| 1 | /////////////////////////////////////////////////////////////////////////////// |
| 2 | // Name: wx/scopeguard.h |
| 3 | // Purpose: declares wxwxScopeGuard and related macros |
| 4 | // Author: Vadim Zeitlin |
| 5 | // Modified by: |
| 6 | // Created: 03.07.2003 |
| 7 | // RCS-ID: $Id$ |
| 8 | // Copyright: (c) 2003 Vadim Zeitlin <vadim@wxwidgets.org> |
| 9 | // Licence: wxWindows licence |
| 10 | /////////////////////////////////////////////////////////////////////////////// |
| 11 | |
| 12 | /* |
| 13 | Acknowledgements: this header is heavily based on (well, almost the exact |
| 14 | copy of) ScopeGuard.h by Andrei Alexandrescu and Petru Marginean published |
| 15 | in December 2000 issue of C/C++ Users Journal. |
| 16 | http://www.cuj.com/documents/cujcexp1812alexandr/ |
| 17 | */ |
| 18 | |
| 19 | #ifndef _WX_SCOPEGUARD_H_ |
| 20 | #define _WX_SCOPEGUARD_H_ |
| 21 | |
| 22 | #include "wx/defs.h" |
| 23 | |
| 24 | #include "wx/except.h" |
| 25 | |
| 26 | // ---------------------------------------------------------------------------- |
| 27 | // helpers |
| 28 | // ---------------------------------------------------------------------------- |
| 29 | |
| 30 | #ifdef __WATCOMC__ |
| 31 | |
| 32 | // WATCOM-FIXME: C++ of Open Watcom 1.3 doesn't like OnScopeExit() created |
| 33 | // through template so it must be workarounded with dedicated inlined macro. |
| 34 | // For compatibility with Watcom compilers wxPrivate::OnScopeExit must be |
| 35 | // replaced with wxPrivateOnScopeExit but in user code (for everyone who |
| 36 | // doesn't care about OW compatibility) wxPrivate::OnScopeExit still works. |
| 37 | |
| 38 | #define wxPrivateOnScopeExit(guard) \ |
| 39 | { \ |
| 40 | if ( !(guard).WasDismissed() ) \ |
| 41 | { \ |
| 42 | wxTRY \ |
| 43 | { \ |
| 44 | (guard).Execute(); \ |
| 45 | } \ |
| 46 | wxCATCH_ALL(;) \ |
| 47 | } \ |
| 48 | } |
| 49 | |
| 50 | #define wxPrivateUse(n) wxUnusedVar(n) |
| 51 | |
| 52 | #else |
| 53 | |
| 54 | // namespace support was first implemented in gcc-2.95, |
| 55 | // so avoid using it for older versions. |
| 56 | #if !defined(__GNUC__) || wxCHECK_GCC_VERSION(2, 95) |
| 57 | |
| 58 | #define wxHAS_NAMESPACES |
| 59 | |
| 60 | namespace wxPrivate |
| 61 | { |
| 62 | #else |
| 63 | #define wxPrivate |
| 64 | #endif |
| 65 | // in the original implementation this was a member template function of |
| 66 | // ScopeGuardImplBase but gcc 2.8 which is still used for OS/2 doesn't |
| 67 | // support member templates and so we must make it global |
| 68 | template <class ScopeGuardImpl> |
| 69 | void OnScopeExit(ScopeGuardImpl& guard) |
| 70 | { |
| 71 | if ( !guard.WasDismissed() ) |
| 72 | { |
| 73 | // we're called from ScopeGuardImpl dtor and so we must not throw |
| 74 | wxTRY |
| 75 | { |
| 76 | guard.Execute(); |
| 77 | } |
| 78 | wxCATCH_ALL(;) // do nothing, just eat the exception |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | // just to avoid the warning about unused variables |
