package re;
-our $VERSION = 0.03;
+# pragma for controlling the regexp engine
+use strict;
+use warnings;
+
+our $VERSION = "0.37";
+our @ISA = qw(Exporter);
+our @EXPORT_OK = ('regmust',
+ qw(is_regexp regexp_pattern
+ regname regnames regnames_count));
+our %EXPORT_OK = map { $_ => 1 } @EXPORT_OK;
+
+my %bitmask = (
+ taint => 0x00100000, # HINT_RE_TAINT
+ eval => 0x00200000, # HINT_RE_EVAL
+);
+
+my $flags_hint = 0x02000000; # HINT_RE_FLAGS
+my $PMMOD_SHIFT = 0;
+my %reflags = (
+ m => 1 << ($PMMOD_SHIFT + 0),
+ s => 1 << ($PMMOD_SHIFT + 1),
+ i => 1 << ($PMMOD_SHIFT + 2),
+ x => 1 << ($PMMOD_SHIFT + 3),
+ xx => 1 << ($PMMOD_SHIFT + 4),
+ n => 1 << ($PMMOD_SHIFT + 5),
+ p => 1 << ($PMMOD_SHIFT + 6),
+ strict => 1 << ($PMMOD_SHIFT + 10),
+# special cases:
+ d => 0,
+ l => 1,
+ u => 2,
+ a => 3,
+ aa => 4,
+);
+
+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} = $colors;
+ };
+ if ($@) {
+ $ENV{PERL_RE_COLORS} ||= qq'\t\t> <\t> <\t\t';
+ }
+
+}
+
+my %flags = (
+ COMPILE => 0x0000FF,
+ PARSE => 0x000001,
+ OPTIMISE => 0x000002,
+ TRIEC => 0x000004,
+ DUMP => 0x000008,
+ FLAGS => 0x000010,
+ TEST => 0x000020,
+
+ EXECUTE => 0x00FF00,
+ INTUIT => 0x000100,
+ MATCH => 0x000200,
+ TRIEE => 0x000400,
+
+ EXTRA => 0xFF0000,
+ TRIEM => 0x010000,
+ OFFSETS => 0x020000,
+ OFFSETSDBG => 0x040000,
+ STATE => 0x080000,
+ OPTIMISEM => 0x100000,
+ STACK => 0x280000,
+ BUFFERS => 0x400000,
+ GPOS => 0x800000,
+);
+$flags{ALL} = -1 & ~($flags{OFFSETS}|$flags{OFFSETSDBG}|$flags{BUFFERS});
+$flags{All} = $flags{all} = $flags{DUMP} | $flags{EXECUTE};
+$flags{Extra} = $flags{EXECUTE} | $flags{COMPILE} | $flags{GPOS};
+$flags{More} = $flags{MORE} = $flags{All} | $flags{TRIEC} | $flags{TRIEM} | $flags{STATE};
+$flags{State} = $flags{DUMP} | $flags{EXECUTE} | $flags{STATE};
+$flags{TRIE} = $flags{DUMP} | $flags{EXECUTE} | $flags{TRIEC};
+
+if (defined &DynaLoader::boot_DynaLoader) {
+ require XSLoader;
+ XSLoader::load();
+}
+# else we're miniperl
+# We need to work for miniperl, because the XS toolchain uses Text::Wrap, which
+# uses re 'taint'.
+
+sub _load_unload {
+ my ($on)= @_;
+ if ($on) {
+ # We call install() every time, as if we didn't, we wouldn't
+ # "see" any changes to the color environment var since
+ # the last time it was called.
+
+ # install() returns an integer, which if casted properly
+ # in C resolves to a structure containing the regexp
+ # hooks. Setting it to a random integer will guarantee
+ # segfaults.
+ $^H{regcomp} = install();
+ } else {
+ delete $^H{regcomp};
+ }
+}
+
+sub bits {
+ my $on = shift;
+ my $bits = 0;
+ my $turning_all_off = ! @_ && ! $on;
+ if ($turning_all_off) {
+
+ # Pretend were called with certain parameters, which are best dealt
+ # with that way.
