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postgresql/contrib/seg/seg.c

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/*
* contrib/seg/seg.c
*
******************************************************************************
This file contains routines that can be bound to a Postgres backend and
called by the backend in the process of processing queries. The calling
format for these routines is dictated by Postgres architecture.
******************************************************************************/
#include "postgres.h"
#include <float.h>
#include "access/gist.h"
#include "access/stratnum.h"
#include "fmgr.h"
#include "segdata.h"
#define DatumGetSegP(X) ((SEG *) DatumGetPointer(X))
#define PG_GETARG_SEG_P(n) DatumGetSegP(PG_GETARG_DATUM(n))
/*
#define GIST_DEBUG
#define GIST_QUERY_DEBUG
*/
PG_MODULE_MAGIC;
/*
* Auxiliary data structure for picksplit method.
*/
typedef struct
{
float center;
OffsetNumber index;
SEG *data;
} gseg_picksplit_item;
/*
** Input/Output routines
*/
PG_FUNCTION_INFO_V1(seg_in);
PG_FUNCTION_INFO_V1(seg_out);
PG_FUNCTION_INFO_V1(seg_size);
PG_FUNCTION_INFO_V1(seg_lower);
PG_FUNCTION_INFO_V1(seg_upper);
PG_FUNCTION_INFO_V1(seg_center);
/*
** GiST support methods
*/
PG_FUNCTION_INFO_V1(gseg_consistent);
PG_FUNCTION_INFO_V1(gseg_compress);
PG_FUNCTION_INFO_V1(gseg_decompress);
PG_FUNCTION_INFO_V1(gseg_picksplit);
PG_FUNCTION_INFO_V1(gseg_penalty);
PG_FUNCTION_INFO_V1(gseg_union);
PG_FUNCTION_INFO_V1(gseg_same);
static Datum gseg_leaf_consistent(Datum key, Datum query, StrategyNumber strategy);
static Datum gseg_internal_consistent(Datum key, Datum query, StrategyNumber strategy);
static Datum gseg_binary_union(Datum r1, Datum r2, int *sizep);
/*
** R-tree support functions
*/
PG_FUNCTION_INFO_V1(seg_same);
PG_FUNCTION_INFO_V1(seg_contains);
PG_FUNCTION_INFO_V1(seg_contained);
PG_FUNCTION_INFO_V1(seg_overlap);
PG_FUNCTION_INFO_V1(seg_left);
PG_FUNCTION_INFO_V1(seg_over_left);
PG_FUNCTION_INFO_V1(seg_right);
PG_FUNCTION_INFO_V1(seg_over_right);
PG_FUNCTION_INFO_V1(seg_union);
PG_FUNCTION_INFO_V1(seg_inter);
static void rt_seg_size(SEG *a, float *size);
/*
** Various operators
*/
PG_FUNCTION_INFO_V1(seg_cmp);
PG_FUNCTION_INFO_V1(seg_lt);
PG_FUNCTION_INFO_V1(seg_le);
PG_FUNCTION_INFO_V1(seg_gt);
PG_FUNCTION_INFO_V1(seg_ge);
PG_FUNCTION_INFO_V1(seg_different);
/*
** Auxiliary functions
*/
static int restore(char *s, float val, int n);
/*****************************************************************************
* Input/Output functions
*****************************************************************************/
Datum
seg_in(PG_FUNCTION_ARGS)
{
char *str = PG_GETARG_CSTRING(0);
SEG *result = palloc(sizeof(SEG));
seg_scanner_init(str);
if (seg_yyparse(result) != 0)
seg_yyerror(result, "bogus input");
seg_scanner_finish();
PG_RETURN_POINTER(result);
}
Datum
seg_out(PG_FUNCTION_ARGS)
{
SEG *seg = PG_GETARG_SEG_P(0);
char *result;
char *p;
p = result = (char *) palloc(40);
if (seg->l_ext == '>' || seg->l_ext == '<' || seg->l_ext == '~')
p += sprintf(p, "%c", seg->l_ext);
if (seg->lower == seg->upper && seg->l_ext == seg->u_ext)
{
/*
* indicates that this interval was built by seg_in off a single point
*/
p += restore(p, seg->lower, seg->l_sigd);
}
else
{
