LoanableSequence< T, _NonConstEnabler > Class Template Reference

A type-safe, ordered collection of elements that can receive the buffer from outside (loan). More...

#include <LoanableSequence.hpp>

Inheritance diagram for LoanableSequence< T, _NonConstEnabler >:

Public Types
using	size_type = LoanableCollection::size_type
using	element_type = LoanableCollection::element_type
Public Types inherited from LoanableCollection
using	size_type = int32_t
using	element_type = void *

Public Member Functions
	LoanableSequence ()=default
	Default constructor.
	LoanableSequence (size_type max)
	Pre-allocation constructor.
	~LoanableSequence ()
	Deallocate this sequence's buffer.
	LoanableSequence (const LoanableSequence &other)
	Construct a sequence with the contents of another sequence.
LoanableSequence &	operator= (const LoanableSequence &other)
	Copy the contents of another sequence into this one.
Public Member Functions inherited from LoanableTypedCollection< T, _NonConstEnabler >
template<typename Enabler = _NonConstEnabler>
std::enable_if< Enabler::value, T >::type &	operator[] (size_type n)
	Set an element of the sequence.
const T &	operator[] (size_type n) const
	Get an element of the sequence.
Public Member Functions inherited from LoanableCollection
const element_type *	buffer () const
	Get the pointer to the elements buffer.
bool	has_ownership () const
	Get the ownership flag.
size_type	maximum () const
	Get the maximum number of elements currently allocated.
size_type	length () const
	Get the number of elements currently accessible.
bool	length (size_type new_length)
	Set the number of elements currently accessible.
bool	loan (element_type *buffer, size_type new_maximum, size_type new_length)
	Loan a buffer to the collection.
element_type *	unloan (size_type &maximum, size_type &length)
	Remove the loan from the collection.
element_type *	unloan ()
	Remove the loan from the collection.

Protected Attributes
size_type	maximum_
size_type	length_
element_type *	elements_
bool	has_ownership_
Protected Attributes inherited from LoanableCollection
size_type	maximum_ = 0
size_type	length_ = 0
element_type *	elements_ = nullptr
bool	has_ownership_ = true

Additional Inherited Members
Protected Member Functions inherited from LoanableCollection
	LoanableCollection ()=default
	Default constructor.

Detailed Description

template<typename T, typename _NonConstEnabler = std::true_type>
class eprosima::fastdds::dds::LoanableSequence< T, _NonConstEnabler >

A type-safe, ordered collection of elements that can receive the buffer from outside (loan).

For users who define data types in OMG IDL, this type corresponds to the IDL express sequence<T>.

For any user-data type Foo that an application defines for the purpose of data-distribution with Fast DDS, a 'using FooSeq = LoanableSequence<Foo>' is generated. The sequence offers a subset of the methods defined by the standard OMG IDL to C++ mapping for sequences. We refer to an IDL 'sequence<Foo>' as FooSeq.

The state of a sequence is described by the properties 'maximum', 'length' and 'has_ownership'.

• The 'maximum' represents the size of the underlying buffer; this is the maximum number of elements it can possibly hold. It is returned by the maximum() operation.
• The 'length' represents the actual number of elements it currently holds. It is returned by the length() operation.
• The 'has_ownership' flag represents whether the sequence owns the underlying buffer. It is returned by the has_ownership() operation. If the sequence does not own the underlying buffer, the underlying buffer is loaned from somewhere else. This flag influences the lifecycle of the sequence and what operations are allowed on it. The general guidelines are provided below and more details are described in detail as pre-conditions and post-conditions of each of the sequence's operations:

• If has_ownership == true, the sequence has ownership on the buffer. It is then responsible for destroying the buffer when the sequence is destroyed.
• If has_ownership == false, the sequence does not have ownership on the buffer. This implies that the sequence is loaning the buffer. The sequence should not be destroyed until the loan is returned.
• A sequence with a zero maximum always has has_ownership == true

Member Typedef Documentation

element_type

template<typename T , typename _NonConstEnabler = std::true_type>

using element_type = LoanableCollection::element_type

size_type

template<typename T , typename _NonConstEnabler = std::true_type>

using size_type = LoanableCollection::size_type

Constructor & Destructor Documentation

LoanableSequence() [1/3]

template<typename T , typename _NonConstEnabler = std::true_type>

LoanableSequence ( )

default

Default constructor.

Creates the sequence with no data.

Postcondition

buffer() == nullptr

has_ownership() == true

length() == 0

maximum() == 0

LoanableSequence() [2/3]

template<typename T , typename _NonConstEnabler = std::true_type>

LoanableSequence ( size_type  max )

inline

Pre-allocation constructor.

Creates the sequence with an initial number of allocated elements. When the input parameter is less than or equal to 0, the behavior is equivalent to the default constructor. Otherwise, the post-conditions below will apply.

Parameters

[in]

max

Number of elements to pre-allocate.

Postcondition

buffer() != nullptr

has_ownership() == true

length() == 0

maximum() == max

~LoanableSequence()

template<typename T , typename _NonConstEnabler = std::true_type>

~LoanableSequence ( )

inline

Deallocate this sequence's buffer.

Precondition

has_ownership() == true. If this precondition is not met, no memory will be released and a warning will be logged.

Postcondition

maximum() == 0 and the underlying buffer is released.

LoanableSequence() [3/3]

template<typename T , typename _NonConstEnabler = std::true_type>

LoanableSequence ( const LoanableSequence< T, _NonConstEnabler > &  other )

inline

Construct a sequence with the contents of another sequence.

This method performs a deep copy of the sequence received into this one. Allocations will happen when other.length() > 0

Parameters

[in]

other

The sequence from where contents are to be copied.

Postcondition

has_ownership() == true

maximum() == other.length()

length() == other.length()

buffer() != nullptr when other.length() > 0

Member Function Documentation

operator=()

template<typename T , typename _NonConstEnabler = std::true_type>

LoanableSequence & operator= ( const LoanableSequence< T, _NonConstEnabler > &  other )

inline

Copy the contents of another sequence into this one.

This method performs a deep copy of the sequence received into this one. If this sequence had a buffer loaned, it will behave as if unloan has been called. Allocations will happen when (a) has_ownership() == false and other.length() > 0 (b) has_ownership() == true and other.length() > maximum()

Parameters

[in]

other

The sequence from where contents are to be copied.

Postcondition

has_ownership() == true

maximum() >= other.length()

length() == other.length()

buffer() != nullptr when other.length() > 0

Member Data Documentation

elements_

template<typename T , typename _NonConstEnabler = std::true_type>

element_type* elements_

protected

has_ownership_

template<typename T , typename _NonConstEnabler = std::true_type>

bool has_ownership_

protected

length_

template<typename T , typename _NonConstEnabler = std::true_type>

size_type length_

protected

maximum_

template<typename T , typename _NonConstEnabler = std::true_type>

size_type maximum_

protected

---

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

• include/fastdds/dds/core/LoanableSequence.hpp