/* $Id: strspace.cpp 4071 2007-08-07 17:07:59Z vboxsync $ */ /** @file * innotek Portable Runtime - Unique String Spaces. */ /* * Copyright (C) 2006-2007 innotek GmbH * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file 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, * in version 2 as it comes in the "COPYING" file of the VirtualBox OSE * distribution. VirtualBox OSE is distributed in the hope that it will * be useful, but WITHOUT ANY WARRANTY of any kind. */ /******************************************************************************* * Header Files * *******************************************************************************/ #include #include /******************************************************************************* * Defined Constants And Macros * *******************************************************************************/ /* * AVL configuration. */ #define KAVL_FN(a) rtstrspace##a #define KAVL_MAX_STACK 27 /* Up to 2^24 nodes. */ #define KAVL_EQUAL_ALLOWED 1 #define KAVLNODECORE RTSTRSPACECORE #define PKAVLNODECORE PRTSTRSPACECORE #define PPKAVLNODECORE PPRTSTRSPACECORE #define KAVLKEY uint32_t #define PKAVLKEY uint32_t * #define PKAVLCALLBACK PFNRTSTRSPACECALLBACK /* * AVL Compare macros */ #define KAVL_G(key1, key2) (key1 > key2) #define KAVL_E(key1, key2) (key1 == key2) #define KAVL_NE(key1, key2) (key1 != key2) /* * Include the code. */ #define SSToDS(ptr) ptr #define KMAX RT_MAX #define kASSERT Assert #include "table/avl_Base.cpp.h" #include "table/avl_Get.cpp.h" #include "table/avl_DoWithAll.cpp.h" #include "table/avl_Destroy.cpp.h" /* sdbm: This algorithm was created for sdbm (a public-domain reimplementation of ndbm) database library. it was found to do well in scrambling bits, causing better distribution of the keys and fewer splits. it also happens to be a good general hashing function with good distribution. the actual function is hash(i) = hash(i - 1) * 65599 + str[i]; what is included below is the faster version used in gawk. [there is even a faster, duff-device version] the magic constant 65599 was picked out of thin air while experimenting with different constants, and turns out to be a prime. this is one of the algorithms used in berkeley db (see sleepycat) and elsewhere. */ inline uint32_t sdbm(const char *str, size_t *pcch) { uint8_t *pu8 = (uint8_t *)str; uint32_t hash = 0; int c; while ((c = *pu8++)) hash = c + (hash << 6) + (hash << 16) - hash; *pcch = (uintptr_t)pu8 - (uintptr_t)str; return hash; } /** * Inserts a string into a unique string space. * * @returns true on success. * @returns false if the string collieded with an existing string. * @param pStrSpace The space to insert it into. * @param pStr The string node. */ RTDECL(bool) RTStrSpaceInsert(PRTSTRSPACE pStrSpace, PRTSTRSPACECORE pStr) { pStr->Key = sdbm(pStr->pszString, &pStr->cchString); PRTSTRSPACECORE pMatch = KAVL_FN(Get)(pStrSpace, pStr->Key); if (!pMatch) return KAVL_FN(Insert)(pStrSpace, pStr); /* Check for clashes. */ for (PRTSTRSPACECORE pCur = pMatch; pCur; pCur = pCur->pList) if ( pCur->cchString == pStr->cchString && !memcmp(pCur->pszString, pStr->pszString, pStr->cchString)) return false; pStr->pList = pMatch->pList; pMatch->pList = pStr; return false; } /** * Removes a string from a unique string space. * * @returns Pointer to the removed string node. * @returns NULL if the string was not found in the string space. * @param pStrSpace The space to insert it into. * @param pszString The string to remove. */ RTDECL(PRTSTRSPACECORE) RTStrSpaceRemove(PRTSTRSPACE pStrSpace, const char *pszString) { size_t cchString; KAVLKEY Key = sdbm(pszString, &cchString); PRTSTRSPACECORE pCur = KAVL_FN(Get)(pStrSpace, Key); if (!pCur) return NULL; /* find the right one. */ PRTSTRSPACECORE pPrev = NULL; for (; pCur; pPrev = pCur, pCur = pCur->pList) if ( pCur->cchString == cchString && !memcmp(pCur->pszString, pszString, cchString)) break; if (pCur) { if (pPrev) /* simple, it's in the linked list. */ pPrev->pList = pCur->pList; else { /* in the tree. remove and reinsert list head. */ PRTSTRSPACECORE pInsert = pCur->pList; pCur->pList = NULL; pCur = KAVL_FN(Remove)(pStrSpace, Key); Assert(pCur); if (pInsert) { PRTSTRSPACECORE pList = pInsert->pList; bool fRc = KAVL_FN(Insert)(pStrSpace, pInsert); Assert(fRc); NOREF(fRc); pInsert->pList = pList; } } } return pCur; } /** * Gets a string from a unique string space. * * @returns Pointer to the string node. * @returns NULL if the string was not found in the string space. * @param pStrSpace The space to insert it into. * @param pszString The string to get. */ RTDECL(PRTSTRSPACECORE) RTStrSpaceGet(PRTSTRSPACE pStrSpace, const char *pszString) { size_t cchString; KAVLKEY Key = sdbm(pszString, &cchString); PRTSTRSPACECORE pCur = KAVL_FN(Get)(pStrSpace, Key); if (!pCur) return NULL; /* Linear search. */ for (; pCur; pCur = pCur->pList) if ( pCur->cchString == cchString && !memcmp(pCur->pszString, pszString, cchString)) return pCur; return NULL; } /** * Enumerates the string space. * The caller supplies a callback which will be called for each of * the string nodes. * * @returns 0 or what ever non-zero return value pfnCallback returned * when aborting the destruction. * @param pStrSpace The space to insert it into. * @param pfnCallback The callback. * @param pvUser The user argument. */ RTDECL(int) RTStrSpaceEnumerate(PRTSTRSPACE pStrSpace, PFNRTSTRSPACECALLBACK pfnCallback, void *pvUser) { return KAVL_FN(DoWithAll)(pStrSpace, true, pfnCallback, pvUser); } /** * Destroys the string space. * The caller supplies a callback which will be called for each of * the string nodes in for freeing their memory and other resources. * * @returns 0 or what ever non-zero return value pfnCallback returned * when aborting the destruction. * @param pStrSpace The space to insert it into. * @param pfnCallback The callback. * @param pvUser The user argument. */ RTDECL(int) RTStrSpaceDestroy(PRTSTRSPACE pStrSpace, PFNRTSTRSPACECALLBACK pfnCallback, void *pvUser) { return KAVL_FN(Destroy)(pStrSpace, pfnCallback, pvUser); }