dorfmt.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * 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 <stdarg.h>
#include <string.h>
#include "utf.h"
#include "fmt.h"
#include "fmtdef.h"

/* format the output into f->to and return the number of characters fmted  */

int
dorfmt(Fmt *f, const Rune *fmt)
{
	Rune *rt, *rs;
	int r;
	char *t, *s;
	int nfmt;

	nfmt = f->nfmt;
	for(;;){
		if(f->runes){
			rt = f->to;
			rs = f->stop;
			while((r = *fmt++) && r != '%'){
				FMTRCHAR(f, rt, rs, r);
			}
			f->nfmt += rt - (Rune *)f->to;
			f->to = rt;
			if(!r)
				return f->nfmt - nfmt;
			f->stop = rs;
		}else{
			t = f->to;
			s = f->stop;
			while((r = *fmt++) && r != '%'){
				FMTRUNE(f, t, f->stop, r);
			}
			f->nfmt += t - (char *)f->to;
			f->to = t;
			if(!r)
				return f->nfmt - nfmt;
			f->stop = s;
		}

		fmt = __fmtdispatch(f, fmt, 1);
		if(fmt == nil)
			return -1;
	}
	return 0;		/* not reached */
}