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

   1 /*-------------------------------------------------------------------------
   2  *
   3  * sdir.h
   4  *        POSTGRES scan direction definitions.
   5  *
   6  *
   7  * Copyright (c) 1994, Regents of the University of California
   8  *
   9  * $Id: sdir.h,v 1.6 1999/05/25 16:13:34 momjian Exp $
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #ifndef SDIR_H
  14 #define SDIR_H
  15
  16
  17 /*
  18  * ScanDirection was an int8 for no apparent reason. I kept the original
  19  * values because I'm not sure if I'll break anything otherwise.  -ay 2/95
  20  */
  21 typedef enum ScanDirection
  22 {
  23         BackwardScanDirection = -1,
  24         NoMovementScanDirection = 0,
  25         ForwardScanDirection = 1
  26 } ScanDirection;
  27
  28 /*
  29  * ScanDirectionIsValid
  30  *              True iff scan direction is valid.
  31  */
  32 #define ScanDirectionIsValid(direction) \
  33         ((bool) (BackwardScanDirection <= direction && \
  34                          direction <= ForwardScanDirection))
  35
  36 /*
  37  * ScanDirectionIsBackward
  38  *              True iff scan direction is backward.
  39  */
  40 #define ScanDirectionIsBackward(direction) \
  41         ((bool) (direction == BackwardScanDirection))
  42
  43 /*
  44  * ScanDirectionIsNoMovement
  45  *              True iff scan direction indicates no movement.
  46  */
  47 #define ScanDirectionIsNoMovement(direction) \
  48         ((bool) (direction == NoMovementScanDirection))
  49
  50 /*
  51  * ScanDirectionIsForward
  52  *              True iff scan direction is forward.
  53  */
  54 #define ScanDirectionIsForward(direction) \
  55         ((bool) (direction == ForwardScanDirection))
  56
  57 #endif   /* SDIR_H */