arrayfuncs.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,367 行 · 第 1/5 页

	/* 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])
			ereport(ERROR,
					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
					 errmsg("invalid array subscripts")));
	}

	/*
	 * Make sure source array has enough entries.  Note we ignore the
	 * shape of the source array and just read entries serially.
	 */
	mda_get_range(ndim, span, lowerIndx, upperIndx);
	nsrcitems = ArrayGetNItems(ndim, span);
	if (nsrcitems > ArrayGetNItems(ARR_NDIM(srcArray), ARR_DIMS(srcArray)))
		ereport(ERROR,
				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
				 errmsg("source array too small")));

	/*
	 * Compute space occupied by new entries, space occupied by replaced
	 * entries, and required space for new array.
	 */
	newitemsize = array_nelems_size(ARR_DATA_PTR(srcArray), nsrcitems,
									elmlen, elmbyval, elmalign);
	overheadlen = ARR_OVERHEAD(ndim);
	olddatasize = ARR_SIZE(array) - overheadlen;
	if (ndim > 1)
	{
		/*
		 * here we do not need to cope with extension of the array; it
		 * would be a lot more complicated if we had to do so...
		 */
		olditemsize = array_slice_size(ndim, dim, lb, ARR_DATA_PTR(array),
									   lowerIndx, upperIndx,
									   elmlen, elmbyval, elmalign);
		lenbefore = lenafter = 0;		/* keep compiler quiet */
	}
	else
	{
		/*
		 * here we must allow for possibility of slice larger than orig
		 * array
		 */
		int			oldlb = ARR_LBOUND(array)[0];
		int			oldub = oldlb + ARR_DIMS(array)[0] - 1;
		int			slicelb = Max(oldlb, lowerIndx[0]);
		int			sliceub = Min(oldub, upperIndx[0]);
		char	   *oldarraydata = ARR_DATA_PTR(array);

		lenbefore = array_nelems_size(oldarraydata, slicelb - oldlb,
									  elmlen, elmbyval, elmalign);
		if (slicelb > sliceub)
			olditemsize = 0;
		else
			olditemsize = array_nelems_size(oldarraydata + lenbefore,
											sliceub - slicelb + 1,
											elmlen, elmbyval, elmalign);
		lenafter = olddatasize - lenbefore - olditemsize;
	}

	newsize = overheadlen + olddatasize - olditemsize + newitemsize;

	newarray = (ArrayType *) palloc(newsize);
	newarray->size = newsize;
	newarray->ndim = ndim;
	newarray->flags = 0;
	newarray->elemtype = ARR_ELEMTYPE(array);
	memcpy(ARR_DIMS(newarray), dim, ndim * sizeof(int));
	memcpy(ARR_LBOUND(newarray), lb, ndim * sizeof(int));

	if (ndim > 1)
	{
		/*
		 * here we do not need to cope with extension of the array; it
		 * would be a lot more complicated if we had to do so...
		 */
		array_insert_slice(ndim, dim, lb, ARR_DATA_PTR(array), olddatasize,
						   ARR_DATA_PTR(newarray),
						   lowerIndx, upperIndx, ARR_DATA_PTR(srcArray),
						   elmlen, elmbyval, elmalign);
	}
	else
	{
		memcpy((char *) newarray + overheadlen,
			   (char *) array + overheadlen,
			   lenbefore);
		memcpy((char *) newarray + overheadlen + lenbefore,
			   ARR_DATA_PTR(srcArray),
			   newitemsize);
		memcpy((char *) newarray + overheadlen + lenbefore + newitemsize,
			   (char *) array + overheadlen + lenbefore + olditemsize,
			   lenafter);
	}

