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#include <cassert> 30#include <cstring> 31 32#include "stack_cleaner.hpp" 33#include "state.ipp" 34 35 36/// Internal implementation for lutok::stack_cleaner. 37struct lutok::stack_cleaner::impl { 38 /// Reference to the Lua state this stack_cleaner refers to. 39 state& state_ref; 40 41 /// The depth of the Lua stack to be restored. 42 unsigned int original_depth; 43 44 /// Constructor. 45 /// 46 /// \param state_ref_ Reference to the Lua state. 47 /// \param original_depth_ The depth of the Lua stack. 48 impl(state& state_ref_, const unsigned int original_depth_) : 49 state_ref(state_ref_), 50 original_depth(original_depth_) 51 { 52 } 53}; 54 55 56/// Creates a new stack cleaner. 57/// 58/// This gathers the current height of the stack so that extra elements can be 59/// popped during destruction. 60/// 61/// \param state_ The Lua state. 62lutok::stack_cleaner::stack_cleaner(state& state_) : 63 _pimpl(new impl(state_, state_.get_top())) 64{ 65} 66 67 68/// Pops any values from the stack not known at construction time. 69/// 70/// \pre The current height of the stack must be equal or greater to the height 71/// of the stack when this object was instantiated. 72lutok::stack_cleaner::~stack_cleaner(void) 73{ 74 const unsigned int current_depth = _pimpl->state_ref.get_top(); 75 assert(current_depth >= _pimpl->original_depth); 76 const unsigned int diff = current_depth - _pimpl->original_depth; 77 if (diff > 0) 78 _pimpl->state_ref.pop(diff); 79} 80 81 82/// Forgets about any elements currently in the stack. 83/// 84/// This allows a function to return values on the stack because all the 85/// elements that are currently in the stack will not be touched during 86/// destruction when the function is called. 87void 88lutok::stack_cleaner::forget(void) 89{ 90 _pimpl->original_depth = _pimpl->state_ref.get_top(); 91} 92