implement Convcs; include "sys.m";include "cfg.m";include "convcs.m"; DEFCSFILE : con "/lib/convcs/charsets"; sys : Sys;cfg : Cfg; Record, Tuple : import cfg; init(csfile : string) : string{	sys = load Sys Sys->PATH;	cfg = load Cfg Cfg->PATH;	if (cfg == nil)		return sys->sprint("cannot load module %s: %r", Cfg->PATH);	if (csfile == nil)		csfile = DEFCSFILE;	err := cfg->init(csfile);	if (err != nil) {		cfg = nil;		return err;	}	return nil;} getbtos(cs : string) : (Btos, string){	cs = normalize(cs);	(rec, err) := csalias(cs);	if (err != nil)		return (nil, err); 	(path, btostup) := rec.lookup("btos");	if (path == nil)		return (nil, sys->sprint("no converter for %s", cs));	arg := btostup.lookup("arg"); 	btos := load Btos path;	if (btos == nil)		return (nil, sys->sprint("cannot load converter: %r"));	err = btos->init(arg);	if (err != nil)		return (nil, err);	return (btos, nil);} getstob(cs : string) : (Stob, string){	cs = normalize(cs);	(rec, err) := csalias(cs);	if (err != nil)		return (nil, err); 	(path, stobtup) := rec.lookup("stob");	if (path == nil)		return (nil, sys->sprint("no converter for %s", cs));	arg := stobtup.lookup("arg"); 	stob := load Stob path;	if (stob == nil)		return (nil, sys->sprint("cannot load converter: %r"));	err = stob->init(arg);	if (err != nil)		return (nil, err);	return (stob, nil);} csalias(cs : string) : (ref Cfg->Record, string){	# search out charset record - allow for one level of renaming	for (i := 0; i < 2; i++) {		recs := cfg->lookup(cs);		if (recs == nil)			return (nil, sys->sprint("unknown charset %s", cs));		(val, rec) := hd recs;		if (val != nil) {			cs = val;			continue;		}		return (rec, nil);	}	return (nil, sys->sprint("too man aliases for %s\n", cs));} enumcs() : list of (string, string, int){	d : list of (string, string, int);	for (csl := cfg->getkeys(); csl != nil; csl = tl csl) {		cs := hd csl;		recs := cfg->lookup(cs);		if (recs == nil)			continue;	# shouldn't happen!		(val, rec) := hd recs;		if (val != nil)			# an alias - ignore			continue; 		(btos, nil) := rec.lookup("btos");		(stob, nil) := rec.lookup("stob"); 		if (btos == nil && stob == nil)			continue;		mode := 0;		if (btos != nil)			mode = BTOS;		if (stob != nil)			mode |= STOB; 		(desc, nil) := rec.lookup("desc");		if (desc == nil)			desc = cs; 		d = (cs, desc, mode) :: d;	}	# d is in reverse order to that in the csfile file	l : list of (string, string, int);	for (; d != nil; d = tl d)		l = hd d :: l;	return l;} aliases(cs : string) : (string, list of string){	cs = normalize(cs);	(mainrec, err) := csalias(cs);	if (err != nil)		return (err, nil); 	cs = (hd (hd mainrec.tuples).attrs).name; 	(desc, nil) := mainrec.lookup("desc");	if (desc == nil)		desc = cs; 	al := cs :: nil;	for (csl := cfg->getkeys(); csl != nil; csl = tl csl) {		name := hd csl;		recs := cfg->lookup(name);		if (recs == nil)			continue;	# shouldn't happen!		(val, nil) := hd recs;		if (val != cs)			continue;		al = name :: al;	} 	r : list of string;	for (; al != nil; al = tl al)		r = hd al :: r;	return (desc, r);} normalize(s : string) : string{	for (i := 0; i < len s; i++) {		r := s[i];		if (r >= 'A' && r <= 'Z')			s[i] = r + ('a' - 'A');	}	return s;}