+ push @_, keys %bitmask; # taint and eval
+ push @_, 'strict';
+ }
+
+ # Process each subpragma parameter
+ ARG:
+ foreach my $idx (0..$#_){
+ my $s=$_[$idx];
+ if ($s eq 'Debug' or $s eq 'Debugcolor') {
+ setcolor() if $s =~/color/i;
+ ${^RE_DEBUG_FLAGS} = 0 unless defined ${^RE_DEBUG_FLAGS};
+ for my $idx ($idx+1..$#_) {
+ if ($flags{$_[$idx]}) {
+ if ($on) {
+ ${^RE_DEBUG_FLAGS} |= $flags{$_[$idx]};
+ } else {
+ ${^RE_DEBUG_FLAGS} &= ~ $flags{$_[$idx]};
+ }
+ } else {
+ require Carp;
+ Carp::carp("Unknown \"re\" Debug flag '$_[$idx]', possible flags: ",
+ join(", ",sort keys %flags ) );
+ }
+ }
+ _load_unload($on ? 1 : ${^RE_DEBUG_FLAGS});
+ last;
+ } elsif ($s eq 'debug' or $s eq 'debugcolor') {
+ setcolor() if $s =~/color/i;
+ _load_unload($on);
+ last;
+ } elsif (exists $bitmask{$s}) {
+ $bits |= $bitmask{$s};
+ } elsif ($EXPORT_OK{$s}) {
+ require Exporter;
+ re->export_to_level(2, 're', $s);
+ } elsif ($s eq 'strict') {
+ if ($on) {
+ $^H{reflags} |= $reflags{$s};
+ warnings::warnif('experimental::re_strict',
+ "\"use re 'strict'\" is experimental");
+
+ # Turn on warnings if not already done.
+ if (! warnings::enabled('regexp')) {
+ require warnings;
+ warnings->import('regexp');
+ $^H{re_strict} = 1;
+ }
+ }
+ else {
+ $^H{reflags} &= ~$reflags{$s} if $^H{reflags};
+
+ # Turn off warnings if we turned them on.
+ warnings->unimport('regexp') if $^H{re_strict};
+ }
+ if ($^H{reflags}) {
+ $^H |= $flags_hint;
+ }
+ else {
+ $^H &= ~$flags_hint;
+ }
+ } elsif ($s =~ s/^\///) {
+ my $reflags = $^H{reflags} || 0;
+ my $seen_charset;
+ my $x_count = 0;
+ while ($s =~ m/( . )/gx) {
+ local $_ = $1;
+ if (/[adul]/) {
+ # The 'a' may be repeated; hide this from the rest of the
+ # code by counting and getting rid of all of them, then
+ # changing to 'aa' if there is a repeat.
+ if ($_ eq 'a') {
+ my $sav_pos = pos $s;
+ my $a_count = $s =~ s/a//g;
+ pos $s = $sav_pos - 1; # -1 because got rid of the 'a'
+ if ($a_count > 2) {
+ require Carp;
+ Carp::carp(
+ qq 'The "a" flag may only appear a maximum of twice'
+ );
+ }
+ elsif ($a_count == 2) {
+ $_ = 'aa';
+ }
+ }
+ if ($on) {
+ if ($seen_charset) {
+ require Carp;
+ if ($seen_charset ne $_) {
+ Carp::carp(
+ qq 'The "$seen_charset" and "$_" flags '
+ .qq 'are exclusive'
+ );
+ }
+ else {
+ Carp::carp(
+ qq 'The "$seen_charset" flag may not appear '
+ .qq 'twice'
+ );
+ }
+ }
+ $^H{reflags_charset} = $reflags{$_};
+ $seen_charset = $_;
+ }
+ else {
+ delete $^H{reflags_charset}
+ if defined $^H{reflags_charset}
+ && $^H{reflags_charset} == $reflags{$_};
+ }
+ } elsif (exists $reflags{$_}) {
+ if ($_ eq 'x') {
+ $x_count++;
+ if ($x_count > 2) {
+ require Carp;
+ Carp::carp(
+ qq 'The "x" flag may only appear a maximum of twice'
+ );
+ }
+ elsif ($x_count == 2) {
+ $_ = 'xx'; # First time through got the /x
+ }
+ }
+
+ $on
+ ? $reflags |= $reflags{$_}
+ : ($reflags &= ~$reflags{$_});
+ } else {
+ require Carp;
+ Carp::carp(
+ qq'Unknown regular expression flag "$_"'
+ );
+ next ARG;
+ }
+ }
+ ($^H{reflags} = $reflags or defined $^H{reflags_charset})
