SQLite

** attached to handle "db". Invoke the supplied conflict handler callback
** to resolve any conflicts encountered while applying the change.
*/
int sqlite3changeset_apply(
  sqlite3 *db,                    /* Apply change to "main" db of this handle */
  int nChangeset,                 /* Size of changeset in bytes */
  void *pChangeset,               /* Changeset blob */
  int(*xFilter)(
    void *pCtx,                   /* Copy of sixth arg to _apply() */
    const char *zTab              /* Table name */
  ),
  int(*xConflict)(
    void *pCtx,                   /* Copy of fifth arg to _apply() */
    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
  ),
  void *pCtx                      /* First argument passed to xConflict */
){

    const char *zNew;
    
    sqlite3changeset_op(pIter, &zNew, &nCol, &op, 0);

    if( zTab==0 || sqlite3_strnicmp(zNew, zTab, nTab+1) ){
      u8 *abPK;


      sqlite3_free((char*)sApply.azCol);  /* cast works around VC++ bug */
      sqlite3_finalize(sApply.pDelete);
      sqlite3_finalize(sApply.pUpdate); 
      sqlite3_finalize(sApply.pInsert);
      sqlite3_finalize(sApply.pSelect);
      memset(&sApply, 0, sizeof(sApply));
      sApply.db = db;

      /* If an xFilter() callback was specified, invoke it now. If the 
      ** xFilter callback returns zero, skip this table. If it returns
      ** non-zero, proceed. */
      schemaMismatch = (xFilter && (0==xFilter(pCtx, zNew)));
      if( schemaMismatch ){
        zTab = sqlite3_mprintf("%s", zNew);
        nTab = strlen(zTab);
        sApply.azCol = (const char **)zTab;
      }else{
        sqlite3changeset_pk(pIter, &abPK, 0);
        rc = sessionTableInfo(
            db, "main", zNew, &sApply.nCol, &zTab, &sApply.azCol, &sApply.abPK
        );
        if( rc!=SQLITE_OK ) break;
  
        if( sApply.nCol==0 ){
          schemaMismatch = 1;
          sqlite3_log(SQLITE_SCHEMA, 
              "sqlite3changeset_apply(): no such table: %s", zTab
          );
        }
        else if( sApply.nCol!=nCol ){
          schemaMismatch = 1;
          sqlite3_log(SQLITE_SCHEMA, 
              "sqlite3changeset_apply(): table %s has %d columns, expected %d", 
              zTab, sApply.nCol, nCol
          );
        }
        else if( memcmp(sApply.abPK, abPK, nCol)!=0 ){
          schemaMismatch = 1;
          sqlite3_log(SQLITE_SCHEMA, "sqlite3changeset_apply(): "
              "primary key mismatch for table %s", zTab
          );
        }
        else if( 
            (rc = sessionSelectRow(db, zTab, &sApply))
         || (rc = sessionUpdateRow(db, zTab, &sApply))
         || (rc = sessionDeleteRow(db, zTab, &sApply))
         || (rc = sessionInsertRow(db, zTab, &sApply))
        ){
          break;
        }
        nTab = sqlite3Strlen30(zTab);
      }
    }

    /* If there is a schema mismatch on the current table, proceed to the
    ** next change. A log message has already been issued. */
    if( schemaMismatch ) continue;

    rc = sessionApplyOneOp(pIter, &sApply, xConflict, pCtx, &bReplace, &bRetry);

/*
** CAPI3REF: Apply A Changeset To A Database
**
** Apply a changeset to a database. This function attempts to update the
** "main" database attached to handle db with the changes found in the
** changeset passed via the second and third arguments.
**
** The fourth argument (xFilter) passed to this function is the "filter
** callback". If it is not NULL, then for each table affected by at least one
** change in the changeset, the filter callback is invoked with
** the table name as the second argument, and a copy of the context pointer
** passed as the sixth argument to this function as the first. If the "filter
** callback" returns zero, then no attempt is made to apply any changes to 
** the table. Otherwise, if the return value is non-zero or the xFilter
** argument to this function is NULL, all changes related to the table are
** attempted.
**
** For each table that is not excluded by the filter callback, this function 
** tests that the target database contains a compatible table. A table is 
** considered compatible if all of the following are true:
**
** <ul>
**   <li> The table has the same name as the name recorded in the 
**        changeset, and
**   <li> The table has the same number of columns as recorded in the 
**        changeset, and
**   <li> The table has primary key columns in the same position as 
**        recorded in the changeset.
** </ul>
**
** If there is no compatible table, it is not an error, but none of the
** changes associated with the table are applied. A warning message is issued
** via the sqlite3_log() mechanism with the error code SQLITE_SCHEMA. At most
** one such warning is issued for each table in the changeset.
**
** For each change for which there is a compatible table, an attempt is made 
** to modify the table contents according to the UPDATE, INSERT or DELETE 
** change. If a change cannot be applied cleanly, the conflict handler 
** function passed as the fifth argument to sqlite3changeset_apply() may be 
** invoked. A description of exactly when the conflict handler is invoked for 
** each type of change is below.
**
** Each time the conflict handler function is invoked, it must return one
** of [SQLITE_CHANGESET_OMIT], [SQLITE_CHANGESET_ABORT] or 
** [SQLITE_CHANGESET_REPLACE]. SQLITE_CHANGESET_REPLACE may only be returned
** if the second argument passed to the conflict handler is either
** SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If the conflict-handler
** returns an illegal value, any changes already made are rolled back and