| 83 | template <class T> |
| 84 | void Use(const T& WXUNUSED(t)) |
| 85 | { |
| 86 | } |
| 87 | #if !defined(__GNUC__) || wxCHECK_GCC_VERSION(2, 95) |
| 88 | } // namespace wxPrivate |
| 89 | #endif |
| 90 | |
| 91 | #define wxPrivateOnScopeExit(n) wxPrivate::OnScopeExit(n) |
| 92 | #define wxPrivateUse(n) wxPrivate::Use(n) |
| 93 | |
| 94 | #endif |
| 95 | |
| 96 | // ============================================================================ |
| 97 | // wxScopeGuard for functions and functors |
| 98 | // ============================================================================ |
| 99 | |
| 100 | // ---------------------------------------------------------------------------- |
| 101 | // wxScopeGuardImplBase: used by wxScopeGuardImpl[0..N] below |
| 102 | // ---------------------------------------------------------------------------- |
| 103 | |
| 104 | class wxScopeGuardImplBase |
| 105 | { |
| 106 | public: |
| 107 | wxScopeGuardImplBase() : m_wasDismissed(false) { } |
| 108 | |
| 109 | wxScopeGuardImplBase(const wxScopeGuardImplBase& other) |
| 110 | : m_wasDismissed(other.m_wasDismissed) |
| 111 | { |
| 112 | other.Dismiss(); |
| 113 | } |
| 114 | |
| 115 | void Dismiss() const { m_wasDismissed = true; } |
| 116 | |
| 117 | // for OnScopeExit() only (we can't make it friend, unfortunately)! |
| 118 | bool WasDismissed() const { return m_wasDismissed; } |
| 119 | |
| 120 | protected: |
| 121 | ~wxScopeGuardImplBase() { } |
| 122 | |
| 123 | // must be mutable for copy ctor to work |
| 124 | mutable bool m_wasDismissed; |
| 125 | |
| 126 | private: |
| 127 | wxScopeGuardImplBase& operator=(const wxScopeGuardImplBase&); |
| 128 | }; |
| 129 | |
| 130 | // wxScopeGuard is just a reference, see the explanation in CUJ article |
| 131 | typedef const wxScopeGuardImplBase& wxScopeGuard; |
| 132 | |
| 133 | // ---------------------------------------------------------------------------- |
| 134 | // wxScopeGuardImpl0: scope guard for actions without parameters |
| 135 | // ---------------------------------------------------------------------------- |
| 136 | |
| 137 | template <class F> |
| 138 | class wxScopeGuardImpl0 : public wxScopeGuardImplBase |
| 139 | { |
| 140 | public: |
| 141 | static wxScopeGuardImpl0<F> MakeGuard(F fun) |
| 142 | { |
| 143 | return wxScopeGuardImpl0<F>(fun); |
| 144 | } |
| 145 | |
| 146 | ~wxScopeGuardImpl0() { wxPrivateOnScopeExit(*this); } |
| 147 | |
| 148 | void Execute() { m_fun(); } |
| 149 | |
| 150 | protected: |
| 151 | wxScopeGuardImpl0(F fun) : m_fun(fun) { } |
| 152 | |
| 153 | F m_fun; |
| 154 | |
| 155 | wxScopeGuardImpl0& operator=(const wxScopeGuardImpl0&); |
| 156 | }; |
| 157 | |
| 158 | template <class F> |
| 159 | inline wxScopeGuardImpl0<F> wxMakeGuard(F fun) |
| 160 | { |
| 161 | return wxScopeGuardImpl0<F>::MakeGuard(fun); |
| 162 | } |
| 163 | |
| 164 | // ---------------------------------------------------------------------------- |
