rw_hashmap(3C++)
rw_hashmap - Rogue Wave library class
As shipped in IRIX 6.5.5. Unchanged since IRIX 6.5.
Name rw_hashmap - Rogue Wave library class Synopsis #include <rw/rwstl/hashmap.h> rw_hashmap<K,V,Hash,EQ> map; Description Class rw_hashmap<K,V,Hash,EQ> maintains a collection of mappings between K and V, implemented as a hash table of pair<const K,V> . Pairs with duplicate keys are not allowed. Two pairs having duplicate keys is the result of the EQ comparison, applied to the first element of each, is TRUE. Since this is a value based collection, objects are copied into and out of the collection. As with all classes that meet the ANSI associative container specification, rw_hashmap provides for iterators that reference its elements. Operations that alter the contents of rw_hashmap may invalidate other iterators that reference the container. Since the contents of rw_hashmap are in pseudo-random order, the only iterator ranges that will usually make sense are the results of calling equal_range(key), and the entire range from begin() to end(). Persistence None Public Typedefs typedef K key_type; typedef Hash key_hash; typedef EQ key_equal; typedef pair<K,V> value_type; // or ... "const K" typedef (unsigned) size_type; //from rw_slist typedef (int) difference_type; // from rw_slist typedef (value_type&) reference; typedef (const value_type&) const_reference; //from rw_slist Iterators over rw_hashmap<K,V,Hash,EQ> are forward iterators. typedef (scoped Iterator) iterator; typedef (scoped ConstIterator) const_iterator; Public Constructors rw_hashmap<K,V,Hash,EQ>(size_type sz = 1024, const Hash& h = Hash(), const EQ& eq = EQ()); Construct an empty rw_hashmap<K,V,Hash,EQ> with sz slots, using h as the hash object, and eq as the equality comparator. rw_hashmap<K,V,Hash,EQ>(const rw_hashmap<K,V,Hash,EQ>& map); Construct an rw_hashmap<K,V,Hash,EQ> which is a copy of map. Each element from map will be copied into self. rw_hashmap<K,V,Hash,EQ>(const_iterator first, const_iterator bound size_type sz=1024, const Hash& h = Hash(), const EQ& eq = EQ()); Construct an rw_hashmap<K,V,Hash,EQ> with sz slots, using h as the hash object, and eq as the equality comparator, containing a copy of each pair referenced by the range starting with first and bounded by bound. rw_hashmap<K,V,Hash,EQ>(const value_type* first, const value_type* bound size_type sz=1024, const Hash& h = Hash(), const EQ& eq = EQ()); Construct an rw_hashmap<K,V,Hash,EQ> with sz slots, using h as the hash object, and eq as the equality comparator, containing a copy of each pair referenced by the range starting with first and bounded by bound. If there are items in the range for which the K parts of the pairs match EQ, then only the first such item will be inserted into self. Public Destructor ~rw_hashmap<K,V,Hash,EQ>(); The destructor releases the memory used by the container's implementation. Public Operators rw_hashmap<K,V,Hash,EQ>& operator=(const rw_hashmap<K,V,Hash,EQ>& rhs); Sets self to have the same capacity, Hash and EQ as rhs, removes all self's current contents, and replaces them with copies of the elements in rhs. bool operator==(const rw_hashmap<K,V,Hash,EQ> & rhs) const; Returns true if self and rhs have the same number of elements, and for each value_type in self, there is a value_type in rhs that has a first part for which the EQ object in self returns true, and a second part for which operator==() returns true. The need to test both parts means that this operator is slightly slower than the method equal_by_keys() described below. V& operator[](const key_type& key); Returns a reference to the V part of a pair held in self which has a part EQ to key, either by finding such a pair, or inserting one (in which case the reference is to an instance of V created by its default constructor). Accessors iterator begin(); The iterator returned references the first item in self. If self is empty, the iterator is equal to end(). Note that because items are stored in pseudo-random order, this iterator might reference any item that has been stored in self. const_iterator begin() const; The iterator returned references the first item in self. If self is empty, the iterator is equal to end(). Note that because items are stored in pseudo-random order, this iterator might reference any item that has been stored in self. iterator end(); The iterator returned marks the location "off the end" of self. It may not be dereferenced. const_iterator end() const; The iterator returned marks the location "off the end" of self. It may not be dereferenced. pair<const_iterator, const_iterator> equal_range(const key_type key) const; Returns pair<const_iterator, const_iterator>(lower_bound(key), upper_bound(key)). Upper