RWBag Class Reference

Corresponds to the Smalltalk class Bag, representing a group of unordered elements not accessible by an external key. More...

#include <rw/rwbag.h>

Inheritance diagram for RWBag:

Public Member Functions
	RWBag ()
	RWBag (size_t n)
	RWBag (const RWBag &b)
	RWBag (RWBag &&b)
virtual	~RWBag ()
virtual void	apply (RWapplyCollectable ap, void *)
size_t	buckets () const
virtual void	clear ()
virtual void	clearAndDestroy ()
virtual RWCollectable *	copy () const
virtual size_t	entries () const
virtual RWCollectable *	find (const RWCollectable *target) const
virtual RWCollectable *	insert (RWCollectable *c)
RWCollectable *	insertWithOccurrences (RWCollectable *c, int n)
virtual RWClassID	isA () const
virtual bool	isEmpty () const
virtual bool	isEqual (const RWCollectable *a) const
virtual RWConstIterator *	newConstIterator () const
virtual RWIterator *	newIterator ()
virtual RWCollectable *	newSpecies () const
virtual size_t	occurrencesOf (const RWCollectable *target) const
RWBag &	operator= (const RWBag &b)
RWBag &	operator= (RWBag &&b)
bool	operator== (const RWBag &b) const
virtual RWCollectable *	remove (const RWCollectable *target)
virtual void	removeAndDestroy (const RWCollectable *target)
void	resize (size_t n=0)
void	swap (RWBag &b)
Public Member Functions inherited from RWCollection
virtual	~RWCollection ()
RWBag	asBag () const
RWBinaryTree	asBinaryTree () const
RWOrdered	asOrderedCollection () const
RWSet	asSet () const
RWBinaryTree	asSortedCollection () const
virtual RWspace	binaryStoreSize () const
virtual bool	contains (const RWCollectable *target) const
void	operator+= (const RWCollection &c)
void	operator-= (const RWCollection &c)
virtual void	restoreGuts (RWvistream &)
virtual void	restoreGuts (RWFile &)
virtual void	saveGuts (RWvostream &) const
virtual void	saveGuts (RWFile &) const
RWCollection *	select (RWtestCollectable tst, void *vp) const
Public Member Functions inherited from RWCollectable
virtual	~RWCollectable ()
virtual int	compareTo (const RWCollectable *) const
virtual unsigned	hash () const
RWspace	recursiveStoreSize () const
RWStringID	stringID () const

Static Public Member Functions
static RWClassID	classIsA ()
Static Public Member Functions inherited from RWCollectable
static RWClassID	classID (const RWStringID &name)
static RWClassID	classIsA ()
static bool	isAtom (RWClassID id)
static RWspace	nilStoreSize ()

Additional Inherited Members
Static Public Attributes inherited from RWCollection
static size_t	DEFAULT_CAPACITY
Related Functions inherited from RWCollection
typedef void(*	RWapplyCollectable) (RWCollectable *, void *)
typedef bool(*	RWtestCollectable) (const RWCollectable *, const void *)
typedef bool(*	RWtestCollectablePair) (const RWCollectable *, const RWCollectable *, const void *)

Detailed Description

Class RWBag corresponds to the Smalltalk class Bag. It represents a group of unordered elements, not accessible by an external key. Duplicates are allowed.

An object stored by RWBag must inherit abstract base class RWCollectable, with suitable definition for virtual functions RWCollectable::hash() and RWCollectable::isEqual(). The function hash() is used to find objects with the same hash value, then isEqual() is used to confirm the match.

Class RWBag is implemented by using an internal hashed dictionary (RWHashDictionary) which keeps track of the number of occurrences of an item. If an item is added to the collection that compares equal (isEqual()) to an existing item in the collection, then the count is incremented. Note that this means that only the first instance of a value is actually inserted: subsequent instances cause the occurrence count to be incremented. This behavior parallels the Smalltalk implementation of Bag.

Member function apply() and the iterator are called repeatedly according to the count for an item.

See class RWHashTable if you want duplicates to be stored, rather than merely counted.

Synopsis

typedef RWBag Bag;     // Smalltalk typedef .
#include <rw/rwbag.h>
RWBag h;

Persistence

Polymorphic

Constructor & Destructor Documentation

RWBag::RWBag

(

)

Constructs an empty bag with RWCollection::DEFAULT_CAPACITY buckets.

RWBag::RWBag

(

size_t

n

)

Constructs an empty bag with n buckets.

RWBag::RWBag

(

const RWBag &

b

)

Copy constructor. Makes a shallow copy of b.

RWBag::RWBag

(

RWBag &&

b

)

Move constructor. The constructed RWBag takes ownership of the data owned by b.

