implement Look; ##	Copyright © 2002 Lucent Technologies Inc.#	transliteration of the Plan 9 command; subject to the Lucent Public License 1.02#	-r option added by Caerwyn Jones to print a range# include "sys.m";	sys: Sys; include "draw.m"; include "bufio.m";	bufio: Bufio;	Iobuf: import bufio; include "arg.m"; Look: module{	init: fn(nil: ref Draw->Context, nil: list of string);}; filename := "/lib/words";dfile: ref Iobuf;bout: ref Iobuf;debug := 0;fold, direc, exact, iflag, range: int;rev := 1;	# -1 for reverse-ordered file, not implementedcompare: ref fn(a, b: string): int;tab := '\t';entry: string;word: string;key: string;latin_fold_tab := array[64] of {	# 	Table to fold latin 1 characters to ASCII equivalents	# 	based at Rune value 0xc0	# 	#	 À    Á    Â    Ã    Ä    Å    Æ    Ç	#	 È    É    Ê    Ë    Ì    Í    Î    Ï	#	 Ð    Ñ    Ò    Ó    Ô    Õ    Ö    ×	#	 Ø    Ù    Ú    Û    Ü    Ý    Þ    ß	#	 à    á    â    ã    ä    å    æ    ç	#	 è    é    ê    ë    ì    í    î    ï	#	 ð    ñ    ò    ó    ô    õ    ö    ÷	#	 ø    ù    ú    û    ü    ý    þ    ÿ	# 	'a',	'a',	'a',	'a',	'a',	'a',	'a',	'c',		'e',	'e',	'e',	'e',	'i',	'i',	'i',	'i',	'd',	'n',	'o',	'o',	'o',	'o',	'o',	0,	'o',	'u',	'u',	'u',	'u',	'y',	0,	0,	'a',	'a',	'a',	'a',	'a',	'a',	'a',	'c',	'e',	'e',	'e',	'e',	'i',	'i',	'i',	'i',	'd',	'n',	'o',	'o',	'o',	'o',	'o',	0,	'o',	'u',	'u',	'u',	'u',	'y',	0,	'y',}; init(nil: ref Draw->Context, args: list of string){	sys = load Sys Sys->PATH;	bufio = load Bufio Bufio->PATH;	arg := load Arg Arg->PATH; 	lastkey: string; 	arg->init(args);	arg->setusage("look -[dfinx] [-r lastkey] [-t c] [string] [file]");	compare = acomp;	while((c := arg->opt()) != 0)		case c {		'D' =>			debug = 1;		'd' =>			direc++;		'f' =>			fold++;		'i' =>			iflag++;		'n' =>			compare = ncomp;		't' =>			tab = (arg->earg())[0];		'x' =>			exact++;		'r' =>			range++;			lastkey = rcanon(arg->earg());		* =>			arg->usage();		}	args = arg->argv();	arg = nil; 	bin := bufio->fopen(sys->fildes(0), Sys->OREAD); 	bout = bufio->fopen(sys->fildes(1), Sys->OWRITE);	orig: string;	if(!iflag){		if(args != nil){			orig = hd args;			args = tl args;		}else			iflag++;	}	if(args == nil){		direc++;		fold++;	}else		filename = hd args;	if(!iflag)		key = rcanon(orig);	if(debug)		sys->fprint(sys->fildes(2), "orig %s key %s %s\n", orig, key, filename);	dfile = bufio->open(filename, Sys->OREAD);	if(dfile == nil){		sys->fprint(sys->fildes(2), "look: can't open %s\n", filename);		raise "fail:no dictionary";	}	if(!iflag) 		if(!locate() && !range)			raise "fail:not found";	do{		if(iflag){			bout.flush();			if((orig = bin.gets('\n')) == nil)				exit;			key = rcanon(orig);			if(!locate())				continue;		}		if(range){			if(compare(key, word) <= 0 && compare(word, lastkey) <= 0)				bout.puts(entry);		}else if(!exact || acomp(word, orig) == 0)			bout.puts(entry);	Matches:		while((entry = dfile.gets('\n')) != nil){			word = rcanon(entry);			if(range)				n := compare(word, lastkey);			else				n = compare(key, word);			if(debug)				sys->print("compare %d %q\n", n, word);			case n {			-2 =>				if(!range)					break Matches;				bout.puts(entry);			-1 =>				if(exact)					break Matches;				bout.puts(entry);			0 =>				if(!exact || acomp(word, orig) == 0)					bout.puts(entry);			* =>				break Matches;			}		}	}while(iflag);	bout.flush();} locate(): int{	bot := big 0;	top := dfile.seek(big 0, 2);	mid: big;Search:	for(;;){		mid = (top+bot)/big 2;		if(debug)			