92 lines
3.3 KiB
C++
92 lines
3.3 KiB
C++
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// Copyright 2011 Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors
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// may be used to endorse or promote products derived from this software
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// without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include <cassert>
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#include <cstring>
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#include "stack_cleaner.hpp"
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#include "state.ipp"
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/// Internal implementation for lutok::stack_cleaner.
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struct lutok::stack_cleaner::impl {
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/// Reference to the Lua state this stack_cleaner refers to.
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state& state_ref;
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/// The depth of the Lua stack to be restored.
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unsigned int original_depth;
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/// Constructor.
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///
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/// \param state_ref_ Reference to the Lua state.
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/// \param original_depth_ The depth of the Lua stack.
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impl(state& state_ref_, const unsigned int original_depth_) :
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state_ref(state_ref_),
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original_depth(original_depth_)
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{
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}
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};
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/// Creates a new stack cleaner.
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///
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/// This gathers the current height of the stack so that extra elements can be
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/// popped during destruction.
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///
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/// \param state_ The Lua state.
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lutok::stack_cleaner::stack_cleaner(state& state_) :
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_pimpl(new impl(state_, state_.get_top()))
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{
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}
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/// Pops any values from the stack not known at construction time.
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///
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/// \pre The current height of the stack must be equal or greater to the height
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/// of the stack when this object was instantiated.
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lutok::stack_cleaner::~stack_cleaner(void)
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{
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const unsigned int current_depth = _pimpl->state_ref.get_top();
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assert(current_depth >= _pimpl->original_depth);
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const unsigned int diff = current_depth - _pimpl->original_depth;
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if (diff > 0)
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_pimpl->state_ref.pop(diff);
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}
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/// Forgets about any elements currently in the stack.
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///
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/// This allows a function to return values on the stack because all the
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/// elements that are currently in the stack will not be touched during
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/// destruction when the function is called.
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void
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lutok::stack_cleaner::forget(void)
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{
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_pimpl->original_depth = _pimpl->state_ref.get_top();
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}
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