regina::ListView< Container > Class Template Reference

A lightweight object that can be used for iteration and random access to all elements of a given list. More...

#include <utilities/listview.h>

Public Types
using	value_type = typename Container::value_type
	The type of element that is stored in this list. More...
using	size_type = typename Container::size_type
	The type used for indexing into this list. More...
using	reference = typename Container::const_reference
	A reference to a list element. More...
using	const_reference = typename Container::const_reference
	A reference to a list element. More...
using	iterator = typename Container::const_iterator
	The iterator type for this list view. More...
using	const_iterator = typename Container::const_iterator
	The iterator type for this list view. More...

Public Member Functions
	ListView (const Container &list)
	Returns a view for the given list. More...
	ListView (const ListView &)=default
	Creates a new copy of the given list view. More...
ListView &	operator= (const ListView &)=default
	Sets this to be a copy of the given list view. More...
bool	empty () const
	Determines if this list is empty. More...
size_type	size () const
	Returns the number of elements in this list. More...
const_reference	operator[] (size_type index) const
	Returns the requested element of this list. More...
const_reference	front () const
	Returns the first element of this list. More...
const_reference	back () const
	Returns the last element of this list. More...
const_iterator	begin () const
	Returns an iterator pointing to the first element. More...
const_iterator	end () const
	Returns an iterator pointing beyond the last element. More...

Detailed Description

template<class Container>
class regina::ListView< Container >

A lightweight object that can be used for iteration and random access to all elements of a given list.

Typically a ListView would be returned from a class member function to grant the user some basic read-only access to a much richer private data structure, in a way that allows the internal data structure to change at some later date without affecting the public API.

The ListView class supports two different ways of representing a list:

• If your list is stored using a container class (e.g., std::vector or regina::MarkedVector), then you can create a ListView directly from the container using the syntax ListView(container). This uses the generic ListView<Container> class template. There is no need to explicitly specify the ListView template arguments.
• If your list is stored using a C-style array, you can create a ListView using either the syntax ListView(array, size) or ListView(begin, end). Here begin and end are an iterator pair (that is, begin == array and end == array + size). This syntax uses the specialised ListView<Element*> class template. Again, there is no need to explicitly specify the ListView template arguments.

End users should always store ListView objects using auto, not by explicitly writing out the full ListView type. One reason for this is that, if/when Regina moves to C++20, the ListView class will most likely be removed completely (in favour of the new C++20 ranges library).

ListView objects are small enough to pass by value and swap with std::swap(), with no need for any specialised move operations or swap functions.

Template Parameters

Container

the internal type of the list that this object grants access to. This type must support at least the same operations as this class itself, except for the copy semantics. In particular, both std::vector and regina::MarkedVector types (as well as many other standard container types) are suitable.

Member Typedef Documentation

const_iterator

template<class Container >

using regina::ListView< Container >::const_iterator = typename Container::const_iterator

The iterator type for this list view.

Both iterator and const_iterator are the same, since this class only offers read-only access to the underlying list.

const_reference

template<class Container >

using regina::ListView< Container >::const_reference = typename Container::const_reference

A reference to a list element.

Both reference and const_reference are the same, since this class only offers read-only access to the underlying list.

iterator

template<class Container >

using regina::ListView< Container >::iterator = typename Container::const_iterator

The iterator type for this list view.

Both iterator and const_iterator are the same, since this class only offers read-only access to the underlying list.

reference

template<class Container >

using regina::ListView< Container >::reference = typename Container::const_reference

A reference to a list element.

Both reference and const_reference are the same, since this class only offers read-only access to the underlying list.

size_type

template<class Container >

using regina::ListView< Container >::size_type = typename Container::size_type

The type used for indexing into this list.

value_type

template<class Container >

using regina::ListView< Container >::value_type = typename Container::value_type

The type of element that is stored in this list.

Constructor & Destructor Documentation

ListView() [1/2]

template<class Container >

regina::ListView< Container >::ListView

(

const Container &

list

)

Returns a view for the given list.

Parameters

list	the list that this object will access. Internally, this object will store a reference to list (which means list needs to exist for at least as long as this object).

ListView() [2/2]

template<class Container >

regina::ListView< Container >::ListView ( const ListView< Container > &  )

default

Creates a new copy of the given list view.

Member Function Documentation

back()

template<class Container >

ListView< Container >::const_reference regina::ListView< Container >::back

inline

Returns the last element of this list.

Precondition

This list is not empty.

Returns

the last element in this list.

begin()

template<class Container >

ListView< Container >::const_iterator regina::ListView< Container >::begin

inline

Returns an iterator pointing to the first element.

Python

ListView is an iterable object: instead of providing begin() and end(), it implements the Python iterable interface.

Returns

an iterator at the beginning of this list.

empty()

template<class Container >

bool regina::ListView< Container >::empty

inline

Determines if this list is empty.

Returns

true if and only if this list is empty.

end()

template<class Container >

ListView< Container >::const_iterator regina::ListView< Container >::end

inline

Returns an iterator pointing beyond the last element.

Python

ListView is an iterable object: instead of providing begin() and end(), it implements the Python iterable interface.

Returns

an iterator beyond the end of this list.

front()

template<class Container >

ListView< Container >::const_reference regina::ListView< Container >::front

inline

Returns the first element of this list.

Precondition

This list is not empty.

Returns

the first element in this list.

operator=()

template<class Container >

ListView & regina::ListView< Container >::operator= ( const ListView< Container > &  )

default

Sets this to be a copy of the given list view.

Returns

a reference to this list view.

operator[]()

template<class Container >

ListView< Container >::const_reference regina::ListView< Container >::operator[] ( size_type  index ) const

inline

Returns the requested element of this list.

Parameters

index

indicates which element to return; this must be between 0 and size()-1 inclusive.

Returns

the (index)th element in this list.

size()

template<class Container >

ListView< Container >::size_type regina::ListView< Container >::size

inline

Returns the number of elements in this list.

Returns

the number of elements.

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

• utilities/listview.h