RWTPtrHashMap(3C++) RWTPtrHashMap(3C++)
Name
RWTPtrHashMap<K,T,H,EQ> - Rogue Wave library class
Synopsis
#include <rw/tphdict.h>
RWTPtrHashMap<K,T,H,EQ> m;
Please Note!
If you have the Standard C++ Library, use the interface described here.
Otherwise, use the interface for RWTPtrHashDictionary described in
Appendix A.
Description
This class maintains a pointer-based collection of associations of type
pair<K* const, T*>. These pairs are stored according to a hash object of
type H. H must provide a hash function on elements of type K via a
public member
unsigned long operator()(const K& x)
Equivalent keys within the collection will be grouped together based on
an equality object of type EQ. EQ must ensure this grouping via public
member
bool operator()(const K& x, const K& y)
which should return true if x and y are equivalent.
RWTPtrHashMap<K,T,H,EQ> will not accept a key that compares equal to any
key already in the collection. (RWTPtrHashMultiMap<K,T,H,EQ> may contain
multiple keys that compare equal to each other.) Equality is based on
the comparison object and not on the == operator.
Persistence
Isomorphic
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Examples
//
// tphmap.cpp
//
#include<rw/tphdict.h>
#include<rw/cstring.h>
#include<iostream.h>
struct silly_hash{
unsigned long operator()(RWCString x) const
{ return x.length() * (long)x(0); }
};
int main(){
RWCString snd = "Second";
RWTPtrHashMap<RWCString,int,silly_hash,equal_to<RWCString> >
contest;
contest.insert(new RWCString("First"), new int(7));
contest.insert(&snd,new int(3));
//duplicate insertion rejected
contest.insert(&snd,new int(6));
contest.insert(new RWCString("Third"), new int(2));
cout << "There was "
<< contest.occurrencesOf(new RWCString("Second"))
<< " second place winner." << endl;
return 0;
}
Program Output:
There was 1 second place winner.
Related Classes
Class RWTPtrHashMultiMap<K,T,H,EQ> offers the same interface to a
pointer-based collection that accepts multiple keys that compare equal to
each other. Class
rw_hashmap<K*,T*,rw_deref_hash<H,K>,rw_deref_compare<C,K> > is the C++-
standard library style collection that serves as the underlying
implementation for this collection.
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Public Typedefs
typedef rw_deref_hash<H,K> container_hash;
typedef rw_deref_compare<EQ,K> container_eq;
typedef rw_hashmap<K*,T*,container_hash,container_eq >
container_type;
typedef container_type::size_type size_type;
typedef container_type::difference_type difference_type;
typedef container_type::iterator iterator;
typedef container_type::const_iterator const_iterator;
typedef pair <K* const, T*> value_type;
typedef pair <K* const, T*>& reference;
typedef const pair <K* const, T*>& const_reference;
typedef K* value_type_key;
typedef T* value_type_data;
typedef K*& reference_key;
typedef T*& reference_data;
typedef const K*const& const_reference_key;
typedef const T*const& const_reference_data;
Public Constructors
RWTPtrHashMap<K,T,H,EQ>();
Constructs an empty map.
RWTPtrHashMap<K,T,H,EQ>(const RWTPtrHashMap<K,T,H,EQ>& rwm);
Copy constructor.
RWTPtrHashMap<K,T,H,EQ>
(const container_type & m);
Constructs a pointer based hash map by copying all elements from m.
RWTPtrHashMap<K,T,H,EQ>
(const H& h, size_type sz = RWDEFAULT_CAPACITY);
This Tools.h++ 6.x style constructor creates an empty hashed map which
uses the hash object h and has an initial capacity of sz.
RWTPtrHashMap<K,T,H,EQ>
(const value_type* first,value_type* last);
Constructs a map by copying elements from the array of pairs pointed to
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by first, up to, but not including, the pair pointed to by last.
Public Member Operators
RWTPtrHashMap<K,T,H,EQ>&
operator=(const container_type& m);
RWTPtrHashMap<K,T,H,EQ>&
operator=(const RWTPtrHashMap<K,T,H,EQ>& m);
Destroys all associations in self and replaces them by copying all
associations from m.
bool
operator==(const RWTPtrHashMap<K,T,H,EQ>& m) const;
Returns true if self compares equal to m, otherwise returns false. Two
collections are equal if both have the same number of entries, and
iterating through both collections produces, in turn, individual keys
that compare equal to each other. Keys are dereferenced before being
compared.
T*&
operator[](K* key);
Looks up key and returns a reference to its associated item. If the key
is not in the dictionary, then it will be added with an associated
uninitialized pointer of type T*. Because of this, if there is a
possibility that a key will not be in the dictionary, then this operator
should only be used as an lvalue.
Public Member Functions
void
apply(void (*fn)(const K*, T*&,void*),void* d);
void
apply(void (*fn)(const K*,const T*,void*),void* d) const;
Applies the user-defined function pointed to by fn to every association
in the collection. self function must have one of the prototypes:
void yourfun(const K* key, T*& a, void* d);
void yourfun(const K* key, const T* a, void* d);
Client data may be passed through parameter d.
