obj_.*memFun_)(p1_, p2_);
    }
protected:
    ObjScopeGuardImpl2(Obj& obj, MemFun memFun, P1 p1, P2 p2) 
        : obj_(obj), memFun_(memFun), p1_(p1), p2_(p2) {}
    Obj& obj_;
    MemFun memFun_;
    const P1 p1_;
    const P2 p2_;
};

template <class Obj, typename MemFun, typename P1, typename P2>
inline ObjScopeGuardImpl2<Obj, MemFun, P1, P2> MakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2)
{
    return ObjScopeGuardImpl2<Obj, MemFun, P1, P2>::MakeObjGuard(obj, memFun, p1, p2);
}

#define CONCATENATE_DIRECT(s1, s2) s1##s2
#define CONCATENATE(s1, s2) CONCATENATE_DIRECT(s1, s2)
#define ANONYMOUS_VARIABLE(str) CONCATENATE(str, __LINE__)

#ifdef __GNUC__
#  define UNUSED_VARIABLE __attribute__((unused))
#else
#  define UNUSED_VARIABLE
#endif

#define ON_BLOCK_EXIT ScopeGuard UNUSED_VARIABLE ANONYMOUS_VARIABLE(scopeGuard) = MakeGuard
#define ON_BLOCK_EXIT_OBJ ScopeGuard UNUSED_VARIABLE ANONYMOUS_VARIABLE(scopeGuard) = MakeObjGuard

#endif //SCOPEGUARD_H_