database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-29 10:41:53 +03:00
Code Activity

Add generate_subscripts, a series-generation function which generates an

Browse Source 
array's subscripts.

Pavel Stehule, some editorialization by me.
This commit is contained in:
Alvaro Herrera
2008-04-28 14:48:58 +00:00
parent a1d479f518
commit 1fcb977a13
7 changed files with 253 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
src/backend/utils/adt/arrayfuncs.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.143 2008/04/11 22:52:05 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.144 2008/04/28 14:48:57 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@ -17,6 +17,7 @@
#include <ctype.h>
#include "access/tupmacs.h"
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "parser/parse_coerce.h"
#include "utils/array.h"
@ -4231,3 +4232,86 @@ array_smaller(PG_FUNCTION_ARGS)
PG_RETURN_ARRAYTYPE_P(result);
}
typedef struct generate_subscripts_fctx
{
int4 lower;
int4 upper;
bool reverse;
} generate_subscripts_fctx;
/*
* generate_subscripts(array anyarray, dim int [, reverse bool])
* Returns all subscripts of the array for any dimension
*/
Datum
generate_subscripts(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
MemoryContext oldcontext;
generate_subscripts_fctx *fctx;
/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
ArrayType *v = PG_GETARG_ARRAYTYPE_P(0);
int reqdim = PG_GETARG_INT32(1);
int *lb,
*dimv;
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/* Sanity check: does it look like an array at all? */
if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
SRF_RETURN_DONE(funcctx);
/* Sanity check: was the requested dim valid */
if (reqdim <= 0 || reqdim > ARR_NDIM(v))
SRF_RETURN_DONE(funcctx);
/*
* switch to memory context appropriate for multiple function calls
*/
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
fctx = (generate_subscripts_fctx *) palloc(sizeof(generate_subscripts_fctx));
lb = ARR_LBOUND(v);
dimv = ARR_DIMS(v);
fctx->lower = lb[reqdim - 1];
fctx->upper = dimv[reqdim - 1] + lb[reqdim - 1] - 1;
fctx->reverse = (PG_NARGS() < 3) ? false : PG_GETARG_BOOL(2);
funcctx->user_fctx = fctx;
MemoryContextSwitchTo(oldcontext);
}
funcctx = SRF_PERCALL_SETUP();
fctx = funcctx->user_fctx;
if (fctx->lower <= fctx->upper)
{
if (!fctx->reverse)
SRF_RETURN_NEXT(funcctx, Int32GetDatum(fctx->lower++));
else
SRF_RETURN_NEXT(funcctx, Int32GetDatum(fctx->upper--));
}
else
/* done when there are no more elements left */
SRF_RETURN_DONE(funcctx);
}
/*
* generate_subscripts_nodir
* Implements the 2-argument version of generate_subscripts
*/
Datum
generate_subscripts_nodir(PG_FUNCTION_ARGS)
{
/* just call the other one -- it can handle both cases */
return generate_subscripts(fcinfo);
}