implement Arg; ## Copyright © 1997 Roger Peppe# include "sys.m";include "arg.m"; name:= "";args: list of string;usagemsg:="";printusage := 1; curropt: string; init(argv: list of string){	(curropt, args, name) = (nil, nil, nil);	if (argv == nil)		return;	name = hd argv;	args = tl argv;} setusage(u: string){	usagemsg = u;	printusage = u != nil;} progname(): string{	return name;} # don't allow any more options after this function is invokedargv(): list of string{	ret := args;	args = nil;	return ret;} earg(): string{	if (curropt != nil) {		ret := curropt;		curropt = nil;		return ret;	} 	if (args == nil)		usage(); 	ret := hd args;	args = tl args;	return ret;} # get next option argumentarg(): string{	if (curropt != nil) {		ret := curropt;		curropt = nil;		return ret;	} 	if (args == nil)		return nil; 	ret := hd args;	args = tl args;	return ret;} # get next option letter# return 0 at end of optionsopt(): int{	if (curropt != nil) {		opt := curropt[0];		curropt = curropt[1:];		return opt;	} 	if (args == nil)		return 0; 	nextarg := hd args;	if (len nextarg < 2 || nextarg[0] != '-')		return 0; 	if (nextarg == "--") {		args = tl args;		return 0;	} 	opt := nextarg[1];	if (len nextarg > 2)		curropt = nextarg[2:];	args = tl args;	return opt;} usage(){	if(printusage){		if(usagemsg != nil)			u := "usage: "+usagemsg;		else			u = name + ": argument expected";		sys := load Sys Sys->PATH;		sys->fprint(sys->fildes(2), "%s\n", u);	}	raise "fail:usage";}