Vc/common/iif.h

0001 /*  This file is part of the Vc library. {{{
0002 Copyright © 2012-2015 Matthias Kretz <kretz@kde.org>
0003
0004 Redistribution and use in source and binary forms, with or without
0005 modification, are permitted provided that the following conditions are met:
0006     * Redistributions of source code must retain the above copyright
0007       notice, this list of conditions and the following disclaimer.
0008     * Redistributions in binary form must reproduce the above copyright
0009       notice, this list of conditions and the following disclaimer in the
0010       documentation and/or other materials provided with the distribution.
0011     * Neither the names of contributing organizations nor the
0012       names of its contributors may be used to endorse or promote products
0013       derived from this software without specific prior written permission.
0014
0015 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
0016 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
0017 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
0018 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
0019 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
0020 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
0021 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
0022 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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0024 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
0025
0026 }}}*/
0027
0028 #ifndef VC_COMMON_IIF_H_
0029 #define VC_COMMON_IIF_H_
0030
0031 #include "../type_traits"
0032 #include "macros.h"
0033
0034 namespace Vc_VERSIONED_NAMESPACE
0035 {
0036 /**
0037  * \ingroup Utilities
0038  *
0039  * Function to mimic the ternary operator '?:' (inline-if).
0040  *
0041  * \param condition  Determines which values are returned. This is analog to the first argument to
0042  *                   the ternary operator.
0043  * \param trueValue  The values to return where \p condition is \c true.
0044  * \param falseValue The values to return where \p condition is \c false.
0045  * \return A combination of entries from \p trueValue and \p falseValue, according to \p condition.
0046  *
0047  * So instead of the scalar variant
0048  * \code
0049  * float x = a > 1.f ? b : b + c;
0050  * \endcode
0051  * you'd write
0052  * \code
0053  * float_v x = Vc::iif (a > 1.f, b, b + c);
0054  * \endcode
0055  *
0056  * Assuming \c a has the values [0, 3, 5, 1], \c b is [1, 1, 1, 1], and \c c is [1, 2, 3, 4], then x
0057  * will be [2, 2, 3, 5].
0058  */
0059 template <typename Mask, typename T>
0060 Vc_ALWAYS_INLINE enable_if<is_simd_mask<Mask>::value && is_simd_vector<T>::value, T> iif(
0061     const Mask &condition, const T &trueValue, const T &falseValue)
0062 {
0063     T result(falseValue);
0064     Vc::where(condition) | result = trueValue;
0065     return result;
0066 }
0067
0068 /**\internal
0069  * The following declaration makes it explicit that `iif (Mask, non-vector, non-vector)`
0070  * is not supposed to work. Doing the same thing with \c static_assert would break SFINAE.
0071  */
0072 template <typename Mask, typename T>
0073 enable_if<is_simd_mask<Mask>::value && !is_simd_vector<T>::value, T> iif(
0074     const Mask &, const T &, const T &) = delete;
0075
0076 /**
0077  * \ingroup Utilities
0078  *
0079  * Overload of the above for boolean conditions.
0080  *
0081  * This typically results in direct use of the ternary operator. This function makes it easier to
0082  * switch from a Vc type to a builtin type.
0083  *
0084  * \param condition  Determines which value is returned. This is analog to the first argument to
0085  *                   the ternary operator.
0086  * \param trueValue  The value to return if \p condition is \c true.
0087  * \param falseValue The value to return if \p condition is \c false.
0088  * \return Either \p trueValue or \p falseValue, depending on \p condition.
0089  */
0090 template<typename T> constexpr T iif (bool condition, const T &trueValue, const T &falseValue)
0091 {
0092     return condition ? trueValue : falseValue;
0093 }
0094
0095 }  // namespace Vc
0096
0097 #endif // VC_COMMON_IIF_H_