use re 'taint';
($x) = ($^X =~ /^(.*)$/s); # $x is tainted here
+ $pat = '(?{ $foo = 1 })';
use re 'eval';
- /foo(?{ $foo = 1 })bar/; # won't fail (when not under -T switch)
+ /foo${pat}bar/; # won't fail (when not under -T switch)
{
no re 'taint'; # the default
($x) = ($^X =~ /^(.*)$/s); # $x is not tainted here
no re 'eval'; # the default
- /foo(?{ $foo = 1 })bar/; # disallowed (with or without -T switch)
+ /foo${pat}bar/; # disallowed (with or without -T switch)
}
+ use re 'debug'; # NOT lexically scoped (as others are)
+ /^(.*)$/s; # output debugging info during
+ # compile and run time
+
+ use re 'debugcolor'; # same as 'debug', but with colored output
+ ...
+
+(We use $^X in these examples because it's tainted by default.)
+
=head1 DESCRIPTION
When C<use re 'taint'> is in effect, and a tainted string is the target
other transformations.
When C<use re 'eval'> is in effect, a regex is allowed to contain
-C<(?{ ... })> zero-width assertions (which may not be interpolated in
-the regex). That is normally disallowed, since it is a potential security
-risk. Note that this pragma is ignored when perl detects tainted data,
-i.e. evaluation is always disallowed with tainted data. See
-L<perlre/(?{ code })>.
+C<(?{ ... })> zero-width assertions even if regular expression contains
+variable interpolation. That is normally disallowed, since it is a
+potential security risk. Note that this pragma is ignored when the regular
+expression is obtained from tainted data, i.e. evaluation is always
+disallowed with tainted regular expresssions. See L<perlre/(?{ code })>.
+
+For the purpose of this pragma, interpolation of precompiled regular
+expressions (i.e., the result of C<qr//>) is I<not> considered variable
+interpolation. Thus:
+
+ /foo${pat}bar/
+
+I<is> allowed if $pat is a precompiled regular expression, even
+if $pat contains C<(?{ ... })> assertions.
+
+When C<use re 'debug'> is in effect, perl emits debugging messages when
+compiling and using regular expressions. The output is the same as that
+obtained by running a C<-DDEBUGGING>-enabled perl interpreter with the
+B<-Dr> switch. It may be quite voluminous depending on the complexity
+of the match. Using C<debugcolor> instead of C<debug> enables a
+form of output that can be used to get a colorful display on terminals
+that understand termcap color sequences. Set C<$ENV{PERL_RE_TC}> to a
+comma-separated list of C<termcap> properties to use for highlighting
+strings on/off, pre-point part on/off.
+See L<perldebug/"Debugging regular expressions"> for additional info.
+
+The directive C<use re 'debug'> is I<not lexically scoped>, as the
+other directives are. It has both compile-time and run-time effects.
See L<perlmodlib/Pragmatic Modules>.
eval => 0x00200000,
);
+sub setcolor {
+ eval { # Ignore errors
+ require Term::Cap;
+
+ my $terminal = Tgetent Term::Cap ({OSPEED => 9600}); # Avoid warning.
+ my $props = $ENV{PERL_RE_TC} || 'md,me,so,se'; # can use us/ue later
+ my @props = split /,/, $props;
+
+
+ $ENV{TERMCAP_COLORS} = join "\t", map {$terminal->Tputs($_,1)} @props;
+ };
+
+ not defined $ENV{TERMCAP_COLORS} or ($ENV{TERMCAP_COLORS} =~ tr/\t/\t/) >= 4
+ or not defined $ENV{PERL_RE_TC}
+ or die "Not enough fields in \$ENV{PERL_RE_TC}=`$ENV{PERL_RE_TC}'";
+}
+
sub bits {
my $on = shift;
my $bits = 0;
Carp::carp("Useless use of \"re\" pragma");
}
foreach my $s (@_){
- if ($s eq 'debug') {
- eval <<'EOE';
- use DynaLoader;
- @ISA = ('DynaLoader');
- bootstrap re;
-EOE
+ if ($s eq 'debug' or $s eq 'debugcolor') {
+ setcolor() if $s eq 'debugcolor';
+ require DynaLoader;
+ @ISA = ('DynaLoader');
+ bootstrap re;
install() if $on;
uninstall() unless $on;
next;