wxWidgets/include/wx/scopeguard.h
Francesco Montorsi 22c5cac637 fix typo (missing P2 argument in template)
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56197 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
2008-10-09 14:23:06 +00:00

569 lines
16 KiB
C++

///////////////////////////////////////////////////////////////////////////////
// Name: wx/scopeguard.h
// Purpose: declares wxwxScopeGuard and related macros
// Author: Vadim Zeitlin
// Modified by:
// Created: 03.07.2003
// RCS-ID: $Id$
// Copyright: (c) 2003 Vadim Zeitlin <vadim@wxwidgets.org>
// Licence: wxWindows licence
///////////////////////////////////////////////////////////////////////////////
/*
Acknowledgements: this header is heavily based on (well, almost the exact
copy of) ScopeGuard.h by Andrei Alexandrescu and Petru Marginean published
in December 2000 issue of C/C++ Users Journal.
http://www.cuj.com/documents/cujcexp1812alexandr/
*/
#ifndef _WX_SCOPEGUARD_H_
#define _WX_SCOPEGUARD_H_
#include "wx/defs.h"
#include "wx/except.h"
// ----------------------------------------------------------------------------
// helpers
// ----------------------------------------------------------------------------
#ifdef __WATCOMC__
// WATCOM-FIXME: C++ of Open Watcom 1.3 doesn't like OnScopeExit() created
// through template so it must be workarounded with dedicated inlined macro.
// For compatibility with Watcom compilers wxPrivate::OnScopeExit must be
// replaced with wxPrivateOnScopeExit but in user code (for everyone who
// doesn't care about OW compatibility) wxPrivate::OnScopeExit still works.
#define wxPrivateOnScopeExit(guard) \
{ \
if ( !(guard).WasDismissed() ) \
{ \
wxTRY \
{ \
(guard).Execute(); \
} \
wxCATCH_ALL(;) \
} \
}
#define wxPrivateUse(n) wxUnusedVar(n)
#else
// namespace support was first implemented in gcc-2.95,
// so avoid using it for older versions.
#if !defined(__GNUC__) || wxCHECK_GCC_VERSION(2, 95)
#define wxHAS_NAMESPACES
namespace wxPrivate
{
#else
#define wxPrivate
#endif
// in the original implementation this was a member template function of
// ScopeGuardImplBase but gcc 2.8 which is still used for OS/2 doesn't
// support member templates and so we must make it global
template <class ScopeGuardImpl>
void OnScopeExit(ScopeGuardImpl& guard)
{
if ( !guard.WasDismissed() )
{
// we're called from ScopeGuardImpl dtor and so we must not throw
wxTRY
{
guard.Execute();
}
wxCATCH_ALL(;) // do nothing, just eat the exception
}
}
// just to avoid the warning about unused variables
template <class T>
void Use(const T& WXUNUSED(t))
{
}
#if !defined(__GNUC__) || wxCHECK_GCC_VERSION(2, 95)
} // namespace wxPrivate
#endif
#define wxPrivateOnScopeExit(n) wxPrivate::OnScopeExit(n)
#define wxPrivateUse(n) wxPrivate::Use(n)
#endif
// ============================================================================
// wxScopeGuard for functions and functors
// ============================================================================
// ----------------------------------------------------------------------------
// wxScopeGuardImplBase: used by wxScopeGuardImpl[0..N] below
// ----------------------------------------------------------------------------
class wxScopeGuardImplBase
{
public:
wxScopeGuardImplBase() : m_wasDismissed(false) { }
wxScopeGuardImplBase(const wxScopeGuardImplBase& other)
: m_wasDismissed(other.m_wasDismissed)
{
other.Dismiss();
}
void Dismiss() const { m_wasDismissed = true; }
// for OnScopeExit() only (we can't make it friend, unfortunately)!
