Common/include/itkFixedArray.h

/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkFixedArray_h
#define itkFixedArray_h

#include "itkMacro.h"
#include <algorithm>
#include <array>

namespace itk
{

/** \class FixedArray
 *  \brief Simulate a standard C array with copy semantics.
 *
 * Simulates a standard C array, except that copy semantics are used instead
 * of reference semantics.  Also, arrays of different sizes cannot be
 * assigned to one another, and size information is known for function
 * returns.
 *
 * \tparam TValue Element type stored at each location in the array.
 * \tparam VLength    = Length of the array.
 *
 * The length of the array is fixed at compile time. If you wish to
 * specify the length of the array at run-time, use the class itk::Array.
 * If you wish to change to change the length of the array at run-time,
 * you're best off using std::vector<>.
 *
 * \ingroup DataRepresentation
 * \ingroup ITKCommon
 *
 * \wiki
 * \wikiexample{Utilities/FixedArray,C-style array}
 * \endwiki
 */
template< typename TValue, unsigned int VLength = 3 >
class ITK_TEMPLATE_EXPORT FixedArray
{
public:
  /** Length constant */
  static constexpr unsigned int Length = VLength;

  /** Dimension constant */
  static constexpr unsigned int Dimension = VLength;

  /** The element type stored at each location in the FixedArray. */
  using ValueType = TValue;

  /** A type representing the C-array version of this FixedArray. */
  typedef ValueType CArray[VLength];

  /** An iterator through the array. */
  using Iterator = ValueType *;

  /** A const iterator through the array. */
  using ConstIterator = const ValueType *;

  class ConstReverseIterator;

  /** \class ReverseIterator
   * \brief A reverse iterator through an array.
   * \ingroup ITKCommon
   */
  class ReverseIterator
  {
  public:
    explicit ReverseIterator(Iterator i):m_Iterator(i) {}
    ReverseIterator operator++()        { return ReverseIterator( --m_Iterator ); }
    ReverseIterator operator++(int)     { return ReverseIterator( m_Iterator-- ); }
    ReverseIterator operator--()        { return ReverseIterator( ++m_Iterator ); }
    ReverseIterator operator--(int)     { return ReverseIterator( m_Iterator++ ); }
    Iterator operator->() const { return ( m_Iterator - 1 ); }
    ValueType & operator*() const { return *( m_Iterator - 1 ); }
    bool operator!=(const ReverseIterator & rit) const { return m_Iterator != rit.m_Iterator; }
    bool operator==(const ReverseIterator & rit) const { return m_Iterator == rit.m_Iterator; }

  private:
    Iterator m_Iterator;
    friend class ConstReverseIterator;
  };

  /** \class ConstReverseIterator
   * \brief A const reverse iterator through an array.
   * \ingroup ITKCommon
   */
  class ConstReverseIterator
  {
  public:
    explicit ConstReverseIterator(ConstIterator i):m_Iterator(i) {}
    ConstReverseIterator(const ReverseIterator & rit) { m_Iterator = rit.m_Iterator; }
    ConstReverseIterator operator++()         { return ConstReverseIterator( --m_Iterator ); }
    ConstReverseIterator operator++(int)      { return ConstReverseIterator( m_Iterator-- ); }
    ConstReverseIterator operator--()         { return ConstReverseIterator( ++m_Iterator ); }
    ConstReverseIterator operator--(int)      { return ConstReverseIterator( m_Iterator++ ); }
    ConstIterator operator->() const { return ( m_Iterator - 1 ); }
    const ValueType & operator*() const { return *( m_Iterator - 1 ); }
    bool operator!=(const ConstReverseIterator & rit) const { return m_Iterator != rit.m_Iterator; }
    bool operator==(const ConstReverseIterator & rit) const { return m_Iterator == rit.m_Iterator; }

  private:
    ConstIterator m_Iterator;
  };

  /** A pointer to the ValueType. */
  using pointer = ValueType *;

  /** A const pointer to the ValueType. */
  using const_pointer = const ValueType *;

  /** A reference to the ValueType. */
  using reference = ValueType &;

  /** A const reference to the ValueType. */
  using const_reference = const ValueType &;

  /** The return type of the non-const overloads of begin() and end(). */
  using iterator = ValueType *;

  /** The return type of cbegin() and cend(), and the const overloads of begin() and end(). */
  using const_iterator = const ValueType *;

  using reverse_iterator = std::reverse_iterator<iterator>;

  using const_reverse_iterator = std::reverse_iterator<const_iterator>;

  using SizeType = unsigned int;

public:
  /** Constructors */
  FixedArray() = default;
  FixedArray(const FixedArray &) = default;
  FixedArray & operator=(const FixedArray & ) = default;
  FixedArray(FixedArray &&) = default;
  FixedArray & operator=(FixedArray && ) = default;
  ~FixedArray() = default;

  /** Conversion constructors */
  FixedArray(const ValueType r[VLength]);
  FixedArray(const ValueType & );

  /** Explicit constructor for std::array. */
  explicit FixedArray(const std::array<ValueType, VLength>& stdArray)
  {
    std::copy_n(stdArray.cbegin(), VLength, m_InternalArray);
  }

