freebsd-nq/contrib/lutok/stack_cleaner.hpp
Brooks Davis c697fb7f7c Add liblutok a lightweight C++ API for lua.
It is added an INTERNALLIB and not installed.  It will be used by kyua.

This is a preparatory commit for D24103.

Reviewed by:	emaste
Obtained from:	CheriBSD
Sponsored by:	DARPA
2020-03-23 18:26:23 +00:00

94 lines
3.2 KiB
C++

// Copyright 2011 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/// \file stack_cleaner.hpp
/// Provides the stack_cleaner class.
#if !defined(LUTOK_STACK_CLEANER_HPP)
#define LUTOK_STACK_CLEANER_HPP
#include <memory>
#include <lutok/state.hpp>
namespace lutok {
/// A RAII model for values on the Lua stack.
///
/// At creation time, the object records the current depth of the Lua stack and,
/// during destruction, restores the recorded depth by popping as many stack
/// entries as required. As a corollary, the stack can only grow during the
/// lifetime of a stack_cleaner object (or shrink, but cannot become shorter
/// than the depth recorded at creation time).
///
/// Use this class as follows:
///
/// state s;
/// {
/// stack_cleaner cleaner1(s);
/// s.push_integer(3);
/// s.push_integer(5);
/// ... do stuff here ...
/// for (...) {
/// stack_cleaner cleaner2(s);
/// s.load_string("...");
/// s.pcall(0, 1, 0);
/// ... do stuff here ...
/// }
/// // cleaner2 destroyed; the result of pcall is gone.
/// }
/// // cleaner1 destroyed; the integers 3 and 5 are gone.
///
/// You must give a name to the instantiated objects even if they cannot be
/// accessed later. Otherwise, the instance will be destroyed right away and
/// will not have the desired effect.
class stack_cleaner {
struct impl;
/// Pointer to the shared internal implementation.
std::auto_ptr< impl > _pimpl;
/// Disallow copies.
stack_cleaner(const stack_cleaner&);
/// Disallow assignment.
stack_cleaner& operator=(const stack_cleaner&);
public:
stack_cleaner(state&);
~stack_cleaner(void);
void forget(void);
};
} // namespace lutok
#endif // !defined(LUTOK_STACK_CLEANER_HPP)