+ ? $^H |= $flags_hint
+ : ($^H &= ~$flags_hint);
+ } else {
+ require Carp;
+ Carp::carp("Unknown \"re\" subpragma '$s' (known ones are: ",
+ join(', ', map {qq('$_')} 'debug', 'debugcolor', sort keys %bitmask),
+ ")");
+ }
+ }
+
+ if ($turning_all_off) {
+ _load_unload(0);
+ $^H{reflags} = 0;
+ $^H{reflags_charset} = 0;
+ $^H &= ~$flags_hint;
+ }
+
+ $bits;
+}
+
+sub import {
+ shift;
+ $^H |= bits(1, @_);
+}
+
+sub unimport {
+ shift;
+ $^H &= ~ bits(0, @_);
+}
+
+1;
+
+__END__
=head1 NAME
$pat = '(?{ $foo = 1 })';
use re 'eval';
- /foo${pat}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); # $x is not tainted here
no re 'eval'; # the default
- /foo${pat}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 'strict'; # Raise warnings for more conditions
+
+ use re '/ix';
+ "FOO" =~ / foo /; # /ix implied
+ no re '/x';
+ "FOO" =~ /foo/; # just /i implied
+
+ use re 'debug'; # output debugging info during
+ /^(.*)$/s; # compile and run time
- use re 'debugcolor'; # same as 'debug', but with colored output
+
+ use re 'debugcolor'; # same as 'debug', but with colored
+ # output
...
+ use re qw(Debug All); # Same as "use re 'debug'", but you
+ # can use "Debug" with things other
+ # than 'All'
+ use re qw(Debug More); # 'All' plus output more details
+ no re qw(Debug ALL); # Turn on (almost) all re debugging
+ # in this scope
+
+ use re qw(is_regexp regexp_pattern); # import utility functions
+ my ($pat,$mods)=regexp_pattern(qr/foo/i);
+ if (is_regexp($obj)) {
+ print "Got regexp: ",
+ scalar regexp_pattern($obj); # just as perl would stringify
+ } # it but no hassle with blessed
+ # re's.
+
(We use $^X in these examples because it's tainted by default.)
=head1 DESCRIPTION
+=head2 'taint' mode
+
When C<use re 'taint'> is in effect, and a tainted string is the target
-of a regex, the regex memories (or values returned by the m// operator
-in list context) are tainted. This feature is useful when regex operations
+of a regexp, the regexp memories (or values returned by the m// operator
+in list context) are tainted. This feature is useful when regexp operations
on tainted data aren't meant to extract safe substrings, but to perform
other transformations.
-When C<use re 'eval'> is in effect, a regex is allowed to contain
-C<(?{ ... })> zero-width assertions even if regular expression contains
-variable interpolation. That is normally disallowed, since it is a
+=head2 'eval' mode
+
+When C<use re 'eval'> is in effect, a regexp is allowed to contain
+C<(?{ ... })> zero-width assertions and C<(??{ ... })> postponed
+subexpressions that are derived from variable interpolation, rather than
+appearing literally within the regexp. That is normally disallowed, since
+it is a
potential security risk. Note that this pragma is ignored when the regular
expression is obtained from tainted data, i.e. evaluation is always
-disallowed with tainted regular expresssions. See L<perlre/(?{ code })>.
+disallowed with tainted regular expressions. See L<perlre/(?{ code })>
+and L<perlre/(??{ code })>.