if (seg->l_ext != '-')
{
/* print the lower boundary if exists */
p += restore(p, seg->lower, seg->l_sigd);
p += sprintf(p, " ");
}
p += sprintf(p, "..");
if (seg->u_ext != '-')
{
/* print the upper boundary if exists */
p += sprintf(p, " ");
if (seg->u_ext == '>' || seg->u_ext == '<' || seg->l_ext == '~')
p += sprintf(p, "%c", seg->u_ext);
p += restore(p, seg->upper, seg->u_sigd);
}
}
PG_RETURN_CSTRING(result);
}
Datum
seg_center(PG_FUNCTION_ARGS)
{
SEG *seg = PG_GETARG_SEG_P(0);
PG_RETURN_FLOAT4(((float) seg->lower + (float) seg->upper) / 2.0);
}
Datum
seg_lower(PG_FUNCTION_ARGS)
{
SEG *seg = PG_GETARG_SEG_P(0);
PG_RETURN_FLOAT4(seg->lower);
}
Datum
seg_upper(PG_FUNCTION_ARGS)
{
SEG *seg = PG_GETARG_SEG_P(0);
PG_RETURN_FLOAT4(seg->upper);
}
/*****************************************************************************
* GiST functions
*****************************************************************************/
/*
** The GiST Consistent method for segments
** Should return false if for all data items x below entry,
** the predicate x op query == false, where op is the oper
** corresponding to strategy in the pg_amop table.
*/
Datum
gseg_consistent(PG_FUNCTION_ARGS)
{
GISTENTRY *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
Datum query = PG_GETARG_DATUM(1);
StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2);
/* Oid subtype = PG_GETARG_OID(3); */
bool *recheck = (bool *) PG_GETARG_POINTER(4);
/* All cases served by this function are exact */
*recheck = false;
/*
* if entry is not leaf, use gseg_internal_consistent, else use
* gseg_leaf_consistent
*/
if (GIST_LEAF(entry))
return gseg_leaf_consistent(entry->key, query, strategy);
else
return gseg_internal_consistent(entry->key, query, strategy);
}
/*
** The GiST Union method for segments
** returns the minimal bounding seg that encloses all the entries in entryvec
*/
Datum
gseg_union(PG_FUNCTION_ARGS)
{
GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
int *sizep = (int *) PG_GETARG_POINTER(1);
int numranges,
i;
Datum out = 0;
Datum tmp;
#ifdef GIST_DEBUG
fprintf(stderr, "union\n");
#endif
numranges = entryvec->n;
tmp = entryvec->vector[0].key;
*sizep = sizeof(SEG);
for (i = 1; i < numranges; i++)
{
out = gseg_binary_union(tmp, entryvec->vector[i].key, sizep);
tmp = out;
}
PG_RETURN_DATUM(out);
}
/*
** GiST Compress and Decompress methods for segments
** do not do anything.
*/
Datum
gseg_compress(PG_FUNCTION_ARGS)
{
PG_RETURN_POINTER(PG_GETARG_POINTER(0));
}
Datum
gseg_decompress(PG_FUNCTION_ARGS)
{
PG_RETURN_POINTER(PG_GETARG_POINTER(0));
}
/*
** The GiST Penalty method for segments
** As in the R-tree paper, we use change in area as our penalty metric
*/
Datum
gseg_penalty(PG_FUNCTION_ARGS)
{
GISTENTRY *origentry = (GISTENTRY *) PG_GETARG_POINTER(0);
GISTENTRY *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
float *result = (float *) PG_GETARG_POINTER(2);
SEG *ud;
float tmp1,
tmp2;
ud = DatumGetSegP(DirectFunctionCall2(seg_union,
origentry->key,
newentry->key));
rt_seg_size(ud, &tmp1);
rt_seg_size(DatumGetSegP(origentry->key), &tmp2);
*result = tmp1 - tmp2;
#ifdef GIST_DEBUG
fprintf(stderr, "penalty\n");
fprintf(stderr, "\t%g\n", *result);
#endif
PG_RETURN_POINTER(result);
}
/*
* Compare function for gseg_picksplit_item: sort by center.
