arrayfuncs.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

							 elmlen, elmbyval, elmalign);
		lenbefore = (int) (elt_ptr - ARR_DATA_PTR(array));
		olditemlen = att_addlength(0, elmlen, PointerGetDatum(elt_ptr));
		olditemlen = att_align(olditemlen, elmalign);
		lenafter = (int) (olddatasize - lenbefore - olditemlen);
	}

	newitemlen = att_addlength(0, elmlen, dataValue);
	newitemlen = att_align(newitemlen, elmalign);

	newsize = overheadlen + lenbefore + newitemlen + lenafter;

	/*
	 * OK, do the assignment
	 */
	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));
	memcpy((char *) newarray + overheadlen,
		   (char *) array + overheadlen,
		   lenbefore);
	memcpy((char *) newarray + overheadlen + lenbefore + newitemlen,
		   (char *) array + overheadlen + lenbefore + olditemlen,
		   lenafter);

	ArrayCastAndSet(dataValue, elmlen, elmbyval, elmalign,
					(char *) newarray + overheadlen + lenbefore);

	return newarray;
}

/*----------------------------------------------------------------------------
 * array_set_slice :
 *		  This routine sets the value of a range of array locations (specified
 *		  by upper and lower index values ) to new values passed as
 *		  another array
 * result :
 *		  A new array is returned, just like the old except for the
 *		  modified range.
 *
 * NOTE: we assume it is OK to scribble on the provided index arrays
 * lowerIndx[] and upperIndx[].  These are generally just temporaries.
 *
 * NOTE: For assignments, we throw an error for silly subscripts etc,
 * rather than returning a NULL as the fetch operations do.  The reasoning
 * is that returning a NULL would cause the user's whole array to be replaced
 * with NULL, which will probably not make him happy.
 *----------------------------------------------------------------------------
 */
ArrayType *
array_set_slice(ArrayType *array,
				int nSubscripts,
				int *upperIndx,
				int *lowerIndx,
				ArrayType *srcArray,
				int arraylen,
				int elmlen,
				bool elmbyval,
				char elmalign,
				bool *isNull)
{
	int			i,
				ndim,
				dim[MAXDIM],
				lb[MAXDIM],
				span[MAXDIM];
	ArrayType  *newarray;
	int			nsrcitems,
				olddatasize,
				newsize,
				olditemsize,
				newitemsize,
				overheadlen,
				lenbefore,
				lenafter;

	if (array == NULL)
		RETURN_NULL(ArrayType *);
	if (srcArray == NULL)
		return array;

	if (arraylen > 0)
	{
		/*
		 * fixed-length arrays -- not got round to doing this...
		 */
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
		errmsg("updates on slices of fixed-length arrays not implemented")));
	}

	/* detoast arrays if necessary */
	array = DatumGetArrayTypeP(PointerGetDatum(array));
	srcArray = DatumGetArrayTypeP(PointerGetDatum(srcArray));

	/* note: we assume srcArray contains no toasted elements */

	ndim = ARR_NDIM(array);

	/*
	 * if number of dims is zero, i.e. an empty array, create an array with
	 * nSubscripts dimensions, and set the upper and lower bounds to the
	 * supplied subscripts
	 */
	if (ndim == 0)
	{
		Datum	   *dvalues;
		int			nelems;
		Oid			elmtype = ARR_ELEMTYPE(array);

		deconstruct_array(srcArray, elmtype, elmlen, elmbyval, elmalign,
						  &dvalues, &nelems);

		for (i = 0; i < nSubscripts; i++)
		{
			dim[i] = 1 + upperIndx[i] - lowerIndx[i];
			lb[i] = lowerIndx[i];
		}

		/* complain if too few source items; we ignore extras, however */
		if (nelems < ArrayGetNItems(nSubscripts, dim))
			ereport(ERROR,
					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
					 errmsg("source array too small")));

		return construct_md_array(dvalues, nSubscripts, dim, lb, elmtype,
								  elmlen, elmbyval, elmalign);
	}

	if (ndim < nSubscripts || ndim <= 0 || ndim > MAXDIM)
		ereport(ERROR,
				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
				 errmsg("invalid array subscripts")));

	/* copy dim/lb since we may modify them */
	memcpy(dim, ARR_DIMS(array), ndim * sizeof(int));
	memcpy(lb, ARR_LBOUND(array), ndim * sizeof(int));

	/*
	 * Check provided subscripts.  A slice exceeding the current array limits
	 * throws an error, *except* in the 1-D case where we will extend the
	 * array as long as no hole is created. An empty slice is an error, too.
	 */
	for (i = 0; i < nSubscripts; i++)
	{
		if (lowerIndx[i] > upperIndx[i])
			ereport(ERROR,
					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
					 errmsg("invalid array subscripts")));
		if (lowerIndx[i] < lb[i])
		{
			if (ndim == 1 && upperIndx[i] >= lb[i] - 1)
			{
				dim[i] += lb[i] - lowerIndx[i];
				lb[i] = lowerIndx[i];
			}
			else
				ereport(ERROR,
						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
						 errmsg("invalid array subscripts")));
		}
		if (upperIndx[i] >= (dim[i] + lb[i]))
		{
			if (ndim == 1 && lowerIndx[i] <= (dim[i] + lb[i]))
				dim[i] = upperIndx[i] - lb[i] + 1;
			else
				ereport(ERROR,
						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
						 errmsg("invalid array subscripts")));
		}
	}
	/* 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().
 * * amstate: workspace for array_map.	Must be zeroed by caller before
 *	 first call, and not touched after that.
 *
 * It is legitimate to pass a freshly-zeroed ArrayMapState on each call,
 * but better performance can be had if the state can be preserved across
 * a series of calls.
 *
 * 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,
		  ArrayMapState *amstate)
{
	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;
	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)
	{
		/* Return empty array */
		result = (ArrayType *) palloc0(sizeof(ArrayType));
		result->size = sizeof(ArrayType);
		result->elemtype = retType;
		PG_RETURN_ARRAYTYPE_P(result);
	}

	/*
	 * 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.
	 */
	inp_extra = &amstate->inp_extra;
	ret_extra = &amstate->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, lb