bool WasDismissed() const { return m_wasDismissed; }
protected:
~wxScopeGuardImplBase() { }
// must be mutable for copy ctor to work
mutable bool m_wasDismissed;
private:
wxScopeGuardImplBase& operator=(const wxScopeGuardImplBase&);
};
// wxScopeGuard is just a reference, see the explanation in CUJ article
typedef const wxScopeGuardImplBase& wxScopeGuard;
// ----------------------------------------------------------------------------
// wxScopeGuardImpl0: scope guard for actions without parameters
// ----------------------------------------------------------------------------
template <class F>
class wxScopeGuardImpl0 : public wxScopeGuardImplBase
{
public:
static wxScopeGuardImpl0<F> MakeGuard(F fun)
{
return wxScopeGuardImpl0<F>(fun);
}
~wxScopeGuardImpl0() { wxPrivateOnScopeExit(*this); }
void Execute() { m_fun(); }
protected:
wxScopeGuardImpl0(F fun) : m_fun(fun) { }
F m_fun;
wxScopeGuardImpl0& operator=(const wxScopeGuardImpl0&);
};
template <class F>
inline wxScopeGuardImpl0<F> wxMakeGuard(F fun)
{
return wxScopeGuardImpl0<F>::MakeGuard(fun);
}
// ----------------------------------------------------------------------------
// wxScopeGuardImpl1: scope guard for actions with 1 parameter
// ----------------------------------------------------------------------------
template <class F, class P1>
class wxScopeGuardImpl1 : public wxScopeGuardImplBase
{
public:
static wxScopeGuardImpl1<F, P1> MakeGuard(F fun, P1 p1)
{
return wxScopeGuardImpl1<F, P1>(fun, p1);
}
~wxScopeGuardImpl1() { wxPrivateOnScopeExit(* this); }
void Execute() { m_fun(m_p1); }
protected:
wxScopeGuardImpl1(F fun, P1 p1) : m_fun(fun), m_p1(p1) { }
F m_fun;
const P1 m_p1;
wxScopeGuardImpl1& operator=(const wxScopeGuardImpl1&);
};
template <class F, class P1>
inline wxScopeGuardImpl1<F, P1> wxMakeGuard(F fun, P1 p1)
{
return wxScopeGuardImpl1<F, P1>::MakeGuard(fun, p1);
}
// ----------------------------------------------------------------------------
// wxScopeGuardImpl2: scope guard for actions with 2 parameters
// ----------------------------------------------------------------------------
template <class F, class P1, class P2>
class wxScopeGuardImpl2 : public wxScopeGuardImplBase
{
public:
static wxScopeGuardImpl2<F, P1, P2> MakeGuard(F fun, P1 p1, P2 p2)
{
return wxScopeGuardImpl2<F, P1, P2>(fun, p1, p2);
}
~wxScopeGuardImpl2() { wxPrivateOnScopeExit(*this); }
void Execute() { m_fun(m_p1, m_p2); }
protected:
wxScopeGuardImpl2(F fun, P1 p1, P2 p2) : m_fun(fun), m_p1(p1), m_p2(p2) { }
F m_fun;
const P1 m_p1;
const P2 m_p2;
wxScopeGuardImpl2& operator=(const wxScopeGuardImpl2&);
};
template <class F, class P1, class P2>
inline wxScopeGuardImpl2<F, P1, P2> wxMakeGuard(F fun, P1 p1, P2 p2)
{
return wxScopeGuardImpl2<F, P1, P2>::MakeGuard(fun, p1, p2);
}
// ----------------------------------------------------------------------------
// wxScopeGuardImpl3: scope guard for actions with 3 parameters
// ----------------------------------------------------------------------------
template <class F, class P1, class P2, class P3>
class wxScopeGuardImpl3 : public wxScopeGuardImplBase
{
public:
static wxScopeGuardImpl3<F, P1, P2, P3> MakeGuard(F fun, P1 p1, P2 p2, P3 p3)
{
return wxScopeGuardImpl3<F, P1, P2, P3>(fun, p1, p2, p3);
}
