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include
itkEnableIf.h
Go to the documentation of this file.
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/*=========================================================================
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*
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* Copyright Insight Software Consortium
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0.txt
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*=========================================================================*/
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#ifndef __itkEnableIf_h
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#define __itkEnableIf_h
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namespace
itk
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{
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/* \brief This is an implementation of the enable if idiom.
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*
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* Enable if is a common C++ meta-programming technique for example
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* there is a boost implementation, for more information on its usage
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* please see:
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* http://www.boost.org/doc/libs/1_49_0/libs/utility/enable_if.html
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*
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* This template enables specialization of a templated function based
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* on some traits or concepts. It is implemented with SFINAE.
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*
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* If the parameter V is true then the Type trait is the second
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* template parameter, otherwise an implementation does not exist and
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* with SFIANE another implementation may be choosen.
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*
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* Example:
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* \code
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*
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* template< typename T>
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* typename EnableIfC<
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* IsSame<T, typename NumericTraits<T>::ValueType>::Value,
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* T >::Type
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* GetComponent(const T pix,
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* unsigned int itkNotUsed( idx ) ) const
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* {
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* return pix;
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* }
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* \endcode
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*
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*/
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template
<
bool
V,
class
T =
void
>
struct
EnableIfC
{};
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template
<
class
T>
struct
EnableIfC
<true, T> {
typedef
T Type; };
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/* \brief An implementation of the negation of the enable if idiom.
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*
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* \sa EnableIf
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*/
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template
<
bool
V,
class
T =
void
>
struct
DisableIfC
{};
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template
<
class
T>
struct
DisableIfC
<false, T> {
typedef
T Type; };
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}
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#endif // __itkEnableIf_h
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