root/src/lib9/utf/utfrune.c

DEFINITIONS

1. utfrune

/*
 * The authors of this software are Rob Pike and Ken Thompson.
 *              Copyright (c) 2002 by Lucent Technologies.
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <u.h>
#include <libc.h>
#include "utf.h"
#include "utfdef.h"

/* const - removed for go code */
char*
utfrune(const char *s, Rune c)
{
        long c1;
        Rune r;
        int n;

        if(c < Runesync)                /* not part of utf sequence */
                return strchr(s, (char)c);

        for(;;) {
                c1 = *(uchar*)s;
                if(c1 < Runeself) {     /* one byte rune */
                        if(c1 == 0)
                                return 0;
                        if(c1 == c)
                                return (char*)s;
                        s++;
                        continue;
                }
                n = chartorune(&r, s);
                if(r == c)
                        return (char*)s;
                s += n;
        }
}