<<interface>> <<generic>> <<cert>> A type-safe, ordered collection of elements. The type of these elements is referred to in this documentation as "Foo". More...

#include <dds_cpp_sequence_defn.hxx>

Public Member Functions
FooSeq &	operator= (const struct FooSeq &src_seq)
	Copy elements from another sequence, resizing the sequence if necessary.
bool	copy_no_alloc (const struct FooSeq &src_seq)
	Copy elements from another sequence, only if the destination sequence has enough capacity.
bool	from_array (const Foo array[], DDS_Long length)
	Copy elements from an array of elements, resizing the sequence if necessary. The original contents of the sequence (if any) are replaced.
bool	to_array (Foo array[], DDS_Long length)
	Copy elements to an array of elements. The original contents of the array (if any) are replaced.
Foo &	operator[] (DDS_Long i)
	Get the `i-th` element of the sequence.
const Foo &	operator[] (DDS_Long i) const
	Get the `i-th` element for a `const` sequence.
DDS_Long	length () const
	<<cert>> Get the logical length of this sequence.
bool	length (DDS_Long new_length)
	<<cert>> Change the length of this sequence.
bool	ensure_length (DDS_Long length, DDS_Long max)
	Set the sequence to the desired length, and resize the sequence if necessary.
DDS_Long	maximum () const
	<<cert>> Get the current maximum number of elements that can be stored in this sequence.
bool	maximum (DDS_Long new_max)
	<<cert>> Resize this sequence to a new desired maximum.
bool	loan_contiguous (Foo *buffer, DDS_Long new_length, DDS_Long new_max)
	Loan a contiguous buffer to this sequence.
bool	unloan ()
	Return the loaned buffer in the sequence and set the maximum to 0.
Foo *	get_contiguous_buffer () const
	Access the internal buffer of a sequence.
bool	has_ownership ()
	Return the value of the owned flag.
	~FooSeq ()
	Deallocate this sequence's buffer.
	FooSeq (DDS_Long new_max=0)
	Create a sequence with the given maximum.
	FooSeq (const struct FooSeq &foo_seq)
	Create a sequence by copying from an existing sequence.

Public Attributes
Foo *	_contiguous_buffer
	Pointer to array of contiguous or discontiguous data.
DDS_UnsignedLong	_maximum
	Maximum size of the sequence.
DDS_UnsignedLong	_length
	Actual length of the sequence that contains data.
DDS_Long	_element_size
	Size of data element in the sequence.
void *	_token1
	Reserved for internal use.
void *	_token2
	Reserved for internal use.
DDS_UnsignedLong	max_alloc_size
	The maximum allocation for pointer elements (string,wstring) Only in debug librarires.
DDS_Char	_flags
	Reserved for internal use.

Detailed Description

<<interface>> <<generic>> <<cert>> A type-safe, ordered collection of elements. The type of these elements is referred to in this documentation as "Foo".

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', and 'length'.

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 FooSeq::maximum() operation.

The 'length' represents the actual number of elements it currently holds. It is returned by the FooSeq::length() operation.

Constructor & Destructor Documentation

FooSeq::~FooSeq ( )

Deallocate this sequence's buffer.

Precondition:: (owned == DDS_BOOLEAN_TRUE). If this precondition is not met, no memory will be freed and an error will be logged.

Postcondition:: maximum == 0 and the underlying buffer is freed.

See also:: FooSeq::maximum(), FooSeq::unloan

FooSeq::FooSeq ( DDS_Long new_max = 0 )

Create a sequence with the given maximum.

This is a constructor for the sequence. The constructor will automatically allocate memory to hold new_max elements of type Foo.

This constructor will be used when the application creates a sequence using one of the following:

 FooSeq mySeq(5);
  // or
  FooSeq mySeq;
  // or
  FooSeq* mySeqPtr = new FooSeq(5);

Postcondition:: maximum == new_max; length == 0; owned == DDS_BOOLEAN_TRUE,

Parameters:

new_max Must be >= 0. Otherwise the sequence will be initialized to a new_max=0.

FooSeq::FooSeq ( const struct FooSeq & foo_seq )

Create a sequence by copying from an existing sequence.

This is a constructor for the sequence. The constructor will automatically allocate memory to hold foo_seq::maximum() elements of type Foo and will copy the current contents of foo_seq into the new sequence.