*/
static int
gseg_picksplit_item_cmp(const void *a, const void *b)
{
const gseg_picksplit_item *i1 = (const gseg_picksplit_item *) a;
const gseg_picksplit_item *i2 = (const gseg_picksplit_item *) b;
if (i1->center < i2->center)
return -1;
else if (i1->center == i2->center)
return 0;
else
return 1;
}
/*
* The GiST PickSplit method for segments
*
* We used to use Guttman's split algorithm here, but since the data is 1-D
* it's easier and more robust to just sort the segments by center-point and
* split at the middle.
*/
Datum
gseg_picksplit(PG_FUNCTION_ARGS)
{
GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
int i;
SEG *seg,
*seg_l,
*seg_r;
gseg_picksplit_item *sort_items;
OffsetNumber *left,
*right;
OffsetNumber maxoff;
OffsetNumber firstright;
#ifdef GIST_DEBUG
fprintf(stderr, "picksplit\n");
#endif
/* Valid items in entryvec->vector[] are indexed 1..maxoff */
maxoff = entryvec->n - 1;
/*
* Prepare the auxiliary array and sort it.
*/
sort_items = (gseg_picksplit_item *)
palloc(maxoff * sizeof(gseg_picksplit_item));
for (i = 1; i <= maxoff; i++)
{
seg = DatumGetSegP(entryvec->vector[i].key);
/* center calculation is done this way to avoid possible overflow */
sort_items[i - 1].center = seg->lower * 0.5f + seg->upper * 0.5f;
sort_items[i - 1].index = i;
sort_items[i - 1].data = seg;
}
qsort(sort_items, maxoff, sizeof(gseg_picksplit_item),
gseg_picksplit_item_cmp);
/* sort items below "firstright" will go into the left side */
firstright = maxoff / 2;
v->spl_left = (OffsetNumber *) palloc(maxoff * sizeof(OffsetNumber));
v->spl_right = (OffsetNumber *) palloc(maxoff * sizeof(OffsetNumber));
left = v->spl_left;
v->spl_nleft = 0;
right = v->spl_right;
v->spl_nright = 0;
/*
* Emit segments to the left output page, and compute its bounding box.
*/
seg_l = (SEG *) palloc(sizeof(SEG));
memcpy(seg_l, sort_items[0].data, sizeof(SEG));
*left++ = sort_items[0].index;
v->spl_nleft++;
for (i = 1; i < firstright; i++)
{
Datum sortitem = PointerGetDatum(sort_items[i].data);
seg_l = DatumGetSegP(DirectFunctionCall2(seg_union,
PointerGetDatum(seg_l),
sortitem));
*left++ = sort_items[i].index;
v->spl_nleft++;
}
/*
* Likewise for the right page.