For the purpose of this pragma, interpolation of precompiled regular
expressions (i.e., the result of C<qr//>) is I<not> considered variable
/foo${pat}bar/
I<is> allowed if $pat is a precompiled regular expression, even
-if $pat contains C<(?{ ... })> assertions.
+if $pat contains C<(?{ ... })> assertions or C<(??{ ... })> subexpressions.
+
+=head2 'strict' mode
+
+Note that this is an experimental feature which may be changed or removed in a
+future Perl release.
+
+When C<use re 'strict'> is in effect, stricter checks are applied than
+otherwise when compiling regular expressions patterns. These may cause more
+warnings to be raised than otherwise, and more things to be fatal instead of
+just warnings. The purpose of this is to find and report at compile time some
+things, which may be legal, but have a reasonable possibility of not being the
+programmer's actual intent. This automatically turns on the C<"regexp">
+warnings category (if not already on) within its scope.
+
+As an example of something that is caught under C<"strict'>, but not
+otherwise, is the pattern
+
+ qr/\xABC/
+
+The C<"\x"> construct without curly braces should be followed by exactly two
+hex digits; this one is followed by three. This currently evaluates as
+equivalent to
+
+ qr/\x{AB}C/
+
+that is, the character whose code point value is C<0xAB>, followed by the
+letter C<C>. But since C<C> is a a hex digit, there is a reasonable chance
+that the intent was
+
+ qr/\x{ABC}/
+
+that is the single character at C<0xABC>. Under C<'strict'> it is an error to
+not follow C<\x> with exactly two hex digits. When not under C<'strict'> a
+warning is generated if there is only one hex digit, and no warning is raised
+if there are more than two.
+
+It is expected that what exactly C<'strict'> does will evolve over time as we
+gain experience with it. This means that programs that compile under it in
+today's Perl may not compile, or may have more or fewer warnings, in future
+Perls. There is no backwards compatibility promises with regards to it. Also
+there are already proposals for an alternate syntax for enabling it. For
+these reasons, using it will raise a C<experimental::re_strict> class warning,
+unless that category is turned off.
+
+Note that if a pattern compiled within C<'strict'> is recompiled, say by
+interpolating into another pattern, outside of C<'strict'>, it is not checked
+again for strictness. This is because if it works under strict it must work
+under non-strict.
+
+=head2 '/flags' mode
+
+When C<use re '/I<flags>'> is specified, the given I<flags> are automatically
+added to every regular expression till the end of the lexical scope.
+I<flags> can be any combination of
+C<'a'>,
+C<'aa'>,
+C<'d'>,
+C<'i'>,
+C<'l'>,
+C<'m'>,
+C<'n'>,
+C<'p'>,
+C<'s'>,
+C<'u'>,
+C<'x'>,
+and/or
+C<'xx'>.
+
+C<no re '/I<flags>'> will turn off the effect of C<use re '/I<flags>'> for the
+given flags.
+
+For example, if you want all your regular expressions to have /msxx on by
+default, simply put
+
+ use re '/msxx';
+
+at the top of your code.
+
+The character set C</adul> flags cancel each other out. So, in this example,
+
+ use re "/u";
+ "ss" =~ /\xdf/;
+ use re "/d";
+ "ss" =~ /\xdf/;
+
+the second C<use re> does an implicit C<no re '/u'>.
+
+Similarly,
+
+ use re "/xx"; # Doubled-x
+ ...
+ use re "/x"; # Single x from here on
+ ...
+
+Turning on one of the character set flags with C<use re> takes precedence over the
+C<locale> pragma and the 'unicode_strings' C<feature>, for regular
+expressions. Turning off one of these flags when it is active reverts to
+the behaviour specified by whatever other pragmata are in scope. For
+example:
+
+ use feature "unicode_strings";
+ no re "/u"; # does nothing
+ use re "/l";
+ no re "/l"; # reverts to unicode_strings behaviour
+
+=head2 'debug' mode
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
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.
+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.
+As of 5.9.5 the directive C<use re 'debug'> and its equivalents are
+lexically scoped, as the other directives are. However they have both
+compile-time and run-time effects.
