Function array_set_element

src/backend/utils/adt/arrayfuncs.c:2214–2506

* array_set_element : * This routine sets the value of one array element (specified by * a subscript array) to a new value specified by "dataValue". * * This handles both ordinary varlena arrays and fixed-length arrays. * * Inputs: * arraydatum: the initial array object (mustn't be NULL) * nSubscripts: number of subscripts supplied * indx[]: the subscript values * dataValue: the da

 * rather than returning a NULL as the fetch operations do.
 */
Datum
array_set_element(Datum arraydatum,
				  int nSubscripts,
				  int *indx,
				  Datum dataValue,
				  bool isNull,
				  int arraytyplen,
				  int elmlen,
				  bool elmbyval,
				  char elmalign)
{
	ArrayType  *array;
	ArrayType  *newarray;
	int			i,
				ndim,
				dim[MAXDIM],
				lb[MAXDIM],
				offset;
	char	   *elt_ptr;
	bool		newhasnulls;
	bits8	   *oldnullbitmap;
	int			oldnitems,
				newnitems,
				olddatasize,
				newsize,
				olditemlen,
				newitemlen,
				overheadlen,
				oldoverheadlen,
				addedbefore,
				addedafter,
				lenbefore,
				lenafter;

	if (arraytyplen > 0)
	{
		/*
		 * fixed-length arrays -- these are assumed to be 1-d, 0-based. We
		 * cannot extend them, either.
		 */
		char	   *resultarray;

		if (nSubscripts != 1)
			ereport(ERROR,
					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
					 errmsg("wrong number of array subscripts")));

		if (indx[0] < 0 || indx[0] >= arraytyplen / elmlen)
			ereport(ERROR,
					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
					 errmsg("array subscript out of range")));

		if (isNull)
			ereport(ERROR,
					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
					 errmsg("cannot assign null value to an element of a fixed-length array")));

		resultarray = (char *) palloc(arraytyplen);