diff options
Diffstat (limited to 'src/interfaces/odbc/windev/tuplelist.c')
| -rw-r--r-- | src/interfaces/odbc/windev/tuplelist.c | 216 |
1 files changed, 0 insertions, 216 deletions
diff --git a/src/interfaces/odbc/windev/tuplelist.c b/src/interfaces/odbc/windev/tuplelist.c deleted file mode 100644 index 0ae2130bff4..00000000000 --- a/src/interfaces/odbc/windev/tuplelist.c +++ /dev/null @@ -1,216 +0,0 @@ -/*-------- - * Module: tuplelist.c - * - * Description: This module contains functions for creating a manual - * result set (the TupleList) and retrieving data from - * it for a specific row/column. - * - * Classes: TupleListClass (Functions prefix: "TL_") - * - * API functions: none - * - * Comments: See "notice.txt" for copyright and license information. - *-------- - */ - -#include "tuplelist.h" - -#include <stdlib.h> -#include "tuple.h" - - -TupleListClass * -TL_Constructor(UInt4 fieldcnt) -{ - TupleListClass *rv; - - mylog("in TL_Constructor\n"); - - rv = (TupleListClass *) malloc(sizeof(TupleListClass)); - if (rv) - { - rv->num_fields = fieldcnt; - rv->num_tuples = 0; - rv->list_start = NULL; - rv->list_end = NULL; - rv->lastref = NULL; - rv->last_indexed = -1; - } - - mylog("exit TL_Constructor\n"); - - return rv; -} - - -void -TL_Destructor(TupleListClass *self) -{ - int lf; - TupleNode *node, - *tp; - - mylog("TupleList: in DESTRUCTOR\n"); - - node = self->list_start; - while (node != NULL) - { - for (lf = 0; lf < self->num_fields; lf++) - if (node->tuple[lf].value != NULL) - free(node->tuple[lf].value); - tp = node->next; - free(node); - node = tp; - } - - free(self); - - mylog("TupleList: exit DESTRUCTOR\n"); -} - - -void * -TL_get_fieldval(TupleListClass *self, Int4 tupleno, Int2 fieldno) -{ - Int4 lf; - Int4 delta, - from_end; - char end_is_closer, - start_is_closer; - TupleNode *rv; - - if (self->last_indexed == -1) - /* we have an empty tuple list */ - return NULL; - - /* some more sanity checks */ - if ((tupleno >= self->num_tuples) || (tupleno < 0)) - /* illegal tuple number range */ - return NULL; - - if ((fieldno >= self->num_fields) || (fieldno < 0)) - /* illegel field number range */ - return NULL; - - /* - * check if we are accessing the same tuple that was used in the last - * fetch (e.g: for fetching all the fields one after another. Do this - * to speed things up - */ - if (tupleno == self->last_indexed) - return self->lastref->tuple[fieldno].value; - - /* now for the tricky part... */ - - /* - * Since random access is quite inefficient for linked lists we use - * the lastref pointer that points to the last element referenced by a - * get_fieldval() call in conjunction with the its index number that - * is stored in last_indexed. (So we use some locality of reference - * principle to speed things up) - */ - - delta = tupleno - self->last_indexed; - /* if delta is positive, we have to go forward */ - - /* - * now check if we are closer to the start or the end of the list than - * to our last_indexed pointer - */ - from_end = (self->num_tuples - 1) - tupleno; - - start_is_closer = labs(delta) > tupleno; - - /* - * true if we are closer to the start of the list than to the - * last_indexed pointer - */ - - end_is_closer = labs(delta) > from_end; - /* true if we are closer at the end of the list */ - - if (end_is_closer) - { - /* scanning from the end is the shortest way. so we do that... */ - rv = self->list_end; - for (lf = 0; lf < from_end; lf++) - rv = rv->prev; - } - else if (start_is_closer) - { - /* - * the shortest way is to start the search from the head of the - * list - */ - rv = self->list_start; - for (lf = 0; lf < tupleno; lf++) - rv = rv->next; - } - else - { - /* the closest way is starting from our lastref - pointer */ - rv = self->lastref; - - /* - * at first determine whether we have to search forward or - * backwards - */ - if (delta < 0) - { - /* we have to search backwards */ - for (lf = 0; lf < (-1) * delta; lf++) - rv = rv->prev; - } - else - { - /* ok, we have to search forward... */ - for (lf = 0; lf < delta; lf++) - rv = rv->next; - } - } - - /* - * now we have got our return pointer, so update the lastref and the - * last_indexed values - */ - self->lastref = rv; - self->last_indexed = tupleno; - - return rv->tuple[fieldno].value; -} - - -char -TL_add_tuple(TupleListClass *self, TupleNode *new_field) -{ - /* - * we append the tuple at the end of the doubly linked list of the - * tuples we have already read in - */ - - new_field->prev = NULL; - new_field->next = NULL; - - if (self->list_start == NULL) - { - /* the list is empty, we have to add the first tuple */ - self->list_start = new_field; - self->list_end = new_field; - self->lastref = new_field; - self->last_indexed = 0; - } - else - { - /* - * there is already an element in the list, so add the new one at - * the end of the list - */ - self->list_end->next = new_field; - new_field->prev = self->list_end; - self->list_end = new_field; - } - self->num_tuples++; - - /* this method of building a list cannot fail, so we return 1 */ - return 1; -} |