SQLite

/* An instance of the CSV virtual table */
typedef struct CsvTable {
  sqlite3_vtab base;              /* Base class.  Must be first */
  char *zFilename;                /* Name of the CSV file */
  long iStart;                    /* Offset to start of data in zFilename */
  int nCol;                       /* Number of columns in the CSV file */
  unsigned int tstFlags;          /* Bit values used for testing */
} CsvTable;

/* Allowed values for tstFlags */
#define CSVTEST_FIDX  0x0001      /* Pretend that constrained searchs cost less*/

/* A cursor for the CSV virtual table */
typedef struct CsvCursor {
  sqlite3_vtab_cursor base;       /* Base class.  Must be first */
  CsvReader rdr;                  /* The CsvReader object */
  char **azVal;                   /* Value of the current row */
  sqlite3_int64 iRowid;           /* The current rowid.  Negative for EOF */
} CsvCursor;

/*
** Parameters:
**    filename=FILENAME          Required
**    schema=SCHEMA              Optional
**    header=YES|NO              First row of CSV defines the names of
**                               columns if "yes".  Default "no".
**    testflags=N                Bitmask of test flags.  Optional
**
** If header=no and not columns are listed, then the columns are named
** "c0", "c1", "c2", and so forth.
*/
static int csvtabConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  CsvTable *pNew = 0;
  int bHeader = -1;
  int rc = SQLITE_OK;
  int i;
  char *zFilename = 0;
  char *zSchema = 0;
  int tstFlags = 0;
  CsvReader sRdr;

  memset(&sRdr, 0, sizeof(sRdr));
  for(i=3; i<argc; i++){
    const char *z = argv[i];
    const char *zValue;
    if( (zValue = csv_parameter("filename",8,z))!=0 ){

      }else if( x==0 ){
        bHeader = 0;
      }else{
        csv_errmsg(&sRdr, "unrecognized argument to 'header': %s", zValue);
        goto csvtab_connect_error;
      }
    }else
    if( (zValue = csv_parameter("testflags",9,z))!=0 ){
      tstFlags = (unsigned int)atoi(zValue);
    }else
    {
      csv_errmsg(&sRdr, "unrecognized parameter '%s'", z);
      goto csvtab_connect_error;
    }
  }
  if( zFilename==0 ){
    csv_errmsg(&sRdr, "missing 'filename' parameter");

  memset(pNew, 0, sizeof(*pNew));
  do{
    const char *z = csv_read_one_field(&sRdr);
    if( z==0 ) goto csvtab_connect_oom;
    pNew->nCol++;
  }while( sRdr.cTerm==',' );
  pNew->zFilename = zFilename;
  pNew->tstFlags = tstFlags;
  zFilename = 0;
  pNew->iStart = bHeader==1 ? ftell(sRdr.in) : 0;
  csv_reader_reset(&sRdr);
  if( zSchema==0 ){
    char *zSep = "";
    zSchema = sqlite3_mprintf("CREATE TABLE x(");
    if( zSchema==0 ) goto csvtab_connect_oom;

  sqlite3_free(zFilename);
  sqlite3_free(zSchema);
  if( sRdr.zErr[0] ){
    sqlite3_free(*pzErr);
    *pzErr = sqlite3_mprintf("%s", sRdr.zErr);
  }
  csv_reader_reset(&sRdr);
  if( rc==SQLITE_OK ) rc = SQLITE_ERROR;
  return rc;
}

/*
** Reset the current row content held by a CsvCursor.
*/
static void csvtabCursorRowReset(CsvCursor *pCur){

  CsvTable *pTab = (CsvTable*)pVtabCursor->pVtab;
  pCur->iRowid = 0;
  fseek(pCur->rdr.in, pTab->iStart, SEEK_SET);
  return csvtabNext(pVtabCursor);
}

/*
** Only a forwards full table scan is supported.  xBestIndex is mostly
** a no-op.  If CSVTEST_FIDX is set, then the presence of equality
** constraints lowers the estimated cost, which is fiction, but is useful
** for testing certain kinds of virtual table behavior.
*/
static int csvtabBestIndex(
  sqlite3_vtab *tab,
  sqlite3_index_info *pIdxInfo
){
  CsvTable *pTab = (CsvTable*)tab;
  int i;
  pIdxInfo->estimatedCost = 1000000;
  if( (pTab->tstFlags & CSVTEST_FIDX)==0 ){
    return SQLITE_OK;
  }
  for(i=0; i<pIdxInfo->nConstraint; i++){
    if( pIdxInfo->aConstraint[i].usable==0 ) continue;
    if( pIdxInfo->aConstraint[i].op==SQLITE_INDEX_CONSTRAINT_EQ ){
      pIdxInfo->estimatedCost = 10;
      break;
    }
  }
  return SQLITE_OK;
}


static sqlite3_module CsvModule = {
  0,                       /* iVersion */
  csvtabCreate,            /* xCreate */