/*-------------------------------------------------------------------------
 *
 * btstrat.c--
 *	  Srategy map entries for the btree indexed access method
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/access/nbtree/nbtstrat.c,v 1.6 1997/09/08 02:20:59 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#include <postgres.h>

#include <access/istrat.h>
#include <storage/bufpage.h>
#include <access/nbtree.h>

/*
 * Note:
 *		StrategyNegate, StrategyCommute, and StrategyNegateCommute
 *		assume <, <=, ==, >=, > ordering.
 */
static StrategyNumber BTNegate[5] = {
	BTGreaterEqualStrategyNumber,
	BTGreaterStrategyNumber,
	InvalidStrategy,
	BTLessStrategyNumber,
	BTLessEqualStrategyNumber
};

static StrategyNumber BTCommute[5] = {
	BTGreaterStrategyNumber,
	BTGreaterEqualStrategyNumber,
	InvalidStrategy,
	BTLessEqualStrategyNumber,
	BTLessStrategyNumber
};

static StrategyNumber BTNegateCommute[5] = {
	BTLessEqualStrategyNumber,
	BTLessStrategyNumber,
	InvalidStrategy,
	BTGreaterStrategyNumber,
	BTGreaterEqualStrategyNumber
};

static uint16 BTLessTermData[] = {		/* XXX type clash */
	2,
	BTLessStrategyNumber,
	SK_NEGATE,
	BTLessStrategyNumber,
	SK_NEGATE | SK_COMMUTE
};

static uint16 BTLessEqualTermData[] = { /* XXX type clash */
	2,
	BTLessEqualStrategyNumber,
	0x0,
	BTLessEqualStrategyNumber,
	SK_COMMUTE
};

static uint16 BTGreaterEqualTermData[] = {		/* XXX type clash */
	2,
	BTGreaterEqualStrategyNumber,
	0x0,
	BTGreaterEqualStrategyNumber,
	SK_COMMUTE
};

static uint16 BTGreaterTermData[] = {	/* XXX type clash */
	2,
	BTGreaterStrategyNumber,
	SK_NEGATE,
	BTGreaterStrategyNumber,
	SK_NEGATE | SK_COMMUTE
};

static StrategyTerm BTEqualExpressionData[] = {
	(StrategyTerm) BTLessTermData,		/* XXX */
	(StrategyTerm) BTLessEqualTermData, /* XXX */
	(StrategyTerm) BTGreaterEqualTermData,		/* XXX */
	(StrategyTerm) BTGreaterTermData,	/* XXX */
	NULL
};

static StrategyEvaluationData BTEvaluationData = {
	/* XXX static for simplicity */

	BTMaxStrategyNumber,
	(StrategyTransformMap) BTNegate,	/* XXX */
	(StrategyTransformMap) BTCommute,	/* XXX */
	(StrategyTransformMap) BTNegateCommute,		/* XXX */

	{NULL, NULL, (StrategyExpression) BTEqualExpressionData, NULL, NULL,
	NULL, NULL, NULL, NULL, NULL, NULL, NULL}
};

/* ----------------------------------------------------------------
 *		RelationGetBTStrategy
 * ----------------------------------------------------------------
 */

StrategyNumber
_bt_getstrat(Relation rel,
			 AttrNumber attno,
			 RegProcedure proc)
{
	StrategyNumber strat;

	strat = RelationGetStrategy(rel, attno, &BTEvaluationData, proc);

	Assert(StrategyNumberIsValid(strat));

	return (strat);
}

bool
_bt_invokestrat(Relation rel,
				AttrNumber attno,
				StrategyNumber strat,
				Datum left,
				Datum right)
{
	return (RelationInvokeStrategy(rel, &BTEvaluationData, attno, strat,
								   left, right));
}