/*
******************************************************************************
* Copyright (C) 1997-2001, International Business Machines
* Corporation and others. All Rights Reserved.
******************************************************************************
* Date Name Description
* 03/22/00 aliu Adapted from original C++ ICU Hashtable.
* 07/06/01 aliu Modified to support int32_t keys on
* platforms with sizeof(void*) < 32.
******************************************************************************
*/
#ifndef UHASH_H
#define UHASH_H
#include "unicode/utypes.h"
/**
* UHashtable stores key-value pairs and does moderately fast lookup
* based on keys. It provides a good tradeoff between access time and
* storage space. As elements are added to it, it grows to accomodate
* them. By default, the table never shrinks, even if all elements
* are removed from it.
*
* Keys and values are stored as void* pointers. These void* pointers
* may be actual pointers to strings, objects, or any other structure
* in memory, or they may simply be integral values cast to void*.
* UHashtable doesn't care and manipulates them via user-supplied
* functions. These functions hash keys, compare keys, delete keys,
* and delete values. Some function pointers are optional (may be
* NULL); others must be supplied. Several prebuilt functions exist
* to handle common key types.
*
* UHashtable ownership of keys and values is flexible, and controlled
* by whether or not the key deleter and value deleter functions are
* set. If a void* key is actually a pointer to a deletable object,
* then UHashtable can be made to delete that object by setting the
* key deleter function pointer to a non-NULL value. If this is done,
* then keys passed to uhash_put() are owned by the hashtable and will
* be deleted by it at some point, either as keys are replaced, or
* when uhash_close() is finally called. The same is true of values
* and the value deleter function pointer. Keys passed to methods
* other than uhash_put() are never owned by the hashtable.
*
* NULL values are not allowed. uhash_get() returns NULL to indicate
* a key that is not in the table, and having a NULL value in the
* table would generate an ambiguous result. If a key and a NULL
* value is passed to uhash_put(), this has the effect of doing a
* uhash_remove() on that key. This keeps uhash_get(), uhash_count(),
* and uhash_nextElement() consistent with one another.
*
* To see everything in a hashtable, use uhash_nextElement() to
* iterate through its contents. Each call to this function returns a
* UHashElement pointer. A hash element contains a key, value, and
* hashcode. During iteration an element may be deleted by calling
* uhash_removeElement(); iteration may safely continue thereafter.
* The uhash_remove() function may also be safely called in
* mid-iteration. However, if uhash_put() is called during iteration
* then the iteration will be out of sync. Under no circumstances
* should the UHashElement returned by uhash_nextElement be modified
* directly.
*
* By default, the hashtable grows when necessary, but never shrinks,
* even if all items are removed. For most applications this is
* optimal. However, in a highly dynamic usage where memory is at a
* premium, the table can be set to both grow and shrink by calling
* uhash_setResizePolicy() with the policy U_GROW_AND_SHRINK. In a
* situation where memory is critical and the client wants a table
* that does not grow at all, the constant U_FIXED can be used.
*/
/********************************************************************
* Data Structures
********************************************************************/
U_CDECL_BEGIN
/**
* A key or value within the hashtable. It may be either a 32-bit
* integral value or an opaque void* pointer. The void* pointer may
* be smaller than 32 bits (e.g. 24 bits) or may be larger (e.g. 64
* bits). The hashing and comparison functions take a pointer to a
* UHashTok, but the deleter receives the void* pointer within it.
*
* Because a UHashTok is the size of a native pointer or a 32-bit
* integer, we pass it around by value.
*/
union UHashTok {
void* pointer;
int32_t integer;
};
typedef union UHashTok UHashTok;
/**
* This is a single hash element.
*/
struct UHashElement {
/* Reorder these elements to pack nicely if necessary */
int32_t hashcode;
UHashTok value;
UHashTok key;
};
typedef struct UHashElement UHashElement;
/**
* A hashing function.
* @param key A key stored in a hashtable
* @return A NON-NEGATIVE hash code for parm.
*/
typedef int32_t U_CALLCONV UHashFunction(const UHashTok key);
/**
* A key comparison function.
* @param key1 A key stored in a hashtable
* @param key2 A key stored in a hashtable
* @return TRUE if the two keys are equal.
