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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
commit46651ce6fe013220ed397add242004d764fc0153 (patch)
tree6e5299f990f88e60174a1d3ae6e48eedd2688b2b /contrib/seg/seg.c
parentInitial commit. (diff)
downloadpostgresql-14-46651ce6fe013220ed397add242004d764fc0153.tar.xz
postgresql-14-46651ce6fe013220ed397add242004d764fc0153.zip
Adding upstream version 14.5.upstream/14.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'contrib/seg/seg.c')
-rw-r--r--contrib/seg/seg.c1090
1 files changed, 1090 insertions, 0 deletions
diff --git a/contrib/seg/seg.c b/contrib/seg/seg.c
new file mode 100644
index 0000000..4a8e2be
--- /dev/null
+++ b/contrib/seg/seg.c
@@ -0,0 +1,1090 @@
+/*
+ * 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 = 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;
+}