%%% General Purpose Routines for Manipulating Linked-Lists
%%% Copyright (C) 1998 Stanley J. Brooks

typedef struct { n,p,l,v } LLP_Type; % next, prev, list , element
typedef struct { f,ct } LL_Type;     % first element, count of elements

define make_list()
{
	variable list = @LL_Type;
	list.f = NULL;
	list.ct = 0;
	return list;
}

define s_putlast(ls,v)
{
	variable el = @LLP_Type;
	el.l = ls;
	el.v = v;
	ls.ct++;
	if (ls.f == NULL) {
		ls.f = el;
		el.p = el;
		el.n = el;
		return el;
	}
	variable el0 = ls.f;
	variable ell = el0.p;
	el.p = el0.p;
	el.n = el0;
	el0.p = el;
	ell.n = el;
	return el;
}

define s_put1st(ls,v)
{
	ls.f = s_putlast(ls,v);
	return ls.f;
}

define s_del(el)
{
	if (el == NULL) return;
	variable ls = el.l;
	ls.ct--;
	!if (ls.ct) {
		ls.f = NULL;
		return;
	}
	variable el1 = el.p;
	variable el2 = el.n;
	el1.n = el2;
	el2.p = el1;
	if (ls.f == el)
		ls.f = el2;
}

define s_put(p,wher,v)
{
	!if(wher) {
		p.v = v;
		return p;
	}
	variable ls = p.l;
	variable el = @LLP_Type;
	el.l = ls;
	el.v = v;
	ls.ct++;
	variable el1,el2;
	if (wher > 0) {
		el1 = p;
		el2 = p.n;
	}else{
		el1 = p.p;
		el2 = p;
	}
	variable el0 = ls.f;
	el.n = el2;
	el.p = el1;
	el2.p = el;
	el1.n = el;
	
	if (wher < 0)
		if (p == ls.f)
			ls.f = el;
	return el;
}

define s_move(tgt,wher,el)
{
	if (el != tgt) {
		s_del(el);
		el = s_put(tgt,wher,el.v);
	}
	return el;
}

define s_ord(el)
{
	variable ls = el.l;
	variable el0 = ls.f, elx, i = 0;
	for (elx = el0; elx != el; ) {
		i++;
		elx = elx.n;
		if (elx == el0) return -1;
	}
	return i;
}

define s_nth(ls,n)
{
	variable elx;
	elx = ls.f;
	if (n < 0) n += ls.ct;
	if (mul2(n) > ls.ct) {
		if (n >= ls.ct) return NULL;
		loop (ls.ct - n) elx = elx.p;
	}else{
		if (n < 0) return NULL;
		loop (n) elx = elx.n;
	}
	return elx;
}	

define s_dofunc(ls,func)
{
	if (ls.f == NULL) return;

	variable el0,el,i = 0;
	el0 = ls.f;
	el = el0;
	do {
		@func(el,i);
		i++; el = el.n;
	}while (el != el0);
}

define s_find_n(p,func)
{
	if (p == NULL) return NULL;
	variable ls = p.l;
	variable el0,el;
	el0 = ls.f;
	el = p;
	do {
		!if (@func(el.v)) return el;
		el = el.n;
	}while (el != el0);
	return NULL;
}

define s_find_p(p,func)
{
	if (p == NULL) return NULL;
	variable ls = p.l;
	variable el0,el;
	el0 = ls.f;
	el = p;
	do {
		!if (@func(el.v)) return el;
		el = el.p;
	}while (el != el0);
	return NULL;
}

% this should be jazzed up to take variable number of pm's
define s_find_n1(p,func,pm2)
{
	if (p == NULL) return NULL;
	variable ls = p.l;
	variable el0,el;
	el0 = ls.f;
	el = p;
	do {
		if (@func(el.v,pm2)) return el;
		el = el.n;
	}while (el != el0);
	return NULL;
}

define s_pr1(el,i)
{
	vmessage("[%3d] %s",i,el.v);
}

define s_print(ls)
{
	variable el0,el,i = 0;
	vmessage("List has %d elements",ls.ct);
	s_dofunc(ls,&s_pr1);
	message("List END -----------");
}

define NC0_cmp(v,s) { return streq_i(v.nick,s);}
define NC0_cmp_p(v,pfx) { return is_prefix_i(v.nick,pfx); }