GDAL
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
 Opaque type for a hash set.
 
typedef unsigned long(* CPLHashSetHashFunc )(const void *elt)
 CPLHashSetHashFunc.
 
typedef int(* CPLHashSetEqualFunc )(const void *elt1, const void *elt2)
 CPLHashSetEqualFunc.
 
typedef void(* CPLHashSetFreeEltFunc )(void *elt)
 CPLHashSetFreeEltFunc.
 
typedef int(* CPLHashSetIterEltFunc )(void *elt, void *user_data)
 CPLHashSetIterEltFunc.
 

Functions

CPLHashSetCPLHashSetNew (CPLHashSetHashFunc fnHashFunc, CPLHashSetEqualFunc fnEqualFunc, CPLHashSetFreeEltFunc fnFreeEltFunc)
 Creates a new hash set. More...
 
void CPLHashSetDestroy (CPLHashSet *set)
 Destroys an allocated hash set. More...
 
void CPLHashSetClear (CPLHashSet *set)
 Clear all elements from a hash set. More...
 
int CPLHashSetSize (const CPLHashSet *set)
 Returns the number of elements inserted in the hash set. More...
 
void CPLHashSetForeach (CPLHashSet *set, CPLHashSetIterEltFunc fnIterFunc, void *user_data)
 Walk through the hash set and runs the provided function on all the elements. More...
 
int CPLHashSetInsert (CPLHashSet *set, void *elt)
 Inserts an element into a hash set. More...
 
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. More...
 
int CPLHashSetRemove (CPLHashSet *set, const void *elt)
 Removes an element from a hash set. More...
 
int CPLHashSetRemoveDeferRehash (CPLHashSet *set, const void *elt)
 Removes an element from a hash set. More...
 
unsigned long CPLHashSetHashPointer (const void *elt)
 Hash function for an arbitrary pointer. More...
 
int CPLHashSetEqualPointer (const void *elt1, const void *elt2)
 Equality function for arbitrary pointers. More...
 
unsigned long CPLHashSetHashStr (const void *pszStr)
 Hash function for a zero-terminated string. More...
 
int CPLHashSetEqualStr (const void *pszStr1, const void *pszStr2)
 Equality function for strings. More...
 

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 CPLHashSetClear ( CPLHashSet set)

Clear all elements from a hash set.

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

Parameters
setthe hash set
Since
GDAL 2.1
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
setthe hash set
int CPLHashSetEqualPointer ( const void *  elt1,
const void *  elt2 
)

Equality function for arbitrary pointers.

Parameters
elt1the first arbitrary pointer to compare
elt2the 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
elt1the first string to compare. May be NULL.
elt2the 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
setthe hash set.
fnIterFuncthe function called on each element.
user_datathe user data provided to the function.
unsigned long CPLHashSetHashPointer ( const void *  elt)

Hash function for an arbitrary pointer.

Parameters
eltthe 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
eltthe 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
setthe hash set
eltthe 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
setthe hash set
eltthe 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
fnHashFunchash function. May be NULL.
fnEqualFuncequal function. May be NULL.
fnFreeEltFuncelement 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
setthe hash set
eltthe new element to remove from the hash set
Returns
TRUE if the element was in the hash set
int CPLHashSetRemoveDeferRehash ( CPLHashSet set,
const void *  elt 
)

Removes an element from a hash set.

This will defer potential rehashing of the set to later calls to CPLHashSetInsert() or CPLHashSetRemove().

Parameters
setthe hash set
eltthe new element to remove from the hash set
Returns
TRUE if the element was in the hash set
Since
GDAL 2.1
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
setthe hash set
Returns
the number of elements in the hash set

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