	return newarray;
}

/*
 * array_map()
 *
 * Map an array through an arbitrary function.	Return a new array with
 * same dimensions and each source element transformed by fn().  Each
 * source element is passed as the first argument to fn(); additional
 * arguments to be passed to fn() can be specified by the caller.
 * The output array can have a different element type than the input.
 *
 * Parameters are:
 * * fcinfo: a function-call data structure pre-constructed by the caller
 *	 to be ready to call the desired function, with everything except the
 *	 first argument position filled in.  In particular, flinfo identifies
 *	 the function fn(), and if nargs > 1 then argument positions after the
 *	 first must be preset to the additional values to be passed.  The
 *	 first argument position initially holds the input array value.
 * * inpType: OID of element type of input array.  This must be the same as,
 *	 or binary-compatible with, the first argument type of fn().
 * * retType: OID of element type of output array.	This must be the same as,
 *	 or binary-compatible with, the result type of fn().
 *
 * NB: caller must assure that input array is not NULL.  Currently,
 * any additional parameters passed to fn() may not be specified as NULL
 * either.
 */
Datum
array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType)
{
	ArrayType  *v;
	ArrayType  *result;
	Datum	   *values;
	Datum		elt;
	int		   *dim;
	int			ndim;
	int			nitems;
	int			i;
	int			nbytes = 0;
	int			inp_typlen;
	bool		inp_typbyval;
	char		inp_typalign;
	int			typlen;
	bool		typbyval;
	char		typalign;
	char	   *s;
	typedef struct
	{
		ArrayMetaState inp_extra;
		ArrayMetaState ret_extra;
	} am_extra;
	am_extra   *my_extra;
	ArrayMetaState *inp_extra;
	ArrayMetaState *ret_extra;

	/* Get input array */
	if (fcinfo->nargs < 1)
		elog(ERROR, "invalid nargs: %d", fcinfo->nargs);
	if (PG_ARGISNULL(0))
		elog(ERROR, "null input array");
	v = PG_GETARG_ARRAYTYPE_P(0);

	Assert(ARR_ELEMTYPE(v) == inpType);

	ndim = ARR_NDIM(v);
	dim = ARR_DIMS(v);
	nitems = ArrayGetNItems(ndim, dim);

	/* Check for empty array */
	if (nitems <= 0)
		PG_RETURN_ARRAYTYPE_P(v);

	/*
	 * We arrange to look up info about input and return element types
	 * only once per series of calls, assuming the element type doesn't
	 * change underneath us.
	 */
	my_extra = (am_extra *) fcinfo->flinfo->fn_extra;
	if (my_extra == NULL)
	{
		fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
													  sizeof(am_extra));
		my_extra = (am_extra *) fcinfo->flinfo->fn_extra;
		inp_extra = &my_extra->inp_extra;
		inp_extra->element_type = InvalidOid;
		ret_extra = &my_extra->ret_extra;
		ret_extra->element_type = InvalidOid;
	}
	else
	{
		inp_extra = &my_extra->inp_extra;
		ret_extra = &my_extra->ret_extra;
	}

	if (inp_extra->element_type != inpType)
	{
		get_typlenbyvalalign(inpType,
							 &inp_extra->typlen,
							 &inp_extra->typbyval,
							 &inp_extra->typalign);
		inp_extra->element_type = inpType;
	}
	inp_typlen = inp_extra->typlen;
	inp_typbyval = inp_extra->typbyval;
	inp_typalign = inp_extra->typalign;

	if (ret_extra->element_type != retType)
	{
		get_typlenbyvalalign(retType,
							 &ret_extra->typlen,
							 &ret_extra->typbyval,
							 &ret_extra->typalign);
		ret_extra->element_type = retType;
	}
	typlen = ret_extra->typlen;
	typbyval = ret_extra->typbyval;
	typalign = ret_extra->typalign;

	/* Allocate temporary array for new values */
	values = (Datum *) palloc(nitems * sizeof(Datum));

	/* Loop over source data */
	s = (char *) ARR_DATA_PTR(v);
	for (i = 0; i < nitems; i++)
	{
		/* Get source element */
		elt = fetch_att(s, inp_typbyval, inp_typlen);

		s = att_addlength(s, inp_typlen, PointerGetDatum(s));
		s = (char *) att_align(s, inp_typalign);

