CxxUtils::PackedArray Class Reference

An array of unsigned values of some bit size, packed tightly. More...

#include <PackedArray.h>

List of all members.

Classes
class	proxy
	proxy class for representing an lvalue to an element of PackedArray. More...
Public Types
typedef size_t	size_type
typedef unsigned int	value_type
typedef basetype::allocator_type	allocator_type
Public Member Functions
	PackedArray (int bitsize, const allocator_type &allocator=allocator_type())
	Constructor.
	PackedArray (int bitsize, size_type n, value_type val=0, const allocator_type &allocator=allocator_type())
	Constructor.
void	assign (size_type n, value_type u)
	Set the container to multiple copies of the same value.
allocator_type	get_allocator () const
	Returns the allocator of the underlying vector.
size_type	size () const
	Returns the number of elements in the collection.
size_type	max_size () const
	Returns the size() of the largest possible collection.
size_type	capacity () const
	Returns the total number of elements that the collection can hold before needing to allocate more memory.
void	resize (size_type sz, value_type c=0)
	Resizes the collection to the specified number of elements.
bool	empty () const
	Returns true if the collection is empty.
void	reserve (size_type n)
	Attempt to preallocate enough memory for a specified number of elements.
value_type	get (size_type n) const
	Return the entry at index n.
void	set (size_type n, value_type val)
	Set the entry at index n.
value_type	operator[] (size_type n) const
	Access an element, as an rvalue.
proxy	operator[] (size_type n)
	Access an element, as an lvalue.
value_type	at (size_type n) const
	Access an element, as an rvalue.
proxy	at (size_type n)
	Access an element, as an lvalue.
value_type	front () const
	Access the first element in the collection as an rvalue.
value_type	back () const
	Access the last element in the collection as an rvalue.
proxy	front ()
	Access the first element in the collection as an lvalue.
proxy	back ()
	Access the last element in the collection as an lvalue.
void	push_back (value_type x)
	Add an element to the end of the collection.
void	pop_back ()
	Remove the last element from the collection.
void	swap (PackedArray &other)
	Swap this collection with another.
void	clear ()
	Erase all the elements in the collection.
void	set_bitsize (int bitsize)
	Change the bitsize of the container.
int	bitsize () const
	Return the bitsize of the container.

---

Detailed Description

An array of unsigned values of some bit size, packed tightly.

When creating an instance of this class, specify the bit size of the entries. The entries will be packed so that each takes exactly that many bits. For example, if the bit size is 10, 16 entries will be packed into 5 32-bit words. The bitsize may be changed, but only if the container is empty.

Any values assigned to the array that are too large to be represented in the specified number of bits will have the high bits silently dropped.

The interface is modeled after std::vector, except that there are no iterators. They could be added if there is a need for them.

---

Constructor & Destructor Documentation

CxxUtils::PackedArray::PackedArray	(	int	bitsize,
		const allocator_type &	allocator = allocator_type()
	)

Constructor.

Parameters:

	bitsize	The size, in bits, of each element. Must be greater than zero, and not larger than the size of an unsigned int.
	allocator	Allocator for the underlying vector.

CxxUtils::PackedArray::PackedArray	(	int	bitsize,
		size_type	n,
		value_type	val = 0,
		const allocator_type &	allocator = allocator_type()
	)

Constructor.

Parameters:

	bitsize	The size, in bits, of each element. Must be greater than zero, and not larger than the size of an unsigned int.
	n	Initial number of entries in the container.
	val	Value to which the initial entries are to be set.
	allocator	Allocator for the underlying vector.

---

Member Function Documentation

void CxxUtils::PackedArray::assign	(	size_type	n,
		value_type	u
	)

Set the container to multiple copies of the same value.

Parameters:

	n	Number of entries to which the container is to be set.
	u	Value to which the entries are to be set.
	n	Number of entries to which the container is to be set.
	val	Value to which the entries are to be set.

PackedArray::proxy CxxUtils::PackedArray::at

(

size_type

n

)

Access an element, as an lvalue.

Parameters:

n

Array index to access.

Returns:

Proxy to the element at n.

Will raise std::out_of_range if the index is out-of-bounds. Note that we return a proxy object rather than a reference.

PackedArray::value_type CxxUtils::PackedArray::at

(

size_type

n

)

const

Access an element, as an rvalue.

Parameters:

n

Array index to access.

Returns:

The element at n.

Will raise std::out_of_range if the index is out-of-bounds. Note that we return a value_type rather than a reference.

PackedArray::proxy CxxUtils::PackedArray::back

(

)

Access the last element in the collection as an lvalue.

Returns:

Proxy to the last element in the collection.

No checking is done to ensure that the container is not empty. Note that we return a proxy object rather than a reference.

PackedArray::value_type CxxUtils::PackedArray::back

(

)

const

Access the last element in the collection as an rvalue.

Returns:

The last element in the collection.

No checking is done to ensure that the container is not empty. Note that we return a value_type rather than a reference.

PackedArray::proxy CxxUtils::PackedArray::front

(

)

Access the first element in the collection as an lvalue.

Returns:

Proxy to the first element in the collection.

No checking is done to ensure that the container is not empty. Note that we return a proxy object rather than a reference.

PackedArray::value_type CxxUtils::PackedArray::front

(

)

const

Access the first element in the collection as an rvalue.

Returns:

The first element in the collection.

No checking is done to ensure that the container is not empty. Note that we return a value_type rather than a reference.

PackedArray::value_type CxxUtils::PackedArray::get

(

size_type

n

)

const

Return the entry at index n.

Parameters:

n

The index of the entry to retrieve.

PackedArray::proxy CxxUtils::PackedArray::operator[]

(

size_type

n

)

Access an element, as an lvalue.

Parameters:

n

Array index to access.

Returns:

Proxy to the element at n.

No bounds checking is done. Note that we return a proxy object rather than a reference.

PackedArray::value_type CxxUtils::PackedArray::operator[]

(

size_type

n

)

const

Access an element, as an rvalue.

Parameters:

n

Array index to access.

Returns:

The element at n.

No bounds checking is done. Note that we return a value_type rather than a reference.

void CxxUtils::PackedArray::push_back

(

value_type

x

)

Add an element to the end of the collection.

Parameters:

x

The element to add to the collection.

void CxxUtils::PackedArray::reserve

(

size_type

n

)

Attempt to preallocate enough memory for a specified number of elements.

Parameters:

n

Number of elements required.

void CxxUtils::PackedArray::resize	(	size_type	sz,
		value_type	c = 0
	)

Resizes the collection to the specified number of elements.

Parameters:

	sz	The new size of the collection.
	c	Value to which any new elements are to be set.

void CxxUtils::PackedArray::set	(	size_type	n,
		value_type	val
	)

Set the entry at index n.

Parameters:

	n	The index of the entry to set.
	val	The new value for the entry at index n.

void CxxUtils::PackedArray::set_bitsize

(

int

bitsize

)

Change the bitsize of the container.

bitsize The new bitsize. This method may only be called when the container is empty.

void CxxUtils::PackedArray::swap

(

PackedArray &

other

)

Swap this collection with another.

Parameters:

other

The collection with which to swap.

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

• /cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisBase/2.4.28/CxxUtils/CxxUtils/PackedArray.h
• /cvmfs/atlas.cern.ch/repo/sw/ASG/AnalysisBase/2.4.28/CxxUtils/Root/PackedArray.cxx