From: drh Date: Mon, 14 Jan 2019 16:16:30 +0000 (+0000) Subject: Add the "prefixes" table-valued function in the ext/misc folder. X-Git-Tag: version-3.27.0~154 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4ead96348e5aacfcf480aae141d0ab8dccfa4760;p=thirdparty%2Fsqlite.git Add the "prefixes" table-valued function in the ext/misc folder. FossilOrigin-Name: f0fd2163fc23a555ef03af43294a14fcabae6921f52e64c979286c745b4f6218 --- diff --git a/ext/misc/prefixes.c b/ext/misc/prefixes.c new file mode 100644 index 0000000000..b74cb61a67 --- /dev/null +++ b/ext/misc/prefixes.c @@ -0,0 +1,265 @@ +/* +** 2018-04-19 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** +** This file implements a table-valued function: +** +** prefixes('abcdefg') +** +** The function has a single (non-HIDDEN) column named prefix that takes +** on all prefixes of the string in its argument, including an empty string +** and the input string itself. The order of prefixes is from longest +** to shortest. +*/ +#if !defined(SQLITEINT_H) +#include "sqlite3ext.h" +#endif +SQLITE_EXTENSION_INIT1 +#include +#include + +/* prefixes_vtab is a subclass of sqlite3_vtab which is +** underlying representation of the virtual table +*/ +typedef struct prefixes_vtab prefixes_vtab; +struct prefixes_vtab { + sqlite3_vtab base; /* Base class - must be first */ + /* No additional fields are necessary */ +}; + +/* prefixes_cursor is a subclass of sqlite3_vtab_cursor which will +** serve as the underlying representation of a cursor that scans +** over rows of the result +*/ +typedef struct prefixes_cursor prefixes_cursor; +struct prefixes_cursor { + sqlite3_vtab_cursor base; /* Base class - must be first */ + sqlite3_int64 iRowid; /* The rowid */ + char *zStr; /* Original string to be prefixed */ + int nStr; /* Length of the string in bytes */ +}; + +/* +** The prefixesConnect() method is invoked to create a new +** template virtual table. +** +** Think of this routine as the constructor for prefixes_vtab objects. +** +** All this routine needs to do is: +** +** (1) Allocate the prefixes_vtab object and initialize all fields. +** +** (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the +** result set of queries against the virtual table will look like. +*/ +static int prefixesConnect( + sqlite3 *db, + void *pAux, + int argc, const char *const*argv, + sqlite3_vtab **ppVtab, + char **pzErr +){ + prefixes_vtab *pNew; + int rc; + + rc = sqlite3_declare_vtab(db, + "CREATE TABLE prefixes(prefix TEXT, original_string TEXT HIDDEN)" + ); + if( rc==SQLITE_OK ){ + pNew = sqlite3_malloc( sizeof(*pNew) ); + *ppVtab = (sqlite3_vtab*)pNew; + if( pNew==0 ) return SQLITE_NOMEM; + memset(pNew, 0, sizeof(*pNew)); + } + return rc; +} + +/* +** This method is the destructor for prefixes_vtab objects. +*/ +static int prefixesDisconnect(sqlite3_vtab *pVtab){ + prefixes_vtab *p = (prefixes_vtab*)pVtab; + sqlite3_free(p); + return SQLITE_OK; +} + +/* +** Constructor for a new prefixes_cursor object. +*/ +static int prefixesOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){ + prefixes_cursor *pCur; + pCur = sqlite3_malloc( sizeof(*pCur) ); + if( pCur==0 ) return SQLITE_NOMEM; + memset(pCur, 0, sizeof(*pCur)); + *ppCursor = &pCur->base; + return SQLITE_OK; +} + +/* +** Destructor for a prefixes_cursor. +*/ +static int prefixesClose(sqlite3_vtab_cursor *cur){ + prefixes_cursor *pCur = (prefixes_cursor*)cur; + sqlite3_free(pCur->zStr); + sqlite3_free(pCur); + return SQLITE_OK; +} + + +/* +** Advance a prefixes_cursor to its next row of output. +*/ +static int prefixesNext(sqlite3_vtab_cursor *cur){ + prefixes_cursor *pCur = (prefixes_cursor*)cur; + pCur->iRowid++; + return SQLITE_OK; +} + +/* +** Return values of columns for the row at which the prefixes_cursor +** is currently pointing. +*/ +static int prefixesColumn( + sqlite3_vtab_cursor *cur, /* The cursor */ + sqlite3_context *ctx, /* First argument to sqlite3_result_...() */ + int i /* Which column to return */ +){ + prefixes_cursor *pCur = (prefixes_cursor*)cur; + switch( i ){ + case 0: + sqlite3_result_text(ctx, pCur->zStr, pCur->nStr - (int)pCur->iRowid, + 0); + break; + default: + sqlite3_result_text(ctx, pCur->zStr, pCur->nStr, 0); + break; + } + return SQLITE_OK; +} + +/* +** Return the rowid for the current row. In this implementation, the +** rowid is the same as the output value. +*/ +static int prefixesRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){ + prefixes_cursor *pCur = (prefixes_cursor*)cur; + *pRowid = pCur->iRowid; + return SQLITE_OK; +} + +/* +** Return TRUE if the cursor has been moved off of the last +** row of output. +*/ +static int prefixesEof(sqlite3_vtab_cursor *cur){ + prefixes_cursor *pCur = (prefixes_cursor*)cur; + return pCur->iRowid>pCur->nStr; +} + +/* +** This method is called to "rewind" the prefixes_cursor object back +** to the first row of output. This method is always called at least +** once prior to any call to prefixesColumn() or prefixesRowid() or +** prefixesEof(). +*/ +static int prefixesFilter( + sqlite3_vtab_cursor *pVtabCursor, + int idxNum, const char *idxStr, + int argc, sqlite3_value **argv +){ + prefixes_cursor *pCur = (prefixes_cursor *)pVtabCursor; + sqlite3_free(pCur->zStr); + if( argc>0 ){ + pCur->zStr = sqlite3_mprintf("%s", sqlite3_value_text(argv[0])); + pCur->nStr = pCur->zStr ? (int)strlen(pCur->zStr) : 0; + }else{ + pCur->zStr = 0; + pCur->nStr = 0; + } + pCur->iRowid = 0; + return SQLITE_OK; +} + +/* +** SQLite will invoke this method one or more times while planning a query +** that uses the virtual table. This routine needs to create +** a query plan for each invocation and compute an estimated cost for that +** plan. +*/ +static int prefixesBestIndex( + sqlite3_vtab *tab, + sqlite3_index_info *pIdxInfo +){ + /* Search for a usable equality constraint against column 1 + ** (original_string) and use it if at all possible */ + int i; + const struct sqlite3_index_constraint *p; + + for(i=0, p=pIdxInfo->aConstraint; inConstraint; i++, p++){ + if( p->iColumn!=1 ) continue; + if( p->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue; + if( !p->usable ) continue; + pIdxInfo->aConstraintUsage[i].argvIndex = 1; + pIdxInfo->aConstraintUsage[i].omit = 1; + pIdxInfo->estimatedCost = (double)10; + pIdxInfo->estimatedRows = 10; + return SQLITE_OK; + } + pIdxInfo->estimatedCost = (double)1000000000; + pIdxInfo->estimatedRows = 1000000000; + return SQLITE_OK; +} + +/* +** This following structure defines all the methods for the +** virtual table. +*/ +static sqlite3_module prefixesModule = { + /* iVersion */ 0, + /* xCreate */ 0, + /* xConnect */ prefixesConnect, + /* xBestIndex */ prefixesBestIndex, + /* xDisconnect */ prefixesDisconnect, + /* xDestroy */ 0, + /* xOpen */ prefixesOpen, + /* xClose */ prefixesClose, + /* xFilter */ prefixesFilter, + /* xNext */ prefixesNext, + /* xEof */ prefixesEof, + /* xColumn */ prefixesColumn, + /* xRowid */ prefixesRowid, + /* xUpdate */ 0, + /* xBegin */ 0, + /* xSync */ 0, + /* xCommit */ 0, + /* xRollback */ 0, + /* xFindMethod */ 0, + /* xRename */ 0, + /* xSavepoint */ 0, + /* xRelease */ 0, + /* xRollbackTo */ 0, + /* xShadowName */ 0 +}; + + +#ifdef _WIN32 +__declspec(dllexport) +#endif +int sqlite3_prefixes_init( + sqlite3 *db, + char **pzErrMsg, + const sqlite3_api_routines *pApi +){ + int rc = SQLITE_OK; + SQLITE_EXTENSION_INIT2(pApi); + rc = sqlite3_create_module(db, "prefixes", &prefixesModule, 0); + return rc; +} diff --git a/manifest b/manifest index e2f5a2b408..172ea75f99 100644 --- a/manifest +++ b/manifest @@ -1,5 +1,5 @@ -C Fix\sa\sproblem\scausing\sa\scrash\sif\san\sfts5vocab\stable\swas\screated\sto\squery\san\nfts3/4\sFTS\sindex. -D 2019-01-14T15:35:15.573 +C Add\sthe\s"prefixes"\stable-valued\sfunction\sin\sthe\sext/misc\sfolder. +D 2019-01-14T16:16:30.437 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea F Makefile.in 45a3fef4d325ac0220c2172aeec4e4321da351f073f3b8e8ddea655f49ef6f2b @@ -295,6 +295,7 @@ F ext/misc/mmapwarm.c 8c5fe90d807a23e44a8b93e96e8b812b19b300d5fd8c1d40a4fd1d8224 F ext/misc/nextchar.c 279f80fe8ef5ba413242e2704e246503ac601f005eefb180d19e6c920338a0ba F ext/misc/normalize.c b4290464f542bae7a97b43f15bd197949b833ffd668b7c313631bd5d4610212c F ext/misc/percentile.c a6a1594c104da2d0ceab38fe609eb2f65529272377827f6f8a2b5c9fa6119e7e +F ext/misc/prefixes.c ac95cf723927b9e4b6f2b45eec743986259e3c2618f92ffa9fd780e13c75f70e F ext/misc/regexp.c 79345bf03496155a640ee0300d3307296761cebb5e115b4e342cc2fb5861ec10 F ext/misc/remember.c add730f0f7e7436cd15ea3fd6a90fd83c3f706ab44169f7f048438b7d6baa69c F ext/misc/rot13.c 540a169cb0d74f15522a8930b0cccdcb37a4fd071d219a5a083a319fc6e8db77 @@ -1798,7 +1799,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0 -P 65e50706a017751d72d0f9c7f575955194977decd0acf13aaca90c3cb925f20e -R 13fb83cbbd4ed093aa980d87f465f513 -U dan -Z de4b903b843670f3eeae239fb952f2f8 +P 9cd64ce453e4435d80117b8610c22a0a4b53cd6e84b39815e70e684f6b0295c8 +R e9e76e5c2ca649c80198f4ce0b8026d6 +U drh +Z 111aac904e6040781b0bacf239392c1f diff --git a/manifest.uuid b/manifest.uuid index 18b7701301..f3da4967d9 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -9cd64ce453e4435d80117b8610c22a0a4b53cd6e84b39815e70e684f6b0295c8 \ No newline at end of file +f0fd2163fc23a555ef03af43294a14fcabae6921f52e64c979286c745b4f6218 \ No newline at end of file