		/*
		 * Apply the given function to source elt and extra args.
		 *
		 * We assume the extra args are non-NULL, so need not check whether
		 * fn() is strict.	Would need to do more work here to support
		 * arrays containing nulls, too.
		 */
		fcinfo->arg[0] = elt;
		fcinfo->argnull[0] = false;
		fcinfo->isnull = false;
		values[i] = FunctionCallInvoke(fcinfo);
		if (fcinfo->isnull)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("null array elements not supported")));

		/* Ensure data is not toasted */
		if (typlen == -1)
			values[i] = PointerGetDatum(PG_DETOAST_DATUM(values[i]));

		/* Update total result size */
		nbytes = att_addlength(nbytes, typlen, values[i]);
		nbytes = att_align(nbytes, typalign);
	}

	/* Allocate and initialize the result array */
	nbytes += ARR_OVERHEAD(ndim);
	result = (ArrayType *) palloc0(nbytes);

	result->size = nbytes;
	result->ndim = ndim;
	result->elemtype = retType;
	memcpy(ARR_DIMS(result), ARR_DIMS(v), 2 * ndim * sizeof(int));

	/*
	 * Note: do not risk trying to pfree the results of the called
	 * function
	 */
	CopyArrayEls(ARR_DATA_PTR(result), values, nitems,
				 typlen, typbyval, typalign, false);
	pfree(values);

	PG_RETURN_ARRAYTYPE_P(result);
}

/*----------
 * construct_array	--- simple method for constructing an array object
 *
 * elems: array of Datum items to become the array contents
 * nelems: number of items
 * elmtype, elmlen, elmbyval, elmalign: info for the datatype of the items
 *
 * A palloc'd 1-D array object is constructed and returned.  Note that
 * elem values will be copied into the object even if pass-by-ref type.
 * NULL element values are not supported.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given the elmtype.  However, the caller is
 * in a better position to cache this info across multiple uses, or even
 * to hard-wire values if the element type is hard-wired.
 *----------
 */
ArrayType *
construct_array(Datum *elems, int nelems,
				Oid elmtype,
				int elmlen, bool elmbyval, char elmalign)
{
	int			dims[1];
	int			lbs[1];

	dims[0] = nelems;
	lbs[0] = 1;

	return construct_md_array(elems, 1, dims, lbs,
							  elmtype, elmlen, elmbyval, elmalign);
}

/*----------
 * construct_md_array	--- simple method for constructing an array object
 *							with arbitrary dimensions
 *
 * elems: array of Datum items to become the array contents
 * ndims: number of dimensions
 * dims: integer array with size of each dimension
 * lbs: integer array with lower bound of each dimension
 * elmtype, elmlen, elmbyval, elmalign: info for the datatype of the items
 *
 * A palloc'd ndims-D array object is constructed and returned.  Note that
 * elem values will be copied into the object even if pass-by-ref type.
 * NULL element values are not supported.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given the elmtype.  However, the caller is
 * in a better position to cache this info across multiple uses, or even
 * to hard-wire values if the element type is hard-wired.
 *----------
 */
ArrayType *
construct_md_array(Datum *elems,
				   int ndims,
				   int *dims,
				   int *lbs,
				   Oid elmtype, int elmlen, bool elmbyval, char elmalign)
{
	ArrayType  *result;
	int			nbytes;
	int			i;
	int			nelems;

	if (ndims < 0)				/* we do allow zero-dimension arrays */
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("invalid number of dimensions: %d", ndims)));
	if (ndims > MAXDIM)
		ereport(ERROR,
				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
				 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
						ndims, MAXDIM)));

