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/**
* @file debug.h
* @author Nat Goodspeed
* @date 2009-05-28
* @brief Debug output for unit test code
*
* $LicenseInfo:firstyear=2009&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#if ! defined(LL_DEBUG_H)
#define LL_DEBUG_H
#include "print.h"
#include "stringize.h"
#include <exception> // std::uncaught_exceptions()
/*****************************************************************************
* Debugging stuff
*****************************************************************************/
/**
* Return true if the environment variable LOGTEST is non-empty.
*
* The variable LOGTEST is used because that's the environment variable
* checked by test.cpp, our TUT main() program, to turn on LLError logging. It
* is expected that Debug is solely for use in test programs.
*/
inline
bool LOGTEST_enabled()
{
auto LOGTEST{ getenv("LOGTEST") };
// debug output enabled when LOGTEST is set AND non-empty
return LOGTEST && *LOGTEST;
}
/**
* This class is intended to illuminate entry to a given block, exit from the
* same block and checkpoints along the way. It also provides a convenient
* place to turn std::cerr output on and off.
*
* If enabled, each Debug instance will announce its construction and
* destruction, presumably at entry and exit to the block in which it's
* declared. Moreover, any arguments passed to its operator()() will be
* streamed to std::cerr, prefixed by the block description.
*/
class Debug
{
public:
template <typename... ARGS>
Debug(ARGS&&... args):
mBlock(stringize(std::forward<ARGS>(args)...)),
mEnabled(LOGTEST_enabled())
{
(*this)("entry");
}
// non-copyable
Debug(const Debug&) = delete;
Debug& operator=(const Debug&) = delete;
~Debug()
{
auto exceptional{ std::uncaught_exceptions()? "exceptional " : "" };
(*this)(exceptional, "exit");
}
template <typename... ARGS>
void operator()(ARGS&&... args)
{
if (mEnabled)
{
print(mBlock, ' ', std::forward<ARGS>(args)...);
}
}
private:
const std::string mBlock;
bool mEnabled;
};
// It's often convenient to use the name of the enclosing function as the name
// of the Debug block.
#define DEBUG Debug debug(LL_PRETTY_FUNCTION)
/// If enabled, debug_expr(expression) gives you output concerning an inline
/// expression such as a class member initializer.
#define debug_expr(expr) debug_expr_(#expr, [&](){ return expr; })
template <typename EXPR>
inline auto debug_expr_(const char* strexpr, EXPR&& lambda)
{
if (! LOGTEST_enabled())
return std::forward<EXPR>(lambda)();
print("Before: ", strexpr);
auto result{ std::forward<EXPR>(lambda)() };
print(strexpr, " -> ", result);
return result;
}
#endif /* ! defined(LL_DEBUG_H) */
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