84b63045ca
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@5071 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
131 lines
3.9 KiB
TeX
131 lines
3.9 KiB
TeX
\section{\class{wxHashTable}}\label{wxhashtable}
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This class provides hash table functionality for wxWindows, and for an
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application if it wishes. Data can be hashed on an integer or string
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key.
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\wxheading{Derived from}
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\helpref{wxObject}{wxobject}
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\wxheading{Include files}
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<wx/hash.h>
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\wxheading{Example}
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Below is an example of using a hash table.
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\begin{verbatim}
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wxHashTable table(KEY_STRING);
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wxPoint *point = new wxPoint(100, 200);
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table.Put("point 1", point);
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....
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wxPoint *found_point = (wxPoint *)table.Get("point 1");
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\end{verbatim}
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A hash table is implemented as an array of pointers to lists. When no
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data has been stored, the hash table takes only a little more space than
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this array (default size is 1000). When a data item is added, an
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integer is constructed from the integer or string key that is within the
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bounds of the array. If the array element is NULL, a new (keyed) list is
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created for the element. Then the data object is appended to the list,
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storing the key in case other data objects need to be stored in the list
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also (when a `collision' occurs).
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Retrieval involves recalculating the array index from the key, and searching
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along the keyed list for the data object whose stored key matches the passed
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key. Obviously this is quicker when there are fewer collisions, so hashing
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will become inefficient if the number of items to be stored greatly exceeds
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the size of the hash table.
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\wxheading{See also}
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\helpref{wxList}{wxlist}
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxHashTable::wxHashTable}
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\func{}{wxHashTable}{\param{unsigned int}{ key\_type}, \param{int}{ size = 1000}}
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Constructor. {\it key\_type} is one of wxKEY\_INTEGER, or wxKEY\_STRING,
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and indicates what sort of keying is required. {\it size} is optional.
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\membersection{wxHashTable::\destruct{wxHashTable}}
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\func{}{\destruct{wxHashTable}}{\void}
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Destroys the hash table.
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\membersection{wxHashTable::BeginFind}
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\func{void}{BeginFind}{\void}
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The counterpart of {\it Next}. If the application wishes to iterate
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through all the data in the hash table, it can call {\it BeginFind} and
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then loop on {\it Next}.
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\membersection{wxHashTable::Clear}
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\func{void}{Clear}{\void}
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Clears the hash table of all nodes (but as usual, doesn't delete user data).
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\membersection{wxHashTable::Delete}
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\func{wxObject *}{Delete}{\param{long}{ key}}
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\func{wxObject *}{Delete}{\param{const wxString\& }{ key}}
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Deletes entry in hash table and returns the user's data (if found).
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\membersection{wxHashTable::DeleteContents}
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\func{void}{DeleteContents}{\param{bool}{ flag}}
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If set to TRUE data stored in hash table will be deleted when hash table object
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is destroyed.
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\membersection{wxHashTable::Get}
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\func{wxObject *}{Get}{\param{long}{ key}}
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\func{wxObject *}{Get}{\param{const wxString\& }{ key}}
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Gets data from the hash table, using an integer or string key (depending on which
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has table constructor was used).
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\membersection{wxHashTable::MakeKey}
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\func{long}{MakeKey}{\param{const wxString\& }{string}}
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Makes an integer key out of a string. An application may wish to make a key
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explicitly (for instance when combining two data values to form a key).
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\membersection{wxHashTable::Next}
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\func{wxNode *}{Next}{\void}
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If the application wishes to iterate through all the data in the hash
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table, it can call {\it BeginFind} and then loop on {\it Next}. This function
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returns a {\bf wxNode} pointer (or NULL if there are no more nodes). See the
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description for \helpref{wxNode}{wxnode}. The user will probably only wish to use the
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{\bf wxNode::Data} function to retrieve the data; the node may also be deleted.
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\membersection{wxHashTable::Put}
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\func{void}{Put}{\param{long}{ key}, \param{wxObject *}{object}}
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\func{void}{Put}{\param{const wxString\& }{ key}, \param{wxObject *}{object}}
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Inserts data into the hash table, using an integer or string key (depending on which
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has table constructor was used). The key string is copied and stored by the hash
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table implementation.
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