test8.c

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

  if( pIdxInfo->nOrderBy==1 && pVtab->aIndex[pIdxInfo->aOrderBy->iColumn] ){
    int iCol = pIdxInfo->aOrderBy->iColumn;
    char *zCol = pVtab->aCol[iCol];
    char *zDir = pIdxInfo->aOrderBy->desc?"DESC":"ASC";
    if( iCol<0 ){
      zCol = "rowid";
    }
    zNew = sqlite3_mprintf(" ORDER BY %s %s", zCol, zDir);
    string_concat(&zQuery, zNew, 1);
    pIdxInfo->orderByConsumed = 1;
  }

  appendToEchoModule(pVtab->interp, "xBestIndex");;
  appendToEchoModule(pVtab->interp, zQuery);

  pIdxInfo->idxNum = hashString(zQuery);
  pIdxInfo->idxStr = zQuery;
  pIdxInfo->needToFreeIdxStr = 1;
  if (useCost) {
    pIdxInfo->estimatedCost = cost;
  } else if( useIdx ){
    /* Approximation of log2(nRow). */
    for( ii=0; ii<(sizeof(int)*8); ii++ ){
      if( nRow & (1<<ii) ){
        pIdxInfo->estimatedCost = (double)ii;
      }
    }
  } else {
    pIdxInfo->estimatedCost = (double)nRow;
  }
  return rc;
}

/*
** The xUpdate method for echo module virtual tables.
** 
**    apData[0]  apData[1]  apData[2..]
**
**    INTEGER                              DELETE            
**
**    INTEGER    NULL       (nCol args)    UPDATE (do not set rowid)
**    INTEGER    INTEGER    (nCol args)    UPDATE (with SET rowid = <arg1>)
**
**    NULL       NULL       (nCol args)    INSERT INTO (automatic rowid value)
**    NULL       INTEGER    (nCol args)    INSERT (incl. rowid value)
**
*/
int echoUpdate(
  sqlite3_vtab *tab, 
  int nData, 
  sqlite3_value **apData, 
  sqlite_int64 *pRowid
){
  echo_vtab *pVtab = (echo_vtab *)tab;
  sqlite3 *db = pVtab->db;
  int rc = SQLITE_OK;

  sqlite3_stmt *pStmt;
  char *z = 0;               /* SQL statement to execute */
  int bindArgZero = 0;       /* True to bind apData[0] to sql var no. nData */
  int bindArgOne = 0;        /* True to bind apData[1] to sql var no. 1 */
  int i;                     /* Counter variable used by for loops */

  assert( nData==pVtab->nCol+2 || nData==1 );

  /* If apData[0] is an integer and nData>1 then do an UPDATE */
  if( nData>1 && sqlite3_value_type(apData[0])==SQLITE_INTEGER ){
    char *zSep = " SET";
    z = sqlite3_mprintf("UPDATE %Q", pVtab->zTableName);

    bindArgOne = (apData[1] && sqlite3_value_type(apData[1])==SQLITE_INTEGER);
    bindArgZero = 1;

    if( bindArgOne ){
       string_concat(&z, " SET rowid=?1 ", 0);
       zSep = ",";
    }
    for(i=2; i<nData; i++){
      if( apData[i]==0 ) continue;
      string_concat(&z, sqlite3_mprintf(
          "%s %Q=?%d", zSep, pVtab->aCol[i-2], i), 1);
      zSep = ",";
    }
    string_concat(&z, sqlite3_mprintf(" WHERE rowid=?%d", nData), 0);
  }

  /* If apData[0] is an integer and nData==1 then do a DELETE */
  else if( nData==1 && sqlite3_value_type(apData[0])==SQLITE_INTEGER ){
    z = sqlite3_mprintf("DELETE FROM %Q WHERE rowid = ?1", pVtab->zTableName);
    bindArgZero = 1;
  }

  /* If the first argument is NULL and there are more than two args, INSERT */
  else if( nData>2 && sqlite3_value_type(apData[0])==SQLITE_NULL ){
    int ii;
    char *zInsert = 0;
    char *zValues = 0;
  
    zInsert = sqlite3_mprintf("INSERT INTO %Q (", pVtab->zTableName);
    if( sqlite3_value_type(apData[1])==SQLITE_INTEGER ){
      bindArgOne = 1;
      zValues = sqlite3_mprintf("?");
      string_concat(&zInsert, "rowid", 0);
    }

    assert((pVtab->nCol+2)==nData);
    for(ii=2; ii<nData; ii++){
      string_concat(&zInsert, 
          sqlite3_mprintf("%s%Q", zValues?", ":"", pVtab->aCol[ii-2]), 1);
      string_concat(&zValues, 
          sqlite3_mprintf("%s?%d", zValues?", ":"", ii), 1);
    }

    string_concat(&z, zInsert, 1);
    string_concat(&z, ") VALUES(", 0);
    string_concat(&z, zValues, 1);
    string_concat(&z, ")", 0);
  }