Condition:

This method is available only on platforms with rvalue reference support.

virtual RWBag::~RWBag ( )

virtual

Calls the clear() method.

Member Function Documentation

virtual void RWBag::apply ( RWapplyCollectable  ap, void *    )

virtual

Invokes the function pointer ap on each item in the collection in a generally unpredictable order. If an item has been inserted more than once (i.e., more than one item isEqual()), then apply() will be called that many times. The function pointed to by ap should take no action that could change the hash value or the meaning of isEqual() for the items.

Implements RWCollection.

size_t RWBag::buckets ( ) const

inline

Returns the current number of buckets allocated to the internal hash table.

static RWClassID RWBag::classIsA ( )

static

Returns the RWClassID of this class.

virtual void RWBag::clear ( )

virtual

Removes all objects from the collection. Does not delete the objects themselves.

Implements RWCollection.

virtual void RWBag::clearAndDestroy ( )

virtual

Removes all objects from the collection and deletes them. Takes into account duplicate objects within a collection and only deletes them once. However, it does not take into account objects shared between different collections. Either do not use this function if you are sharing objects between separate collections, or put all collections that could be sharing objects into one single "super-collection" and call clearAndDestroy() on that.

Reimplemented from RWCollection.

virtual RWCollectable* RWBag::copy ( ) const

virtual

Returns a new, copy-constructed object of the same type as self. The caller is responsible for deleting the object.

Reimplemented from RWCollectable.

virtual size_t RWBag::entries ( ) const

inlinevirtual

Returns the total number of items in the collection.

Implements RWCollection.

virtual RWCollectable* RWBag::find ( const RWCollectable *  target ) const

virtual

The first item that was inserted into the Bag and which equals target is returned, or rwnil if no item is found. Hashing is used to narrow the search.

Implements RWCollection.

virtual RWCollectable* RWBag::insert ( RWCollectable *  c )

virtual

Inserts the item c into the collection and returns it, or if an item was already in the collection that isEqual() to c, returns the old item and increments its count.

Implements RWCollection.

RWCollectable* RWBag::insertWithOccurrences	(	RWCollectable *	c,
		int	n
	)

Inserts the item c into the collection with count n and returns it, or if an item was already in the collection that isEqual() to c, then returns the old item and increments its count by n.

virtual RWClassID RWBag::isA ( ) const

virtual

Returns the unique id for RWBag.

Reimplemented from RWCollection.

virtual bool RWBag::isEmpty ( ) const

inlinevirtual

Returns true if the collection is empty, otherwise returns false.

Implements RWCollection.

virtual bool RWBag::isEqual ( const RWCollectable *  t ) const

virtual

Behaves as if compareTo(t) was invoked, returning true if the result equals 0, false otherwise.

Reimplemented from RWCollectable.

virtual RWConstIterator* RWBag::newConstIterator ( ) const

virtual

Returns a const pointer to a dynamically allocated iterator for the collection.

Implements RWCollection.

virtual RWIterator* RWBag::newIterator ( )

virtual

Returns a dynamically allocated iterator for the collection.

Implements RWCollection.

virtual RWCollectable* RWBag::newSpecies ( ) const

virtual

Returns a new, default-constructed object of the same type as self. The caller is responsible for deleting the object.

Reimplemented from RWCollectable.

virtual size_t RWBag::occurrencesOf ( const RWCollectable *  target ) const

virtual

Returns the number of items that are equal to the item pointed to by target.

Implements RWCollection.

RWBag& RWBag::operator=

(

const RWBag &

b

)

Assignment operator. Makes a shallow copy of b.

RWBag& RWBag::operator=

(

RWBag &&

b

)

Move assignment. Self takes ownership of the data owned by b.

Condition:

This method is available only on platforms with rvalue reference support.

bool RWBag::operator==

(

const RWBag &

b

)

const

Returns true if self and bag b have the same number of total entries and if for every key in self there is a corresponding key in b which isEqual() and which has the same number of entries.

virtual RWCollectable* RWBag::remove ( const RWCollectable *  target )

virtual

Removes and returns the item that isEqual() to the item pointed to by target. Returns rwnil if no item was found.

Implements RWCollection.

virtual void RWBag::removeAndDestroy ( const RWCollectable *  target )

virtual

Removes the item that isEqual() to the item pointed to by target. Destroys the item as well if it is the last occurrence in the collection.

Reimplemented from RWCollection.

void RWBag::resize

(

size_t

n = 0

)

Resizes the internal hash table to have n buckets. The overhead for this function is the hashing of every element in the collection. If n is zero, then an appropriate size is picked automatically.

void RWBag::swap

(

RWBag &

b

)

Swaps the data owned by self with the data owned by b.