spgproc.c

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/*-------------------------------------------------------------------------
 *
 * spgproc.c
 *    Common supporting procedures for SP-GiST opclasses.
 *
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *          src/backend/access/spgist/spgproc.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include <math.h>
 
#include "access/spgist_private.h"
#include "utils/float.h"
#include "utils/fmgrprotos.h"
#include "utils/geo_decls.h"
 
#define point_point_distance(p1,p2) \
    DatumGetFloat8(DirectFunctionCall2(point_distance, \
                                       PointPGetDatum(p1), PointPGetDatum(p2)))
 
/* Point-box distance in the assumption that box is aligned by axis */
static double
point_box_distance(Point *point, BOX *box)
{
    double      dx,
                dy;
 
    if (isnan(point->x) || isnan(box->low.x) ||
        isnan(point->y) || isnan(box->low.y))
        return get_float8_nan();
 
    if (point->x < box->low.x)
        dx = box->low.x - point->x;
    else if (point->x > box->high.x)
        dx = point->x - box->high.x;
    else
        dx = 0.0;
 
    if (point->y < box->low.y)
        dy = box->low.y - point->y;
    else if (point->y > box->high.y)
        dy = point->y - box->high.y;
    else
        dy = 0.0;
 
    return HYPOT(dx, dy);
}
 
/*
 * Returns distances from given key to array of ordering scan keys.  Leaf key
 * is expected to be point, non-leaf key is expected to be box.  Scan key
 * arguments are expected to be points.
 */
double *
spg_key_orderbys_distances(Datum key, bool isLeaf,
                           ScanKey orderbys, int norderbys)
{
    int         sk_num;
    double     *distances = (double *) palloc(norderbys * sizeof(double)),
               *distance = distances;
 
    for (sk_num = 0; sk_num < norderbys; ++sk_num, ++orderbys, ++distance)
    {
        Point      *point = DatumGetPointP(orderbys->sk_argument);
 
        *distance = isLeaf ? point_point_distance(point, DatumGetPointP(key))
            : point_box_distance(point, DatumGetBoxP(key));
    }
 
    return distances;
}
 
BOX *
box_copy(BOX *orig)
{
    BOX        *result = palloc(sizeof(BOX));
 
    *result = *orig;
    return result;
}