*/
typedef UBool U_CALLCONV UKeyComparator(const UHashTok key1,
const UHashTok key2);
/**
* A function called by uhash_remove,
* uhash_close, or uhash_put to delete
* an existing key or value.
* @param obj A key or value stored in a hashtable
*/
typedef void U_CALLCONV UObjectDeleter(void* obj);
/**
* This specifies whether or not, and how, the hastable resizes itself.
* See uhash_setResizePolicy().
*/
enum UHashResizePolicy {
U_GROW, /* Grow on demand, do not shrink */
U_GROW_AND_SHRINK, /* Grow and shrink on demand */
U_FIXED /* Never change size */
};
/**
* The UHashtable struct. Clients should treat this as an opaque data
* type and manipulate it only through the uhash_... API.
*/
struct UHashtable {
/* Main key-value pair storage array */
UHashElement *elements;
/* Size parameters */
int32_t count; /* The number of key-value pairs in this table.
* 0 <= count <= length. In practice we
* never let count == length (see code). */
int32_t length; /* The physical size of the arrays hashes, keys
* and values. Must be prime. */
int32_t primeIndex; /* Index into our prime table for length.
* length == PRIMES[primeIndex] */
/* Rehashing thresholds */
int32_t highWaterMark; /* If count > highWaterMark, rehash */
int32_t lowWaterMark; /* If count < lowWaterMark, rehash */
float highWaterRatio; /* 0..1; high water as a fraction of length */
float lowWaterRatio; /* 0..1; low water as a fraction of length */
/* Function pointers */
UHashFunction *keyHasher; /* Computes hash from key.
* Never null. */
UKeyComparator *keyComparator; /* Compares keys for equality.
* Never null. */
UObjectDeleter *keyDeleter; /* Deletes keys when required.
* If NULL won't do anything */
UObjectDeleter *valueDeleter; /* Deletes values when required.
* If NULL won't do anything */
};
typedef struct UHashtable UHashtable;
U_CDECL_END
/********************************************************************
* API
********************************************************************/
/**
* Initialize a new UHashtable.
* @param keyHash A pointer to the key hashing function. Must not be
* NULL.
* @param keyComp A pointer to the function that compares keys. Must
* not be NULL.
* @param status A pointer to an UErrorCode to receive any errors.
* @return A pointer to a UHashtable, or 0 if an error occurred.
* @see uhash_openSize
*/
U_CAPI UHashtable* U_EXPORT2
uhash_open(UHashFunction *keyHash,
UKeyComparator *keyComp,
UErrorCode *status);
/**
* Initialize a new UHashtable with a given initial size.
* @param keyHash A pointer to the key hashing function. Must not be
* NULL.
* @param keyComp A pointer to the function that compares keys. Must
* not be NULL.
* @param size The initial capacity of this hash table.
* @param status A pointer to an UErrorCode to receive any errors.
* @return A pointer to a UHashtable, or 0 if an error occurred.
* @see uhash_open
*/
U_CAPI UHashtable* U_EXPORT2
uhash_openSize(UHashFunction *keyHash,
UKeyComparator *keyComp,
int32_t size,
UErrorCode *status);
/**
* Close a UHashtable, releasing the memory used.
* @param hash The UHashtable to close.
*/
U_CAPI void U_EXPORT2
uhash_close(UHashtable *hash);
/**
* Set the function used to hash keys.
* @param hash The UHashtable to set
* @param fn the function to be used hash keys; must not be NULL
* @return the previous key hasher; non-NULL
*/
U_CAPI UHashFunction *U_EXPORT2
uhash_setKeyHasher(UHashtable *hash, UHashFunction *fn);
/**
* Set the function used to compare keys. The default comparison is a
* void* pointer comparison.
* @param hash The UHashtable to set
* @param fn the function to be used compare keys; must not be NULL
* @return the previous key comparator; non-NULL
*/
U_CAPI UKeyComparator *U_EXPORT2
uhash_setKeyComparator(UHashtable *hash, UKeyComparator *fn);
/**
* Set the function used to delete keys. If this function pointer is
* NULL, this hashtable does not delete keys. If it is non-NULL, this
* hashtable does delete keys. This function should be set once
* before any elements are added to the hashtable and should not be
* changed thereafter.
