/** * @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) */