implement Tr; include "sys.m";	sys: Sys; include "draw.m"; include "bufio.m";	bufio: Bufio;	Iobuf: import bufio; include "arg.m";	arg: Arg; Tr: module{	init:	fn(nil: ref Draw->Context, nil: list of string);}; Pcb: adt {	# Control block controlling specification parse	spec: string;	# specification string	end:	int;	# its length	current:	int;	# current parse point	last:	int;	# last Rune returned	final:	int;	# final Rune in a span 	new:	fn(nil: string): ref Pcb;	rewind:	fn(nil: self ref Pcb);	getc:	fn(nil: self ref Pcb): int;	canon:	fn(nil: self ref Pcb): int;}; bits := array [] of { byte 1, byte 2, byte 4, byte 8, byte 16, byte 32, byte 64, byte 128 }; SETBIT(a: array of byte, c: int){	a[c>>3] |= bits[c & 7];} CLEARBIT(a: array of byte, c: int){	a[c>>3] &= ~bits[c & 7];} BITSET(a: array of byte, c: int): int{	return int (a[c>>3] & bits[c&7]);} MAXRUNE: con 16rFFFF; f := array[(MAXRUNE+1)/8] of byte;t := array[(MAXRUNE+1)/8] of byte; pto, pfrom: ref Pcb; cflag := 0;dflag := 0;sflag := 0;stderr: ref Sys->FD; ib: ref Iobuf;ob: ref Iobuf; usage(){	sys->fprint(stderr, "Usage: tr [-sdc] [from-set [to-set]]\n");	raise "fail: usage";} init(nil: ref Draw->Context, args: list of string){	sys = load Sys Sys->PATH;	stderr = sys->fildes(2);	bufio = load Bufio Bufio->PATH;	arg = load Arg Arg->PATH;	arg->init(args);	while((c := arg->opt()) != 0)		case c {		's' => sflag = 1;		'd' => dflag = 1;		'c' => cflag = 1;		* => usage();	}	args = arg->argv();	argc := len args;	if(args != nil){		pfrom = Pcb.new(hd args);		args = tl args;	}	if(args != nil){		pto = Pcb.new(hd args);		args = tl args;	}	if(args != nil)		usage();	ib = bufio->fopen(sys->fildes(0), Bufio->OREAD);	ob = bufio->fopen(sys->fildes(1), Bufio->OWRITE);	if(dflag) {		if(sflag && argc != 2 || !sflag && argc != 1)			usage();		delete();	} else {		if(argc != 2)			usage();		if(cflag)			complement();		else			translit();	}	if(ob.flush() == Bufio->ERROR)		error(sys->sprint("write error: %r"));} delete(){	if (cflag) {		for(i := 0; i < len f; i++)			f[i] = byte 16rFF;		while ((c := pfrom.canon()) >= 0)			CLEARBIT(f, c);	} else {		while ((c := pfrom.canon()) >= 0)			SETBIT(f, c);	}	if (sflag) {		while ((c := pto.canon()) >= 0)			SETBIT(t, c);	} 	last := MAXRUNE+1;	while ((c := ib.getc()) >= 0) {		if(!BITSET(f, c) && (c != last || !BITSET(t,c))) {			last = c;			ob.putc(c);		}	}} complement(){	lastc := 0;	high := 0;	while ((from := pfrom.canon()) >= 0) {		if (from > high)			high = from;		SETBIT(f, from);	}	while ((cto := pto.canon()) >= 0) {		if (cto > high)			high = cto;		SETBIT(t,cto);	}	pto.rewind();	p := array[high+1] of int;	for (i := 0; i <= high; i++){		if (!BITSET(f,i)) {			if ((cto = pto.canon()) < 0)				cto = lastc;			else				lastc = cto;			p[i] = cto;		} else			p[i] = i;	}	if (sflag){		lastc = MAXRUNE+1;		while ((from = ib.getc()) >= 0) {			if (from > high)				from = cto;			else				from = p[from];			if (from != lastc || !BITSET(t,from)) {				lastc = from;				ob.putc(from);			}		}	} else {		while ((from = ib.getc()) >= 0){			if (from > high)				from = cto;			else				from = p[from];			ob.putc(from);		}	}} translit(){	lastc := 0;	high := 0;	while ((from := pfrom.canon()) >= 0)		if (from > high)			high = from;	pfrom.rewind();	p := array[high+1] of int;	for (i := 0; i <= high; i++)		p[i] = i;	while ((from = pfrom.canon()) >= 0) {		if ((cto := pto.canon()) < 0)			cto = lastc;		else			lastc = cto;		if (BITSET(f,from) && p[from] != cto)			error("ambiguous translation");		SETBIT(f,from);		p[from] = cto;		SETBIT(t,cto);	}	while ((cto := pto.canon()) >= 0)		SETBIT(t,cto);	if (sflag){		lastc = MAXRUNE+1;		while ((from = ib.getc()) >= 0) {			if (from <= high)				from = p[from];			if (from != lastc || !BITSET(t,from)) {				lastc = from;				ob.putc(from);			}		}					} else {		while ((from = ib.getc()) >= 0) {			if (from <= high)				from = p[from];			ob.putc(from);		}	}} Pcb.new(s: string): ref Pcb{	return ref Pcb(s, len s, 0, -1, -1);} Pcb.rewind(p: self ref Pcb){	p.current = 0;	p.last = p.final = -1;} Pcb.getc(p: self ref Pcb): int{	if(p.current >= p.end)		return -1;	s := p.current;	r := p.spec[s++];	if(r == '\\' && s < p.end){		n := 0;		if ((r = p.spec[s]) == 'x') {			s++;			for (i := 0; i < 4 && s < p.end; i++) {				p.current = s;				r = p.spec[s++];				if ('0' <= r && r <= '9')					n = 16*n + r - '0';				else if ('a' <= r && r <= 'f')					n = 16*n + r - 'a' + 10;				else if ('A' <= r && r <= 'F')					n = 16*n + r - 'A' + 10;				else {					if (i == 0)						return 'x';					return n;				}			}			r = n;		} else {			for(i := 0; i < 3 && s < p.end; i++) {				p.current = s;				r = p.spec[s++];				if('0' <= r && r <= '7')					n = 8*n + r - '0';				else {					if (i == 0)						return r;					return n;				}			}			if(n > 0377)				error("char>0377");			r = n;		}	}	p.current = s;	return r;} Pcb.canon(p: self ref Pcb): int{	if (p.final >= 0) {		if (p.last < p.final)			return ++p.last;		p.final = -1;	}	if (p.current >= p.end)		return -1;	if(p.spec[p.current] == '-' && p.last >= 0 && p.current+1 < p.end){		p.current++;		r := p.getc();		if (r < p.last)			error ("Invalid range specification");		if (r > p.last) {			p.final = r;			return ++p.last;		}	}	r := p.getc();	p.last = r;	return p.last;} error(s: string){	sys->fprint(stderr, "tr: %s\n", s);	raise "fail: error";}