| 165 | // wxScopeGuardImpl1: scope guard for actions with 1 parameter |
| 166 | // ---------------------------------------------------------------------------- |
| 167 | |
| 168 | template <class F, class P1> |
| 169 | class wxScopeGuardImpl1 : public wxScopeGuardImplBase |
| 170 | { |
| 171 | public: |
| 172 | static wxScopeGuardImpl1<F, P1> MakeGuard(F fun, P1 p1) |
| 173 | { |
| 174 | return wxScopeGuardImpl1<F, P1>(fun, p1); |
| 175 | } |
| 176 | |
| 177 | ~wxScopeGuardImpl1() { wxPrivateOnScopeExit(* this); } |
| 178 | |
| 179 | void Execute() { m_fun(m_p1); } |
| 180 | |
| 181 | protected: |
| 182 | wxScopeGuardImpl1(F fun, P1 p1) : m_fun(fun), m_p1(p1) { } |
| 183 | |
| 184 | F m_fun; |
| 185 | const P1 m_p1; |
| 186 | |
| 187 | wxScopeGuardImpl1& operator=(const wxScopeGuardImpl1&); |
| 188 | }; |
| 189 | |
| 190 | template <class F, class P1> |
| 191 | inline wxScopeGuardImpl1<F, P1> wxMakeGuard(F fun, P1 p1) |
| 192 | { |
| 193 | return wxScopeGuardImpl1<F, P1>::MakeGuard(fun, p1); |
| 194 | } |
| 195 | |
| 196 | // ---------------------------------------------------------------------------- |
| 197 | // wxScopeGuardImpl2: scope guard for actions with 2 parameters |
| 198 | // ---------------------------------------------------------------------------- |
| 199 | |
| 200 | template <class F, class P1, class P2> |
| 201 | class wxScopeGuardImpl2 : public wxScopeGuardImplBase |
| 202 | { |
| 203 | public: |
| 204 | static wxScopeGuardImpl2<F, P1, P2> MakeGuard(F fun, P1 p1, P2 p2) |
| 205 | { |
| 206 | return wxScopeGuardImpl2<F, P1, P2>(fun, p1, p2); |
| 207 | } |
| 208 | |
| 209 | ~wxScopeGuardImpl2() { wxPrivateOnScopeExit(*this); } |
| 210 | |
| 211 | void Execute() { m_fun(m_p1, m_p2); } |
| 212 | |
| 213 | protected: |
| 214 | wxScopeGuardImpl2(F fun, P1 p1, P2 p2) : m_fun(fun), m_p1(p1), m_p2(p2) { } |
| 215 | |
| 216 | F m_fun; |
| 217 | const P1 m_p1; |
| 218 | const P2 m_p2; |
| 219 | |
| 220 | wxScopeGuardImpl2& operator=(const wxScopeGuardImpl2&); |
| 221 | }; |
| 222 | |
| 223 | template <class F, class P1, class P2> |
| 224 | inline wxScopeGuardImpl2<F, P1, P2> wxMakeGuard(F fun, P1 p1, P2 p2) |
| 225 | { |
| 226 | return wxScopeGuardImpl2<F, P1, P2>::MakeGuard(fun, p1, p2); |
| 227 | } |
| 228 | |
| 229 | // ============================================================================ |
| 230 | // wxScopeGuards for object methods |
| 231 | // ============================================================================ |
| 232 | |
| 233 | // ---------------------------------------------------------------------------- |
| 234 | // wxObjScopeGuardImpl0 |
| 235 | // ---------------------------------------------------------------------------- |
| 236 | |
| 237 | template <class Obj, class MemFun> |
| 238 | class wxObjScopeGuardImpl0 : public wxScopeGuardImplBase |
| 239 | { |
| 240 | public: |
| 241 | static wxObjScopeGuardImpl0<Obj, MemFun> |