sys->fprint(sys->fildes(2), "locate %bd %bd %bd\n", top, mid, bot);		dfile.seek(mid, 0);		c: int;		do			c = dfile.getc();		while(c >= 0 && c != '\n');		mid = dfile.offset();		if((entry = dfile.gets('\n')) == nil)			break;		word = rcanon(entry);		if(debug)			sys->fprint(sys->fildes(2), "mid %bd key: %s entry: %s\n", mid, key, word);		n := compare(key, word);		if(debug)			sys->fprint(sys->fildes(2), "compare: %d\n", n);		case n {		-2 or -1 or 0 =>			if(top <= mid)				break Search;			top = mid;		1 or 2 =>			bot = mid;		}	}	if(debug)		sys->fprint(sys->fildes(2), "locate %bd %bd %bd\n", top, mid, bot);	bot = dfile.seek(big bot, 0);	while((entry = dfile.gets('\n')) != nil){		word = rcanon(entry);		if(debug)			sys->fprint(sys->fildes(2), "seekbot %bd key: %s entry: %s\n", bot, key, word);		n := compare(key, word);		if(debug)			sys->fprint(sys->fildes(2), "compare: %d\n", n);		case n {		-2 =>			return 0;		-1 =>			return !exact;		0 =>			return 1;		1 or 2 =>			;		}	}	return 0;} ##	acomp(s, t) returns:#		-2 if s strictly precedes t#		-1 if s is a prefix of t#		0 if s is the same as t#		1 if t is a prefix of s#		2 if t strictly precedes s#  acomp(s, t: string): int{	if(s == t)		return 0;	l := len s;	if(l > len t)		l = len t;	cs, ct: int;	for(i := 0; i < l; i++) {		cs = s[i];		ct = t[i];		if(cs != ct)			break;	}	if(i == len s)		return -1;	if(i == len t)		return 1;	if(cs < ct)		return -2;	return 2;} rcanon(s: string): string{	if(s != nil && s[len s - 1] == '\n')		s = s[0: len s - 1];	o := 0;	for(i := 0; i < len s && (r := s[i]) != tab; i++){		if(islatin1(r) && (mr := latin_fold_tab[r-16rc0]) != 0)			r = mr;		if(direc)			if(!(isalnum(r) || r == ' ' || r == '\t'))				continue;		if(fold)			if(isupper(r))				r = tolower(r);		if(r != s[o])	# avoid copying s unless necessary			s[o] = r;		o++;	}	if(o != i)		return s[0:o];	return s;} sgn(v: int): int{	if(v < 0)		return -1;	if(v > 0)		return 1;	return 0;} ncomp(s: string, t: string): int{	while(len s > 0 && isspace(s[0]))		s = s[1:];	while(len t > 0 && isspace(t[0]))		t = t[1:];	ssgn := tsgn := -2*rev;	if(s != nil && s[0] == '-'){		s = s[1: ];		ssgn = -ssgn;	}	if(t != nil && t[0] == '-'){		t = t[1:];		tsgn = -tsgn;	}	for(i := 0; i < len s && isdigit(s[i]); i++)		;	is := s[0:i];	js := s[i:];	for(i = 0; i < len t && isdigit(t[i]); i++)		;	it := t[0:i];	jt := t[i:];	a := 0;	i = len is;	j := len it;	if(ssgn == tsgn){		while(j > 0 && i > 0)			if((b := it[--j] - is[--i]) != 0)				a = b;	}	while(i > 0)		if(is[--i] != '0')			return -ssgn;	while(j > 0)		if(it[--i] != '0')			return tsgn;	if(a)		return sgn(a)*ssgn;	s = js;	if(len s > 0 && s[0] == '.')		s = s[1: ];	t = jt;	if(len t > 0 && t[0] == '.')		t = t[1: ];	if(ssgn == tsgn)		while((len s > 0 && isdigit(s[0])) && (len t > 0 && isdigit(t[0]))){			if(a = t[0] - s[0])				return sgn(a)*ssgn;			s = s[1:];			t = t[1:];		}	for(; len s > 0 && isdigit(s[0]); s = s[1:])		if(s[0] != '0')			return -ssgn;	for(; len t > 0 && isdigit(t[0]); t = t[1:])		if(t[0] != '0')			return tsgn;	return 0;} isupper(c: int): int{	return c >= 'A' && c <= 'Z';} islower(c: int): int{	return c >= 'a' && c <= 'z';} isalpha(c: int): int{	return islower(c) || isupper(c);} islatin1(c: int): int{	return c >= 16rC0 && c <= 16rFF;} isdigit(c: int): int{	return c >= '0' && c <= '9';} isalnum(c: int): int{	return isdigit(c) || islower(c) || isupper(c);} isspace(c: int): int{	return c == ' ' || c == '\t' || c >= 16r0A && c <= 16r0D;} tolower(c: int): int{	return c-'A'+'a';}