docs/latex/wx/hash.tex

   1 \section{\class{wxHashTable}}\label{wxhashtable}
   2
   3 {\bf Please note} that this class is retained for backward compatibility
   4 reasons; you should use \helpref{wxHashMap}{wxhashmap}.
   5
   6 This class provides hash table functionality for wxWidgets, and for an
   7 application if it wishes.  Data can be hashed on an integer or string
   8 key.
   9
  10 \wxheading{Derived from}
  11
  12 \helpref{wxObject}{wxobject}
  13
  14 \wxheading{Include files}
  15
  16 <wx/hash.h>
  17
  18 \wxheading{Library}
  19
  20 \helpref{wxBase}{librarieslist}
  21
  22 \wxheading{Example}
  23
  24 Below is an example of using a hash table.
  25
  26 \begin{verbatim}
  27   wxHashTable table(wxKEY_STRING);
  28
  29   wxPoint *point = new wxPoint(100, 200);
  30   table.Put("point 1", point);
  31
  32   ....
  33
  34   wxPoint *found_point = (wxPoint *)table.Get("point 1");
  35 \end{verbatim}
  36
  37 A hash table is implemented as an array of pointers to lists. When no
  38 data has been stored, the hash table takes only a little more space than
  39 this array (default size is 1000).  When a data item is added, an
  40 integer is constructed from the integer or string key that is within the
  41 bounds of the array. If the array element is NULL, a new (keyed) list is
  42 created for the element. Then the data object is appended to the list,
  43 storing the key in case other data objects need to be stored in the list
  44 also (when a `collision' occurs).
  45
  46 Retrieval involves recalculating the array index from the key, and searching
  47 along the keyed list for the data object whose stored key matches the passed
  48 key. Obviously this is quicker when there are fewer collisions, so hashing
  49 will become inefficient if the number of items to be stored greatly exceeds
  50 the size of the hash table.
  51
  52 \wxheading{See also}
  53
  54 \helpref{wxList}{wxlist}
  55
  56 \latexignore{\rtfignore{\wxheading{Members}}}
  57
  58 \membersection{wxHashTable::wxHashTable}\label{wxhashtablector}
  59
  60 \func{}{wxHashTable}{\param{unsigned int}{ key\_type}, \param{int}{ size = 1000}}
  61
  62 Constructor. {\it key\_type} is one of wxKEY\_INTEGER, or wxKEY\_STRING,
  63 and indicates what sort of keying is required. {\it size} is optional.
  64
  65 \membersection{wxHashTable::\destruct{wxHashTable}}\label{wxhashtabledtor}
  66
  67 \func{}{\destruct{wxHashTable}}{\void}
  68
  69 Destroys the hash table.
  70
  71 \membersection{wxHashTable::BeginFind}\label{wxhashtablebeginfind}
  72
  73 \func{void}{BeginFind}{\void}
  74
  75 The counterpart of {\it Next}.  If the application wishes to iterate
  76 through all the data in the hash table, it can call {\it BeginFind} and
  77 then loop on {\it Next}.
  78
  79 \membersection{wxHashTable::Clear}\label{wxhashtableclear}
  80
  81 \func{void}{Clear}{\void}
  82
  83 Clears the hash table of all nodes (but as usual, doesn't delete user data).
  84
  85 \membersection{wxHashTable::Delete}\label{wxhashtabledelete}
  86
  87 \func{wxObject *}{Delete}{\param{long}{ key}}
  88
  89 \func{wxObject *}{Delete}{\param{const wxString\& }{ key}}
  90
  91 Deletes entry in hash table and returns the user's data (if found).
  92
  93 \membersection{wxHashTable::DeleteContents}\label{wxhashtabledeletecontents}
  94
  95 \func{void}{DeleteContents}{\param{bool}{ flag}}
  96
  97 If set to true data stored in hash table will be deleted when hash table object
  98 is destroyed.
  99
 100
 101 \membersection{wxHashTable::Get}\label{wxhashtableget}
 102
 103 \func{wxObject *}{Get}{\param{long}{ key}}
 104
 105 \func{wxObject *}{Get}{\param{const char*}{ key}}
 106
 107 Gets data from the hash table, using an integer or string key (depending on which
 108 has table constructor was used).
 109
 110 \membersection{wxHashTable::MakeKey}\label{wxhashtablemakekey}
 111
 112 \func{long}{MakeKey}{\param{const wxString\& }{string}}
 113
 114 Makes an integer key out of a string. An application may wish to make a key
 115 explicitly (for instance when combining two data values to form a key).
 116
 117 \membersection{wxHashTable::Next}\label{wxhashtablenext}
 118
 119 \func{wxHashTable::Node *}{Next}{\void}
 120
 121 If the application wishes to iterate through all the data in the hash
 122 table, it can call {\it BeginFind} and then loop on {\it Next}. This function
 123 returns a {\bf wxHashTable::Node} pointer (or NULL if there are no more nodes).
 124 The return value is functionally equivalent to \textbf{wxNode} but might not be
 125 implemented as a \textbf{wxNode}. The user will probably only wish to use the
 126 \textbf{GetData} method to retrieve the data; the node may also be deleted.
 127
 128 \membersection{wxHashTable::Put}\label{wxhashtableput}
 129
 130 \func{void}{Put}{\param{long}{ key}, \param{wxObject *}{object}}
 131
 132 \func{void}{Put}{\param{const char*}{ key}, \param{wxObject *}{object}}
 133
 134 Inserts data into the hash table, using an integer or string key (depending on which
 135 has table constructor was used). The key string is copied and stored by the hash
 136 table implementation.
 137
 138 \membersection{wxHashTable::GetCount}\label{wxhashtablegetcount}
 139
 140 \constfunc{size\_t}{GetCount}{\void}
 141
 142 Returns the number of elements in the hash table.
 143