This constructor will be used when the application creates a sequence using one of the following:

 FooSeq mySeq(foo_seq);
  // or
  FooSeq mySeq = foo_seq;
  // or
  FooSeq *mySeqPtr = new FooSeq(foo_seq);

Postcondition:: this::maximum == foo_seq::maximum; this::length == foo_seq::length; this[i] == foo_seq[i] for 0 <= i < foo_seq::length; this::owned == DDS_BOOLEAN_TRUE

Note:: If the pre-conditions are not met, the constructor will initialize the new sequence to a maximum of zero.

Member Function Documentation

FooSeq& FooSeq::operator= ( const struct FooSeq & src_seq )

Copy elements from another sequence, resizing the sequence if necessary.

This method invokes copies the content of the specified sequence, after ensuring that this sequence has enough capacity to hold the elements to be copied.

NOTE: If this method is called on a sequence that has been created with set_maximum_w_max or ensure_length_w_max, it will automatically call copy_w_max().

This operator is invoked when the following expression appears in the code:

target_seq = src_seq

Important: This method will allocate memory if this::maximum < src_seq::length.

Therefore, to programatically detect the successful completion of the operator it is recommended that the application first sets the length of this sequence to zero, makes the assignment, and then checks that the length of this sequence matches that of src_seq.

Parameters:

src_seq <<in>> the sequence from which to copy

bool FooSeq::copy_no_alloc ( const struct FooSeq & src_seq )

Copy elements from another sequence, only if the destination sequence has enough capacity.

Fill the elements in this sequence by copying the corresponding elements in src_seq. The original contents in this sequence are replaced via the element assignment operation (Foo_copy() function). By default, elements are discarded; 'delete' is not invoked on the discarded elements.

Precondition:: this::maximum >= src_seq::length; this::owned == DDS_BOOLEAN_TRUE

Postcondition:: this::length == src_seq::length; this[i] == src_seq[i] for 0 <= i < target_seq::length; this::owned == DDS_BOOLEAN_TRUE

Parameters:

src_seq <<in>> the sequence from which to copy

Returns:: DDS_BOOLEAN_TRUE if the sequence was successfully copied; DDS_BOOLEAN_FALSE otherwise.

Note:: If the pre-conditions are not met, the operator will print a message to stdout and leave this sequence unchanged.

See also:: FooSeq::operator=

bool FooSeq::from_array	(	const Foo	array[],
		DDS_Long	length
	)

Copy elements from an array of elements, resizing the sequence if necessary. The original contents of the sequence (if any) are replaced.

Fill the elements in this sequence by copying the corresponding elements in array. The original contents in this sequence are replaced via the element assignment operation (Foo_copy() function). By default, elements are discarded; 'delete' is not invoked on the discarded elements.

Precondition:: this::owned == DDS_BOOLEAN_TRUE

Postcondition:: this::length == length; this[i] == array[i] for 0 <= i < length; this::owned == DDS_BOOLEAN_TRUE

Parameters:

array	<<in>> The array of elements to be copy elements from
length	<<in>> The length of the array.

Returns:: DDS_BOOLEAN_TRUE if the array was successfully copied; DDS_BOOLEAN_FALSE otherwise.

bool FooSeq::to_array	(	Foo	array[],
		DDS_Long	length
	)

Copy elements to an array of elements. The original contents of the array (if any) are replaced.

Copy the elements of this sequence to the corresponding elements in the array. The original contents of the array are replaced via the element assignment operation (Foo_copy() function). By default, elements are discarded; 'delete' is not invoked on the discarded elements.

Parameters:

array	<<in>> The array of elements to be filled with elements from this sequence
length	<<in>> The number of elements to be copied.

Returns:: DDS_BOOLEAN_TRUE if the elements of the sequence were successfully copied; DDS_BOOLEAN_FALSE otherwise.

Foo& FooSeq::operator[] ( DDS_Long i )

Get the i-th element of the sequence.

This is the operator that is invoked when the application indexes into a non-const sequence:

myElement = mySequence[i];

mySequence[i] = myElement;

Parameters:

i	index of element to access, must be >= 0 and less than FooSeq::length()

Returns:: the i-th element

const Foo& FooSeq::operator[] ( DDS_Long i ) const

Get the i-th element for a const sequence.