	/* fast track for empty array */
	if (ndims == 0)
	{
		/* Allocate and initialize 0-D result array */
		nbytes = ARR_OVERHEAD(ndims);
		result = (ArrayType *) palloc(nbytes);

		result->size = nbytes;
		result->ndim = ndims;
		result->flags = 0;
		result->elemtype = elmtype;

		return result;
	}

	nelems = ArrayGetNItems(ndims, dims);

	/* compute required space */
	if (elmlen > 0)
		nbytes = nelems * att_align(elmlen, elmalign);
	else
	{
		Assert(!elmbyval);
		nbytes = 0;
		for (i = 0; i < nelems; i++)
		{
			/* make sure data is not toasted */
			if (elmlen == -1)
				elems[i] = PointerGetDatum(PG_DETOAST_DATUM(elems[i]));
			nbytes = att_addlength(nbytes, elmlen, elems[i]);
			nbytes = att_align(nbytes, elmalign);
		}
	}

	/* Allocate and initialize ndims-D result array */
	nbytes += ARR_OVERHEAD(ndims);
	result = (ArrayType *) palloc(nbytes);

	result->size = nbytes;
	result->ndim = ndims;
	result->flags = 0;
	result->elemtype = elmtype;
	memcpy((char *) ARR_DIMS(result), (char *) dims, ndims * sizeof(int));
	memcpy((char *) ARR_LBOUND(result), (char *) lbs, ndims * sizeof(int));
	CopyArrayEls(ARR_DATA_PTR(result), elems, nelems,
				 elmlen, elmbyval, elmalign, false);

	return result;
}

/*----------
 * deconstruct_array  --- simple method for extracting data from an array
 *
 * array: array object to examine (must not be NULL)
 * elmtype, elmlen, elmbyval, elmalign: info for the datatype of the items
 * elemsp: return value, set to point to palloc'd array of Datum values
 * nelemsp: return value, set to number of extracted values
 *
 * If array elements are pass-by-ref data type, the returned Datums will
 * be pointers into the array object.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given the elmtype.  However, in most current
 * uses the type is hard-wired into the caller and so we can save a lookup
 * cycle by hard-wiring the type info as well.
 *----------
 */
void
deconstruct_array(ArrayType *array,
				  Oid elmtype,
				  int elmlen, bool elmbyval, char elmalign,
				  Datum **elemsp, int *nelemsp)
{
	Datum	   *elems;
	int			nelems;
	char	   *p;
	int			i;

	Assert(ARR_ELEMTYPE(array) == elmtype);

	nelems = ArrayGetNItems(ARR_NDIM(array), ARR_DIMS(array));
	if (nelems <= 0)
	{
		*elemsp = NULL;
		*nelemsp = 0;
		return;
	}
	*elemsp = elems = (Datum *) palloc(nelems * sizeof(Datum));
	*nelemsp = nelems;

	p = ARR_DATA_PTR(array);
	for (i = 0; i < nelems; i++)
	{
		elems[i] = fetch_att(p, elmbyval, elmlen);
		p = att_addlength(p, elmlen, PointerGetDatum(p));
		p = (char *) att_align(p, elmalign);
	}
}


/*-----------------------------------------------------------------------------
 * array_eq :
 *		  compares two arrays for equality
 * result :
 *		  returns true if the arrays are equal, false otherwise.
 *
 * Note: we do not use array_cmp here, since equality may be meaningful in
 * datatypes that don't have a total ordering (and hence no btree support).
 *-----------------------------------------------------------------------------
 */
Datum
array_eq(PG_FUNCTION_ARGS)
{
	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
	char	   *p1 = (char *) ARR_DATA_PTR(array1);
	char	   *p2 = (char *) ARR_DATA_PTR(array2);
	int			ndims1 = ARR_NDIM(array1);
	int			ndims2 = ARR_NDIM(array2);
	int		   *dims1 = ARR_DIMS(array1);
	int		   *dims2 = ARR_DIMS(array2);
	int			nitems1 = ArrayGetNItems(ndims1, dims1);