~wxScopeGuardImpl3() { wxPrivateOnScopeExit(*this); }
void Execute() { m_fun(m_p1, m_p2, m_p3); }
protected:
wxScopeGuardImpl3(F fun, P1 p1, P2 p2, P3 p3)
: m_fun(fun), m_p1(p1), m_p2(p2), m_p3(p3) { }
F m_fun;
const P1 m_p1;
const P2 m_p2;
const P3 m_p3;
wxScopeGuardImpl3& operator=(const wxScopeGuardImpl3&);
};
template <class F, class P1, class P2, class P3>
inline wxScopeGuardImpl3<F, P1, P2, P3> wxMakeGuard(F fun, P1 p1, P2 p2, P3 p3)
{
return wxScopeGuardImpl3<F, P1, P2, P3>::MakeGuard(fun, p1, p2, p3);
}
// ============================================================================
// wxScopeGuards for object methods
// ============================================================================
// ----------------------------------------------------------------------------
// wxObjScopeGuardImpl0
// ----------------------------------------------------------------------------
template <class Obj, class MemFun>
class wxObjScopeGuardImpl0 : public wxScopeGuardImplBase
{
public:
static wxObjScopeGuardImpl0<Obj, MemFun>
MakeObjGuard(Obj& obj, MemFun memFun)
{
return wxObjScopeGuardImpl0<Obj, MemFun>(obj, memFun);
}
~wxObjScopeGuardImpl0() { wxPrivateOnScopeExit(*this); }
void Execute() { (m_obj.*m_memfun)(); }
protected:
wxObjScopeGuardImpl0(Obj& obj, MemFun memFun)
: m_obj(obj), m_memfun(memFun) { }
Obj& m_obj;
MemFun m_memfun;
};
template <class Obj, class MemFun>
inline wxObjScopeGuardImpl0<Obj, MemFun> wxMakeObjGuard(Obj& obj, MemFun memFun)
{
return wxObjScopeGuardImpl0<Obj, MemFun>::MakeObjGuard(obj, memFun);
}
template <class Obj, class MemFun, class P1>
class wxObjScopeGuardImpl1 : public wxScopeGuardImplBase
{
public:
static wxObjScopeGuardImpl1<Obj, MemFun, P1>
MakeObjGuard(Obj& obj, MemFun memFun, P1 p1)
{
return wxObjScopeGuardImpl1<Obj, MemFun, P1>(obj, memFun, p1);
}
~wxObjScopeGuardImpl1() { wxPrivateOnScopeExit(*this); }
void Execute() { (m_obj.*m_memfun)(m_p1); }
protected:
wxObjScopeGuardImpl1(Obj& obj, MemFun memFun, P1 p1)
: m_obj(obj), m_memfun(memFun), m_p1(p1) { }
Obj& m_obj;
MemFun m_memfun;
const P1 m_p1;
};
template <class Obj, class MemFun, class P1>
inline wxObjScopeGuardImpl1<Obj, MemFun, P1>
wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1)
{
return wxObjScopeGuardImpl1<Obj, MemFun, P1>::MakeObjGuard(obj, memFun, p1);
}
template <class Obj, class MemFun, class P1, class P2>
class wxObjScopeGuardImpl2 : public wxScopeGuardImplBase
{
public:
static wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>
MakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2)
{
return wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>(obj, memFun, p1, p2);
}
~wxObjScopeGuardImpl2() { wxPrivateOnScopeExit(*this); }
void Execute() { (m_obj.*m_memfun)(m_p1, m_p2); }
protected:
wxObjScopeGuardImpl2(Obj& obj, MemFun memFun, P1 p1, P2 p2)
: m_obj(obj), m_memfun(memFun), m_p1(p1), m_p2(p2) { }
Obj& m_obj;
MemFun m_memfun;
const P1 m_p1;
const P2 m_p2;
};
template <class Obj, class MemFun, class P1, class P2>
inline wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>
wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2)
{
return wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>::
MakeObjGuard(obj, memFun, p1, p2);
}
template <class Obj, class MemFun, class P1, class P2, class P3>
