RWTPtrHashMap<K,T,H,EQ,A>

Module:  Essential Tools Module   Group:  STL Extension-based Collection Classes

Does not inherit

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Members

apply() applyToKeyAndValue() begin() capacity() clear() clearAndDestroy() const_iterator const_reference const_reference_data const_reference_key container_eq container_hash

container_type contains() difference_type end() entries() fillRatio() find() findKeyAndValue() findValue() insert() insertKeyAndValue() isEmpty()

iterator maxElement() minElement() occurrencesOf() operator=() operator==() operator[]() reference reference_data reference_key remove() removeAll()

removeKeyAndValue() resize() RWTPtrHashMap<K,T,H,EQ,A>() size_type std() std::find() value_type value_type_data value_type_key

Non-Members

operator>>()

operator<<()

#include <rw/tphdict.h> 
RWTPtrHashMap<K,T,H,EQ,A> m;

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 const hash function on elements of type K via public member

unsigned long operator()(const K& x) const;

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) const;

which should return true if x and y are equivalent.

Note: Any two keys that are equivalent must hash to the same value.

RWTPtrHashMap<K,T,H,EQ,A> will not accept a key that is equivalent to any key already in the collection. (RWTPtrHashMultiMap<K,T,H,EQ,A> may contain multiple keys that are equivalent to each other.) Equality is based on the comparison object and not on the == operator.

The value type must have operator==() defined. This requirement is imposed by the C++ Standard Library.

Isomorphic

//
// tphmap.cpp
//
#include<iostream>
#include<functional>
#include<rw/tphdict.h>
#include<rw/cstring.h>

struct simple_hash
{
    unsigned long 
    operator()(const RWCString& ref) const { 
        size_t n = ref.length ();
        return (unsigned long)(n ? n * size_t (ref [0]) : 0);
    }
};

int main ()
{
    RWCString snd = "Second";

    RWTPtrHashMap<RWCString, int, simple_hash, std::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));

    std::cout << "There was " 
              << contest.occurrencesOf(new RWCString("Second"))
              << " second place winner." << std::endl;

    return 0;
}

Program Output:

There was 1 second place winner.

Class RWTPtrHashMultiMap<K,T,H,EQ,A> offers the same interface to a pointer-based collection that accepts multiple keys that compare equal to each other.

Classrw_hashmap<K*,T*,rw_deref_hash<H,K>,rw_deref_compare<C,K>,A> is the C++ Standard Library-style collection that serves as the underlying implementation for this collection.

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,A>
                   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; 

RWTPtrHashMap<K,T,H,EQ,A>();

Constructs an empty map.

RWTPtrHashMap<K,T,H,EQ,A>
  (const RWTPtrHashMap<K,T,H,EQ,A>& rwm);

Copy constructor.

RWTPtrHashMap<K,T,H,EQ,A>(const container_type & m);

Constructs a pointer based hash map by copying all elements from m.

RWTPtrHashMap<K,T,H,EQ,A>(const H& h, 
                          size_type sz = RW_DEFAULT_CAPACITY);

Creates an empty hashed map which uses the hash object h and has an initial capacity of sz.

RWTPtrHashMap<K,T,H,EQ,A>(const value_type* first,
                          value_type* last);

Constructs a map by copying elements from the array of pairs pointed to by first, up to, but not including, the pair pointed to by last.

RWTPtrHashMap<K,T,H,EQ,A>&
operator=(const container_type& m); 
RWTPtrHashMap<K,T,H,EQ,A>&
operator=(const RWTPtrHashMap<K,T,H,EQ,A>& m);

Destroys all associations in self and replaces them by copying all associations from m.

bool
operator==(const RWTPtrHashMap<K,T,H,EQ,A>& 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.

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. This 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.

void
applyToKeyAndValue(void (*fn)(const K*, T*&,void*),
                   void* d); 
void
applyToKeyAndValue
  (void (*fn)(const K*, const T*, void*), void* d) const;

WARNING: This method is deprecated, and is no longer supported. Be aware that it may be removed in a future release. Use the method apply() instead, which behaves exactly the same as this method.

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 this 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; 

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*
std::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);

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); 

WARNING: This method is deprecated, and is no longer supported. Be aware that it may be removed in a future release. Instead, use the insert() member above, which behaves exactly the same as this method.

bool
isEmpty() const; 

Returns true if there are no items in the collection, false otherwise.

const K*
minElement() const;
const K*
maxElement() const;

Returns a pointer to the minimum or maximum key in the collection. Type K must have well-defined less-than semantics (K::operator<(const K&) or equivalent).

size_type
occurrencesOf(const K* key) const; 

Returns the number of keys j in self that compare equal to *key.

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); 

Erases 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);

Erases 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); 

Erases 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);

Erases 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.

Key*
removeKeyAndValue(const KP* k VP*& retVal);

If std::find(k) would succeed, erases the pair associated with k, places the value part in retVal, and returns the key part. Otherwise, returns rwnil.

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>,A>&
std();
const rw_hashmap<K*,T*,rw_deref_hash<H,K>,deref_compare<EQ,K>,A>&
std() const;

Returns a reference to the underlying C++-standard collection that serves as the implementation for self.

RWvostream&
operator<<(RWvostream& strm, 
           const RWTPtrHashMap<K,T,H,EQ,A>& coll);
RWFile&
operator<<(RWFile& strm, 
  const RWTPtrHashMap<K,T,H,EQ,A>& 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,A>& coll); 
RWFile&
operator>>(RWFile& strm, RWTPtrHashMap<K,T,H,EQ,A>& coll);

Restores the contents of the collection coll from the input stream strm.

RWvistream&
operator>>(RWvistream& strm, RWTPtrHashMap<K,T,H,EQ,A>*& p);
RWFile&
operator>>(RWFile& strm, RWTPtrHashMap<K,T,H,EQ,A>*& 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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