src/test_wholenumber.c

   1 /*
   2 ** 2011 April 02
   3 **
   4 ** The author disclaims copyright to this source code.  In place of
   5 ** a legal notice, here is a blessing:
   6 **
   7 **    May you do good and not evil.
   8 **    May you find forgiveness for yourself and forgive others.
   9 **    May you share freely, never taking more than you give.
  10 **
  11 *************************************************************************
  12 **
  13 ** This file implements a virtual table that returns the whole numbers
  14 ** between 1 and 4294967295, inclusive.
  15 **
  16 ** Example:
  17 **
  18 **     CREATE VIRTUAL TABLE nums USING wholenumber;
  19 **     SELECT value FROM nums WHERE value<10;
  20 **
  21 ** Results in:
  22 **
  23 **     1 2 3 4 5 6 7 8 9
  24 */
  25 #include "sqlite3.h"
  26 #include <assert.h>
  27 #include <string.h>
  28
  29 #ifndef SQLITE_OMIT_VIRTUALTABLE
  30
  31
  32 /* A wholenumber cursor object */
  33 typedef struct wholenumber_cursor wholenumber_cursor;
  34 struct wholenumber_cursor {
  35   sqlite3_vtab_cursor base;  /* Base class - must be first */
  36   sqlite3_int64 iValue;      /* Current value */
  37   sqlite3_int64 mxValue;     /* Maximum value */
  38 };
  39
  40 /* Methods for the wholenumber module */
  41 static int wholenumberConnect(
  42   sqlite3 *db,
  43   void *pAux,
  44   int argc, const char *const*argv,
  45   sqlite3_vtab **ppVtab,
  46   char **pzErr
  47 ){
  48   sqlite3_vtab *pNew;
  49   pNew = *ppVtab = sqlite3_malloc( sizeof(*pNew) );
  50   if( pNew==0 ) return SQLITE_NOMEM;
  51   sqlite3_declare_vtab(db, "CREATE TABLE x(value)");
  52   memset(pNew, 0, sizeof(*pNew));
  53   return SQLITE_OK;
  54 }
  55 /* Note that for this virtual table, the xCreate and xConnect
  56 ** methods are identical. */
  57
  58 static int wholenumberDisconnect(sqlite3_vtab *pVtab){
  59   sqlite3_free(pVtab);
  60   return SQLITE_OK;
  61 }
  62 /* The xDisconnect and xDestroy methods are also the same */
  63
  64
  65 /*
  66 ** Open a new wholenumber cursor.
  67 */
  68 static int wholenumberOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  69   wholenumber_cursor *pCur;
  70   pCur = sqlite3_malloc( sizeof(*pCur) );
  71   if( pCur==0 ) return SQLITE_NOMEM;
  72   memset(pCur, 0, sizeof(*pCur));
  73   *ppCursor = &pCur->base;
  74   return SQLITE_OK;
  75 }
  76
  77 /*
  78 ** Close a wholenumber cursor.
  79 */
  80 static int wholenumberClose(sqlite3_vtab_cursor *cur){
  81   sqlite3_free(cur);
  82   return SQLITE_OK;
  83 }
  84
  85
  86 /*
  87 ** Advance a cursor to its next row of output
  88 */
  89 static int wholenumberNext(sqlite3_vtab_cursor *cur){
  90   wholenumber_cursor *pCur = (wholenumber_cursor*)cur;
  91   pCur->iValue++;
  92   return SQLITE_OK;
  93 }
  94
  95 /*
  96 ** Return the value associated with a wholenumber.
  97 */
  98 static int wholenumberColumn(
  99   sqlite3_vtab_cursor *cur,
 100   sqlite3_context *ctx,
 101   int i
 102 ){
 103   wholenumber_cursor *pCur = (wholenumber_cursor*)cur;
 104   sqlite3_result_int64(ctx, pCur->iValue);
 105   return SQLITE_OK;
 106 }
 107
 108 /*
 109 ** The rowid.
