Workaround for the buggy ("internal compiler error")

[p5sagit/p5-mst-13.2.git] / ext / re / re.pm

diff --git a/ext/re/re.pm b/ext/re/re.pm
index 53873fc..3f142d9 100644 (file)
--- a/ext/re/re.pm
+++ b/ext/re/re.pm
@@ -11,17 +11,27 @@ re - Perl pragma to alter regular expression behaviour
     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
@@ -31,21 +41,60 @@ on tainted data aren't meant to extract safe substrings, but to perform
 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>.
 
 =cut
 
+# N.B. File::Basename contains a literal for 'taint' as a fallback.  If
+# taint is changed here, File::Basename must be updated as well.
 my %bitmask = (
 taint  => 0x00100000,
 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,us,ue';
+  my @props = split /,/, $props;
+  my $colors = join "\t", map {$terminal->Tputs($_,1)} @props;
+
+  $colors =~ s/\0//g;
+  $ENV{PERL_RE_COLORS} = $colors;
+ };
+}
+
 sub bits {
     my $on = shift;
     my $bits = 0;
@@ -54,12 +103,10 @@ sub bits {
        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 XSLoader;
+         XSLoader::load('re');
          install() if $on;
          uninstall() unless $on;
          next;