This is the operator that is invoked when the application indexes into a const sequence:

myElement = mySequence[i];

Parameters:

i	index of element to access, must be >= 0 and less than FooSeq::length()

Returns:: the i-th element

DDS_Long FooSeq::length ( ) const

<<cert>> Get the logical length of this sequence.

Get the length that was last set, or zero if the length has never been set.

Returns:: the length of the sequence

bool FooSeq::length ( DDS_Long new_length )

<<cert>> Change the length of this sequence.

This method does not allocate/deallocate memory.

The new length must not exceed the maximum of this sequence as returned by the FooSeq::maximum() operation. (Note that, if necessary, the maximum of this sequence can be increased manually by using the FooSeq::maximum(DDS_Long) operation.)

The elements of the sequence are not modified by this operation. If the new length is larger than the original length, the new elements will be uninitialized; if the length is decreased, the old elements that are beyond the new length will physically remain in the sequence but will not be accessible.

Postcondition:: length = new_length.

Parameters:

new_length the new desired length. This value must be non-negative and cannot exceed maximum of the sequence. In other words 0 <= new_length <= maximum

Returns:: DDS_BOOLEAN_TRUE on sucess or DDS_BOOLEAN_FALSE on failure

bool FooSeq::ensure_length	(	DDS_Long	length,
		DDS_Long	max
	)

Set the sequence to the desired length, and resize the sequence if necessary.

If the current maximum is greater than the desired length, then sequence is not resized.

Otherwise if this sequence owns its buffer, the sequence is resized to the new maximum by freeing and re-allocating the buffer. However, if the sequence does not own its buffer, this operation will fail.

This function allows user to avoid unnecessary buffer re-allocation.

Precondition:: length <= max; owned == DDS_BOOLEAN_TRUE if sequence needs to be resized

Postcondition:: length == length; maximum == max if resized

Parameters:

length	<<in>> The new length that should be set. Must be >= 0.
max	<<in>> If sequence need to be resized, this is the maximum that should be set. max >= length

Returns:: DDS_BOOLEAN_TRUE on success, DDS_BOOLEAN_FALSE if the preconditions are not met. In that case the sequence is not modified.

DDS_Long FooSeq::maximum ( ) const

<<cert>> Get the current maximum number of elements that can be stored in this sequence.

The maximum of the sequence represents the maximum number of elements that the underlying buffer can hold. It does not represent the current number of elements.

The maximum is a non-negative number. It is initialized when the sequence is first created and can only be changed by mean of the FooSeq::maximum(DDS_Long) operation.

Returns:: the current maximum of the sequence.

See also:: FooSeq::length()

bool FooSeq::maximum ( DDS_Long new_max )

<<cert>> Resize this sequence to a new desired maximum.

This operation does nothing if the new desired maximum matches the current maximum.

If this sequence owns its buffer and the new maximum is not equal to the old maximum, then the existing buffer will be freed and re-allocated.

Precondition:: owned == DDS_BOOLEAN_TRUE

Postcondition:: owned == DDS_BOOLEAN_TRUE; length == MINIMUM(original length, new_max)

Parameters:

new_max Must be >= 0.

Returns:: DDS_BOOLEAN_TRUE on success, DDS_BOOLEAN_FALSE if the preconditions are not met. In that case the sequence is not modified.

bool FooSeq::loan_contiguous	(	Foo *	buffer,
		DDS_Long	new_length,
		DDS_Long	new_max
	)

Loan a contiguous buffer to this sequence.

This operation changes the owned flag of the sequence to DDS_BOOLEAN_FALSE and also sets the underlying buffer used by the sequence. See the user's manual for more information about sequences and memory ownership.

Use this method if you want to manage the memory used by the sequence yourself. You must provide an array of elements and integers indicating how many elements are allocated in that array (i.e. the maximum) and how many elements are valid (i.e. the length). The sequence will subsequently use the memory you provide and will not permit it to be freed by a call to FooSeq::maximum(DDS_Long).

Once you have loaned a buffer to a sequence, make sure that you don't free it before calling FooSeq::unloan: the next time you access the sequence, you will be accessing freed memory!