*/
seg_r = (SEG *) palloc(sizeof(SEG));
memcpy(seg_r, sort_items[firstright].data, sizeof(SEG));
*right++ = sort_items[firstright].index;
v->spl_nright++;
for (i = firstright + 1; i < maxoff; i++)
{
Datum sortitem = PointerGetDatum(sort_items[i].data);
seg_r = DatumGetSegP(DirectFunctionCall2(seg_union,
PointerGetDatum(seg_r),
sortitem));
*right++ = sort_items[i].index;
v->spl_nright++;
}
v->spl_ldatum = PointerGetDatum(seg_l);
v->spl_rdatum = PointerGetDatum(seg_r);
PG_RETURN_POINTER(v);
}
/*
** Equality methods
*/
Datum
gseg_same(PG_FUNCTION_ARGS)
{
bool *result = (bool *) PG_GETARG_POINTER(2);
if (DirectFunctionCall2(seg_same, PG_GETARG_DATUM(0), PG_GETARG_DATUM(1)))
*result = true;
else
*result = false;
#ifdef GIST_DEBUG
fprintf(stderr, "same: %s\n", (*result ? "TRUE" : "FALSE"));
#endif
PG_RETURN_POINTER(result);
}
/*
** SUPPORT ROUTINES
*/
static Datum
gseg_leaf_consistent(Datum key, Datum query, StrategyNumber strategy)
{
Datum retval;
#ifdef GIST_QUERY_DEBUG
fprintf(stderr, "leaf_consistent, %d\n", strategy);
#endif
switch (strategy)
{
case RTLeftStrategyNumber:
retval = DirectFunctionCall2(seg_left, key, query);
break;
case RTOverLeftStrategyNumber:
retval = DirectFunctionCall2(seg_over_left, key, query);
break;
case RTOverlapStrategyNumber:
retval = DirectFunctionCall2(seg_overlap, key, query);
break;
case RTOverRightStrategyNumber:
retval = DirectFunctionCall2(seg_over_right, key, query);
break;
case RTRightStrategyNumber:
retval = DirectFunctionCall2(seg_right, key, query);
break;
case RTSameStrategyNumber:
retval = DirectFunctionCall2(seg_same, key, query);
break;
case RTContainsStrategyNumber:
case RTOldContainsStrategyNumber:
retval = DirectFunctionCall2(seg_contains, key, query);
break;
case RTContainedByStrategyNumber:
case RTOldContainedByStrategyNumber:
retval = DirectFunctionCall2(seg_contained, key, query);
break;
default:
retval = false;
}
PG_RETURN_DATUM(retval);
}
static Datum
gseg_internal_consistent(Datum key, Datum query, StrategyNumber strategy)
{
bool retval;
#ifdef GIST_QUERY_DEBUG
fprintf(stderr, "internal_consistent, %d\n", strategy);
#endif
switch (strategy)
{
case RTLeftStrategyNumber:
retval =
!DatumGetBool(DirectFunctionCall2(seg_over_right, key, query));
break;
case RTOverLeftStrategyNumber:
retval =
!DatumGetBool(DirectFunctionCall2(seg_right, key, query));
break;
case RTOverlapStrategyNumber:
retval =
DatumGetBool(DirectFunctionCall2(seg_overlap, key, query));
break;
case RTOverRightStrategyNumber:
retval =
!DatumGetBool(DirectFunctionCall2(seg_left, key, query));
break;
case RTRightStrategyNumber:
retval =
!DatumGetBool(DirectFunctionCall2(seg_over_left, key, query));
break;
case RTSameStrategyNumber:
case RTContainsStrategyNumber:
case RTOldContainsStrategyNumber:
retval =
DatumGetBool(DirectFunctionCall2(seg_contains, key, query));
break;
case RTContainedByStrategyNumber:
case RTOldContainedByStrategyNumber:
retval =
DatumGetBool(DirectFunctionCall2(seg_overlap, key, query));
break;
default:
retval = false;
}
PG_RETURN_BOOL(retval);
}
static Datum
gseg_binary_union(Datum r1, Datum r2, int *sizep)
{
Datum retval;
retval = DirectFunctionCall2(seg_union, r1, r2);
*sizep = sizeof(SEG);
return retval;
}
Datum
seg_contains(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
PG_RETURN_BOOL((a->lower <= b->lower) && (a->upper >= b->upper));
}
Datum
seg_contained(PG_FUNCTION_ARGS)
{
Datum a = PG_GETARG_DATUM(0);
Datum b = PG_GETARG_DATUM(1);
PG_RETURN_DATUM(DirectFunctionCall2(seg_contains, b, a));
}
/*****************************************************************************
* Operator class for R-tree indexing
*****************************************************************************/
Datum
seg_same(PG_FUNCTION_ARGS)
{
int cmp = DatumGetInt32(DirectFunctionCall2(seg_cmp,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(cmp == 0);
}
/* seg_overlap -- does a overlap b?