See L<perlmodlib/Pragmatic Modules>.
-=cut
+=head2 'Debug' mode
-# 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,
-);
+Similarly C<use re 'Debug'> produces debugging output, the difference
+being that it allows the fine tuning of what debugging output will be
+emitted. Options are divided into three groups, those related to
+compilation, those related to execution and those related to special
+purposes. The options are as follows:
-sub setcolor {
- eval { # Ignore errors
- require Term::Cap;
+=over 4
- 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;
+=item Compile related options
- $colors =~ s/\0//g;
- $ENV{PERL_RE_COLORS} = $colors;
- };
-}
+=over 4
-sub bits {
- my $on = shift;
- my $bits = 0;
- unless (@_) {
- require Carp;
- Carp::carp("Useless use of \"re\" pragma");
- }
- foreach my $s (@_){
- if ($s eq 'debug' or $s eq 'debugcolor') {
- setcolor() if $s eq 'debugcolor';
- require XSLoader;
- XSLoader::load('re');
- install() if $on;
- uninstall() unless $on;
- next;
- }
- if (exists $bitmask{$s}) {
- $bits |= $bitmask{$s};
- } else {
- require Carp;
- Carp::carp("Unknown \"re\" subpragma '$s' (known ones are: @{[join(', ', map {qq('$_')} 'debug', 'debugcolor', sort keys %bitmask)]})");
- }
- }
- $bits;
-}
+=item COMPILE
-sub import {
- shift;
- $^H |= bits(1, @_);
-}
+Turns on all compile related debug options.
-sub unimport {
- shift;
- $^H &= ~ bits(0, @_);
-}
+=item PARSE
-1;
+Turns on debug output related to the process of parsing the pattern.
+
+=item OPTIMISE
+
+Enables output related to the optimisation phase of compilation.
+
+=item TRIEC
+
+Detailed info about trie compilation.
+
+=item DUMP
+
+Dump the final program out after it is compiled and optimised.
+
+=item FLAGS
+
+Dump the flags associated with the program
+
+=item TEST
+
+Print output intended for testing the internals of the compile process
+
+=back
+
+=item Execute related options
+
+=over 4
+
+=item EXECUTE
+
+Turns on all execute related debug options.
+
+=item MATCH
+
+Turns on debugging of the main matching loop.
+
+=item TRIEE
+
+Extra debugging of how tries execute.
+
+=item INTUIT
+
+Enable debugging of start-point optimisations.
+
+=back
+
+=item Extra debugging options
+
+=over 4
+
+=item EXTRA
+
+Turns on all "extra" debugging options.
+
+=item BUFFERS
+
+Enable debugging the capture group storage during match. Warning,
+this can potentially produce extremely large output.
+
+=item TRIEM
+
+Enable enhanced TRIE debugging. Enhances both TRIEE
+and TRIEC.
+
+=item STATE
+
+Enable debugging of states in the engine.
+
+=item STACK
+
+Enable debugging of the recursion stack in the engine. Enabling
+or disabling this option automatically does the same for debugging
+states as well. This output from this can be quite large.
+
+=item GPOS
+
+Enable debugging of the \G modifier.
+
+=item OPTIMISEM
+
+Enable enhanced optimisation debugging and start-point optimisations.
+Probably not useful except when debugging the regexp engine itself.
+
+=item OFFSETS
+
+Dump offset information. This can be used to see how regops correlate
+to the pattern. Output format is
+
+ NODENUM:POSITION[LENGTH]
+
+Where 1 is the position of the first char in the string. Note that position
+can be 0, or larger than the actual length of the pattern, likewise length
+can be zero.
+
+=item OFFSETSDBG
+
+Enable debugging of offsets information. This emits copious
+amounts of trace information and doesn't mesh well with other
+debug options.
+
+Almost definitely only useful to people hacking
+on the offsets part of the debug engine.
+
+
+=back
+
+=item Other useful flags
+
+These are useful shortcuts to save on the typing.
+
+=over 4
+
+=item ALL
+
+Enable all options at once except OFFSETS, OFFSETSDBG and BUFFERS.