and lower bound have special meaning for hash- based collections. See discussion elsewhere. pair<iterator, iterator> equal_range(const key_type key); Returns pair<iterator, iterator>(lower_bound(key), upper_bound(key)). Upper and lower bound have special meaning for hash-based collections. See discussion elsewhere. const_iterator lower_bound(const key_type& key) const; Returns the lower bound of key in self. This has a special meaning for hash-based collections. See discussion elsewhere. iterator lower_bound(const key_type& key); Returns the lower bound of key in self. This has a special meaning for hash-based collections. See discussion elsewhere. const_iterator upper_bound(const key_type& key) const; Returns the upper bound of key in self. This has a special meaning for hash-based collections. See discussion elsewhere. iterator upper_bound(const key_type& key); Returns the upper bound of key in self. This has a special meaning for hash-based collections. See discussion elsewhere. Const Public Member Functions size_type capacity() const; Returns the number of slots in the hash table that self uses. bool empty() const; Returns true if self is empty. float fill_ratio() const; Returns the result of calculating size()/capacity(). size_type size() const; Returns the number of pairs currently held in self. Mutators void clear(); A synonym for erase(begin(),end()); size_type erase(const key_type& key); If there is a pair in self for which the first part is EQ to key, that pair is removed, and 1 is returned. Otherwise, 0 is returned. iterator erase(iterator iter); Removes the element referenced by iter and returns an iterator referencing the "next" element. If iter does not reference an item in self, the result is undefined. iterator erase(iterator first, iterator bound); Removes each element in the range which begins with first and is bound by bound. Returns an iterator referencing bound. If first does not reference an item in self (and if first and bound are not equal), the effect is undefined. pair<iterator,bool> insert(const value_type& val); If there is no pair in self with first part EQ to the first part of val then inserts val, returning a pair with an iterator referencing the new element and true. Otherwise, returns a pair with an iterator referencing the matching value_type and false. size_type insert(iterator ignore, const value_type& val); If there is no pair in self with first part EQ to the first part of val then inserts val, returning 1. Otherwise, does nothing and returns 0. Note that the first argument is provided only for conformance with the ANSI associative container specification, and is ignored by the method, since hash table look up can be done in constant time. size_type insert(const value_type* first, const value_type* bound); For each element in the range beginning with first and bounded by bound, if there is no pair in self with first part EQ to the first part of that element, the element is copied into self, or if there is such a pair, the element is skipped. Returns the number of elements inserted. size_type insert(const_iterator first, const_iterator bound); For each element in the range beginning with first and bounded by bound, if there is no pair in self with first part EQ to the first part of that element, the element is copied into self, or if there is such a pair, the element is skipped. Returns the number of elements inserted. void swap(rw_hashmap<K,V,Hash,EQ>& other); Exchanges the contents of self with other including the Hash and EQ objects. This method does not copy or destroy any of the items exchanged but exchanges the underlying hash tables. Special Methods for Maps size_type count(const key_type& key) const; Returns 1 if self contains a pair with its first element EQ to key, else 0. bool equal_by_keys(const rw_hashmap<K,V,Hash,EQ>& rhs) const; Returns true if self and rhs have the same size, and if for each value_type in self, there is a value_type in rhs such that the EQ object in self returns true when called for the first parts of those pairs. Note that this method does not compare the V (second) part of the pair of the items, so it will run slightly faster than operator==(). const_iterator find(const key_type& key) const; Returns a const_iterator referencing the pair with key as its first element if such a pair is contained in self, else returns end(). iterator find(const key_type& key); Returns an iterator referencing the pair with key as its first element, if such a pair is contained in self, else returns end(). void resize(size_type sz); Resizes self's hash table to have sz slots; and re-hashes all self's elements into the new table. Can be very expensive if self holds many elements.