* @param hash The UHashtable to set
* @param fn the function to be used delete keys, or NULL
* @return the previous key deleter; may be NULL
*/
U_CAPI UObjectDeleter *U_EXPORT2
uhash_setKeyDeleter(UHashtable *hash, UObjectDeleter *fn);
/**
* Set the function used to delete values. If this function pointer
* is NULL, this hashtable does not delete values. If it is non-NULL,
* this hashtable does delete values. This function should be set
* once before any elements are added to the hashtable and should not
* be changed thereafter.
* @param hash The UHashtable to set
* @param fn the function to be used delete values, or NULL
* @return the previous value deleter; may be NULL
*/
U_CAPI UObjectDeleter *U_EXPORT2
uhash_setValueDeleter(UHashtable *hash, UObjectDeleter *fn);
/**
* Specify whether or not, and how, the hastable resizes itself.
* By default, tables grow but do not shrink (policy U_GROW).
* See enum UHashResizePolicy.
* @param hash The UHashtable to set
* @param policy The way the hashtable resizes itself, {U_GROW, U_GROW_AND_SHRINK, U_FIXED}
*/
U_CAPI void U_EXPORT2
uhash_setResizePolicy(UHashtable *hash, enum UHashResizePolicy policy);
/**
* Get the number of key-value pairs stored in a UHashtable.
* @param hash The UHashtable to query.
* @return The number of key-value pairs stored in hash.
*/
U_CAPI int32_t U_EXPORT2
uhash_count(const UHashtable *hash);
/**
* Put a (key=pointer, value=pointer) item in a UHashtable. If the
* keyDeleter is non-NULL, then the hashtable owns 'key' after this
* call. If the valueDeleter is non-NULL, then the hashtable owns
* 'value' after this call. Storing a NULL value is the same as
* calling uhash_remove().
* @param hash The target UHashtable.
* @param key The key to store.
* @param value The value to store, may be NULL (see above).
* @param status A pointer to an UErrorCode to receive any errors.
* @return The previous value, or NULL if none.
* @see uhash_get
*/
U_CAPI void* U_EXPORT2
uhash_put(UHashtable *hash,
void *key,
void *value,
UErrorCode *status);
/**
* Put a (key=integer, value=pointer) item in a UHashtable.
* keyDeleter must be NULL. If the valueDeleter is non-NULL, then the
* hashtable owns 'value' after this call. Storing a NULL value is
* the same as calling uhash_remove().
* @param hash The target UHashtable.
* @param key The integer key to store.
* @param value The value to store, may be NULL (see above).
* @param status A pointer to an UErrorCode to receive any errors.
* @return The previous value, or NULL if none.
* @see uhash_get
*/
U_CAPI void* U_EXPORT2
uhash_iput(UHashtable *hash,
int32_t key,
void* value,
UErrorCode *status);
/**
* Put a (key=pointer, value=integer) item in a UHashtable. If the
* keyDeleter is non-NULL, then the hashtable owns 'key' after this
* call. valueDeleter must be NULL. Storing a 0 value is the same as
* calling uhash_remove().
* @param hash The target UHashtable.
* @param key The key to store.
* @param value The integer value to store.
* @param status A pointer to an UErrorCode to receive any errors.
* @return The previous value, or 0 if none.
* @see uhash_get
*/
U_CAPI int32_t U_EXPORT2
uhash_puti(UHashtable *hash,
void* key,
int32_t value,
UErrorCode *status);
/**
* Retrieve a pointer value from a UHashtable using a pointer key,
* as previously stored by uhash_put().
* @param hash The target UHashtable.
* @param key A pointer key stored in a hashtable
* @return The requested item, or NULL if not found.
*/
U_CAPI void* U_EXPORT2
uhash_get(const UHashtable *hash,
const void *key);
/**
* Retrieve a pointer value from a UHashtable using a integer key,
* as previously stored by uhash_iput().
* @param hash The target UHashtable.
* @param key An integer key stored in a hashtable
* @return The requested item, or NULL if not found.
*/
U_CAPI void* U_EXPORT2
uhash_iget(const UHashtable *hash,
int32_t key);
/**
* Retrieve an integer value from a UHashtable using a pointer key,
* as previously stored by uhash_puti().
* @param hash The target UHashtable.
