implement Date; include "sys.m";	sys: Sys; include "daytime.m";	daytime : Daytime; Tm: import daytime; include "date.m";  # print dates in the format # Wkd, DD Mon YYYY HH:MM:SS GMT # parse dates of formats # Wkd, DD Mon YYYY HH:MM:SS GMT # Weekday, DD-Mon-YY HH:MM:SS GMT # Wkd Mon ( D|DD) HH:MM:SS YYYY # plus anything similar SEC2MIN: con 60;SEC2HOUR: con (60*SEC2MIN);SEC2DAY: con (24*SEC2HOUR); #  days per month plus days/year dmsize := array[] of {	365, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; ldmsize := array[] of {	366, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; #  return the days/month for the given year  weekdayname := array[] of {	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}; wdayname := array[] of {	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};  monname := array[] of {	"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};  init(){	sys = load Sys Sys->PATH;	daytime = load Daytime Daytime->PATH;	if (daytime==nil){		sys->print("daytime load: %r\n");		exit;	}} yrsize(yr : int): array of int{	if(yr % 4 == 0 && (yr % 100 != 0 || yr % 400 == 0))		return ldmsize;	else		return dmsize;} tolower(c: int): int{	if(c >= 'A' && c <= 'Z')		return c - 'A' + 'a';	return c;}  isalpha(c: int): int{	return c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z';}  isdig(c: int): int{	return c >= '0' && c <= '9';}  dateconv(t: int): string{	tm : ref Tm;	tm = daytime->gmt(t);	return sys->sprint("%s, %.2d %s %.4d %.2d:%.2d:%.2d GMT",		wdayname[tm.wday], tm.mday, monname[tm.mon], tm.year+1900,		tm.hour, tm.min, tm.sec);	}  dateword(date : string): (string,string){	p : string;	i:=0;	p = "";	while((i<len date) && !isalpha(date[i]) && !isdig(date[i]))		i++;	while((i<len date) && isalpha(date[i])){				p[len p] = tolower(date[i]);		i++;	}	return (date[i:],p);}  datenum(date : string): (string, int){	n, i : int;	i=0;	while((i<len date) && !isdig(date[i]))		i++;	if(i == len date)		return (nil, -1);	n = 0;	while((i<len date) && isdig(date[i])){		n = n * 10 + date[i] - '0';		i++;	}	return (date[i:], n);}   # parse a date and return the seconds since the epoch # return 0 for a failure # could be big?date2sec(date : string): int{	tm : Tm;	buf : string;		 # Weekday|Wday	 	(date,buf) = dateword(date);	tm.wday = dateindex(buf, wdayname);	if(tm.wday < 0)		tm.wday = dateindex(buf, weekdayname); 	if(tm.wday < 0)		return 0; 	 # check for the two major formats		(date,buf) = dateword(date);	tm.mon = dateindex(buf, monname);	if(tm.mon >= 0){		 # MM		(date, tm.mday) = datenum(date);		if(tm.mday < 1 || tm.mday > 31)			return 0; 		 # HH:MM:SS		(date, tm.hour) = datenum(date);		if(tm.hour < 0 || tm.hour >= 24)			return 0;		(date, tm.min) = datenum(date);		if(tm.min < 0 || tm.min >= 60)			return 0;		(date, tm.sec) = datenum(date);		if(tm.sec < 0 || tm.sec >= 60)			return 0; 				 # YYYY 		(nil, tm.year) = datenum(date);		if(tm.year < 70 || tm.year > 99 && tm.year < 1970)			return 0;		if(tm.year >= 1970)			tm.year -= 1900;	}else{		# MM-Mon-(YY|YYYY)		(date, tm.mday) = datenum(date);		if(tm.mday < 1 || tm.mday > 31)			return 0;		(date,buf) = dateword(date);		tm.mon = dateindex(buf, monname);		if(tm.mon < 0 || tm.mon >= 12)			return 0;		(date, tm.year) = datenum(date);		if(tm.year < 70 || tm.year > 99 && tm.year < 1970)			return 0;		if(tm.year >= 1970)			tm.year -= 1900;				 # HH:MM:SS		(date, tm.hour) = datenum(date);		if(tm.hour < 0 || tm.hour >= 24)			return 0;		(date, tm.min) = datenum(date);		if(tm.min < 0 || tm.min >= 60)			return 0;		(date, tm.sec) = datenum(date);		if(tm.sec < 0 || tm.sec >= 60)			return 0; 		 # timezone		(date,buf)=dateword(date);		if(buf[0:3]!="gmt")			return 0;	} 	tm.zone="GMT";	return gmtm2sec(tm);} lowercase(name:string): string{	p: string;	for(i:=0;i<len name;i++)		p[i]=tolower(name[i]);	return p;} dateindex(d : string, tab : array of string): int{	for(i := 0; i < len tab; i++)		if (lowercase(tab[i]) == d)			return i;	return -1;}  # compute seconds since Jan 1 1970 GMT gmtm2sec(tm:Tm): int {	secs,i : int;	d2m: array of int;	secs=0; 	#seconds per year	tm.year += 1900;	if(tm.year < 1970)		return 0;	for(i = 1970; i < tm.year; i++){		d2m = yrsize(i);		secs += d2m[0] * SEC2DAY;	}  	#seconds per month	d2m = yrsize(tm.year);	for(i = 0; i < tm.mon; i++)		secs += d2m[i+1] * SEC2DAY; 	#secs in last month	secs += (tm.mday-1) * SEC2DAY; 	#hours, minutes, seconds		secs += tm.hour * SEC2HOUR;	secs += tm.min * SEC2MIN;	secs += tm.sec; 	return secs;}