*/
Datum
seg_overlap(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
PG_RETURN_BOOL(((a->upper >= b->upper) && (a->lower <= b->upper)) ||
((b->upper >= a->upper) && (b->lower <= a->upper)));
}
/* seg_over_left -- is the right edge of (a) located at or left of the right edge of (b)?
*/
Datum
seg_over_left(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
PG_RETURN_BOOL(a->upper <= b->upper);
}
/* seg_left -- is (a) entirely on the left of (b)?
*/
Datum
seg_left(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
PG_RETURN_BOOL(a->upper < b->lower);
}
/* seg_right -- is (a) entirely on the right of (b)?
*/
Datum
seg_right(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
PG_RETURN_BOOL(a->lower > b->upper);
}
/* seg_over_right -- is the left edge of (a) located at or right of the left edge of (b)?
*/
Datum
seg_over_right(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
PG_RETURN_BOOL(a->lower >= b->lower);
}
Datum
seg_union(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
SEG *n;
n = (SEG *) palloc(sizeof(*n));
/* take max of upper endpoints */
if (a->upper > b->upper)
{
n->upper = a->upper;
n->u_sigd = a->u_sigd;
n->u_ext = a->u_ext;
}
else
{
n->upper = b->upper;
n->u_sigd = b->u_sigd;
n->u_ext = b->u_ext;
}
/* take min of lower endpoints */
if (a->lower < b->lower)
{
n->lower = a->lower;
n->l_sigd = a->l_sigd;
n->l_ext = a->l_ext;
}
else
{
n->lower = b->lower;
n->l_sigd = b->l_sigd;
n->l_ext = b->l_ext;
}
PG_RETURN_POINTER(n);
}
Datum
seg_inter(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
SEG *n;
n = (SEG *) palloc(sizeof(*n));
/* take min of upper endpoints */
if (a->upper < b->upper)
{
n->upper = a->upper;
n->u_sigd = a->u_sigd;
n->u_ext = a->u_ext;
}
else
{
n->upper = b->upper;
n->u_sigd = b->u_sigd;
n->u_ext = b->u_ext;
}
/* take max of lower endpoints */
if (a->lower > b->lower)
{
n->lower = a->lower;
n->l_sigd = a->l_sigd;
n->l_ext = a->l_ext;
}
else
{
n->lower = b->lower;
n->l_sigd = b->l_sigd;
n->l_ext = b->l_ext;
}
PG_RETURN_POINTER(n);
}
static void
rt_seg_size(SEG *a, float *size)
{
if (a == (SEG *) NULL || a->upper <= a->lower)
*size = 0.0;
else
*size = (float) Abs(a->upper - a->lower);
}
Datum
seg_size(PG_FUNCTION_ARGS)
{
SEG *seg = PG_GETARG_SEG_P(0);
PG_RETURN_FLOAT4((float) Abs(seg->upper - seg->lower));
}
/*****************************************************************************
* Miscellaneous operators
*****************************************************************************/
Datum
seg_cmp(PG_FUNCTION_ARGS)
{
SEG *a = PG_GETARG_SEG_P(0);
SEG *b = PG_GETARG_SEG_P(1);
/*
* First compare on lower boundary position
*/
if (a->lower < b->lower)
PG_RETURN_INT32(-1);
if (a->lower > b->lower)
PG_RETURN_INT32(1);
/*
* a->lower == b->lower, so consider type of boundary.
*
* A '-' lower bound is < any other kind (this could only be relevant if
* -HUGE_VAL is used as a regular data value). A '<' lower bound is < any
* other kind except '-'. A '>' lower bound is > any other kind.
*/
if (a->l_ext != b->l_ext)
{
if (a->l_ext == '-')
PG_RETURN_INT32(-1);
if (b->l_ext == '-')
PG_RETURN_INT32(1);
if (a->l_ext == '<')
PG_RETURN_INT32(-1);
if (b->l_ext == '<')
PG_RETURN_INT32(1);
if (a->l_ext == '>')
PG_RETURN_INT32(1);
if (b->l_ext == '>')
PG_RETURN_INT32(-1);
}
/*
* For other boundary types, consider # of significant digits first.
