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/*--- A hash table implementation. pub_tool_hashtable.h ---*/
This file is part of Valgrind, a dynamic binary instrumentation
Copyright (C) 2005-2013 Nicholas Nethercote
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307, USA.
The GNU General Public License is contained in the file COPYING.
#include "pub_tool_basics.h" // VG_ macro
/* Generic type for a separately-chained hash table. Via a kind of dodgy
C-as-C++ style inheritance, tools can extend the VgHashNode type, so long
as the first two fields match the sizes of these two fields. Requires
a bit of casting by the tool. */
// Problems with this data structure:
// - Separate chaining gives bad cache behaviour. Hash tables with linear
// probing give better cache behaviour.
struct _VgHashNode {
struct _VgHashNode * next;
UWord key;
typedef struct _VgHashTable VgHashTable;
/* Make a new table. Allocates the memory with VG_(calloc)(), so can
be freed with VG_(free)(). The table starts small but will
periodically be expanded. This is transparent to the users of this
module. The function never returns NULL. */
extern VgHashTable *VG_(HT_construct) ( const HChar* name );
/* Count the number of nodes in a table. */
extern Int VG_(HT_count_nodes) ( const VgHashTable *table );
/* Add a node to the table. Duplicate keys are permitted. */
extern void VG_(HT_add_node) ( VgHashTable *t, void* node );
/* Looks up a VgHashNode by key in the table.
* Returns NULL if not found. If entries
* with duplicate keys are present, the most recently-added of the dups will
* be returned, but it's probably better to avoid dups altogether. */
extern void* VG_(HT_lookup) ( const VgHashTable *table, UWord key );
/* Removes a VgHashNode by key from the table. Returns NULL if not found. */
extern void* VG_(HT_remove) ( VgHashTable *table, UWord key );
typedef Word (*HT_Cmp_t) ( const void* node1, const void* node2 );
/* Same as VG_(HT_lookup) and VG_(HT_remove), but allowing a part of or
the full element to be compared for equality, not only the key.
The typical use for the below function is to store a hash value of the
element in the key, and have the comparison function checking for equality
of the full element data.
Attention about the comparison function:
* It must *not* compare the 'next' pointer.
* when comparing the rest of the node, if the node data contains holes
between components, either the node memory should be fully initialised
(e.g. allocated using VG_(calloc)) or each component should be compared
individually. */
extern void* VG_(HT_gen_lookup) ( const VgHashTable *table, const void* node,
HT_Cmp_t cmp );
extern void* VG_(HT_gen_remove) ( VgHashTable *table, const void* node,
HT_Cmp_t cmp );
/* Output detailed usage/collision statistics.
cmp will be used to verify if 2 elements with the same key are equal.
Use NULL cmp if the hash table elements are only to be compared by key. */
extern void VG_(HT_print_stats) ( const VgHashTable *table, HT_Cmp_t cmp );
/* Allocates a suitably-sized array, copies pointers to all the hashtable
elements into it, then returns both the array and the size of it. The
array must be freed with VG_(free). If the hashtable is empty, the
function returns NULL and assigns *nelems = 0. */
extern VgHashNode** VG_(HT_to_array) ( const VgHashTable *table,
/*OUT*/ UInt* n_elems );
/* Reset the table's iterator to point to the first element. */
extern void VG_(HT_ResetIter) ( VgHashTable *table );
/* Return the element pointed to by the iterator and move on to the
next one. Returns NULL if the last one has been passed, or if
HT_ResetIter() has not been called previously. Asserts if the
table has been modified (HT_add_node, HT_remove) since
HT_ResetIter. This guarantees that callers cannot screw up by
modifying the table whilst iterating over it (and is necessary to
make the implementation safe; specifically we must guarantee that
the table will not get resized whilst iteration is happening.
Since resizing only happens as a result of calling HT_add_node,
disallowing HT_add_node during iteration should give the required
assurance. */
extern void* VG_(HT_Next) ( VgHashTable *table );
/* Destroy a table and deallocates the memory used by the nodes using
extern void VG_(HT_destruct) ( VgHashTable *table, void(*freenode_fn)(void*) );
/*--- end ---*/