17c478bd9Sstevel@tonic-gate /* 27c478bd9Sstevel@tonic-gate ** 2001 September 22 37c478bd9Sstevel@tonic-gate ** 47c478bd9Sstevel@tonic-gate ** The author disclaims copyright to this source code. In place of 57c478bd9Sstevel@tonic-gate ** a legal notice, here is a blessing: 67c478bd9Sstevel@tonic-gate ** 77c478bd9Sstevel@tonic-gate ** May you do good and not evil. 87c478bd9Sstevel@tonic-gate ** May you find forgiveness for yourself and forgive others. 97c478bd9Sstevel@tonic-gate ** May you share freely, never taking more than you give. 107c478bd9Sstevel@tonic-gate ** 117c478bd9Sstevel@tonic-gate ************************************************************************* 127c478bd9Sstevel@tonic-gate ** This is the header file for the generic hash-table implemenation 137c478bd9Sstevel@tonic-gate ** used in SQLite. 147c478bd9Sstevel@tonic-gate ** 157c478bd9Sstevel@tonic-gate ** $Id: hash.h,v 1.6 2004/01/08 02:17:33 drh Exp $ 167c478bd9Sstevel@tonic-gate */ 177c478bd9Sstevel@tonic-gate #ifndef _SQLITE_HASH_H_ 187c478bd9Sstevel@tonic-gate #define _SQLITE_HASH_H_ 197c478bd9Sstevel@tonic-gate 207c478bd9Sstevel@tonic-gate /* Forward declarations of structures. */ 217c478bd9Sstevel@tonic-gate typedef struct Hash Hash; 227c478bd9Sstevel@tonic-gate typedef struct HashElem HashElem; 237c478bd9Sstevel@tonic-gate 247c478bd9Sstevel@tonic-gate /* A complete hash table is an instance of the following structure. 257c478bd9Sstevel@tonic-gate ** The internals of this structure are intended to be opaque -- client 267c478bd9Sstevel@tonic-gate ** code should not attempt to access or modify the fields of this structure 277c478bd9Sstevel@tonic-gate ** directly. Change this structure only by using the routines below. 287c478bd9Sstevel@tonic-gate ** However, many of the "procedures" and "functions" for modifying and 297c478bd9Sstevel@tonic-gate ** accessing this structure are really macros, so we can't really make 307c478bd9Sstevel@tonic-gate ** this structure opaque. 317c478bd9Sstevel@tonic-gate */ 327c478bd9Sstevel@tonic-gate struct Hash { 337c478bd9Sstevel@tonic-gate char keyClass; /* SQLITE_HASH_INT, _POINTER, _STRING, _BINARY */ 347c478bd9Sstevel@tonic-gate char copyKey; /* True if copy of key made on insert */ 357c478bd9Sstevel@tonic-gate int count; /* Number of entries in this table */ 367c478bd9Sstevel@tonic-gate HashElem *first; /* The first element of the array */ 377c478bd9Sstevel@tonic-gate int htsize; /* Number of buckets in the hash table */ 387c478bd9Sstevel@tonic-gate struct _ht { /* the hash table */ 397c478bd9Sstevel@tonic-gate int count; /* Number of entries with this hash */ 407c478bd9Sstevel@tonic-gate HashElem *chain; /* Pointer to first entry with this hash */ 417c478bd9Sstevel@tonic-gate } *ht; 427c478bd9Sstevel@tonic-gate }; 437c478bd9Sstevel@tonic-gate 44*1da57d55SToomas Soome /* Each element in the hash table is an instance of the following 457c478bd9Sstevel@tonic-gate ** structure. All elements are stored on a single doubly-linked list. 467c478bd9Sstevel@tonic-gate ** 477c478bd9Sstevel@tonic-gate ** Again, this structure is intended to be opaque, but it can't really 487c478bd9Sstevel@tonic-gate ** be opaque because it is used by macros. 