##	Expression evaluation.# ##	Filename pattern matching.#glob(e: ref Env, s: string): (string, list of string){	if (filepat == nil) {		filepat = load Filepat Filepat->PATH;		if (filepat == nil)			e.couldnot("load", Filepat->PATH);	}	l := filepat->expand(s);	if (l != nil)		return (nil, l);	return (s, nil);} ##	RE pattern matching.#match(s1, s2: string): int{	(re, nil) := regex->compile(s2, 0);	return regex->execute(re, s1) != nil;} ##	RE match of two lists.  Two non-singleton lists never match.#match2(e: ref Env, s1: string, l1: list of string, s2: string, l2: list of string): int{	if (regex == nil) {		regex = load Regex Regex->PATH;		if (regex == nil)			e.couldnot("load", Regex->PATH);	}	if (s1 != nil) {		if (s2 != nil)			return match(s1, s2);		while (l2 != nil) {			if (match(s1, hd l2))				return 1;			l2 = tl l2;		}	} else if (l1 != nil) {		if (s2 == nil)			return 0;		while (l1 != nil) {			if (match(hd l1, s2))				return 1;			l1 = tl l1;		}	} else if (s2 != nil)		return match(nil, s2);	else if (l2 != nil) {		while (l2 != nil) {			if (match(nil, hd l2))				return 1;			l2 = tl l2;		}	} else		return 1;	return 0;} ##	Test list equality.  Same length and identical members.#eqlist(l1, l2: list of string): int{	while (l1 != nil && l2 != nil) {		if (hd l1 != hd l2)			return 0;		l1 = tl l1;		l2 = tl l2;	}	return l1 == nil && l2 == nil;} ##	Equality operator.#Cmd.evaleq(c: self ref Cmd, e: ref Env): int{	(s1, l1, nil) := c.left.eeval2(e);	(s2, l2, nil) := c.right.eeval2(e);	if (s1 != nil)		return s1 == s2;	if (l1 != nil)		return eqlist(l1, l2);	return s2 == nil && l2 == nil;} ##	Match operator.#Cmd.evalmatch(c: self ref Cmd, e: ref Env): int{	(s1, l1, nil) := c.left.eeval2(e);	(s2, l2, nil) := c.right.eeval2(e);	return match2(e, s1, l1, s2, l2);} ##	Catenation operator.#Item.caret(i: self ref Item, e: ref Env): (string, list of string, int){	(s1, l1, x1) := i.left.ieval2(e);	(s2, l2, x2) := i.right.ieval2(e);	return caret(s1, l1, x1, s2, l2, x2);} ##	Caret of lists.  A singleton distributes.  Otherwise pairwise, padded with nils.#caret(s1: string, l1: list of string, x1: int, s2: string, l2: list of string, x2: int): (string, list of string, int){	l: list of string;	if (s1 != nil) {		if (s2 != nil)			return (s1 + s2, nil, x1 | x2);		if (l2 == nil)			return (s1, nil, x1);		while (l2 != nil) {			l = (s1 + hd l2) :: l;			l2 = tl l2;		}	} else if (s2 != nil) {		if (l1 == nil)			return (s2, nil, x2);		while (l1 != nil) {			l = (hd l1 + s2) :: l;			l1 = tl l1;		}	} else if (l1 != nil) {		if (l2 == nil)			return (nil, l1, 0);		while (l1 != nil || l2 != nil) {			if (l1 != nil) {				s1 = hd l1;				l1 = tl l1;			} else				s1 = nil;			if (l2 != nil) {				s2 = hd l2;				l2 = tl l2;			} else				s2 = nil;			l = (s1 + s2) :: l;		}	} else if (l2 != nil)		return (nil, l2, 0);	return (nil, revstrs(l), 0);}