Datum
text_unpivot(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
unpivot_fctx *fctx;
MemoryContext oldcontext;
Datum d[2];
bool isna[2];
/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
TupleDesc tupdesc;
ArrayType *labels;
ArrayType *data;
Oid eltype1;
Oid eltype2;
/* see if we were given an explicit step size */
if (PG_NARGS() != 2)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("number of parameters != 2")));
/*
* Type check inputs:
* 0: label text[]
* 1: value anyarray
*/
eltype1 = get_fn_expr_argtype(fcinfo->flinfo, 0);
eltype2 = get_fn_expr_argtype(fcinfo->flinfo, 1);
if (!OidIsValid(eltype1))
elog(ERROR, "could not determine data type of input 'label'");
if (!OidIsValid(eltype2))
elog(ERROR, "could not determine data type of input 'value'");
/* Strict function, return null on null input */
if (PG_ARGISNULL(0) || PG_ARGISNULL(1))
PG_RETURN_NULL();
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/* switch to memory context appropriate for multiple function calls */
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context "
"that cannot accept type record")));
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
/* allocate memory for user context */
fctx = (unpivot_fctx *) palloc(sizeof(unpivot_fctx));
/* Use fctx to keep state from call to call */
labels = PG_GETARG_ARRAYTYPE_P(0);
data = PG_GETARG_ARRAYTYPE_P(1);
array_loop(labels, ARR_LBOUND(labels)[0], &fctx->label_iter);
array_loop(data, ARR_LBOUND(labels)[0], &fctx->data_iter);
funcctx->user_fctx = fctx;
MemoryContextSwitchTo(oldcontext);
}
/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();
/* get the saved state and use current as the result for this iteration */
fctx = (unpivot_fctx*) funcctx->user_fctx;
if (array_next(&fctx->label_iter, &d[0], &isna[0]))
{
HeapTuple tuple;
array_next(&fctx->data_iter, &d[1], &isna[1]);
tuple = heap_form_tuple(funcctx->tuple_desc, d, isna);
SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
}
else
{
SRF_RETURN_DONE(funcctx);
}
}
/**
* @name free_seam_list
*
* Free all the seams that have been allocated in this list. Reclaim
* the memory for each of the splits as well.
*/
void free_seam_list(SEAMS seam_list) {
int x;
array_loop(seam_list, x) delete_seam(array_value (seam_list, x));
array_free(seam_list);
}