 110 */
 111 static int wholenumberRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
 112   wholenumber_cursor *pCur = (wholenumber_cursor*)cur;
 113   *pRowid = pCur->iValue;
 114   return SQLITE_OK;
 115 }
 116
 117 /*
 118 ** When the wholenumber_cursor.rLimit value is 0 or less, that is a signal
 119 ** that the cursor has nothing more to output.
 120 */
 121 static int wholenumberEof(sqlite3_vtab_cursor *cur){
 122   wholenumber_cursor *pCur = (wholenumber_cursor*)cur;
 123   return pCur->iValue>pCur->mxValue || pCur->iValue==0;
 124 }
 125
 126 /*
 127 ** Called to "rewind" a cursor back to the beginning so that
 128 ** it starts its output over again.  Always called at least once
 129 ** prior to any wholenumberColumn, wholenumberRowid, or wholenumberEof call.
 130 **
 131 **    idxNum   Constraints
 132 **    ------   ---------------------
 133 **      0      (none)
 134 **      1      value > $argv0
 135 **      2      value >= $argv0
 136 **      4      value < $argv0
 137 **      8      value <= $argv0
 138 **
 139 **      5      value > $argv0 AND value < $argv1
 140 **      6      value >= $argv0 AND value < $argv1
 141 **      9      value > $argv0 AND value <= $argv1
 142 **     10      value >= $argv0 AND value <= $argv1
 143 */
 144 static int wholenumberFilter(
 145   sqlite3_vtab_cursor *pVtabCursor,
 146   int idxNum, const char *idxStr,
 147   int argc, sqlite3_value **argv
 148 ){
 149   wholenumber_cursor *pCur = (wholenumber_cursor *)pVtabCursor;
 150   sqlite3_int64 v;
 151   int i = 0;
 152   pCur->iValue = 1;
 153   pCur->mxValue = 0xffffffff;  /* 4294967295 */
 154   if( idxNum & 3 ){
 155     v = sqlite3_value_int64(argv[0]) + (idxNum&1);
 156     if( v>pCur->iValue && v<=pCur->mxValue ) pCur->iValue = v;
 157     i++;
 158   }
 159   if( idxNum & 12 ){
 160     v = sqlite3_value_int64(argv[i]) - ((idxNum>>2)&1);
 161     if( v>=pCur->iValue && v<pCur->mxValue ) pCur->mxValue = v;
 162   }
 163   return SQLITE_OK;
 164 }
 165
 166 /*
 167 ** Search for terms of these forms:
 168 **
 169 **  (1)  value > $value
 170 **  (2)  value >= $value
 171 **  (4)  value < $value
 172 **  (8)  value <= $value
 173 **
 174 ** idxNum is an ORed combination of 1 or 2 with 4 or 8.
 175 */
 176 static int wholenumberBestIndex(
 177   sqlite3_vtab *tab,
 178   sqlite3_index_info *pIdxInfo
 179 ){
 180   int i;
 181   int idxNum = 0;
 182   int argvIdx = 1;
 183   int ltIdx = -1;
 184   int gtIdx = -1;
 185   const struct sqlite3_index_constraint *pConstraint;
 186   pConstraint = pIdxInfo->aConstraint;
 187   for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
 188     if( pConstraint->usable==0 ) continue;
 189     if( (idxNum & 3)==0 && pConstraint->op==SQLITE_INDEX_CONSTRAINT_GT ){
 190       idxNum |= 1;
 191       ltIdx = i;
 192     }
 193     if( (idxNum & 3)==0 && pConstraint->op==SQLITE_INDEX_CONSTRAINT_GE ){
 194       idxNum |= 2;
 195       ltIdx = i;
 196     }
 197     if( (idxNum & 12)==0 && pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT ){
 198       idxNum |= 4;
 199       gtIdx = i;
 200     }
 201     if( (idxNum & 12)==0 && pConstraint->op==SQLITE_INDEX_CONSTRAINT_LE ){
 202       idxNum |= 8;
 203       gtIdx = i;
 204     }
 205   }
 206   pIdxInfo->idxNum = idxNum;
 207   if( ltIdx>=0 ){
 208     pIdxInfo->aConstraintUsage[ltIdx].argvIndex = argvIdx++;
 209     pIdxInfo->aConstraintUsage[ltIdx].omit = 1;
 210   }
 211   if( gtIdx>=0 ){
 212     pIdxInfo->aConstraintUsage[gtIdx].argvIndex = argvIdx;
 213     pIdxInfo->aConstraintUsage[gtIdx].omit = 1;
 214   }
 215   if( pIdxInfo->nOrderBy==1
 216    && pIdxInfo->aOrderBy[0].desc==0
 217   ){
 218     pIdxInfo->orderByConsumed = 1;
 219   }
 220   pIdxInfo->estimatedCost = (double)1;
 221   return SQLITE_OK;
 222 }
 223
 224 /*
 225 ** A virtual table module that provides read-only access to a
 226 ** Tcl global variable namespace.
