CRTP base class which implements the entire standard iterator facade in terms of a minimal subset of the interface. More...

#include </home/runner/work/allwpilib/allwpilib/wpiutil/src/main/native/thirdparty/llvm/include/wpi/iterator.h>

Classes
class	PointerProxy
	A proxy object for computing a pointer via indirecting a copy of a reference. More...

class	ReferenceProxy
	A proxy object for computing a reference via indirecting a copy of an iterator. More...

Public Types
using	iterator_category = IteratorCategoryT

using	value_type = T

using	difference_type = DifferenceTypeT

using	pointer = PointerT

using	reference = ReferenceT

Public Member Functions
DerivedT	operator+ (DifferenceTypeT n) const

DerivedT	operator- (DifferenceTypeT n) const

DerivedT &	operator++ ()

DerivedT	operator++ (int)

DerivedT &	operator-- ()

DerivedT	operator-- (int)

bool	operator!= (const DerivedT &RHS) const

bool	operator> (const DerivedT &RHS) const

bool	operator<= (const DerivedT &RHS) const

bool	operator>= (const DerivedT &RHS) const

PointerProxy	operator-> () const

ReferenceProxy	operator[] (DifferenceTypeT n) const

Protected Types
enum	{ IsRandomAccess , IsBidirectional }

Friends
DerivedT	operator+ (DifferenceTypeT n, const DerivedT &i)

Detailed Description

template<typename DerivedT, typename IteratorCategoryT, typename T, typename DifferenceTypeT = std::ptrdiff_t, typename PointerT = T *, typename ReferenceT = T &>
class wpi::iterator_facade_base< DerivedT, IteratorCategoryT, T, DifferenceTypeT, PointerT, ReferenceT >

CRTP base class which implements the entire standard iterator facade in terms of a minimal subset of the interface.

Use this when it is reasonable to implement most of the iterator functionality in terms of a core subset. If you need special behavior or there are performance implications for this, you may want to override the relevant members instead.

Note, one abstraction that this does not provide is implementing subtraction in terms of addition by negating the difference. Negation isn't always information preserving, and I can see very reasonable iterator designs where this doesn't work well. It doesn't really force much added boilerplate anyways.

Another abstraction that this doesn't provide is implementing increment in terms of addition of one. These aren't equivalent for all iterator categories, and respecting that adds a lot of complexity for little gain.

Iterators are expected to have const rules analogous to pointers, with a single, const-qualified operator*() that returns ReferenceT. This matches the second and third pointers in the following example:

int Value;
{ int *I = &Value; }             // ReferenceT 'int&'
{ int *const I = &Value; }       // ReferenceT 'int&'; const
{ const int *I = &Value; }       // ReferenceT 'const int&'
{ const int *const I = &Value; } // ReferenceT 'const int&'; const

If an iterator facade returns a handle to its own state, then T (and PointerT and ReferenceT) should usually be const-qualified. Otherwise, if clients are expected to modify the handle itself, the field can be declared mutable or use const_cast.

Classes wishing to use iterator_facade_base should implement the following methods:

Forward Iterators: (All of the following methods)

DerivedT &operator=(const DerivedT &R);
bool operator==(const DerivedT &R) const;
T &operator*() const;
DerivedT &operator++();

Bidirectional Iterators: (All methods of forward iterators, plus the following)

DerivedT &operator--();

Random-access Iterators: (All methods of bidirectional iterators excluding the following)

DerivedT &operator++();
DerivedT &operator--(); (and plus the following)
bool operator<(const DerivedT &RHS) const;
DifferenceTypeT operator-(const DerivedT &R) const;
DerivedT &operator+=(DifferenceTypeT N);
DerivedT &operator-=(DifferenceTypeT N);