#include <wx/hashmap.h>
wxHashMap is a legacy hash table container similar to std::unordered_map.
Please see https://en.cppreference.com/w/cpp/container/unordered_map for the full description of this class API: in the default build, this class is a thin wrapper inheriting from the standard class.
Example:
Declares a hash map class named CLASSNAME, with wxString keys and VALUE_T values.
Declares a hash map class named CLASSNAME, with void* keys and VALUE_T values.
The HASH_T and KEY_EQ_T are the types used for the hashing function and key comparison. wxWidgets provides three predefined hashing functions: wxIntegerHash
for integer types ( int, long, short, and their unsigned counterparts ), wxStringHash
for strings ( wxString, wxChar*, char* ), and wxPointerHash
for any kind of pointer. Similarly three equality predicates: wxIntegerEqual
, wxStringEqual
, wxPointerEqual
are provided. Using this you could declare a hash map mapping int values to wxString like this:
In the documentation below you should replace wxHashMap with the name you used in the class declaration.
An iterator is similar to a pointer, and so you can use the usual pointer operations: ++it ( and it++ ) to move to the next element, *it to access the element pointed to, it->first ( it->second ) to access the key ( value ) of the element pointed to.
Hash maps provide forward only iterators, this means that you can't use --it, it + 3, it1 - it2.
wxWidgets defines the following hashmap types:
Public Member Functions | |
wxHashMap (size_type size=10) | |
The size parameter is just a hint, the table will resize automatically to preserve performance. More... | |
wxHashMap (const wxHashMap &map) | |
Copy constructor. More... | |
void | clear () |
Removes all elements from the hash map. More... | |
size_type | count (const key_type &key) const |
Counts the number of elements with the given key present in the map. More... | |
bool | empty () const |
Returns true if the hash map does not contain any elements, false otherwise. More... | |
Insert_Result | insert (const value_type &v) |
Inserts the given value in the hash map. More... | |
mapped_type | operator[] (const key_type &key) |
Use the key as an array subscript. More... | |
size_type | size () const |
Returns the number of elements in the map. More... | |
const_iterator | begin () const |
Returns an iterator pointing at the first element of the hash map. More... | |
iterator | begin () |
Returns an iterator pointing at the first element of the hash map. More... | |
const_iterator | end () const |
Returns an iterator pointing at the one-after-the-last element of the hash map. More... | |
iterator | end () |
Returns an iterator pointing at the one-after-the-last element of the hash map. More... | |
size_type | erase (const key_type &key) |
Erases the element with the given key, and returns the number of elements erased (either 0 or 1). More... | |
void | erase (iterator it) |
Erases the element pointed to by the iterator. More... | |
void | erase (const_iterator it) |
Erases the element with the given key, and returns the number of elements erased (either 0 or 1). More... | |
iterator | find (const key_type &key) const |
If an element with the given key is present, the functions returns an iterator pointing at that element, otherwise an invalid iterator is returned. More... | |
const_iterator | find (const key_type &key) const |
If an element with the given key is present, the functions returns an iterator pointing at that element, otherwise an invalid iterator is returned. More... | |
wxHashMap::wxHashMap | ( | size_type | size = 10 | ) |
The size parameter is just a hint, the table will resize automatically to preserve performance.
wxHashMap::wxHashMap | ( | const wxHashMap & | map | ) |
Copy constructor.
iterator wxHashMap::begin | ( | ) |
Returns an iterator pointing at the first element of the hash map.
Please remember that hash maps do not guarantee ordering.
const_iterator wxHashMap::begin | ( | ) | const |
Returns an iterator pointing at the first element of the hash map.
Please remember that hash maps do not guarantee ordering.
void wxHashMap::clear | ( | ) |
Removes all elements from the hash map.
size_type wxHashMap::count | ( | const key_type & | key | ) | const |
Counts the number of elements with the given key present in the map.
This function returns only 0 or 1.
bool wxHashMap::empty | ( | ) | const |
Returns true if the hash map does not contain any elements, false otherwise.
iterator wxHashMap::end | ( | ) |
Returns an iterator pointing at the one-after-the-last element of the hash map.
Please remember that hash maps do not guarantee ordering.
const_iterator wxHashMap::end | ( | ) | const |
Returns an iterator pointing at the one-after-the-last element of the hash map.
Please remember that hash maps do not guarantee ordering.
size_type wxHashMap::erase | ( | const key_type & | key | ) |
Erases the element with the given key, and returns the number of elements erased (either 0 or 1).
void wxHashMap::erase | ( | const_iterator | it | ) |
Erases the element with the given key, and returns the number of elements erased (either 0 or 1).
void wxHashMap::erase | ( | iterator | it | ) |
Erases the element pointed to by the iterator.
After the deletion the iterator is no longer valid and must not be used.
iterator wxHashMap::find | ( | const key_type & | key | ) | const |
If an element with the given key is present, the functions returns an iterator pointing at that element, otherwise an invalid iterator is returned.
const_iterator wxHashMap::find | ( | const key_type & | key | ) | const |
If an element with the given key is present, the functions returns an iterator pointing at that element, otherwise an invalid iterator is returned.
Insert_Result wxHashMap::insert | ( | const value_type & | v | ) |
Inserts the given value in the hash map.
The return value is equivalent to a
The iterator points to the inserted element, the boolean value is true if v was actually inserted.
mapped_type wxHashMap::operator[] | ( | const key_type & | key | ) |
Use the key as an array subscript.
The only difference is that if the given key is not present in the hash map, an element with the default value_type()
is inserted in the table.
size_type wxHashMap::size | ( | ) | const |
Returns the number of elements in the map.