attnum.h

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/*-------------------------------------------------------------------------
 *
 * attnum.h
 *    POSTGRES attribute number definitions.
 *
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/access/attnum.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef ATTNUM_H
#define ATTNUM_H


/*
 * user defined attribute numbers start at 1.   -ay 2/95
 */
typedef int16 AttrNumber;

#define InvalidAttrNumber       0
#define MaxAttrNumber           32767

/* ----------------
 *      support macros
 * ----------------
 */
/*
 * AttributeNumberIsValid
 *      True iff the attribute number is valid.
 */
#define AttributeNumberIsValid(attributeNumber) \
    ((bool) ((attributeNumber) != InvalidAttrNumber))

/*
 * AttrNumberIsForUserDefinedAttr
 *      True iff the attribute number corresponds to an user defined attribute.
 */
#define AttrNumberIsForUserDefinedAttr(attributeNumber) \
    ((bool) ((attributeNumber) > 0))

/*
 * AttrNumberGetAttrOffset
 *      Returns the attribute offset for an attribute number.
 *
 * Note:
 *      Assumes the attribute number is for an user defined attribute.
 */
#define AttrNumberGetAttrOffset(attNum) \
( \
    AssertMacro(AttrNumberIsForUserDefinedAttr(attNum)), \
    ((attNum) - 1) \
)

/*
 * AttributeOffsetGetAttributeNumber
 *      Returns the attribute number for an attribute offset.
 */
#define AttrOffsetGetAttrNumber(attributeOffset) \
     ((AttrNumber) (1 + (attributeOffset)))

#endif   /* ATTNUM_H */