Thanks to everyone.

It seems that the following code does what I want:

#!perl -w

my $test = (
  "olive&(popeye|bluto)",
  "(tom&jerry)|(sylvester&tweety)",
  "moe&(shemp|curly|joe)&larry",
  "tom&jerry|sylvester&tweety", # valid
  "moe ( shemp | curly | joe ) larry", # also valid
  "moe(&shemp|curly|joe)&larry", # invalid: "(&" instead of "&("
  "moe ( shemp | curly | joe", # invalid: missing ")" raises an error
)[(shift) - 1];

my $expr = $test;

$expr =~ s/(\w+)/"(?=.*\\b($1)\\b)"/ge;
$expr =~ s/[\&\s]//g;
$expr = "^($expr)";

print "$test\n$expr\n----\n";

while (<DATA>) {
  print $_ if /$expr/;
}

__DATA__
tom,jerry
jerry,tom
jerry,tomas
sylvester,tweety
tweeter,sylvester
tom,sylvester
popeye,olive
olive,brutus
moe,larry
shemp,curly,joe
larry,moe
larry,curly,moe
[download]

>re.pl 1
olive&(popeye|bluto)
^((?=.*\b(olive)\b)((?=.*\b(popeye)\b)|(?=.*\b(bluto)\b)))
----
popeye,olive

>re.pl 2
(tom&jerry)|(sylvester&tweety)
^(((?=.*\b(tom)\b)(?=.*\b(jerry)\b))|((?=.*\b(sylvester)\b)(?=.*\b(twe
+ety)\b)))
----
tom,jerry
jerry,tom
sylvester,tweety

>re.pl 3
moe&(shemp|curly|joe)&larry
^((?=.*\b(moe)\b)((?=.*\b(shemp)\b)|(?=.*\b(curly)\b)|(?=.*\b(joe)\b))
+(?=.*\b(larry)\b))
----
larry,curly,moe
[download]

I know this will raise an error if the expression is invalid, but I'm sure it could be checked first with something "simple" like the following:

die "Invalid expression <$test>\n"
  if $test =~ /[^a-z\s\&\|\(\)]|^\s*[\&\|]|[\&\|]\s*$|[\&\|]\s*[\&\|]|
+[\&\|]\s*\)|\(\s*[\|\&]/;
[download]

and I'm sure I can find something more to validate that parenthesis are well paired.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.