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use strict;
print "
/**
* A set of tokens that can precede a regular expression literal in
* javascript
* http://web.archive.org/web/20070717142515/http://www.mozilla.org/js/language/js20/rationale/syntax.html
* has the full list, but I've removed ones that might be problematic when
* seen in languages that don't support regular expression literals.
*
* <p>Specifically, I've removed any keywords that can't precede a regexp
* literal in a syntactically legal javascript program, and I've removed the
* \"in\" keyword since it's not a keyword in many languages, and might be used
* as a count of inches.
*
* <p>The link above does not accurately describe EcmaScript rules since
* it fails to distinguish between (a=++/b/i) and (a++/b/i) but it works
* very well in practice.
*
* \@private
* \@const
*/
var REGEXP_PRECEDER_PATTERN = ";
my @preceders = (
"[!=]=?=?", # "!", "!=", "!==", "=", "==", "===",
"\\#",
"%=?", # "%", "%=",
"&&?=?", # "&", "&&", "&&=", "&=",
"\\(",
"\\*=?", # "*", "*=",
"[+\\-]=", # +=, -=. + and - handled below.
"->",
"\\/=?", # "/", "/=",
"::?", # ":", "::",
"<<?=?", # "<", "<<", "<<=", "<=",
">>?>?=?", # ">", ">=", ">>", ">>=", ">>>", ">>>=",
",",
";", # ";"
"\\?",
"@",
"\\[",
"~", # handles =~ and !~
"{",
"\\^\\^?=?", # "^", "^=", "^^", "^^=",
"\\|\\|?=?", # "|", "|=", "||", "||=",
"break", "case", "continue", "delete",
"do", "else", "finally", "instanceof",
"return", "throw", "try", "typeof"
);
# match at beginning, a dot that is not part of a number, or sign.
my $pattern = "'(?:^^\\\\.?|[+-]";
foreach my $preceder (@preceders) {
$preceder =~ s/\\/\\\\/g;
$pattern .= "|$preceder";
}
$pattern .= ")\\\\s*'"; # matches at end, and matches empty string
print "$pattern;\n";
print "
// CAVEAT: this does not properly handle the case where a regular
// expression immediately follows another since a regular expression may
// have flags for case-sensitivity and the like. Having regexp tokens
// adjacent is not valid in any language I'm aware of, so I'm punting.
// TODO: maybe style special characters inside a regexp as punctuation.
";
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