  /* Anything else is an error */
  else{
    assert(0);
    return SQLITE_ERROR;
  }

  rc = sqlite3_prepare(db, z, -1, &pStmt, 0);
  assert( rc!=SQLITE_OK || pStmt );
  sqlite3_free(z);
  if( rc==SQLITE_OK ) {
    if( bindArgZero ){
      sqlite3_bind_value(pStmt, nData, apData[0]);
    }
    if( bindArgOne ){
      sqlite3_bind_value(pStmt, 1, apData[1]);
    }
    for(i=2; i<nData; i++){
      if( apData[i] ) sqlite3_bind_value(pStmt, i, apData[i]);
    }
    sqlite3_step(pStmt);
    rc = sqlite3_finalize(pStmt);
  }

  if( pRowid && rc==SQLITE_OK ){
    *pRowid = sqlite3_last_insert_rowid(db);
  }

  return rc;
}

/*
** xBegin, xSync, xCommit and xRollback callbacks for echo module
** virtual tables. Do nothing other than add the name of the callback
** to the $::echo_module Tcl variable.
*/
static int echoTransactionCall(sqlite3_vtab *tab, const char *zCall){
  char *z;
  echo_vtab *pVtab = (echo_vtab *)tab;
  z = sqlite3_mprintf("echo(%s)", pVtab->zTableName);
  appendToEchoModule(pVtab->interp, zCall);
  appendToEchoModule(pVtab->interp, z);
  sqlite3_free(z);
  return SQLITE_OK;
}
static int echoBegin(sqlite3_vtab *tab){
  echo_vtab *pVtab = (echo_vtab *)tab;
  Tcl_Interp *interp = pVtab->interp;
  const char *zVal; 

  echoTransactionCall(tab, "xBegin");

  /* Check if the $::echo_module_begin_fail variable is defined. If it is,
  ** and it is set to the name of the real table underlying this virtual
  ** echo module table, then cause this xSync operation to fail.
  */
  zVal = Tcl_GetVar(interp, "echo_module_begin_fail", TCL_GLOBAL_ONLY);
  if( zVal && 0==strcmp(zVal, pVtab->zTableName) ){
    return SQLITE_ERROR;
  }
  return SQLITE_OK;
}
static int echoSync(sqlite3_vtab *tab){
  echo_vtab *pVtab = (echo_vtab *)tab;
  Tcl_Interp *interp = pVtab->interp;
  const char *zVal; 

  echoTransactionCall(tab, "xSync");

  /* Check if the $::echo_module_sync_fail variable is defined. If it is,
  ** and it is set to the name of the real table underlying this virtual
  ** echo module table, then cause this xSync operation to fail.
  */
  zVal = Tcl_GetVar(interp, "echo_module_sync_fail", TCL_GLOBAL_ONLY);
  if( zVal && 0==strcmp(zVal, pVtab->zTableName) ){
    return -1;
  }
  return SQLITE_OK;
}
static int echoCommit(sqlite3_vtab *tab){
  return echoTransactionCall(tab, "xCommit");
}
static int echoRollback(sqlite3_vtab *tab){
  return echoTransactionCall(tab, "xRollback");
}

/*
** Implementation of "GLOB" function on the echo module.  Pass
** all arguments to the ::echo_glob_overload procedure of TCL
** and return the result of that procedure as a string.
*/
static void overloadedGlobFunction(
  sqlite3_context *pContext,
  int nArg,
  sqlite3_value **apArg
){
  Tcl_Interp *interp = sqlite3_user_data(pContext);
  Tcl_DString str;
  int i;
  int rc;
  Tcl_DStringInit(&str);
  Tcl_DStringAppendElement(&str, "::echo_glob_overload");
  for(i=0; i<nArg; i++){
    Tcl_DStringAppendElement(&str, (char*)sqlite3_value_text(apArg[i]));
  }
  rc = Tcl_Eval(interp, Tcl_DStringValue(&str));
  Tcl_DStringFree(&str);
  if( rc ){
    sqlite3_result_error(pContext, Tcl_GetStringResult(interp), -1);
  }else{
    sqlite3_result_text(pContext, Tcl_GetStringResult(interp),
                        -1, SQLITE_TRANSIENT);
  }
  Tcl_ResetResult(interp);
}