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void
applyToKeyAndValue(void (*fn)(const K*, T*&,void*),void* d);
void
applyToKeyAndValue
(void (*fn)(const K*, const T*, void*), void* d) const;
This is a deprecated version of the apply member above. It behaves
exactly the same as apply.
iterator
begin();
const_iterator
begin() const;
Returns an iterator positioned at the first pair in self.
size_type
capacity() const;
Returns the number of buckets(slots) available in the underlying hash
representation. See resize below.
void
clear();
Clears the collection by removing all items from self.
void
clearAndDestroy();
Removes all associations from the collection and uses operator delete to
destroy the objects pointed to by the keys and their associated items.
Do not use self method if multiple pointers to the same object are
stored. (If the equality operator is reflexive, the container cannot
hold such multiple pointers.)
bool
contains(const K* key) const;
Returns true if there exists a key j in self that compares equal to
*key, otherwise returns false.
bool
contains
(bool (*fn)(value_type,void*),void* d) const;
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Returns true if there exists an association a in self such that the
expression ((*fn)(a,d)) is true, otherwise returns false. fn points to a
user-defined tester function which must have prototype:
bool yourTester(value_type a, void* d);
Client data may be passed through parameter d.
iterator
end();
const_iterator
end() const;
Returns an iterator positioned "just past" the last association in self.
size_type
entries() const;
Returns the number of associations in self.
float
fillRatio() const;
Returns the ratio entries()/capacity().
const K*
find(const K* key) const;
If there exists a key j in self that compares equal to *key, then j is
returned. Otherwise, returns rwnil.
value_type
find(bool (*fn)(value_type,void*), void* d) const;
If there exists an association a in self such that the expression
((*fn)(a,d)) is true, then returns a. Otherwise, returns
pair<rwnil,rwnil>. fn points to a user-defined tester function which
must have prototype:
bool yourTester(value_type a, void* d);
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Client data may be passed through parameter d.
T*
findValue(const K* key);
const T*
findValue(const K* key) const;
If there exists a key j in self that compares equal to *key, returns the
item associated with j. Otherwise, returns rwnil.
const K*
findKeyAndValue(const K* key, T*& tr);
const K*
findKeyAndValue(const K* key, const T*& tr) const;
If there exists a key j in self that compares equal to *key, assigns the
item associated with j to tr, and returns j. Otherwise, returns rwnil
and leaves the value of tr unchanged.
bool
insert(K* key, T* a);
Adds key with associated item a to the collection. Returns true if the
insertion is successful, otherwise returns false. The function will
return true unless the collection already holds an association with the
equivalent key.
bool
insertKeyAndValue(K* key,T* a);
This is a deprecated version of the insert member above. It behaves
exactly the same as insert.
bool
isEmpty() const;
Returns true if there are no items in the collection, false otherwise.
size_type
occurrencesOf(const K* key) const;
Returns the number of keys j in self that compare equal to *key.
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size_type
occurrencesOf
(bool (*fn)(value_type,void*),void* d) const;
Returns the number of associations a in self such that the
expression((*fn)(a,d)) is true. fn points to a user-defined tester
function which must have prototype:
bool yourTester(value_type a, void* d);
Client data may be passed through parameter d.
K*
remove(const K* key);
Removes the first association with key j in self that compares equal to
*key and returns j. Returns rwnil if there is no such association.
K*
remove(bool (*fn)(value_type,void*), void* d);
Removes the first association a in self such that the expression
((*fn)(a,d)) is true and returns its key. Returns rwnil if there is no
such association. fn points to a user-defined tester function which must
have prototype:
bool yourTester(value_type a, void* d);
Client data may be passed through parameter d.
size_type
removeAll(const K* key);
Removes all associations with key j in self that compare equal to *key.
Returns the number of associations removed.
size_type
removeAll(bool (*fn)(value_type,void*), void* d);
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Removes all associations a in self such that the expression
((*fn)(a,d))is true. Returns the number removed. fn points to a user-
defined tester function which must have prototype:
bool yourTester(value_type a, void* d);
Client data may be passed through parameter d.
void
resize(size_type sz);
Changes the capacity of self by creating a new hashed map with a capacity
of sz . resize copies every element of self into the new container and
finally swaps the internal representation of the new container with the
internal representation of self.
rw_hashmap<K*,T*,rw_deref_hash<H,K>,deref_compare<EQ,K>>&
std();
const rw_hashmap<K*,T*,rw_deref_hash<H,K>,deref_compare<EQ,K>>&
std() const;
Returns a reference to the underlying C++-standard collection that serves
as the implementation for self.
Related Global Operators
RWvostream&
operator<<(RWvostream& strm,
const RWTPtrHashMap<K,T,H,EQ>& coll);
RWFile&
operator<<(RWFile& strm, const RWTPtrHashMap<K,T,H,EQ>& coll);
Saves the collection coll onto the output stream strm, or a reference to
it if it has already been saved.
RWvistream&
operator>>(RWvistream& strm, RWTPtrHashMap<K,T,H,EQ>& coll);
RWFile&
operator>>(RWFile& strm, RWTPtrHashMap<K,T,H,EQ>& coll);
Restores the contents of the collection coll from the input stream strm.
RWvistream&
operator>>(RWvistream& strm, RWTPtrHashMap<K,T,H,EQ>*& p);
RWFile&
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operator>>(RWFile& strm, RWTPtrHashMap<K,T,H,EQ>*& p);
Looks at the next object on the input stream strm and either creates a
new collection off the heap and sets p to point to it, or sets p to point
to a previously read instance. If a collection is created off the heap,
then you are responsible for deleting it.
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