| 242 | MakeObjGuard(Obj& obj, MemFun memFun) |
| 243 | { |
| 244 | return wxObjScopeGuardImpl0<Obj, MemFun>(obj, memFun); |
| 245 | } |
| 246 | |
| 247 | ~wxObjScopeGuardImpl0() { wxPrivateOnScopeExit(*this); } |
| 248 | |
| 249 | void Execute() { (m_obj.*m_memfun)(); } |
| 250 | |
| 251 | protected: |
| 252 | wxObjScopeGuardImpl0(Obj& obj, MemFun memFun) |
| 253 | : m_obj(obj), m_memfun(memFun) { } |
| 254 | |
| 255 | Obj& m_obj; |
| 256 | MemFun m_memfun; |
| 257 | }; |
| 258 | |
| 259 | template <class Obj, class MemFun> |
| 260 | inline wxObjScopeGuardImpl0<Obj, MemFun> wxMakeObjGuard(Obj& obj, MemFun memFun) |
| 261 | { |
| 262 | return wxObjScopeGuardImpl0<Obj, MemFun>::MakeObjGuard(obj, memFun); |
| 263 | } |
| 264 | |
| 265 | template <class Obj, class MemFun, class P1> |
| 266 | class wxObjScopeGuardImpl1 : public wxScopeGuardImplBase |
| 267 | { |
| 268 | public: |
| 269 | static wxObjScopeGuardImpl1<Obj, MemFun, P1> |
| 270 | MakeObjGuard(Obj& obj, MemFun memFun, P1 p1) |
| 271 | { |
| 272 | return wxObjScopeGuardImpl1<Obj, MemFun, P1>(obj, memFun, p1); |
| 273 | } |
| 274 | |
| 275 | ~wxObjScopeGuardImpl1() { wxPrivateOnScopeExit(*this); } |
| 276 | |
| 277 | void Execute() { (m_obj.*m_memfun)(m_p1); } |
| 278 | |
| 279 | protected: |
| 280 | wxObjScopeGuardImpl1(Obj& obj, MemFun memFun, P1 p1) |
| 281 | : m_obj(obj), m_memfun(memFun), m_p1(p1) { } |
| 282 | |
| 283 | Obj& m_obj; |
| 284 | MemFun m_memfun; |
| 285 | const P1 m_p1; |
| 286 | }; |
| 287 | |
| 288 | template <class Obj, class MemFun, class P1> |
| 289 | inline wxObjScopeGuardImpl1<Obj, MemFun, P1> |
| 290 | wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1) |
| 291 | { |
| 292 | return wxObjScopeGuardImpl1<Obj, MemFun, P1>::MakeObjGuard(obj, memFun, p1); |
| 293 | } |
| 294 | |
| 295 | template <class Obj, class MemFun, class P1, class P2> |
| 296 | class wxObjScopeGuardImpl2 : public wxScopeGuardImplBase |
| 297 | { |
| 298 | public: |
| 299 | static wxObjScopeGuardImpl2<Obj, MemFun, P1, P2> |
| 300 | MakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2) |
| 301 | { |
| 302 | return wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>(obj, memFun, p1, p2); |
| 303 | } |
| 304 | |
| 305 | ~wxObjScopeGuardImpl2() { wxPrivateOnScopeExit(*this); } |
| 306 | |
| 307 | void Execute() { (m_obj.*m_memfun)(m_p1, m_p2); } |
| 308 | |
| 309 | protected: |
| 310 | wxObjScopeGuardImpl2(Obj& obj, MemFun memFun, P1 p1, P2 p2) |
| 311 | : m_obj(obj), m_memfun(memFun), m_p1(p1), m_p2(p2) { } |
| 312 | |
| 313 | Obj& m_obj; |
| 314 | MemFun m_memfun; |
| 315 | const P1 m_p1; |
| 316 | const P2 m_p2; |
| 317 | }; |
| 318 | |
| 319 | template <class Obj, class MemFun, class P1, class P2> |
| 320 | inline wxObjScopeGuardImpl2<Obj, MemFun, P1, P2> |
| 321 | wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2) |
| 322 | { |
| 323 | return wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>:: |
| 324 | MakeObjGuard(obj, memFun, p1, p2); |
