implement Comm; # Copyright © 2002 Lucent Technologies Inc.# Subject to the Lucent Public Licence 1.02# Limbo translation by Vita Nuova 2004; bug fixed. include "sys.m";	sys: Sys; include "draw.m"; include "bufio.m";	bufio: Bufio;	Iobuf: import bufio; include "arg.m"; Comm: module{	init: fn(nil: ref Draw->Context, args: list of string);}; One, Two, Three: con 1<<iota;cols := One|Two|Three;ldr := array[3] of {"", "\t", "\t\t"}; init(nil: ref Draw->Context, args: list of string){	sys = load Sys Sys->PATH;	bufio = load Bufio Bufio->PATH; 	arg := load Arg Arg->PATH;	arg->init(args);	arg->setusage("comm [-123] file1 file2");	while((c := arg->opt()) != 0){		case c {		'1' to '3' =>			cols &= ~(1 << (c-'1'));		* =>			arg->usage();		}	}	args = arg->argv();	if(len args != 2)		arg->usage();	arg = nil; 	if((cols & One) == 0){		ldr[1] = "";		ldr[2] = ldr[2][1:];	}	if((cols & Two) == 0)		ldr[2] = ldr[2][1:]; 	ib1 := openfil(hd args);	ib2 := openfil(hd tl args);	if((lb1 := ib1.gets('\n')) == nil){		if((lb2 := ib2.gets('\n')) == nil)			exit;		copy(ib2, lb2, 2);	}	if((lb2 := ib2.gets('\n')) == nil)		copy(ib1, lb1, 1);	for(;;)		case compare(lb1, lb2) {		0 =>			wr(lb1, 3);			if((lb1 = ib1.gets('\n')) == nil){				if((lb2 = ib2.gets('\n')) == nil)					exit;				copy(ib2, lb2, 2);			}			if((lb2 = ib2.gets('\n')) == nil)				copy(ib1, lb1, 1);		1 =>			wr(lb1, 1);			if((lb1 = ib1.gets('\n')) == nil)				copy(ib2, lb2, 2);		2 =>			wr(lb2, 2);			if((lb2 = ib2.gets('\n')) == nil)				copy(ib1, lb1, 1);		}} wr(str: string, n: int){	if(cols & (1<<(n-1)))		sys->print("%s%s", ldr[n-1], str);} copy(ibuf: ref Iobuf, lbuf: string, n: int){	do		wr(lbuf, n);	while((lbuf = ibuf.gets('\n')) != nil);	exit;} compare(a: string, b: string): int{	for(i := 0; i < len a; i++){		if(i >= len b || a[i] < b[i])			return 1;		if(a[i] != b[i])			return 2;	}	if(i == len b)		return 0;	return 2;} openfil(s: string): ref Iobuf{	if(s == "-")		b := bufio->fopen(sys->fildes(0), Bufio->OREAD);	else		b = bufio->open(s, Bufio->OREAD);	if(b != nil)		return b;	sys->fprint(sys->fildes(2), "comm: cannot open %s: %r\n", s);	raise "fail:open";}