497c478bd9Sstevel@tonic-gate */ 507c478bd9Sstevel@tonic-gate struct HashElem { 517c478bd9Sstevel@tonic-gate HashElem *next, *prev; /* Next and previous elements in the table */ 527c478bd9Sstevel@tonic-gate void *data; /* Data associated with this element */ 537c478bd9Sstevel@tonic-gate void *pKey; int nKey; /* Key associated with this element */ 547c478bd9Sstevel@tonic-gate }; 557c478bd9Sstevel@tonic-gate 567c478bd9Sstevel@tonic-gate /* 577c478bd9Sstevel@tonic-gate ** There are 4 different modes of operation for a hash table: 587c478bd9Sstevel@tonic-gate ** 597c478bd9Sstevel@tonic-gate ** SQLITE_HASH_INT nKey is used as the key and pKey is ignored. 607c478bd9Sstevel@tonic-gate ** 617c478bd9Sstevel@tonic-gate ** SQLITE_HASH_POINTER pKey is used as the key and nKey is ignored. 627c478bd9Sstevel@tonic-gate ** 637c478bd9Sstevel@tonic-gate ** SQLITE_HASH_STRING pKey points to a string that is nKey bytes long 647c478bd9Sstevel@tonic-gate ** (including the null-terminator, if any). Case 657c478bd9Sstevel@tonic-gate ** is ignored in comparisons. 667c478bd9Sstevel@tonic-gate ** 67*1da57d55SToomas Soome ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long. 687c478bd9Sstevel@tonic-gate ** memcmp() is used to compare keys. 697c478bd9Sstevel@tonic-gate ** 707c478bd9Sstevel@tonic-gate ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY 71*1da57d55SToomas Soome ** if the copyKey parameter to HashInit is 1. 727c478bd9Sstevel@tonic-gate */ 737c478bd9Sstevel@tonic-gate #define SQLITE_HASH_INT 1 747c478bd9Sstevel@tonic-gate /* #define SQLITE_HASH_POINTER 2 // NOT USED */ 757c478bd9Sstevel@tonic-gate #define SQLITE_HASH_STRING 3 767c478bd9Sstevel@tonic-gate #define SQLITE_HASH_BINARY 4 777c478bd9Sstevel@tonic-gate 787c478bd9Sstevel@tonic-gate /* 797c478bd9Sstevel@tonic-gate ** Access routines. To delete, insert a NULL pointer. 807c478bd9Sstevel@tonic-gate */ 817c478bd9Sstevel@tonic-gate void sqliteHashInit(Hash*, int keytype, int copyKey); 827c478bd9Sstevel@tonic-gate void *sqliteHashInsert(Hash*, const void *pKey, int nKey, void *pData); 837c478bd9Sstevel@tonic-gate void *sqliteHashFind(const Hash*, const void *pKey, int nKey); 847c478bd9Sstevel@tonic-gate void sqliteHashClear(Hash*); 857c478bd9Sstevel@tonic-gate 867c478bd9Sstevel@tonic-gate /* 877c478bd9Sstevel@tonic-gate ** Macros for looping over all elements of a hash table. The idiom is 887c478bd9Sstevel@tonic-gate ** like this: 897c478bd9Sstevel@tonic-gate ** 907c478bd9Sstevel@tonic-gate ** Hash h; 917c478bd9Sstevel@tonic-gate ** HashElem *p; 927c478bd9Sstevel@tonic-gate ** ... 937c478bd9Sstevel@tonic-gate ** for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){ 947c478bd9Sstevel@tonic-gate ** SomeStructure *pData = sqliteHashData(p); 957c478bd9Sstevel@tonic-gate ** // do something with pData 967c478bd9Sstevel@tonic-gate ** } 977c478bd9Sstevel@tonic-gate */ 987c478bd9Sstevel@tonic-gate #define sqliteHashFirst(H) ((H)->first) 997c478bd9Sstevel@tonic-gate #define sqliteHashNext(E) ((E)->next) 1007c478bd9Sstevel@tonic-gate #define sqliteHashData(E) ((E)->data) 1017c478bd9Sstevel@tonic-gate #define sqliteHashKey(E) ((E)->pKey) 1027c478bd9Sstevel@tonic-gate #define sqliteHashKeysize(E) ((E)->nKey) 1037c478bd9Sstevel@tonic-gate 1047c478bd9Sstevel@tonic-gate /* 1057c478bd9Sstevel@tonic-gate ** Number of entries in a hash table 1067c478bd9Sstevel@tonic-gate */ 1077c478bd9Sstevel@tonic-gate #define sqliteHashCount(H) ((H)->count) 1087c478bd9Sstevel@tonic-gate 1097c478bd9Sstevel@tonic-gate #endif /* _SQLITE_HASH_H_ */ 110