IterAdapter< POS, CON > Class Template Reference

#include "lib/iter-adapter.hpp"

Description

template<class POS, class CON>
class lib::IterAdapter< POS, CON >

Adapter for building an implementation of the »Lumiera Forward Iterator« concept.

The "current position" is represented as an opaque element (usually a nested iterator), with callbacks into the controlling container instance to manage this position. This allows to influence and customise the iteration process to a large extent. Basically such an IterAdapter behaves like the similar concept from STL, but

• it is not just a disguised pointer (meaning, it's more expensive)
• it checks validity on every operation and may throw
• it has a distinct back-link to the source container
• the source container needs to support checkPoint() and iterNext() free functions.
• we may need friendship to implement those extension points on the container
• the end-of-iteration can be detected by bool check

  Note

  it is possible to "hide" a smart-ptr within the CON template parameter.

  Template Parameters

  POS	pointer or similar mutable link to the current value. Will be bool() checked to detect iteration end, end else dereferenced.
  CON	type of the backing container, which needs to implement two extension point functions for iteration control

  Stipulations

• POS refers to the current position within the data source of this iterator.
  1. it should be default constructible
  2. it should be copy constructible
  3. when IterAdapter is supposed to be assignable, then POS should be
  4. it should provide embedded typedefs for pointer, reference and value_type, or alternatively resolve these types through specialisation of meta::ValueTypeBinding.
  5. it should be convertible to the pointer type it declares
  6. dereferencing should yield a type that is convertible to the reference type
• CON points to the data source of this iterator (typically a data container type) We store a pointer-like backlink to invoke a special iteration control API:
  1. checkPoint yields true iff the source has yet more result values to yield
  2. iterNext advances the POS to the next element

Note

• when POS is just a pointer, we use the pointee as value type
• but when POS is a class, we expect the usual STL style nested typedefs value_type, reference and pointer

See also

scoped-ptrvect.hpp usage example

value-type-binding.hpp

iter-adapter-test.cpp

Definition at line 206 of file iter-adapter.hpp.

Public Types
using	pointer = typename _ValTrait::pointer
using	reference = typename _ValTrait::reference
using	value_type = typename _ValTrait::value_type

Public Member Functions
	IterAdapter (CON src, POS const &startpos)
bool	empty () const
	ENABLE_USE_IN_STD_RANGE_FOR_LOOPS (IterAdapter)
bool	isValid () const
	operator bool () const
reference	operator* () const
IterAdapter &	operator++ ()
pointer	operator-> () const

Friends
template<class P1 , class P2 , class CX >
bool	operator== (IterAdapter< P1, CX > const &, IterAdapter< P2, CX > const &)
	comparison is allowed to access impl iterator

Protected Types
using	ConRef = typename meta::RefTraits< CON >::Reference

Protected Member Functions
bool	check () const
	ask the controlling container if this position is valid. More...
void	iterate ()
	ask the controlling container to yield the next position. More...
void	resetPos (POS otherPos)
ConRef	source ()
	allow derived classes to access backing container
const ConRef	source () const

Private Types
using	_ValTrait = meta::ValueTypeBinding< std::remove_pointer_t< POS > >

Private Member Functions
void	_maybe_throw () const

Private Attributes
POS	pos_
CON	source_

Member Function Documentation

check()

bool check ( ) const

inlineprotected

ask the controlling container if this position is valid.

Note

this function is called before any operation, thus the container may adjust the position value, for example setting it to a "stop iteration" mark.

Definition at line 283 of file iter-adapter.hpp.

iterate()

void iterate ( )

inlineprotected

ask the controlling container to yield the next position.

The call is dispatched only if the current position is valid; any new position reached will typically be validated prior to any further access, through invocation of check.

Definition at line 294 of file iter-adapter.hpp.

Inheritance diagram for IterAdapter< POS, CON >:

Collaboration diagram for IterAdapter< POS, CON >:

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

• iter-adapter.hpp