class wxObjScopeGuardImpl3 : public wxScopeGuardImplBase
{
public:
static wxObjScopeGuardImpl3<Obj, MemFun, P1, P2, P3>
MakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2, P3 p3)
{
return wxObjScopeGuardImpl3<Obj, MemFun, P1, P2, P3>(obj, memFun, p1, p2, p3);
}
~wxObjScopeGuardImpl3() { wxPrivateOnScopeExit(*this); }
void Execute() { (m_obj.*m_memfun)(m_p1, m_p2, m_p3); }
protected:
wxObjScopeGuardImpl3(Obj& obj, MemFun memFun, P1 p1, P2 p2, P3 p3)
: m_obj(obj), m_memfun(memFun), m_p1(p1), m_p2(p2), m_p3(p3) { }
Obj& m_obj;
MemFun m_memfun;
const P1 m_p1;
const P2 m_p2;
const P3 m_p3;
};
template <class Obj, class MemFun, class P1, class P2, class P3>
inline wxObjScopeGuardImpl3<Obj, MemFun, P1, P2, P3>
wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2, P3 p3)
{
return wxObjScopeGuardImpl3<Obj, MemFun, P1, P2, P3>::
MakeObjGuard(obj, memFun, p1, p2, p3);
}
// ----------------------------------------------------------------------------
// wxVariableSetter: use the same technique as for wxScopeGuard to allow
// setting a variable to some value on block exit
// ----------------------------------------------------------------------------
#ifdef wxHAS_NAMESPACES
namespace wxPrivate
{
// empty class just to be able to define a reference to it
class VariableSetterBase { };
typedef const VariableSetterBase& VariableSetter;
template <typename T, typename U>
class VariableSetterImpl : public VariableSetterBase
{
public:
VariableSetterImpl(T& var, const U& value)
: m_var(var),
m_value(value)
{
}
~VariableSetterImpl()
{
m_var = m_value;
}
private:
T& m_var;
const U& m_value;
// suppress the warning about assignment operator not being generated
VariableSetterImpl<T, U>& operator=(const VariableSetterImpl<T, U>&);
};
template <typename T>
class VariableNullerImpl : public VariableSetterBase
{
public:
VariableNullerImpl(T& var)
: m_var(var)
{
}
~VariableNullerImpl()
{
m_var = NULL;
}
private:
T& m_var;
VariableNullerImpl<T>& operator=(const VariableNullerImpl<T>&);
};
} // namespace wxPrivate
template <typename T, typename U>
inline
wxPrivate::VariableSetterImpl<T, U> wxMakeVarSetter(T& var, const U& value)
{
return wxPrivate::VariableSetterImpl<T, U>(var, value);
}
// calling wxMakeVarSetter(ptr, NULL) doesn't work because U is deduced to be
// "int" and subsequent assignment of "U" to "T *" fails, so provide a special
// function for this special case
template <typename T>
inline
wxPrivate::VariableNullerImpl<T> wxMakeVarNuller(T& var)
{
return wxPrivate::VariableNullerImpl<T>(var);
}
#endif // wxHAS_NAMESPACES
// ============================================================================
// macros for declaring unnamed scoped guards (which can't be dismissed)
// ============================================================================
// NB: the original code has a single (and much nicer) ON_BLOCK_EXIT macro
// but this results in compiler warnings about unused variables and I
// didn't find a way to work around this other than by having different
// macros with different names or using a less natural syntax for passing
// the arguments (e.g. as Boost preprocessor sequences, which would mean
// having to write wxON_BLOCK_EXIT(fwrite, (buf)(size)(n)(fp)) instead of
// wxON_BLOCK_EXIT4(fwrite, buf, size, n, fp)).