* @param key A pointer key stored in a hashtable
* @return The requested item, or 0 if not found.
*/
U_CAPI int32_t U_EXPORT2
uhash_geti(const UHashtable *hash,
const void* key);
/**
* Remove an item from a UHashtable stored by uhash_put().
* @param hash The target UHashtable.
* @param key A key stored in a hashtable
* @return The item removed, or NULL if not found.
*/
U_CAPI void* U_EXPORT2
uhash_remove(UHashtable *hash,
const void *key);
/**
* Remove an item from a UHashtable stored by uhash_iput().
* @param hash The target UHashtable.
* @param key An integer key stored in a hashtable
* @return The item removed, or NULL if not found.
*/
U_CAPI void* U_EXPORT2
uhash_iremove(UHashtable *hash,
int32_t key);
/**
* Remove an item from a UHashtable stored by uhash_puti().
* @param hash The target UHashtable.
* @param key An key stored in a hashtable
* @return The item removed, or 0 if not found.
*/
U_CAPI int32_t U_EXPORT2
uhash_removei(UHashtable *hash,
const void* key);
/**
* Remove all items from a UHashtable.
* @param hash The target UHashtable.
*/
U_CAPI void U_EXPORT2
uhash_removeAll(UHashtable *hash);
/**
* Locate an element of a UHashtable. The caller must not modify the
* returned object. The primary use of this function is to obtain the
* stored key when it may not be identical to the search key. For
* example, if the compare function is a case-insensitive string
* compare, then the hash key may be desired in order to obtain the
* canonical case corresponding to a search key.
* @param hash The target UHashtable.
* @param key A key stored in a hashtable
* @return a hash element, or NULL if the key is not found.
*/
U_CAPI const UHashElement* U_EXPORT2
uhash_find(const UHashtable *hash, const void* key);
/**
* Iterate through the elements of a UHashtable. The caller must not
* modify the returned object. However, uhash_removeElement() may be
* called during iteration to remove an element from the table.
* Iteration may safely be resumed afterwards. If uhash_put() is
* called during iteration the iteration will then be out of sync and
* should be restarted.
* @param hash The target UHashtable.
* @param pos This should be set to -1 initially, and left untouched
* thereafter.
* @return a hash element, or NULL if no further key-value pairs
* exist in the table.
*/
U_CAPI const UHashElement* U_EXPORT2
uhash_nextElement(const UHashtable *hash,
int32_t *pos);
/**
* Remove an element, returned by uhash_nextElement(), from the table.
* Iteration may be safely continued afterwards.
* @param hash The hashtable
* @param e The element, returned by uhash_nextElement(), to remove.
* Must not be NULL. Must not be an empty or deleted element (as long
* as this was returned by uhash_nextElement() it will not be empty or
* deleted). Note: Although this parameter is const, it will be
* modified.
* @return the value that was removed.
*/
U_CAPI void* U_EXPORT2
uhash_removeElement(UHashtable *hash, const UHashElement* e);
/********************************************************************
* UHashTok convenience
********************************************************************/
/**
* Return a UHashTok for an integer.
* @param i The given integer
* @return a UHashTok for an integer.
*/
U_CAPI UHashTok U_EXPORT2
uhash_toki(int32_t i);
/**
* Return a UHashTok for a pointer.
* @param p The given pointer
* @return a UHashTok for a pointer.
*/
U_CAPI UHashTok U_EXPORT2
uhash_tokp(void* p);
/********************************************************************
* UChar* and char* Support Functions
********************************************************************/
/**
* Generate a hash code for a null-terminated UChar* string. If the
* string is not null-terminated do not use this function. Use
* together with uhash_compareUChars.
* @param key The string (const UChar*) to hash.
* @return A hash code for the key.
*/
U_CAPI int32_t U_EXPORT2
uhash_hashUChars(const UHashTok key);
/**
* Generate a hash code for a null-terminated char* string. If the
* string is not null-terminated do not use this function. Use
* together with uhash_compareChars.
* @param key The string (const char*) to hash.
* @return A hash code for the key.