| 325 | } |
| 326 | |
| 327 | // ---------------------------------------------------------------------------- |
| 328 | // wxVariableSetter: use the same technique as for wxScopeGuard to allow |
| 329 | // setting a variable to some value on block exit |
| 330 | // ---------------------------------------------------------------------------- |
| 331 | |
| 332 | #ifdef wxHAS_NAMESPACES |
| 333 | |
| 334 | namespace wxPrivate |
| 335 | { |
| 336 | |
| 337 | // empty class just to be able to define a reference to it |
| 338 | class VariableSetterBase { }; |
| 339 | |
| 340 | typedef const VariableSetterBase& VariableSetter; |
| 341 | |
| 342 | template <typename T, typename U> |
| 343 | class VariableSetterImpl : public VariableSetterBase |
| 344 | { |
| 345 | public: |
| 346 | VariableSetterImpl(T& var, const U& value) |
| 347 | : m_var(var), |
| 348 | m_value(value) |
| 349 | { |
| 350 | } |
| 351 | |
| 352 | ~VariableSetterImpl() |
| 353 | { |
| 354 | m_var = m_value; |
| 355 | } |
| 356 | |
| 357 | private: |
| 358 | T& m_var; |
| 359 | const U& m_value; |
| 360 | |
| 361 | // suppress the warning about assignment operator not being generated |
| 362 | VariableSetterImpl<T, U>& operator=(const VariableSetterImpl<T, U>&); |
| 363 | }; |
| 364 | |
| 365 | template <typename T> |
| 366 | class VariableNullerImpl : public VariableSetterBase |
| 367 | { |
| 368 | public: |
| 369 | VariableNullerImpl(T& var) |
| 370 | : m_var(var) |
| 371 | { |
| 372 | } |
| 373 | |
| 374 | ~VariableNullerImpl() |
| 375 | { |
| 376 | m_var = NULL; |
| 377 | } |
| 378 | |
| 379 | private: |
| 380 | T& m_var; |
| 381 | |
| 382 | VariableNullerImpl<T>& operator=(const VariableNullerImpl<T>&); |
| 383 | }; |
| 384 | |
| 385 | } // namespace wxPrivate |
| 386 | |
| 387 | template <typename T, typename U> |
| 388 | inline |
| 389 | wxPrivate::VariableSetterImpl<T, U> wxMakeVarSetter(T& var, const U& value) |
| 390 | { |
| 391 | return wxPrivate::VariableSetterImpl<T, U>(var, value); |
| 392 | } |
| 393 | |
| 394 | // calling wxMakeVarSetter(ptr, NULL) doesn't work because U is deduced to be |
| 395 | // "int" and subsequent assignment of "U" to "T *" fails, so provide a special |
| 396 | // function for this special case |
| 397 | template <typename T> |
| 398 | inline |
| 399 | wxPrivate::VariableNullerImpl<T> wxMakeVarNuller(T& var) |
| 400 | { |
| 401 | return wxPrivate::VariableNullerImpl<T>(var); |
| 402 | } |
| 403 | |
| 404 | #endif // wxHAS_NAMESPACES |
| 405 | |
| 406 | // ============================================================================ |
| 407 | // macros for declaring unnamed scoped guards (which can't be dismissed) |
| 408 | // ============================================================================ |
| 409 | |
| 410 | // NB: the original code has a single (and much nicer) ON_BLOCK_EXIT macro |
| 411 | // but this results in compiler warnings about unused variables and I |
