src/include/access/attnum.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * attnum.h
   4  *        POSTGRES attribute number definitions.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef ATTNUM_H
  15 #define ATTNUM_H
  16
  17
  18 /*
  19  * user defined attribute numbers start at 1.   -ay 2/95
  20  */
  21 typedef int16 AttrNumber;
  22
  23 #define InvalidAttrNumber               0
  24 #define MaxAttrNumber                   32767
  25
  26 /* ----------------
  27  *              support macros
  28  * ----------------
  29  */
  30 /*
  31  * AttributeNumberIsValid
  32  *              True iff the attribute number is valid.
  33  */
  34 #define AttributeNumberIsValid(attributeNumber) \
  35         ((bool) ((attributeNumber) != InvalidAttrNumber))
  36
  37 /*
  38  * AttrNumberIsForUserDefinedAttr
  39  *              True iff the attribute number corresponds to an user defined attribute.
  40  */
  41 #define AttrNumberIsForUserDefinedAttr(attributeNumber) \
  42         ((bool) ((attributeNumber) > 0))
  43
  44 /*
  45  * AttrNumberGetAttrOffset
  46  *              Returns the attribute offset for an attribute number.
  47  *
  48  * Note:
  49  *              Assumes the attribute number is for an user defined attribute.
  50  */
  51 #define AttrNumberGetAttrOffset(attNum) \
  52 ( \
  53         AssertMacro(AttrNumberIsForUserDefinedAttr(attNum)), \
  54         ((attNum) - 1) \
  55 )
  56
  57 /*
  58  * AttributeOffsetGetAttributeNumber
  59  *              Returns the attribute number for an attribute offset.
  60  */
  61 #define AttrOffsetGetAttrNumber(attributeOffset) \
  62          ((AttrNumber) (1 + (attributeOffset)))
  63
  64 #endif   /* ATTNUM_H */