You can use this method to wrap stack memory with a sequence interface, thereby avoiding dynamic memory allocation. Create a FooSeq and an array of type Foo and then loan the array to the sequence:

 Foo fooArray[10];
  ::FooSeq fooSeq;
  fooSeq.loan_contiguous(fooArray, 0, 10); 

By default, a sequence you create owns its memory unless you explicitly loan memory of your own to it. In a very few cases, RTI Connext DDS Micro will return a sequence to you that has a loan; those cases are documented as such. For example, if you call FooDataReader::read or FooDataReader::take and pass in sequences with no loan and no memory allocated, RTI Connext DDS Micro will loan memory to your sequences which must be unloaned with FooDataReader::return_loan. See the documentation of those methods for more information.

Precondition:: FooSeq::maximum() == 0; i.e. the sequence has no memory allocated to it.; FooSeq::has_ownership == DDS_BOOLEAN_TRUE; i.e. the sequence does not already have an outstanding loan

Postcondition:: The sequence will store its elements in the buffer provided.; FooSeq::has_ownership == DDS_BOOLEAN_FALSE; FooSeq::length() == new_length; FooSeq::maximum() == new_max

Parameters:

buffer	The new buffer that the sequence will use. Must point to enough memory to hold new_max elements of type Foo. It may be NULL if new_max == 0.
new_length	The desired new length for the sequence. It must be the case that that 0 <= new_length <= new_max.
new_max	The allocated number of elements that could fit in the loaned buffer.

Returns:: DDS_BOOLEAN_TRUE if buffer is successfully loaned to this sequence or DDS_BOOLEAN_FALSE otherwise. Failure only occurs due to failing to meet the pre-conditions. Upon failure the sequence remains unmodified.

See also:: FooSeq::unloan

bool FooSeq::unloan ( )

Return the loaned buffer in the sequence and set the maximum to 0.

This method affects only the state of this sequence; it does not change the contents of the buffer in any way.

Only the user who originally loaned a buffer should return that loan, as the user may have dependencies on that memory known only to them. Unloaning someone else's buffer may cause unspecified problems. For example, suppose a sequence is loaning memory from a custom memory pool. A user of the sequence likely has no way to release the memory back into the pool, so unloaning the sequence buffer would result in a resource leak. If the user were to then re-loan a different buffer, the original creator of the sequence would have no way to discover, when freeing the sequence, that the loan no longer referred to its own memory and would thus not free the user's memory properly, exacerbating the situation and leading to undefined behavior.

Precondition:: owned == DDS_BOOLEAN_FALSE

Postcondition:: owned == DDS_BOOLEAN_TRUE; maximum == 0

Returns:: DDS_BOOLEAN_TRUE if the preconditions were met. Otherwise DDS_BOOLEAN_FALSE. The function only fails if the pre-conditions are not met, in which case it leaves the sequence unmodified.

See also:: FooSeq::loan_contiguous FooSeq::maximum(DDS_Long)

Foo* FooSeq::get_contiguous_buffer ( ) const

Access the internal buffer of a sequence.

Use this function to access the memory buffer that a sequence uses to store the values of its elements.

bool FooSeq::has_ownership ( )

Return the value of the owned flag.

Returns:: DDS_BOOLEAN_TRUE if sequence owns the underlying buffer, or DDS_BOOLEAN_FALSE if it has an outstanding loan.

Member Data Documentation

Foo* FooSeq::_contiguous_buffer

Pointer to array of contiguous or discontiguous data.

DDS_UnsignedLong FooSeq::_maximum

Maximum size of the sequence.

The allocated length of this sequence. It applies to whichever of the above buffers is non-NULL, if any. If both a NULL, its value must be 0.

If _maximum == 0, _owned == true.

DDS_UnsignedLong FooSeq::_length

Actual length of the sequence that contains data.

The current logical length of this seqeunce, i.e. the number of valid elements it contains. It applies to whichever of the above buffers is non-null, if any. If both are NULL, its value must be 0.

DDS_Long FooSeq::_element_size

Size of data element in the sequence.

Each element in the sequence has this size.

void* FooSeq::_token1

Reserved for internal use.

void* FooSeq::_token2

Reserved for internal use.

DDS_UnsignedLong FooSeq::max_alloc_size

The maximum allocation for pointer elements (string,wstring) Only in debug librarires.

DDS_Char FooSeq::_flags

Reserved for internal use.

Public Member Functions

Public Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation