arrayfuncs.c

来自「postgresql8.3.4源码,开源数据库」· C语言 代码 · 共 2,484 行 · 第 1/5 页

	bitmap = ARR_NULLBITMAP(v);
	bitmask = 1;

	for (i = 0; i < nitems; i++)
	{
		/* Get source element, checking for NULL */
		if (bitmap && (*bitmap & bitmask) == 0)
		{
			/* -1 length means a NULL */
			pq_sendint(&buf, -1, 4);
		}
		else
		{
			Datum		itemvalue;
			bytea	   *outputbytes;

			itemvalue = fetch_att(p, typbyval, typlen);
			outputbytes = SendFunctionCall(&my_extra->proc, itemvalue);
			pq_sendint(&buf, VARSIZE(outputbytes) - VARHDRSZ, 4);
			pq_sendbytes(&buf, VARDATA(outputbytes),
						 VARSIZE(outputbytes) - VARHDRSZ);
			pfree(outputbytes);

			p = att_addlength_pointer(p, typlen, p);
			p = (char *) att_align_nominal(p, typalign);
		}

		/* advance bitmap pointer if any */
		if (bitmap)
		{
			bitmask <<= 1;
			if (bitmask == 0x100)
			{
				bitmap++;
				bitmask = 1;
			}
		}
	}

	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * array_dims :
 *		  returns the dimensions of the array pointed to by "v", as a "text"
 */
Datum
array_dims(PG_FUNCTION_ARGS)
{
	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
	text	   *result;
	char	   *p;
	int			nbytes,
				i;
	int		   *dimv,
			   *lb;

	/* Sanity check: does it look like an array at all? */
	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
		PG_RETURN_NULL();

	nbytes = ARR_NDIM(v) * 33 + 1;

	/*
	 * 33 since we assume 15 digits per number + ':' +'[]'
	 *
	 * +1 allows for temp trailing null
	 */

	result = (text *) palloc(nbytes + VARHDRSZ);
	p = VARDATA(result);

	dimv = ARR_DIMS(v);
	lb = ARR_LBOUND(v);

	for (i = 0; i < ARR_NDIM(v); i++)
	{
		sprintf(p, "[%d:%d]", lb[i], dimv[i] + lb[i] - 1);
		p += strlen(p);
	}
	SET_VARSIZE(result, strlen(VARDATA(result)) + VARHDRSZ);

	PG_RETURN_TEXT_P(result);
}

/*
 * array_lower :
 *		returns the lower dimension, of the DIM requested, for
 *		the array pointed to by "v", as an int4
 */
Datum
array_lower(PG_FUNCTION_ARGS)
{
	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
	int			reqdim = PG_GETARG_INT32(1);
	int		   *lb;
	int			result;

	/* Sanity check: does it look like an array at all? */
	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
		PG_RETURN_NULL();

	/* Sanity check: was the requested dim valid */
	if (reqdim <= 0 || reqdim > ARR_NDIM(v))
		PG_RETURN_NULL();

	lb = ARR_LBOUND(v);
	result = lb[reqdim - 1];

	PG_RETURN_INT32(result);
}

/*
 * array_upper :
 *		returns the upper dimension, of the DIM requested, for
 *		the array pointed to by "v", as an int4
 */
Datum
array_upper(PG_FUNCTION_ARGS)
{
	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
	int			reqdim = PG_GETARG_INT32(1);
	int		   *dimv,
			   *lb;
	int			result;

	/* Sanity check: does it look like an array at all? */
	if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
		PG_RETURN_NULL();

	/* Sanity check: was the requested dim valid */
	if (reqdim <= 0 || reqdim > ARR_NDIM(v))
		PG_RETURN_NULL();

	lb = ARR_LBOUND(v);
	dimv = ARR_DIMS(v);

	result = dimv[reqdim - 1] + lb[reqdim - 1] - 1;

	PG_RETURN_INT32(result);
}

/*
 * array_ref :
 *	  This routine takes an array pointer and a subscript array and returns
 *	  the referenced item as a Datum.  Note that for a pass-by-reference
 *	  datatype, the returned Datum is a pointer into the array object.
 *
 * This handles both ordinary varlena arrays and fixed-length arrays.
 *
 * Inputs:
 *	array: the array object (mustn't be NULL)
 *	nSubscripts: number of subscripts supplied
 *	indx[]: the subscript values
 *	arraytyplen: pg_type.typlen for the array type
 *	elmlen: pg_type.typlen for the array's element type
 *	elmbyval: pg_type.typbyval for the array's element type
 *	elmalign: pg_type.typalign for the array's element type
 *
 * Outputs:
 *	The return value is the element Datum.
 *	*isNull is set to indicate whether the element is NULL.
 */
Datum
array_ref(ArrayType *array,
		  int nSubscripts,
		  int *indx,
		  int arraytyplen,
		  int elmlen,
		  bool elmbyval,
		  char elmalign,
		  bool *isNull)
{
	int			i,
				ndim,
			   *dim,
			   *lb,
				offset,
				fixedDim[1],
				fixedLb[1];
	char	   *arraydataptr,
			   *retptr;
	bits8	   *arraynullsptr;

	if (arraytyplen > 0)
	{
		/*
		 * fixed-length arrays -- these are assumed to be 1-d, 0-based
		 */
		ndim = 1;
		fixedDim[0] = arraytyplen / elmlen;
		fixedLb[0] = 0;
		dim = fixedDim;
		lb = fixedLb;
		arraydataptr = (char *) array;
		arraynullsptr = NULL;
	}
	else
	{
		/* detoast input array if necessary */
		array = DatumGetArrayTypeP(PointerGetDatum(array));

		ndim = ARR_NDIM(array);
		dim = ARR_DIMS(array);
		lb = ARR_LBOUND(array);
		arraydataptr = ARR_DATA_PTR(array);
		arraynullsptr = ARR_NULLBITMAP(array);
	}

	/*
	 * Return NULL for invalid subscript
	 */
	if (ndim != nSubscripts || ndim <= 0 || ndim > MAXDIM)
	{
		*isNull = true;
		return (Datum) 0;
	}
	for (i = 0; i < ndim; i++)
	{
		if (indx[i] < lb[i] || indx[i] >= (dim[i] + lb[i]))
		{
			*isNull = true;
			return (Datum) 0;
		}
	}

	/*
	 * Calculate the element number
	 */
	offset = ArrayGetOffset(nSubscripts, dim, lb, indx);

	/*
	 * Check for NULL array element
	 */
	if (array_get_isnull(arraynullsptr, offset))
	{
		*isNull = true;
		return (Datum) 0;
	}

	/*
	 * OK, get the element
	 */
	*isNull = false;
	retptr = array_seek(arraydataptr, 0, arraynullsptr, offset,
						elmlen, elmbyval, elmalign);
	return ArrayCast(retptr, elmbyval, elmlen);
}

/*
 * array_get_slice :
 *		   This routine takes an array and a range of indices (upperIndex and
 *		   lowerIndx), creates a new array structure for the referred elements
 *		   and returns a pointer to it.
 *
 * This handles both ordinary varlena arrays and fixed-length arrays.
 *
 * Inputs:
 *	array: the array object (mustn't be NULL)
 *	nSubscripts: number of subscripts supplied (must be same for upper/lower)
 *	upperIndx[]: the upper subscript values
 *	lowerIndx[]: the lower subscript values
 *	arraytyplen: pg_type.typlen for the array type
 *	elmlen: pg_type.typlen for the array's element type
 *	elmbyval: pg_type.typbyval for the array's element type
 *	elmalign: pg_type.typalign for the array's element type
 *
 * Outputs:
 *	The return value is the new array Datum (it's never NULL)
 *
 * NOTE: we assume it is OK to scribble on the provided subscript arrays
 * lowerIndx[] and upperIndx[].  These are generally just temporaries.
 */
ArrayType *
array_get_slice(ArrayType *array,
				int nSubscripts,
				int *upperIndx,
				int *lowerIndx,
				int arraytyplen,
				int elmlen,
				bool elmbyval,
				char elmalign)
{
	ArrayType  *newarray;
	int			i,
				ndim,
			   *dim,
			   *lb,
			   *newlb;
	int			fixedDim[1],
				fixedLb[1];
	Oid			elemtype;
	char	   *arraydataptr;
	bits8	   *arraynullsptr;
	int32		dataoffset;
	int			bytes,
				span[MAXDIM];

	if (arraytyplen > 0)
	{
		/*
		 * fixed-length arrays -- currently, cannot slice these because parser
		 * labels output as being of the fixed-length array type! Code below
		 * shows how we could support it if the parser were changed to label
		 * output as a suitable varlena array type.
		 */
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("slices of fixed-length arrays not implemented")));

		/*
		 * fixed-length arrays -- these are assumed to be 1-d, 0-based
		 *
		 * XXX where would we get the correct ELEMTYPE from?
		 */
		ndim = 1;
		fixedDim[0] = arraytyplen / elmlen;
		fixedLb[0] = 0;
		dim = fixedDim;
		lb = fixedLb;
		elemtype = InvalidOid;	/* XXX */
		arraydataptr = (char *) array;
		arraynullsptr = NULL;
	}
	else
	{
		/* detoast input array if necessary */
		array = DatumGetArrayTypeP(PointerGetDatum(array));

		ndim = ARR_NDIM(array);
		dim = ARR_DIMS(array);
		lb = ARR_LBOUND(array);
		elemtype = ARR_ELEMTYPE(array);
		arraydataptr = ARR_DATA_PTR(array);
		arraynullsptr = ARR_NULLBITMAP(array);
	}

	/*
	 * Check provided subscripts.  A slice exceeding the current array limits
	 * is silently truncated to the array limits.  If we end up with an empty
	 * slice, return an empty array.
	 */
	if (ndim < nSubscripts || ndim <= 0 || ndim > MAXDIM)
		return construct_empty_array(elemtype);

	for (i = 0; i < nSubscripts; i++)
	{
		if (lowerIndx[i] < lb[i])
			lowerIndx[i] = lb[i];
		if (upperIndx[i] >= (dim[i] + lb[i]))
			upperIndx[i] = dim[i] + lb[i] - 1;
		if (lowerIndx[i] > upperIndx[i])
			return construct_empty_array(elemtype);
	}
	/* fill any missing subscript positions with full array range */
	for (; i < ndim; i++)
	{
		lowerIndx[i] = lb[i];
		upperIndx[i] = dim[i] + lb[i] - 1;
		if (lowerIndx[i] > upperIndx[i])
			return construct_empty_array(elemtype);
	}

	mda_get_range(ndim, span, lowerIndx, upperIndx);

	bytes = array_slice_size(arraydataptr, arraynullsptr,
							 ndim, dim, lb,
							 lowerIndx, upperIndx,
							 elmlen, elmbyval, elmalign);

	/*
	 * Currently, we put a null bitmap in the result if the source has one;
	 * could be smarter ...
	 */
	if (arraynullsptr)
	{
		dataoffset = ARR_OVERHEAD_WITHNULLS(ndim, ArrayGetNItems(ndim, span));
		bytes += dataoffset;
	}
	else
	{
		dataoffset = 0;			/* marker for no null bitmap */
		bytes += ARR_OVERHEAD_NONULLS(ndim);
	}

	newarray = (ArrayType *) palloc(bytes);
	SET_VARSIZE(newarray, bytes);
	newarray->ndim = ndim;
	newarray->dataoffset = dataoffset;
	newarray->elemtype = elemtype;
	memcpy(ARR_DIMS(newarray), span, ndim * sizeof(int));

	/*
	 * Lower bounds of the new array are set to 1.	Formerly (before 7.3) we
	 * copied the given lowerIndx values ... but that seems confusing.
	 */
	newlb = ARR_LBOUND(newarray);
	for (i = 0; i < ndim; i++)
		newlb[i] = 1;

	array_extract_slice(newarray,
						ndim, dim, lb,
						arraydataptr, arraynullsptr,
						lowerIndx, upperIndx,
						elmlen, elmbyval, elmalign);

	return newarray;
}

/*
 * array_set :
 *		  This routine sets the value of an 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:
 *	array: the initial array object (mustn't be NULL)
 *	nSubscripts: number of subscripts supplied
 *	indx[]: the subscript values
 *	dataValue: the datum to be inserted at the given position
 *	isNull: whether dataValue is NULL
 *	arraytyplen: pg_type.typlen for the array type
 *	elmlen: pg_type.typlen for the array's element type
 *	elmbyval: pg_type.typbyval for the array's element type
 *	elmalign: pg_type.typalign for the array's element type
 *
 * Result:
 *		  A new array is returned, just like the old except for the one
 *		  modified entry.  The original array object is not changed.
 *
 * For one-dimensional arrays only, we allow the array to be extended
 * by assigning to a position outside the existing subscript range; any
 * positions between the existing elements and the new one are set to NULLs.
 * (XXX TODO: allow a corresponding behavior for multidimensional arrays)
 *
 * NOTE: For assignments, we throw an error for invalid subscripts etc,
 * rather than returning a NULL as the fetch operations do.
 */
ArrayType *
array_set(ArrayType *array,
		  int nSubscripts,
		  int *indx,
		  Datum dataValue,
		  bool isNull,
		  int arraytyplen,
		  int elmlen,
		  bool elmbyval,
		  char elmalign)
{
	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.
		 */
		if (nSubscripts != 1)
			ereport(ERROR,
					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
					 errmsg("wrong number of array subscripts")));

		if (indx[0] < 0 || indx[0] * elmlen >= arraytyplen)
			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")));

		newarray = (ArrayType *) palloc(arraytyplen);
		memcpy(newarray, array, arraytyplen);
		elt_ptr = (char *) newarray + indx[0] * elmlen;
		ArrayCastAndSet(dataValue, elmlen, elmbyval, elmalign, elt_ptr);