#define wxGuardName wxMAKE_UNIQUE_NAME(wxScopeGuard)
#define wxON_BLOCK_EXIT0_IMPL(n, f) \
wxScopeGuard n = wxMakeGuard(f); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT0(f) \
wxON_BLOCK_EXIT0_IMPL(wxGuardName, f)
#define wxON_BLOCK_EXIT_OBJ0_IMPL(n, o, m) \
wxScopeGuard n = wxMakeObjGuard(o, m); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT_OBJ0(o, m) \
wxON_BLOCK_EXIT_OBJ0_IMPL(wxGuardName, o, &m)
#define wxON_BLOCK_EXIT_THIS0(m) \
wxON_BLOCK_EXIT_OBJ0(*this, m)
#define wxON_BLOCK_EXIT1_IMPL(n, f, p1) \
wxScopeGuard n = wxMakeGuard(f, p1); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT1(f, p1) \
wxON_BLOCK_EXIT1_IMPL(wxGuardName, f, p1)
#define wxON_BLOCK_EXIT_OBJ1_IMPL(n, o, m, p1) \
wxScopeGuard n = wxMakeObjGuard(o, m, p1); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT_OBJ1(o, m, p1) \
wxON_BLOCK_EXIT_OBJ1_IMPL(wxGuardName, o, &m, p1)
#define wxON_BLOCK_EXIT_THIS1(m, p1) \
wxON_BLOCK_EXIT_OBJ1(*this, m, p1)
#define wxON_BLOCK_EXIT2_IMPL(n, f, p1, p2) \
wxScopeGuard n = wxMakeGuard(f, p1, p2); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT2(f, p1, p2) \
wxON_BLOCK_EXIT2_IMPL(wxGuardName, f, p1, p2)
#define wxON_BLOCK_EXIT_OBJ2_IMPL(n, o, m, p1, p2) \
wxScopeGuard n = wxMakeObjGuard(o, m, p1, p2); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT_OBJ2(o, m, p1, p2) \
wxON_BLOCK_EXIT_OBJ2_IMPL(wxGuardName, o, &m, p1, p2)
#define wxON_BLOCK_EXIT_THIS2(m, p1, p2) \
wxON_BLOCK_EXIT_OBJ2(*this, m, p1, p2)
#define wxON_BLOCK_EXIT3_IMPL(n, f, p1, p2, p3) \
wxScopeGuard n = wxMakeGuard(f, p1, p2, p3); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT3(f, p1, p2, p3) \
wxON_BLOCK_EXIT3_IMPL(wxGuardName, f, p1, p2, p3)
#define wxON_BLOCK_EXIT_OBJ3_IMPL(n, o, m, p1, p2, p3) \
wxScopeGuard n = wxMakeObjGuard(o, m, p1, p2, p3); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT_OBJ3(o, m, p1, p2, p3) \
wxON_BLOCK_EXIT_OBJ3_IMPL(wxGuardName, o, &m, p1, p2, p3)
#define wxON_BLOCK_EXIT_THIS3(m, p1, p2, p3) \
wxON_BLOCK_EXIT_OBJ3(*this, m, p1, p2, p3)
#define wxSetterName wxMAKE_UNIQUE_NAME(wxVarSetter)
#define wxON_BLOCK_EXIT_SET_IMPL(n, var, value) \
wxPrivate::VariableSetter n = wxMakeVarSetter(var, value); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT_SET(var, value) \
wxON_BLOCK_EXIT_SET_IMPL(wxSetterName, var, value)
#define wxON_BLOCK_EXIT_NULL_IMPL(n, var) \
wxPrivate::VariableSetter n = wxMakeVarNuller(var); \
wxPrivateUse(n)
#define wxON_BLOCK_EXIT_NULL(ptr) \
wxON_BLOCK_EXIT_NULL_IMPL(wxSetterName, ptr)
#endif // _WX_SCOPEGUARD_H_