regina::PacketDescendants< const_ > Class Template Reference

A lightweight object that gives access to all strict descendants of a given packet. More...

#include <packet/packet.h>

Public Types
using	packet_type = typename std::conditional< const_, const Packet, Packet >::type
	Either Packet or const Packet, according to the template argument const_. More...

Public Member Functions
	PacketDescendants (const PacketDescendants &)=default
	Default copy constructor. More...
	PacketDescendants (std::shared_ptr< packet_type > subtree)
	Creates a new object for iterating through the strict descendants of the given packet. More...
PacketDescendants &	operator= (const PacketDescendants &)=default
	Default copy assignment operator. More...
SubtreeIterator< const_ >	begin () const
	Returns an iterator at the beginning of the range of strict descendants. More...
SubtreeIterator< const_ >	end () const
	Returns an iterator at the end of the range of strict descendants. More...
bool	operator== (const PacketDescendants &rhs) const
	Determines whether this and the given object are designed to iterate over strict descendants of the same packet. More...
bool	operator!= (const PacketDescendants &rhs) const
	Determines whether this and the given object are designed to iterate over strict descendants of different packets. More...

Detailed Description

template<bool const_>
class regina::PacketDescendants< const_ >

A lightweight object that gives access to all strict descendants of a given packet.

The purpose of this class is to support iteration through all strict descendants of a packet p using C++11 range-based for loops:

std::shared_ptr<Packet> parent = ...;
for (Packet& desc : parent->descendants()) { ... }

In Python, PacketDescendants is an iterable object:

parent = ...
for desc in parent.descendants():
    ...

Each object of this class will hold a std::shared_ptr to the packet whose descendants it gives access to. This guarantees that the packet will not be destroyed during iteration, but it also means that you must ensure that you dispose of these objects once you are finished with them.

These are lightweight objects, small enough to pass by value and swap with std::swap(), with no need for any specialised move operations or swap functions. Copies of a PacketDescendants will iterate over the descendants of the same underlying packet.

Template Parameters

const_

Indicates whether this iterator should offer const or non-const access to the packet tree.

Python

Instead of the C++ interface described here, in Python the classes PacketDescendants and SubtreeIterator together implement the Python iterable/iterator interface. The class PacketDescendants has just the single function iter(), which returns a SubtreeIterator; then SubtreeIterator implements next(), which either returns the next descendant packet in the iteration or else throws a StopException if there are no more children to return. All iteration in Python is non-const (i.e., Python exclusively uses the classes where const_ is false).

Member Typedef Documentation

packet_type

template<bool const_>

using regina::PacketDescendants< const_ >::packet_type = typename std::conditional<const_, const Packet, Packet>::type

Either Packet or const Packet, according to the template argument const_.

Constructor & Destructor Documentation

PacketDescendants() [1/2]

template<bool const_>

regina::PacketDescendants< const_ >::PacketDescendants ( const PacketDescendants< const_ > &  )

default

Default copy constructor.

Python

Not present.

PacketDescendants() [2/2]

template<bool const_>

regina::PacketDescendants< const_ >::PacketDescendants ( std::shared_ptr< packet_type >  subtree )

inline

Creates a new object for iterating through the strict descendants of the given packet.

Python

Not present.

Parameters

subtree

the packet whose strict descendants we will iterate through.

Member Function Documentation

begin()

template<bool const_>

SubtreeIterator< const_ > regina::PacketDescendants< const_ >::begin

inline

Returns an iterator at the beginning of the range of strict descendants.

This will point to the first child packet (if one exists) of the packet whose descendants we are iterating over.

Python

Not present; instead this class implements iter(), as described in the class notes.

Returns

the beginning iterator.

end()

template<bool const_>

SubtreeIterator< const_ > regina::PacketDescendants< const_ >::end

inline

Returns an iterator at the end of the range of strict descendants.

Python

Not present; instead this class implements iter(), as described in the class notes.

Returns

the past-the-end iterator.

operator!=()

template<bool const_>

bool regina::PacketDescendants< const_ >::operator!=

(

const PacketDescendants< const_ > &

rhs

)

const

Determines whether this and the given object are designed to iterate over strict descendants of different packets.

Returns

true if and only if this object and rhs iterate over descendants of different packets.

operator=()

template<bool const_>

PacketDescendants & regina::PacketDescendants< const_ >::operator= ( const PacketDescendants< const_ > &  )

default

Default copy assignment operator.

Python

Not present.

operator==()

template<bool const_>

bool regina::PacketDescendants< const_ >::operator==

(

const PacketDescendants< const_ > &

rhs

)

const

Determines whether this and the given object are designed to iterate over strict descendants of the same packet.

Returns

true if and only if this object and rhs iterate over descendants of the same packet.

---

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

• packet/packet.h