From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <cc8c2a661e86bdb12378ab71b38075aa@coraid.com>
From: erik quanstrom <quanstro@coraid.com>
Date: Thu,  8 Mar 2007 23:38:03 -0500
To: 9fans@cse.psu.edu
Subject: Re: [9fans] How can I shift a variable other than ?
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... or the deleterious effects of insomnia.

i decided to see how hard this is.  after considering "shift var", 
and hd and tl, i added ranges to rc, as in

	cpu% 8.out
	broken! a=(1 2 3 4)
	broken! echo $a(1 4)
	1 4
	broken! echo $a(2-3)
	2 3
	broken! echo $a(2-)
	2 3 4
	broken! fn myshift{echo $*; '*' = $*(2-) ; echo $*}
	broken! myshift 1 2 3 4 5
	1 2 3 4 5

less than 20 lines of code.  (attached so you can avert your eyes.)

- erik
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word*
copynwords(word *a, word *tail, int n)
{
	word *v = 0, **end;
	for(end=&v;a && n-- != 0;a = a->next,end=&(*end)->next)
		*end = newword(a->word, 0);
	*end = tail;
	return v;
}

word*
subwords(word *val, int len, word *sub, word *a)
{
	int n, m;
	char *s;
	if(!sub)
		return a;
	s = sub->word;
	deglob(s);
	a = subwords(val, len, sub->next, a);
	n = 0; m = 0;
	while('0'<=*s && *s<='9') n = n*10+ *s++ -'0';
	if(*s++ == '-'){
		if(*s)	while('0'<=*s && *s<='9') m = m*10+ *s++ -'0';
		else	m = len;
		m -= n;
	}
	if(n<1 || len<n)
		return a;
	while(--n) val = val->next;
	return copynwords(val, a, m+1);
}
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