proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType > Class Template Reference

Simple iterator wrapper for manipulation of dereferenced result. More...

#include <AssociatedData.h>

Inheritance diagram for proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >:

Classes
class	ValuePtr
	Value box for use with pointer dereference operator->(). More...

Public Types
using	iterator = Iter
Iterator traits
!< The type of base iterator wrapper.
using	value_type = ValueType
using	pointer = std::add_pointer_t< value_type >
using	reference = std::add_lvalue_reference_t< value_type >
using	iterator_category = std::forward_iterator_tag

Public Member Functions
	IteratorWrapperBase ()=default
	Default constructor: default-constructs the underlying iterator. More...
	IteratorWrapperBase (data_iterator_t const &from)
	Copy-from-base constructor. More...
iterator &	operator++ ()
	Prefix increment operator. More...
bool	operator!= (data_iterator_t const &other) const
	Comparison with a data iterator (makes unnecessary to wrap end iterators). More...
bool	operator!= (iterator const &other) const
	Comparison with another iterator. More...
auto	operator[] (std::size_t index) const -> decltype(auto)
auto	operator* () const -> decltype(auto)
	Dereference operator; need to be redefined by derived classes. More...
auto	operator-> () const -> decltype(auto)
	Dereference operator; need to be redefined by derived classes. More...

Protected Types
using	data_iterator_t = DataIter

Protected Member Functions
data_iterator_t const &	asDataIterator () const

Static Protected Member Functions
static auto	transform (data_iterator_t const &) -> decltype(auto)
	Transforms and returns the value at the specified data iterator. More...

Private Member Functions
iterator const &	asIterator () const
iterator &	asIterator ()

Static Private Member Functions
template<typename Value >
static ValuePtr< Value >	makeValuePointer (Value &&value)

Detailed Description

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>
class proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >

Simple iterator wrapper for manipulation of dereferenced result.

Template Parameters

Iter	final iterator
BaseIter	base iterator
ValueType	type returned by the new dereference operator

This class is designed to be used as base class for an iterator that redefines the dereference operations without changing anything else. An example of such iterator is:

using int_iterator_t = std::vector<int>::const_iterator;

class twice_iterator
  : public IteratorWrapperBase<twice_iterator, int_iterator_t, float>
{
  using base_iterator_t
    = IteratorWrapperBase<twice_iterator, int_iterator_t, float>;

    public:

  using base_iterator_t::base_iterator_t; // inherit constructors

  float operator*() const -> decltype(auto)
    { return 2.0F * base_iterator_t::operator*(); }

}; // twice_iterator

This new iterator twice_iterator effectively inherits int_iterator_t constructors (via base_iterator_t). Its operator++() returns a twice_iterator, so that operations like *++it are correctly handled.

Note that the derived classes need to redefine all the dereferencing operators that are supported:

• operator*()

The operator->() is not supported. Typically, operator*() returns a reference and operator->() a pointer to an existing structure. The operator*() is not required to return a reference when the iterator does not allow to modify the pointed data, and the wrapper can manipulate values and return temporary results. To have a similar feature for operator->() requires more work, as it should return a smart pointer that would perform the transformation on dereference.

Definition at line 103 of file AssociatedData.h.

Member Typedef Documentation

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

using proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::data_iterator_t = DataIter

protected

Definition at line 105 of file AssociatedData.h.

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

using proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::iterator = Iter

Definition at line 108 of file AssociatedData.h.

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

using proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::iterator_category = std::forward_iterator_tag

Definition at line 116 of file AssociatedData.h.

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

using proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::pointer = std::add_pointer_t<value_type>

Definition at line 114 of file AssociatedData.h.

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

using proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::reference = std::add_lvalue_reference_t<value_type>

Definition at line 115 of file AssociatedData.h.

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

using proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::value_type = ValueType

Definition at line 113 of file AssociatedData.h.

Constructor & Destructor Documentation

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::IteratorWrapperBase ( )

default

Default constructor: default-constructs the underlying iterator.

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::IteratorWrapperBase ( data_iterator_t const &  from )

inline

Copy-from-base constructor.

Definition at line 123 of file AssociatedData.h.

: data_iterator_t(from) {}

Member Function Documentation

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

data_iterator_t const& proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::asDataIterator ( ) const

inlineprotected

Definition at line 154 of file AssociatedData.h.

        { return static_cast<data_iterator_t const&>(*this); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

iterator const& proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::asIterator ( ) const

inlineprivate

Definition at line 172 of file AssociatedData.h.

        { return static_cast<iterator const&>(*this); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

iterator& proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::asIterator ( )

inlineprivate

Definition at line 174 of file AssociatedData.h.

{ return static_cast<iterator&>(*this); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

template<typename Value >

static ValuePtr<Value> proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::makeValuePointer ( Value &&  value )

inlinestaticprivate

Definition at line 169 of file AssociatedData.h.

        { return { std::forward<Value>(value) }; }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

bool proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::operator!= ( data_iterator_t const &  other ) const

inline

Comparison with a data iterator (makes unnecessary to wrap end iterators).

Definition at line 130 of file AssociatedData.h.

        { return other != asDataIterator(); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

bool proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::operator!= ( iterator const &  other ) const

inline

Comparison with another iterator.

Definition at line 134 of file AssociatedData.h.

        { return operator!=(other.asDataIterator()); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

auto proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::operator* ( ) const -> decltype(auto)

inline

Dereference operator; need to be redefined by derived classes.

Definition at line 141 of file AssociatedData.h.

        { return asIterator().transform(asDataIterator()); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

iterator& proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::operator++ ( )

inline

Prefix increment operator.

Definition at line 126 of file AssociatedData.h.

        { data_iterator_t::operator++(); return asIterator(); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

auto proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::operator-> ( ) const -> decltype(auto)

inline

Dereference operator; need to be redefined by derived classes.

Definition at line 145 of file AssociatedData.h.

        { return makeValuePointer(operator*()); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

auto proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::operator[] ( std::size_t  index ) const -> decltype(auto)

inline

Definition at line 137 of file AssociatedData.h.

        { return asIterator().transform(asDataIterator() + index); }

template<typename Iter, typename DataIter, typename ValueType = typename DataIter::value_type>

static auto proxy::details::IteratorWrapperBase< Iter, DataIter, ValueType >::transform ( data_iterator_t const &  ) -> decltype(auto)

inlinestaticprotected

Transforms and returns the value at the specified data iterator.

Definition at line 151 of file AssociatedData.h.

        { return data_iterator_t::operator*(); }

---

The documentation for this class was generated from the following file:

• AssociatedData.h