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 /*****************************************************************************
  *   Copyright 2013 - 2015 Yichao Yu <yyc1992@gmail.com>                     *
  *                                                                           *
  *   This program 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; either version 2.1 of the    *
  *   License, or (at your option) version 3, or any later version accepted   *
  *   by the membership of KDE e.V. (or its successor approved by the         *
  *   membership of KDE e.V.), which shall act as a proxy defined in          *
  *   Section 6 of version 3 of the license.                                  *
  *                                                                           *
  *   This program 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,                                *
  *   see <http://www.gnu.org/licenses/>.                                     *
  *****************************************************************************/
 
 #ifndef _QTC_UTILS_MACROS_H_
 #define _QTC_UTILS_MACROS_H_
 
 /**
  * \file macros.h
  * \author Yichao Yu <yyc1992@gmail.com>
  * \brief Definitions of some useful macros.
  */
 
 /** \defgroup qtc_switch Macros for detecting empty arguments
  * \brief Used to implement function overloading and default arguments in c.
  *
  * The idea of this implementation is borrowed from the following
  * [post](https://gustedt.wordpress.com/2010/06/08/detect-empty-macro-arguments)
  * and is modified in order to fit with our usage.
  * @{
  */
 
 #define __QTC_USE_3(_1, _2, _3, ...) _3
 // Test if args has one comma
 #define __QTC_HAS_COMMA1(ret_true, ret_false, args...)  \
     __QTC_USE_3(args, ret_true, ret_false)
 // Convert parentheses to comma, used to check if the next character is "("
 #define __QTC_CONVERT_PAREN(...) ,
 // Check if arg starts with "("
 #define __QTC_IS_PAREN_(ret_true, ret_false, arg)                       \
     __QTC_HAS_COMMA1(ret_true, ret_false, __QTC_CONVERT_PAREN arg)
 // Extra layer just to make sure more evaluation (if any) is done than the
 // separator path.
 #define __QTC_IS_PAREN(ret_true, ret_false, arg)        \
     __QTC_IS_PAREN_(ret_true, ret_false, arg)
 // Check if arg is not empty and does not start with "("
 // Will not work if arg has comma or is the name of a function like macro
 #define __QTC_IS_SEP(ret_true, ret_false, arg)                          \
     __QTC_HAS_COMMA1(ret_false, ret_true, __QTC_CONVERT_PAREN arg())
 #define __QTC_IS_EMPTY_PAREN_TRUE(ret_true, ret_false, arg) ret_false
 #define __QTC_IS_EMPTY_PAREN_FALSE(ret_true, ret_false, arg)    \
     __QTC_IS_SEP(ret_false, ret_true, arg)
 
 /**
  * \brief Test if \param arg is empty.
  * Evaluate to \param ret_true if it is not empty,
  * evaluate to \param ret_false otherwise.
  *
  * NOTE: this may not work if \param arg is a macro that can be evaluated to a
  * comma separate list without parentheses or is the name of
  * a function like macro.
  */
 #define QTC_SWITCH(arg, ret_true, ret_false)                            \
     __QTC_IS_PAREN(__QTC_IS_EMPTY_PAREN_TRUE, __QTC_IS_EMPTY_PAREN_FALSE, arg) \
     (ret_false, ret_true, arg)
 /**
  * Evaluate to \param def if \param v is empty and to \param v otherwise.
  * \sa QTC_SWITCH for restrictions.
  **/
 #define QTC_DEFAULT(v, def) QTC_SWITCH(v, v, def)
 
 /** @} */
 
 #define qtcMakeVersion(a, b, c...)                      \
     ((a) << 16 | (b) << 8 | (QTC_DEFAULT(c, 0)))
 #ifdef __GNUC__
 #  define QTC_GCC_VERSION                                               \
     qtcMakeVersion(__GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__)
 #else
 #  define QTC_GCC_VERSION 0
 #endif
 #define QTC_CHECK_GCC_VERSION(args...)          \
     (QTC_GCC_VERSION >= qtcMakeVersion(args))
 
 /**
  * \brief Export symbol.
  */
 #define QTC_EXPORT __attribute__((visibility("default")))
 
 /**
  * \def QTC_BEGIN_DECLS
  * \brief start declaring c-linked functions.
  */
 /**
  * \def QTC_END_DECLS
  * \brief end declaring c-linked functions.
  */
 // For public c headers
 #ifdef __cplusplus
 #  define QTC_BEGIN_DECLS extern "C" {
 #  define QTC_END_DECLS }
 #else
 #  define QTC_BEGIN_DECLS
 #  define QTC_END_DECLS
 #endif
 
 /**
  * \brief always inline the function.
  *
  * Should only be used for small functions
  */
 #define QTC_ALWAYS_INLINE __attribute__((always_inline))
 
 /**
  * Suppress unused parameter warning on variable \param x.
  */
 #define QTC_UNUSED(x) ((void)(x))
 
 /**
  * cast the \param member pointer \param ptr of a structure \param type to
  * the containing structure.
  */
 #define qtcContainerOf(ptr, type, member)               \
     ((type*)(((char*)(ptr)) - offsetof(type, member)))
 
 /**
  * Tell the compiler that \param exp is likely to be \param var.
  */
 #if QTC_CHECK_GCC_VERSION(3, 0)
 #  define qtcExpect(exp, var) __builtin_expect(exp, var)
 #else
 #  define qtcExpect(exp, var) (exp)
 #endif
 
 /**
  * Tell the compiler that \param x is likely to be true.
  */
 #define qtcLikely(x) qtcExpect(!!(x), 1)
 
 /**
  * Tell the compiler that \param x is likely to be false.
  */
 #define qtcUnlikely(x) qtcExpect(!!(x), 0)
 
 #endif