 227 */
 228 static sqlite3_module wholenumberModule = {
 229   0,                         /* iVersion */
 230   wholenumberConnect,
 231   wholenumberConnect,
 232   wholenumberBestIndex,
 233   wholenumberDisconnect,
 234   wholenumberDisconnect,
 235   wholenumberOpen,           /* xOpen - open a cursor */
 236   wholenumberClose,          /* xClose - close a cursor */
 237   wholenumberFilter,         /* xFilter - configure scan constraints */
 238   wholenumberNext,           /* xNext - advance a cursor */
 239   wholenumberEof,            /* xEof - check for end of scan */
 240   wholenumberColumn,         /* xColumn - read data */
 241   wholenumberRowid,          /* xRowid - read data */
 242   0,                         /* xUpdate */
 243   0,                         /* xBegin */
 244   0,                         /* xSync */
 245   0,                         /* xCommit */
 246   0,                         /* xRollback */
 247   0,                         /* xFindMethod */
 248   0,                         /* xRename */
 249 };
 250
 251 #endif /* SQLITE_OMIT_VIRTUALTABLE */
 252
 253
 254 /*
 255 ** Register the wholenumber virtual table
 256 */
 257 int wholenumber_register(sqlite3 *db){
 258   int rc = SQLITE_OK;
 259 #ifndef SQLITE_OMIT_VIRTUALTABLE
 260   rc = sqlite3_create_module(db, "wholenumber", &wholenumberModule, 0);
 261 #endif
 262   return rc;
 263 }
 264
 265 #ifdef SQLITE_TEST
 266 #include <tcl.h>
 267 /*
 268 ** Decode a pointer to an sqlite3 object.
 269 */
 270 extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
 271
 272 /*
 273 ** Register the echo virtual table module.
 274 */
 275 static int register_wholenumber_module(
 276   ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
 277   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
 278   int objc,              /* Number of arguments */
 279   Tcl_Obj *CONST objv[]  /* Command arguments */
 280 ){
 281   sqlite3 *db;
 282   if( objc!=2 ){
 283     Tcl_WrongNumArgs(interp, 1, objv, "DB");
 284     return TCL_ERROR;
 285   }
 286   if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
 287   wholenumber_register(db);
 288   return TCL_OK;
 289 }
 290
 291
 292 /*
 293 ** Register commands with the TCL interpreter.
 294 */
 295 int Sqlitetestwholenumber_Init(Tcl_Interp *interp){
 296   static struct {
 297      char *zName;
 298      Tcl_ObjCmdProc *xProc;
 299      void *clientData;
 300   } aObjCmd[] = {
 301      { "register_wholenumber_module",   register_wholenumber_module, 0 },
 302   };
 303   int i;
 304   for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
 305     Tcl_CreateObjCommand(interp, aObjCmd[i].zName,
 306         aObjCmd[i].xProc, aObjCmd[i].clientData, 0);
 307   }
 308   return TCL_OK;
 309 }
 310
 311 #endif /* SQLITE_TEST */