** rolled back, restoring the target database to its original state, and an 
** SQLite error code returned.
*/
int sqlite3changeset_apply(
  sqlite3 *db,                    /* Apply change to "main" db of this handle */
  int nChangeset,                 /* Size of changeset in bytes */
  void *pChangeset,               /* Changeset blob */
  int(*xFilter)(
    void *pCtx,                   /* Copy of sixth arg to _apply() */
    const char *zTab              /* Table name */
  ),
  int(*xConflict)(
    void *pCtx,                   /* Copy of sixth arg to _apply() */
    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
  ),
  void *pCtx                      /* First argument passed to xConflict */
);

/* 

    Tcl_ListObjAppendElement(0, pList, pObj);
  }
}

typedef struct TestConflictHandler TestConflictHandler;
struct TestConflictHandler {
  Tcl_Interp *interp;
  Tcl_Obj *pConflictScript;
  Tcl_Obj *pFilterScript;
};

static int test_obj_eq_string(Tcl_Obj *p, const char *z){
  int n;
  int nObj;
  char *zObj;

  n = strlen(z);
  zObj = Tcl_GetStringFromObj(p, &nObj);

  return (nObj==n && (n==0 || 0==memcmp(zObj, z, n)));
}

static int test_filter_handler(
  void *pCtx,                     /* Pointer to TestConflictHandler structure */
  const char *zTab                /* Table name */
){
  TestConflictHandler *p = (TestConflictHandler *)pCtx;
  int res = 1;
  Tcl_Obj *pEval;
  Tcl_Interp *interp = p->interp;

  pEval = Tcl_DuplicateObj(p->pFilterScript);
  Tcl_IncrRefCount(pEval);

  if( TCL_OK!=Tcl_ListObjAppendElement(0, pEval, Tcl_NewStringObj(zTab, -1))
   || TCL_OK!=Tcl_EvalObjEx(interp, pEval, TCL_EVAL_GLOBAL) 
   || TCL_OK!=Tcl_GetIntFromObj(interp, Tcl_GetObjResult(interp), &res)
  ){
    Tcl_BackgroundError(interp);
  }

  Tcl_DecrRefCount(pEval);
  return res;
}  

static int test_conflict_handler(
  void *pCtx,                     /* Pointer to TestConflictHandler structure */
  int eConf,                      /* DATA, MISSING, CONFLICT, CONSTRAINT */
  sqlite3_changeset_iter *pIter   /* Handle describing change and conflict */
){
  TestConflictHandler *p = (TestConflictHandler *)pCtx;
  Tcl_Obj *pEval;
  Tcl_Interp *interp = p->interp;
  int ret = 0;                    /* Return value */

  int op;                         /* SQLITE_UPDATE, DELETE or INSERT */
  const char *zTab;               /* Name of table conflict is on */
  int nCol;                       /* Number of columns in table zTab */

  pEval = Tcl_DuplicateObj(p->pConflictScript);
  Tcl_IncrRefCount(pEval);

  sqlite3changeset_op(pIter, &zTab, &nCol, &op, 0);

  /* Append the operation type. */
  Tcl_ListObjAppendElement(0, pEval, Tcl_NewStringObj(
      op==SQLITE_INSERT ? "INSERT" :

  }

  Tcl_DecrRefCount(pEval);
  return ret;
}

/*
** sqlite3changeset_apply DB CHANGESET CONFLICT-SCRIPT ?FILTER-SCRIPT?
*/
static int test_sqlite3changeset_apply(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3 *db;                    /* Database handle */
  Tcl_CmdInfo info;               /* Database Tcl command (objv[1]) info */
  int rc;                         /* Return code from changeset_invert() */
  void *pChangeset;               /* Buffer containing changeset */
  int nChangeset;                 /* Size of buffer aChangeset in bytes */
  TestConflictHandler ctx;

  if( objc!=4 && objc!=5 ){
    Tcl_WrongNumArgs(interp, 1, objv, 
        "DB CHANGESET CONFLICT-SCRIPT ?FILTER-SCRIPT?"
    );
    return TCL_ERROR;
  }
  if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(objv[1]), &info) ){
    Tcl_AppendResult(interp, "no such handle: ", Tcl_GetString(objv[2]), 0);
    return TCL_ERROR;
  }
  db = *(sqlite3 **)info.objClientData;
  pChangeset = (void *)Tcl_GetByteArrayFromObj(objv[2], &nChangeset);
  ctx.pConflictScript = objv[3];
  ctx.pFilterScript = objc==5 ? objv[4] : 0;
  ctx.interp = interp;

  rc = sqlite3changeset_apply(db, nChangeset, pChangeset, 
      (objc==5) ? test_filter_handler : 0, test_conflict_handler, (void *)&ctx
  );
  if( rc!=SQLITE_OK ){
    return test_session_error(interp, rc);
  }
  Tcl_ResetResult(interp);
  return TCL_OK;
}