*/
U_CAPI int32_t U_EXPORT2
uhash_hashChars(const UHashTok key);
/* Used by UnicodeString to compute its hashcode - Not public API. */
U_CAPI int32_t U_EXPORT2
uhash_hashUCharsN(const UChar *key, int32_t length);
/**
* Generate a case-insensitive hash code for a null-terminated char*
* string. If the string is not null-terminated do not use this
* function. Use together with uhash_compareIChars.
* @param key The string (const char*) to hash.
* @return A hash code for the key.
*/
U_CAPI int32_t U_EXPORT2
uhash_hashIChars(const UHashTok key);
/**
* Comparator for null-terminated UChar* strings. Use together with
* uhash_hashUChars.
* @param key1 The string for comparison
* @param key2 The string for comparison
* @return true if key1 and key2 are equal, return false otherwise.
*/
U_CAPI UBool U_EXPORT2
uhash_compareUChars(const UHashTok key1, const UHashTok key2);
/**
* Comparator for null-terminated char* strings. Use together with
* uhash_hashChars.
* @param key1 The string for comparison
* @param key2 The string for comparison
* @return true if key1 and key2 are equal, return false otherwise.
*/
U_CAPI UBool U_EXPORT2
uhash_compareChars(const UHashTok key1, const UHashTok key2);
/**
* Case-insensitive comparator for null-terminated char* strings. Use
* together with uhash_hashIChars.
* @param key1 The string for comparison
* @param key2 The string for comparison
* @return true if key1 and key2 are equal, return false otherwise.
*/
U_CAPI UBool U_EXPORT2
uhash_compareIChars(const UHashTok key1, const UHashTok key2);
/********************************************************************
* UnicodeString Support Functions
********************************************************************/
/**
* Hash function for UnicodeString* keys.
* @param key The string (const char*) to hash.
* @return A hash code for the key.
*/
U_CAPI int32_t U_EXPORT2
uhash_hashUnicodeString(const UHashTok key);
/**
* Hash function for UnicodeString* keys (case insensitive).
* Make sure to use together with uhash_compareCaselessUnicodeString.
* @param key The string (const char*) to hash.
* @return A hash code for the key.
*/
U_CAPI int32_t U_EXPORT2
uhash_hashCaselessUnicodeString(const UHashTok key);
/**
* Comparator function for UnicodeString* keys.
* @param key1 The string for comparison
* @param key2 The string for comparison
* @return true if key1 and key2 are equal, return false otherwise.
*/
U_CAPI UBool U_EXPORT2
uhash_compareUnicodeString(const UHashTok key1, const UHashTok key2);
/**
* Comparator function for UnicodeString* keys (case insensitive).
* Make sure to use together with uhash_hashCaselessUnicodeString.
* @param key1 The string for comparison
* @param key2 The string for comparison
* @return true if key1 and key2 are equal, return false otherwise.
*/
U_CAPI UBool U_EXPORT2
uhash_compareCaselessUnicodeString(const UHashTok key1, const UHashTok key2);
/**
* Deleter function for UnicodeString* keys or values.
* @param obj The object to be deleted
*/
U_CAPI void U_EXPORT2
uhash_deleteUnicodeString(void *obj);
/********************************************************************
* int32_t Support Functions
********************************************************************/
/**
* Hash function for 32-bit integer keys.
* @param key The string (const char*) to hash.
* @return A hash code for the key.
*/
U_CAPI int32_t U_EXPORT2
uhash_hashLong(const UHashTok key);
/**
* Comparator function for 32-bit integer keys.
* @param key1 The integer for comparison
* @param Key2 The integer for comparison
* @return true if key1 and key2 are equal, return false otherwise
*/
U_CAPI UBool U_EXPORT2
uhash_compareLong(const UHashTok key1, const UHashTok key2);
/********************************************************************
* Other Support Functions
********************************************************************/
/**
* Deleter for Hashtable objects.
* @param obj The object to be deleted
*/
U_CAPI void U_EXPORT2
uhash_deleteHashtable(void *obj);
/**
* Deleter for UVector objects.
* @param obj The object to be deleted
*/
U_CAPI void U_EXPORT2
uhash_deleteUVector(void *obj);
/**
* Deleter for any key or value allocated using uprv_malloc. Calls
* uprv_free.
* @param obj The object to be deleted
*/
U_CAPI void U_EXPORT2
uhash_freeBlock(void *obj);
#endif