+(To get every single option without exception, use both ALL and EXTRA, or
+starting in 5.30 on a C<-DDEBUGGING>-enabled perl interpreter, use
+the B<-Drv> command-line switches.)
+
+=item All
+
+Enable DUMP and all execute options. Equivalent to:
+
+ use re 'debug';
+
+=item MORE
+
+=item More
+
+Enable the options enabled by "All", plus STATE, TRIEC, and TRIEM.
+
+=back
+
+=back
+
+As of 5.9.5 the directive C<use re 'debug'> and its equivalents are
+lexically scoped, as are the other directives. However they have both
+compile-time and run-time effects.
+
+=head2 Exportable Functions
+
+As of perl 5.9.5 're' debug contains a number of utility functions that
+may be optionally exported into the caller's namespace. They are listed
+below.
+
+=over 4
+
+=item is_regexp($ref)
+
+Returns true if the argument is a compiled regular expression as returned
+by C<qr//>, false if it is not.
+
+This function will not be confused by overloading or blessing. In
+internals terms, this extracts the regexp pointer out of the
+PERL_MAGIC_qr structure so it cannot be fooled.
+
+=item regexp_pattern($ref)
+
+If the argument is a compiled regular expression as returned by C<qr//>,
+then this function returns the pattern.
+
+In list context it returns a two element list, the first element
+containing the pattern and the second containing the modifiers used when
+the pattern was compiled.
+
+ my ($pat, $mods) = regexp_pattern($ref);
+
+In scalar context it returns the same as perl would when stringifying a raw
+C<qr//> with the same pattern inside. If the argument is not a compiled
+reference then this routine returns false but defined in scalar context,
+and the empty list in list context. Thus the following
+
+ if (regexp_pattern($ref) eq '(?^i:foo)')
+
+will be warning free regardless of what $ref actually is.
+
+Like C<is_regexp> this function will not be confused by overloading
+or blessing of the object.
+
+=item regmust($ref)
+
+If the argument is a compiled regular expression as returned by C<qr//>,
+then this function returns what the optimiser considers to be the longest
+anchored fixed string and longest floating fixed string in the pattern.
+
+A I<fixed string> is defined as being a substring that must appear for the
+pattern to match. An I<anchored fixed string> is a fixed string that must
+appear at a particular offset from the beginning of the match. A I<floating
+fixed string> is defined as a fixed string that can appear at any point in
+a range of positions relative to the start of the match. For example,
+
+ my $qr = qr/here .* there/x;
+ my ($anchored, $floating) = regmust($qr);
+ print "anchored:'$anchored'\nfloating:'$floating'\n";
+
+results in
+
+ anchored:'here'
+ floating:'there'
+
+Because the C<here> is before the C<.*> in the pattern, its position
+can be determined exactly. That's not true, however, for the C<there>;
+it could appear at any point after where the anchored string appeared.
+Perl uses both for its optimisations, preferring the longer, or, if they are
+equal, the floating.
+
+B<NOTE:> This may not necessarily be the definitive longest anchored and
+floating string. This will be what the optimiser of the Perl that you
+are using thinks is the longest. If you believe that the result is wrong
+please report it via the L<perlbug> utility.
+
+=item regname($name,$all)
+
+Returns the contents of a named buffer of the last successful match. If
+$all is true, then returns an array ref containing one entry per buffer,
+otherwise returns the first defined buffer.
+
+=item regnames($all)
+
+Returns a list of all of the named buffers defined in the last successful
+match. If $all is true, then it returns all names defined, if not it returns
+only names which were involved in the match.
+
+=item regnames_count()
+
+Returns the number of distinct names defined in the pattern used
+for the last successful match.
+
+B<Note:> this result is always the actual number of distinct
+named buffers defined, it may not actually match that which is
+returned by C<regnames()> and related routines when those routines
+have not been called with the $all parameter set.
+
+=back
+
+=head1 SEE ALSO
+
+L<perlmodlib/Pragmatic Modules>.
+
+=cut