  /** Constructor to initialize a fixed array from another of any data type */
  template< typename TFixedArrayValueType >
  FixedArray(const FixedArray< TFixedArrayValueType, VLength > & r)
  {
    auto input = r.cbegin();

    for (auto& element : m_InternalArray)
    {
      element = static_cast< TValue >( *input++ );
    }
  }

  template< typename TScalarValue >
  FixedArray(const TScalarValue *r)
  {
    std::copy_n(r, VLength, m_InternalArray);
  }

  /** Operator= defined for a variety of types. */
  template< typename TFixedArrayValueType >
  FixedArray & operator=(const FixedArray< TFixedArrayValueType, VLength > & r)
  {
    auto input = r.cbegin();

    for (auto& element : m_InternalArray)
    {
      element = static_cast< TValue >( *input++ );
    }
    return *this;
  }

  FixedArray & operator=(const ValueType r[VLength]);

  /** Operators == and != are used to compare whether two arrays are equal.
   * Note that arrays are equal when the number of components (size) is the
   * same, and each component value is equal. */
  bool operator==(const FixedArray & r) const;

  bool operator!=(const FixedArray & r) const
  { return !operator==(r); }

  /** Allow the FixedArray to be indexed normally.  No bounds checking is done.
   * The separate versions are a work-around for an integer conversion bug in
   * Visual C++. */
  reference operator[](short index)                { return m_InternalArray[index]; }
  const_reference operator[](short index) const { return m_InternalArray[index]; }
  reference operator[](unsigned short index)       { return m_InternalArray[index]; }
  const_reference operator[](unsigned short index) const { return m_InternalArray[index]; }
  reference operator[](int index)                  { return m_InternalArray[index]; }
  const_reference operator[](int index) const { return m_InternalArray[index]; }
// false positive warnings with GCC
#if defined( __GNUC__ )
#if ( __GNUC__ == 4 ) && ( __GNUC_MINOR__ == 9 ) || ( __GNUC__ >= 7 )
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Warray-bounds"
#endif
#endif
  reference operator[](unsigned int index)         { return m_InternalArray[index]; }
  const_reference operator[](unsigned int index) const { return m_InternalArray[index]; }
#if defined( __GNUC__ )
#if ( __GNUC__ == 4 ) && ( __GNUC_MINOR__ == 9 ) || ( __GNUC__ >= 7 )
#pragma GCC diagnostic pop
#endif
#endif
  reference operator[](long index)                 { return m_InternalArray[index]; }
  const_reference operator[](long index) const { return m_InternalArray[index]; }
  reference operator[](unsigned long index)        { return m_InternalArray[index]; }
  const_reference operator[](unsigned long index) const { return m_InternalArray[index]; }
  reference operator[](long long index)                 { return m_InternalArray[index]; }
  const_reference operator[](long long index) const { return m_InternalArray[index]; }
  reference operator[](unsigned long long index)        { return m_InternalArray[index]; }
  const_reference operator[](unsigned long long index) const { return m_InternalArray[index]; }

  /** Set/Get element methods are more convenient in wrapping languages */
  void SetElement(unsigned int index, const_reference value)
  { m_InternalArray[index] = value; }
  const_reference GetElement(unsigned int index) const { return m_InternalArray[index]; }

  /** Return a pointer to the data. */
  ValueType * GetDataPointer()
  {
    return m_InternalArray;
  }

  const ValueType * GetDataPointer() const
  {
    return m_InternalArray;
  }

  /** Get various iterators to the array. */
  Iterator      Begin();

  ConstIterator Begin() const;

  Iterator      End();

  ConstIterator End() const;

  itkLegacyMacro(ReverseIterator      rBegin());

  itkLegacyMacro(ConstReverseIterator rBegin() const);

  itkLegacyMacro(ReverseIterator      rEnd());

  itkLegacyMacro(ConstReverseIterator rEnd() const);

  const_iterator cbegin() const noexcept
  {
    return m_InternalArray;
  }

  iterator begin() noexcept
  {
    return m_InternalArray;
  }

  const_iterator begin() const noexcept
  {
    return this->cbegin();
  }

  const_iterator cend() const noexcept
  {
    return m_InternalArray + VLength;
  }

  iterator end() noexcept
  {
    return m_InternalArray + VLength;
  }

  const_iterator end() const noexcept
  {
    return this->cend();
  }

  reverse_iterator rbegin()
  {
    return reverse_iterator{ this->end() };
  }

  const_reverse_iterator crbegin() const
  {
    return const_reverse_iterator{ this->cend() };
  }

  const_reverse_iterator rbegin() const
  {
    return this->crbegin();
  }

  reverse_iterator rend()
  {
    return reverse_iterator{ this->begin() };
  }

  const_reverse_iterator crend() const
  {
    return const_reverse_iterator{ this->cbegin() };
  }

  const_reverse_iterator rend() const
  {
    return this->crend();
  }

  SizeType      Size() const;

  void Fill(const ValueType &);

  void swap(FixedArray &other)
    {
      std::swap(m_InternalArray, other.m_InternalArray);
    }

private:
  /** Internal C array representation. */
  CArray m_InternalArray;

public:

  static FixedArray Filled(const ValueType &);
};

template< typename TValue, unsigned int VLength >
std::ostream & operator<<(std::ostream & os, const FixedArray< TValue, VLength > & arr);


template< typename TValue, unsigned int VLength >
inline void swap( FixedArray<TValue, VLength> &a, FixedArray<TValue, VLength> &b )
{
  a.swap(b);
}

} // namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkFixedArray.hxx"
#endif

#include "itkNumericTraitsFixedArrayPixel.h"

#endif