/*
** This is the xFindFunction implementation for the echo module.
** SQLite calls this routine when the first argument of a function
** is a column of an echo virtual table.  This routine can optionally
** override the implementation of that function.  It will choose to
** do so if the function is named "glob", and a TCL command named
** ::echo_glob_overload exists.
*/
static int echoFindFunction(
  sqlite3_vtab *vtab,
  int nArg,
  const char *zFuncName,
  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  void **ppArg
){
  echo_vtab *pVtab = (echo_vtab *)vtab;
  Tcl_Interp *interp = pVtab->interp;
  Tcl_CmdInfo info;
  if( strcmp(zFuncName,"glob")!=0 ){
    return 0;
  }
  if( Tcl_GetCommandInfo(interp, "::echo_glob_overload", &info)==0 ){
    return 0;
  }
  *pxFunc = overloadedGlobFunction;
  *ppArg = interp;
  return 1;
}

static int echoRename(sqlite3_vtab *vtab, const char *zNewName){
  int rc = SQLITE_OK;
  echo_vtab *p = (echo_vtab *)vtab;

  if( p->isPattern ){
    int nThis = strlen(p->zThis);
    char *zSql = sqlite3MPrintf("ALTER TABLE %s RENAME TO %s%s", 
        p->zTableName, zNewName, &p->zTableName[nThis]
    );
    rc = sqlite3_exec(p->db, zSql, 0, 0, 0);
    sqliteFree(zSql);
  }

  return rc;
}

/*
** A virtual table module that merely "echos" the contents of another
** table (like an SQL VIEW).
*/
static sqlite3_module echoModule = {
  0,                         /* iVersion */
  echoCreate,
  echoConnect,
  echoBestIndex,
  echoDisconnect, 
  echoDestroy,
  echoOpen,                  /* xOpen - open a cursor */
  echoClose,                 /* xClose - close a cursor */
  echoFilter,                /* xFilter - configure scan constraints */
  echoNext,                  /* xNext - advance a cursor */
  echoEof,                   /* xEof */
  echoColumn,                /* xColumn - read data */
  echoRowid,                 /* xRowid - read data */
  echoUpdate,                /* xUpdate - write data */
  echoBegin,                 /* xBegin - begin transaction */
  echoSync,                  /* xSync - sync transaction */
  echoCommit,                /* xCommit - commit transaction */
  echoRollback,              /* xRollback - rollback transaction */
  echoFindFunction,          /* xFindFunction - function overloading */
  echoRename,                /* xRename - rename the table */
};

/*
** Decode a pointer to an sqlite3 object.
*/
static int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb){
  *ppDb = (sqlite3*)sqlite3TextToPtr(zA);
  return TCL_OK;
}

/*
** Register the echo virtual table module.
*/
static int register_echo_module(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3 *db;
  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  sqlite3_create_module(db, "echo", &echoModule, (void *)interp);
  return TCL_OK;
}

/*
** Tcl interface to sqlite3_declare_vtab, invoked as follows from Tcl:
**
** sqlite3_declare_vtab DB SQL
*/
static int declare_vtab(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3 *db;
  int rc;
  if( objc!=3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB SQL");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  rc = sqlite3_declare_vtab(db, Tcl_GetString(objv[2]));
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)sqlite3_errmsg(db), TCL_VOLATILE);
    return TCL_ERROR;
  }
  return TCL_OK;
}

#endif /* ifndef SQLITE_OMIT_VIRTUALTABLE */

/*
** Register commands with the TCL interpreter.
*/
int Sqlitetest8_Init(Tcl_Interp *interp){
  static struct {
     char *zName;
     Tcl_ObjCmdProc *xProc;
     void *clientData;
  } aObjCmd[] = {
#ifndef SQLITE_OMIT_VIRTUALTABLE
     { "register_echo_module",   register_echo_module, 0 },
     { "sqlite3_declare_vtab",   declare_vtab, 0 },
#endif
  };
  int i;
  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, 
        aObjCmd[i].xProc, aObjCmd[i].clientData, 0);
  }
  return TCL_OK;
}