+
−/*
+
− * The contents of this file are subject to the MonetDB Public License
+
− * Version 1.1 (the "License"); you may not use this file except in
+
− * compliance with the License. You may obtain a copy of the License at
+
− * http://www.monetdb.org/Legal/MonetDBLicense
+
− *
+
− * Software distributed under the License is distributed on an "AS IS"
+
− * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
+
− * License for the specific language governing rights and limitations
+
− * under the License.
+
− *
+
− * The Original Code is the MonetDB Database System.
+
− *
+
− * The Initial Developer of the Original Code is CWI.
+
− * Portions created by CWI are Copyright (C) 1997-July 2008 CWI.
+
− * Copyright August 2008-2013 MonetDB B.V.
+
− * All Rights Reserved.
+
− */
+
−
+
−/* monetdb_config.h must be included as the first include file */
+
−#include <monetdb_config.h>
+
−/* mal_exception.h actually contains everything we need */
+
−#include <mal_exception.h>
+
−
+
−/* system include files */
+
−#include <string.h>
+
−
+
−/* dst is a buffer of length larger than len, src is a UTF-8-encoded
+
− * string of length exactly len bytes */
+
−static void
+
−do_reverse(char *dst, const char *src, size_t len)
+
−{
+
−	dst[len] = 0;
+
−	if (strcmp(src, str_nil) == 0) {
+
−		/* special case for nil */
+
−		strcpy(dst, str_nil);
+
−		assert(len == strlen(str_nil));
+
−		return;
+
−	}
+
−	while (*src) {
+
−		if ((*src & 0xF8) == 0xF0) {
+
−			/* 4 byte UTF-8 sequence */
+
−			assert(len >= 4);
+
−			dst[len - 4] = *src++;
+
−			assert((*src & 0xC0) == 0x80);
+
−			dst[len - 3] = *src++;
+
−			assert((*src & 0xC0) == 0x80);
+
−			dst[len - 2] = *src++;
+
−			assert((*src & 0xC0) == 0x80);
+
−			dst[len - 1] = *src++;
+
−			len -= 4;
+
−		} else if ((*src & 0xF0) == 0xE0) {
+
−			/* 3 byte UTF-8 sequence */
+
−			assert(len >= 3);
+
−			dst[len - 3] = *src++;
+
−			assert((*src & 0xC0) == 0x80);
+
−			dst[len - 2] = *src++;
+
−			assert((*src & 0xC0) == 0x80);
+
−			dst[len - 1] = *src++;
+
−			len -= 3;
+
−		} else if ((*src & 0xE0) == 0xC0) {
+
−			/* 2 byte UTF-8 sequence */
+
−			assert(len >= 2);
+
−			dst[len - 2] = *src++;
+
−			assert((*src & 0xC0) == 0x80);
+
−			dst[len - 1] = *src++;
+
−			len -= 2;
+
−		} else {
+
−			assert(len >= 1);
+
−			assert((*src & 0x80) == 0);
+
−			dst[--len] = *src++;
+
−		}
+
−	}
+
−	assert(len == 0);
+
−}
+
−
+
−/* __declspec() must be used on Windows, but not on other systems */
+
−#ifndef _MSC_VER
+
−/* not Windows */
+
−#define __declspec(x)	/* nothing */
+
−#endif
+
−
+
−extern __declspec(dllexport) char *UDFreverse(char **retval, const char **arg);
+
−extern __declspec(dllexport) char *UDFBATreverse(bat *retval, const bat *arg);
+
−
+
−char *
+
−UDFreverse(char **retval, const char **arg)
+
−{
+
−	size_t len;
+
−
+
−	len = strlen(*arg);
+
−	*retval = GDKmalloc(len + 1);
+
−	if (*retval == NULL)
+
−		throw(MAL, "reverse.reverse", MAL_MALLOC_FAIL);
+
−
+
−	do_reverse(*retval, *arg, len);
+
−
+
−	return MAL_SUCCEED;
+
−
+
−}
+
−
+
−char *
+
−UDFBATreverse(bat *retval, const bat *arg)
+
−{
+
−	BAT *b, *bn;
+
−	BATiter bi;
+
−	BUN p, q;
+
−	const char *src;
+
−	size_t len;
+
−	char *dst;
+
−	size_t dstlen;
+
−
+
−	/* allocate temporary space for reversed strings; we grow this
+
−	 * if we need more */
+
−	dstlen = 1024;
+
−	dst = GDKmalloc(dstlen);
+
−	if (dst == NULL)
+
−		throw(MAL, "batreverse.reverse", MAL_MALLOC_FAIL);
+
−
+
−	b = BATdescriptor(*arg);
+
−	if (b == NULL)
+
−		throw(MAL, "batreverse.reverse", RUNTIME_OBJECT_MISSING);
+
−
+
−	/* we should only get called for string BATs */
+
−	assert(b->ttype == TYPE_str);
+
−
+
−	/* allocate result BAT */
+
−	bn = BATnew(TYPE_void, TYPE_str, BATcount(b));
+
−	if (bn == NULL) {
+
−		BBPreleaseref(b->batCacheid);
+
−		throw(MAL, "batreverse.reverse", MAL_MALLOC_FAIL);
+
−	}
+
−
+
−	/* copy seqbase from old to new */
+
−	BATseqbase(bn, b->hseqbase);
+
−
+
−	/* loop through BAT b; p is index of the entry we're working
+
−	 * on, q is used internally by BATloop to do the iterating */
+
−	bi = bat_iterator(b);
+
−	BATloop(b, p, q) {
+
−		src = (const char *) BUNtail(bi, p);
+
−		len = strlen(src);
+
−		/* make sure dst is large enough */
+
−		if (len >= dstlen) {
+
−			char *ndst;
+
−
+
−			dstlen = len + 1024;
+
−			ndst = GDKrealloc(dst, dstlen);
+
−			if (ndst == NULL) {
+
−				/* if GDKrealloc fails, dst is still
+
−				 * allocated */
+
−				goto bailout;
+
−			}
+
−			dst = ndst;
+
−		}
+
−		do_reverse(dst, src, len);
+
−		if (BUNappend(bn, dst, 0) == NULL) {
+
−			/* BUNappend can fail since it may have to
+
−			 * grow memory areas--especially true for
+
−			 * string BATs */
+
−			goto bailout;
+
−		}
+
−	}
+
−	GDKfree(dst);
+
−
+
−	BBPreleaseref(b->batCacheid);
+
−
+
−	*retval = bn->batCacheid;
+
−	BBPkeepref(bn->batCacheid);
+
−
+
−	return MAL_SUCCEED;
+
−
+
−  bailout:
+
−	/* we only get here in the case of an allocation error; clean
+
−	 * up the mess we've created and throw an exception */
+
−	GDKfree(dst);
+
−	BBPreleaseref(b->batCacheid);
+
−	BBPreleaseref(bn->batCacheid);
+
−	throw(MAL, "batreverse.reverse", MAL_MALLOC_FAIL);
+
−}