granicus.if.org Git - postgresql/blob - src/include/access/sdir.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * sdir.h
   4  *        POSTGRES scan direction definitions.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL: pgsql/src/include/access/sdir.h,v 1.18 2006/03/05 15:58:53 momjian Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef SDIR_H
  15 #define SDIR_H
  16
  17
  18 /*
  19  * ScanDirection was an int8 for no apparent reason. I kept the original
  20  * values because I'm not sure if I'll break anything otherwise.  -ay 2/95
  21  */
  22 typedef enum ScanDirection
  23 {
  24         BackwardScanDirection = -1,
  25         NoMovementScanDirection = 0,
  26         ForwardScanDirection = 1
  27 } ScanDirection;
  28
  29 /*
  30  * ScanDirectionIsValid
  31  *              True iff scan direction is valid.
  32  */
  33 #define ScanDirectionIsValid(direction) \
  34         ((bool) (BackwardScanDirection <= (direction) && \
  35                          (direction) <= ForwardScanDirection))
  36
  37 /*
  38  * ScanDirectionIsBackward
  39  *              True iff scan direction is backward.
  40  */
  41 #define ScanDirectionIsBackward(direction) \
  42         ((bool) ((direction) == BackwardScanDirection))
  43
  44 /*
  45  * ScanDirectionIsNoMovement
  46  *              True iff scan direction indicates no movement.
  47  */
  48 #define ScanDirectionIsNoMovement(direction) \
  49         ((bool) ((direction) == NoMovementScanDirection))
  50
  51 /*
  52  * ScanDirectionIsForward
  53  *              True iff scan direction is forward.
  54  */
  55 #define ScanDirectionIsForward(direction) \
  56         ((bool) ((direction) == ForwardScanDirection))
  57
  58 #endif   /* SDIR_H */