*/
if (a->l_sigd < b->l_sigd) /* (a) is blurred and is likely to include (b) */
PG_RETURN_INT32(-1);
if (a->l_sigd > b->l_sigd) /* (a) is less blurred and is likely to be
* included in (b) */
PG_RETURN_INT32(1);
/*
* For same # of digits, an approximate boundary is more blurred than
* exact.
*/
if (a->l_ext != b->l_ext)
{
if (a->l_ext == '~') /* (a) is approximate, while (b) is exact */
PG_RETURN_INT32(-1);
if (b->l_ext == '~')
PG_RETURN_INT32(1);
/* can't get here unless data is corrupt */
elog(ERROR, "bogus lower boundary types %d %d",
(int) a->l_ext, (int) b->l_ext);
}
/* at this point, the lower boundaries are identical */
/*
* First compare on upper boundary position
*/
if (a->upper < b->upper)
PG_RETURN_INT32(-1);
if (a->upper > b->upper)
PG_RETURN_INT32(1);
/*
* a->upper == b->upper, so consider type of boundary.
*
* A '-' upper bound is > any other kind (this could only be relevant if
* HUGE_VAL is used as a regular data value). A '<' upper bound is < any
* other kind. A '>' upper bound is > any other kind except '-'.
*/
if (a->u_ext != b->u_ext)
{
if (a->u_ext == '-')
PG_RETURN_INT32(1);
if (b->u_ext == '-')
PG_RETURN_INT32(-1);
if (a->u_ext == '<')
PG_RETURN_INT32(-1);
if (b->u_ext == '<')
PG_RETURN_INT32(1);
if (a->u_ext == '>')
PG_RETURN_INT32(1);
if (b->u_ext == '>')
PG_RETURN_INT32(-1);
}
/*
* For other boundary types, consider # of significant digits first. Note
* result here is converse of the lower-boundary case.
*/
if (a->u_sigd < b->u_sigd) /* (a) is blurred and is likely to include (b) */
PG_RETURN_INT32(1);
if (a->u_sigd > b->u_sigd) /* (a) is less blurred and is likely to be
* included in (b) */
PG_RETURN_INT32(-1);
/*
* For same # of digits, an approximate boundary is more blurred than
* exact. Again, result is converse of lower-boundary case.
*/
if (a->u_ext != b->u_ext)
{
if (a->u_ext == '~') /* (a) is approximate, while (b) is exact */
PG_RETURN_INT32(1);
if (b->u_ext == '~')
PG_RETURN_INT32(-1);
/* can't get here unless data is corrupt */
elog(ERROR, "bogus upper boundary types %d %d",
(int) a->u_ext, (int) b->u_ext);
}
PG_RETURN_INT32(0);
}
Datum
seg_lt(PG_FUNCTION_ARGS)
{
int cmp = DatumGetInt32(DirectFunctionCall2(seg_cmp,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(cmp < 0);
}
Datum
seg_le(PG_FUNCTION_ARGS)
{
int cmp = DatumGetInt32(DirectFunctionCall2(seg_cmp,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(cmp <= 0);
}
Datum
seg_gt(PG_FUNCTION_ARGS)
{
int cmp = DatumGetInt32(DirectFunctionCall2(seg_cmp,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(cmp > 0);
}
Datum
seg_ge(PG_FUNCTION_ARGS)
{
int cmp = DatumGetInt32(DirectFunctionCall2(seg_cmp,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(cmp >= 0);
}
Datum
seg_different(PG_FUNCTION_ARGS)
{
int cmp = DatumGetInt32(DirectFunctionCall2(seg_cmp,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(cmp != 0);
}
/*****************************************************************************
* Auxiliary functions
*****************************************************************************/
/*
* The purpose of this routine is to print the given floating point
* value with exactly n significant digits. Its behaviour
* is similar to %.ng except it prints 8.00 where %.ng would
* print 8. Returns the length of the string written at "result".