| 412 | // didn't find a way to work around this other than by having different |
| 413 | // macros with different names or using a less natural syntax for passing |
| 414 | // the arguments (e.g. as Boost preprocessor sequences, which would mean |
| 415 | // having to write wxON_BLOCK_EXIT(fwrite, (buf)(size)(n)(fp)) instead of |
| 416 | // wxON_BLOCK_EXIT4(fwrite, buf, size, n, fp)). |
| 417 | |
| 418 | #define wxGuardName wxMAKE_UNIQUE_NAME(wxScopeGuard) |
| 419 | |
| 420 | #define wxON_BLOCK_EXIT0_IMPL(n, f) \ |
| 421 | wxScopeGuard n = wxMakeGuard(f); \ |
| 422 | wxPrivateUse(n) |
| 423 | #define wxON_BLOCK_EXIT0(f) \ |
| 424 | wxON_BLOCK_EXIT0_IMPL(wxGuardName, f) |
| 425 | |
| 426 | #define wxON_BLOCK_EXIT_OBJ0_IMPL(n, o, m) \ |
| 427 | wxScopeGuard n = wxMakeObjGuard(o, m); \ |
| 428 | wxPrivateUse(n) |
| 429 | #define wxON_BLOCK_EXIT_OBJ0(o, m) \ |
| 430 | wxON_BLOCK_EXIT_OBJ0_IMPL(wxGuardName, o, &m) |
| 431 | |
| 432 | #define wxON_BLOCK_EXIT_THIS0(m) \ |
| 433 | wxON_BLOCK_EXIT_OBJ0(*this, m) |
| 434 | |
| 435 | |
| 436 | #define wxON_BLOCK_EXIT1_IMPL(n, f, p1) \ |
| 437 | wxScopeGuard n = wxMakeGuard(f, p1); \ |
| 438 | wxPrivateUse(n) |
| 439 | #define wxON_BLOCK_EXIT1(f, p1) \ |
| 440 | wxON_BLOCK_EXIT1_IMPL(wxGuardName, f, p1) |
| 441 | |
| 442 | #define wxON_BLOCK_EXIT_OBJ1_IMPL(n, o, m, p1) \ |
| 443 | wxScopeGuard n = wxMakeObjGuard(o, m, p1); \ |
| 444 | wxPrivateUse(n) |
| 445 | #define wxON_BLOCK_EXIT_OBJ1(o, m, p1) \ |
| 446 | wxON_BLOCK_EXIT_OBJ1_IMPL(wxGuardName, o, &m, p1) |
| 447 | |
| 448 | #define wxON_BLOCK_EXIT_THIS1(m, p1) \ |
| 449 | wxON_BLOCK_EXIT_OBJ1(*this, m, p1) |
| 450 | |
| 451 | |
| 452 | #define wxON_BLOCK_EXIT2_IMPL(n, f, p1, p2) \ |
| 453 | wxScopeGuard n = wxMakeGuard(f, p1, p2); \ |
| 454 | wxPrivateUse(n) |
| 455 | #define wxON_BLOCK_EXIT2(f, p1, p2) \ |
| 456 | wxON_BLOCK_EXIT2_IMPL(wxGuardName, f, p1, p2) |
| 457 | |
| 458 | #define wxON_BLOCK_EXIT_OBJ2_IMPL(n, o, m, p1, p2) \ |
| 459 | wxScopeGuard n = wxMakeObjGuard(o, m, p1, p2); \ |
| 460 | wxPrivateUse(n) |
| 461 | #define wxON_BLOCK_EXIT_OBJ2(o, m, p1, p2) \ |
| 462 | wxON_BLOCK_EXIT_OBJ2_IMPL(wxGuardName, o, &m, p1, p2) |
| 463 | |
| 464 | #define wxON_BLOCK_EXIT_THIS2(m, p1, p2) \ |
| 465 | wxON_BLOCK_EXIT_OBJ2(*this, m, p1, p2) |
| 466 | |
| 467 | |
| 468 | #define wxSetterName wxMAKE_UNIQUE_NAME(wxVarSetter) |
| 469 | |
| 470 | #define wxON_BLOCK_EXIT_SET_IMPL(n, var, value) \ |
| 471 | wxPrivate::VariableSetter n = wxMakeVarSetter(var, value); \ |
| 472 | wxPrivateUse(n) |
| 473 | |
| 474 | #define wxON_BLOCK_EXIT_SET(var, value) \ |
| 475 | wxON_BLOCK_EXIT_SET_IMPL(wxSetterName, var, value) |
| 476 | |
| 477 | #define wxON_BLOCK_EXIT_NULL_IMPL(n, var) \ |
| 478 | wxPrivate::VariableSetter n = wxMakeVarNuller(var); \ |
| 479 | wxPrivateUse(n) |
| 480 | |
| 481 | #define wxON_BLOCK_EXIT_NULL(ptr) \ |
| 482 | wxON_BLOCK_EXIT_NULL_IMPL(wxSetterName, ptr) |
| 483 | |
| 484 | #endif // _WX_SCOPEGUARD_H_ |