Typedefs | Functions

cpl_hash_set.h File Reference

Hash set implementation. More...

#include "cpl_port.h"

Go to the source code of this file.

Typedefs

typedef struct _CPLHashSet CPLHashSet
typedef unsigned long(* CPLHashSetHashFunc )(const void *elt)
typedef int(* CPLHashSetEqualFunc )(const void *elt1, const void *elt2)
typedef void(* CPLHashSetFreeEltFunc )(void *elt)
typedef int(* CPLHashSetIterEltFunc )(void *elt, void *user_data)

Functions

CPLHashSet * CPLHashSetNew (CPLHashSetHashFunc fnHashFunc, CPLHashSetEqualFunc fnEqualFunc, CPLHashSetFreeEltFunc fnFreeEltFunc)
 Creates a new hash set.
void CPLHashSetDestroy (CPLHashSet *set)
 Destroys an allocated hash set.
int CPLHashSetSize (const CPLHashSet *set)
 Returns the number of elements inserted in the hash set.
void CPLHashSetForeach (CPLHashSet *set, CPLHashSetIterEltFunc fnIterFunc, void *user_data)
 Walk through the hash set and runs the provided function on all the elements.
int CPLHashSetInsert (CPLHashSet *set, void *elt)
 Inserts an element into a hash set.
void * CPLHashSetLookup (CPLHashSet *set, const void *elt)
 Returns the element found in the hash set corresponding to the element to look up The element must not be modified.
int CPLHashSetRemove (CPLHashSet *set, const void *elt)
 Removes an element from a hash set.
unsigned long CPLHashSetHashPointer (const void *elt)
 Hash function for an arbitrary pointer.
int CPLHashSetEqualPointer (const void *elt1, const void *elt2)
 Equality function for arbitrary pointers.
unsigned long CPLHashSetHashStr (const void *pszStr)
 Hash function for a zero-terminated string.
int CPLHashSetEqualStr (const void *pszStr1, const void *pszStr2)
 Equality function for strings.

Detailed Description

Hash set implementation.

An hash set is a data structure that holds elements that are unique according to a comparison function. Operations on the hash set, such as insertion, removal or lookup, are supposed to be fast if an efficient "hash" function is provided.


Function Documentation

void CPLHashSetDestroy ( CPLHashSet *  set  ) 

Destroys an allocated hash set.

This function also frees the elements if a free function was provided at the creation of the hash set.

Parameters:
set the hash set
int CPLHashSetEqualPointer ( const void *  elt1,
const void *  elt2 
)

Equality function for arbitrary pointers.

Parameters:
elt1 the first arbitrary pointer to compare
elt2 the second arbitrary pointer to compare
Returns:
TRUE if the pointers are equal
int CPLHashSetEqualStr ( const void *  elt1,
const void *  elt2 
)

Equality function for strings.

Parameters:
elt1 the first string to compare. May be NULL.
elt2 the second string to compare. May be NULL.
Returns:
TRUE if the strings are equal
void CPLHashSetForeach ( CPLHashSet *  set,
CPLHashSetIterEltFunc  fnIterFunc,
void *  user_data 
)

Walk through the hash set and runs the provided function on all the elements.

This function is provided the user_data argument of CPLHashSetForeach. It must return TRUE to go on the walk through the hash set, or FALSE to make it stop.

Note : the structure of the hash set must *NOT* be modified during the walk.

Parameters:
set the hash set.
fnIterFunc the function called on each element.
user_data the user data provided to the function.
unsigned long CPLHashSetHashPointer ( const void *  elt  ) 

Hash function for an arbitrary pointer.

Parameters:
elt the arbitrary pointer to hash
Returns:
the hash value of the pointer
unsigned long CPLHashSetHashStr ( const void *  elt  ) 

Hash function for a zero-terminated string.

Parameters:
elt the string to hash. May be NULL.
Returns:
the hash value of the string
int CPLHashSetInsert ( CPLHashSet *  set,
void *  elt 
)

Inserts an element into a hash set.

If the element was already inserted in the hash set, the previous element is replaced by the new element. If a free function was provided, it is used to free the previously inserted element

Parameters:
set the hash set
elt the new element to insert in the hash set
Returns:
TRUE if the element was not already in the hash set
void* CPLHashSetLookup ( CPLHashSet *  set,
const void *  elt 
)

Returns the element found in the hash set corresponding to the element to look up The element must not be modified.

Parameters:
set the hash set
elt the element to look up in the hash set
Returns:
the element found in the hash set or NULL
CPLHashSet* CPLHashSetNew ( CPLHashSetHashFunc  fnHashFunc,
CPLHashSetEqualFunc  fnEqualFunc,
CPLHashSetFreeEltFunc  fnFreeEltFunc 
)

Creates a new hash set.

The hash function must return a hash value for the elements to insert. If fnHashFunc is NULL, CPLHashSetHashPointer will be used.

The equal function must return if two elements are equal. If fnEqualFunc is NULL, CPLHashSetEqualPointer will be used.

The free function is used to free elements inserted in the hash set, when the hash set is destroyed, when elements are removed or replaced. If fnFreeEltFunc is NULL, elements inserted into the hash set will not be freed.

Parameters:
fnHashFunc hash function. May be NULL.
fnEqualFunc equal function. May be NULL.
fnFreeEltFunc element free function. May be NULL.
Returns:
a new hash set
int CPLHashSetRemove ( CPLHashSet *  set,
const void *  elt 
)

Removes an element from a hash set.

Parameters:
set the hash set
elt the new element to remove from the hash set
Returns:
TRUE if the element was in the hash set
int CPLHashSetSize ( const CPLHashSet *  set  ) 

Returns the number of elements inserted in the hash set.

Note: this is not the internal size of the hash set

Parameters:
set the hash set
Returns:
the number of elements in the hash set

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