*
* Caller must provide a sufficiently large result buffer; 16 bytes
* should be enough for all known float implementations.
*/
static int
restore(char *result, float val, int n)
{
char buf[25] = {
'0', '0', '0', '0', '0',
'0', '0', '0', '0', '0',
'0', '0', '0', '0', '0',
'0', '0', '0', '0', '0',
'0', '0', '0', '0', '\0'
};
char *p;
int exp;
int i,
dp,
sign;
/*
* Put a cap on the number of significant digits to avoid garbage in the
* output and ensure we don't overrun the result buffer. (n should not be
* negative, but check to protect ourselves against corrupted data.)
*/
if (n <= 0)
n = FLT_DIG;
else
n = Min(n, FLT_DIG);
/* remember the sign */
sign = (val < 0 ? 1 : 0);
/* print, in %e style to start with */
sprintf(result, "%.*e", n - 1, val);
/* find the exponent */
p = strchr(result, 'e');
/* punt if we have 'inf' or similar */
if (p == NULL)
return strlen(result);
exp = atoi(p + 1);
if (exp == 0)
{
/* just truncate off the 'e+00' */
*p = '\0';
}
else
{
if (Abs(exp) <= 4)
{
/*
* remove the decimal point from the mantissa and write the digits
* to the buf array
*/
for (p = result + sign, i = 10, dp = 0; *p != 'e'; p++, i++)
{
buf[i] = *p;
if (*p == '.')
{
dp = i--; /* skip the decimal point */
}
}
if (dp == 0)
dp = i--; /* no decimal point was found in the above
* for() loop */
if (exp > 0)
{
if (dp - 10 + exp >= n)
{
/*
* the decimal point is behind the last significant digit;
* the digits in between must be converted to the exponent
* and the decimal point placed after the first digit
*/
exp = dp - 10 + exp - n;
buf[10 + n] = '\0';
/* insert the decimal point */
if (n > 1)
{
dp = 11;
for (i = 23; i > dp; i--)
buf[i] = buf[i - 1];
buf[dp] = '.';
}
/*
* adjust the exponent by the number of digits after the
* decimal point
*/
if (n > 1)
sprintf(&buf[11 + n], "e%d", exp + n - 1);
else
sprintf(&buf[11], "e%d", exp + n - 1);
if (sign)
{
buf[9] = '-';
strcpy(result, &buf[9]);
}
else
strcpy(result, &buf[10]);
}
else
{ /* insert the decimal point */
dp += exp;
for (i = 23; i > dp; i--)
buf[i] = buf[i - 1];
buf[11 + n] = '\0';
buf[dp] = '.';
if (sign)
{
buf[9] = '-';
strcpy(result, &buf[9]);
}
else
strcpy(result, &buf[10]);
}
}
else
{ /* exp <= 0 */
dp += exp - 1;
buf[10 + n] = '\0';
buf[dp] = '.';
if (sign)
{
buf[dp - 2] = '-';
strcpy(result, &buf[dp - 2]);
}
else
strcpy(result, &buf[dp - 1]);
}
}
/* do nothing for Abs(exp) > 4; %e must be OK */
/* just get rid of zeroes after [eE]- and +zeroes after [Ee]. */
/* ... this is not done yet. */
}
return strlen(result);
}
/*
** Miscellany
*/
/* find out the number of significant digits in a string representing
* a floating point number
*/
int
significant_digits(const char *s)
{
const char *p = s;
int n,
c,
zeroes;
zeroes = 1;
/* skip leading zeroes and sign */
for (c = *p; (c == '0' || c == '+' || c == '-') && c != 0; c = *(++p));
/* skip decimal point and following zeroes */
for (c = *p; (c == '0' || c == '.') && c != 0; c = *(++p))
{
if (c != '.')
zeroes++;
}
/* count significant digits (n) */
for (c = *p, n = 0; c != 0; c = *(++p))
{
if (!((c >= '0' && c <= '9') || (c == '.')))
break;
if (c != '.')
n++;
}
if (!n)
return zeroes;
return n;
}
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