1 // Copyright 2011 Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above copyright 11 // notice, this list of conditions and the following disclaimer in the 12 // documentation and/or other materials provided with the distribution. 13 // * Neither the name of Google Inc. nor the names of its contributors 14 // may be used to endorse or promote products derived from this software 15 // without specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29 /// \file stack_cleaner.hpp 30 /// Provides the stack_cleaner class. 31 32 #if !defined(LUTOK_STACK_CLEANER_HPP) 33 #define LUTOK_STACK_CLEANER_HPP 34 35 #include <memory> 36 37 #include <lutok/state.hpp> 38 39 namespace lutok { 40 41 42 /// A RAII model for values on the Lua stack. 43 /// 44 /// At creation time, the object records the current depth of the Lua stack and, 45 /// during destruction, restores the recorded depth by popping as many stack 46 /// entries as required. As a corollary, the stack can only grow during the 47 /// lifetime of a stack_cleaner object (or shrink, but cannot become shorter 48 /// than the depth recorded at creation time). 49 /// 50 /// Use this class as follows: 51 /// 52 /// state s; 53 /// { 54 /// stack_cleaner cleaner1(s); 55 /// s.push_integer(3); 56 /// s.push_integer(5); 57 /// ... do stuff here ... 58 /// for (...) { 59 /// stack_cleaner cleaner2(s); 60 /// s.load_string("..."); 61 /// s.pcall(0, 1, 0); 62 /// ... do stuff here ... 63 /// } 64 /// // cleaner2 destroyed; the result of pcall is gone. 65 /// } 66 /// // cleaner1 destroyed; the integers 3 and 5 are gone. 67 /// 68 /// You must give a name to the instantiated objects even if they cannot be 69 /// accessed later. Otherwise, the instance will be destroyed right away and 70 /// will not have the desired effect. 71 class stack_cleaner { 72 struct impl; 73 74 /// Pointer to the shared internal implementation. 75 std::auto_ptr< impl > _pimpl; 76 77 /// Disallow copies. 78 stack_cleaner(const stack_cleaner&); 79 80 /// Disallow assignment. 81 stack_cleaner& operator=(const stack_cleaner&); 82 83 public: 84 stack_cleaner(state&); 85 ~stack_cleaner(void); 86 87 void forget(void); 88 }; 89 90 91 } // namespace lutok 92 93 #endif // !defined(LUTOK_STACK_CLEANER_HPP) 94