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/*
* sf-chkid.cc: Part of GNU CSSC.
*
*
* Copyright (C) 1997,1998, Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
*
* CSSC was originally Based on MySC, by Ross Ridge, which was
* placed in the Public Domain.
*
*
*/
#include "cssc.h"
#include "sccsfile.h"
#include "linebuf.h"
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef CONFIG_SCCS_IDS
static const char rcs_id[] = "CSSC $Id: sf-chkid.cc,v 1.8 2001/09/29 19:39:41 james_youngman Exp $";
#endif
bool
is_id_keyword_letter(char ch)
{
return strchr("MIRLBSDHTEGUYFPQCZWA", ch) != NULL;
}
/* check_id_keywords():
*
* Returns true if the string contains a valid SCCS id keyword. This
* version is 8-bit-clean. We use memchr() if available. No harm
* done if it is not.
*
* memchr() is probably not a great deal faster than the while loop we
* use below, so it's not worth bothering with it inside the loop.
* However, it provides a quick way of eliminating the majority of
* cases.
*
* If we know s[2] is a % then s[1] cannot be the start of a keyword,
* because "%%%" is not a valid keyword. This optimisation probably
* isn't worth the extra opaqueness of the resulting code. It might
* even be slower. So we don't use it.
*
* We need three characters to contain an ID. subtracting two at the
* start allows us to test against (>) zero for the loop.
*/
bool
check_id_keywords(const char *s, size_t len)
{
if (len < 3)
return false; // anything shorter cannot contain an ID.
#ifdef HAVE_MEMCHR
const void *pv = memchr(s, '%', len);
if (0 == pv)
{
return false; // no %, hence no keywords.
}
else // skip forward to first percent sign.
{
const char *pc = (const char *)pv;
len -= (pc - s);
s = pc;
// Having adjusted len, we need to retest it.
if (len < 3)
return false;
}
#endif
len -= 2u;
while (len-- > 0)
{
// test the % characters first to avoid some unneccesary function calls.
if ('%' == s[0] && '%' == s[2] && is_id_keyword_letter(s[1]))
return true;
++s;
}
return false;
}
int cssc_linebuf::check_id_keywords() const
{
return ::check_id_keywords(buf, strlen(buf)); // TODO: make NUL-safe!
}
/* Local variables: */
/* mode: c++ */
/* End: */
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