This and other RFCs are available on the web at
http://dev.perl.org/rfc/
=head1 TITLE
C<\v> for Vertical Tab
=head1 VERSION
Maintainer: Nicholas Clark <[EMAIL PROTECTED]>
Date: 26 Sep 2000
Mailing List: [EMAIL PROTECTED]
Number: 327
Version: 1
Status: Developing
=head1 ABSTRACT
perl5 includes all of C's escapes except C<\v> (vertical tab). Treating
C<\v> the same as C<\a> C<\b> C<\e> C<\f> C<\h> C<\r> C<\t> would remove a
special case.
=head1 DESCRIPTION
man perl says:
Perl combines (in the author's opinion, anyway) some of
the best features of C, sed, awk, and sh, so people
familiar with those languages should have little
difficulty with it.
However, lack of C<\v> represents a special case for a C programmer to
learn. C<\v> isn't used for anything else in double quoted strings, nor is
it used in regular expressions, so it won't require removal of an existing
feature to add it. Currently a C<\v> in a double quoted strings will be
treated as C<v>, with a warning about unknown escape issued if warnings are
in force.
Vertical tab was also omitted from the range of characters considered
whitespace by C<\s> in regular expressions.
This RFC proposes
=over 4
=item 1
C<\v> becomes a recognised escape for a vertical tab in interpolated
contexts (double quoted strings and regular expressions)
=item 2
That vertical tab is moved from the C<\S> (non-whitespace) to C<\s>
(whitespace) class in regular expressions.
=back
=head1 IMPLEMENTATION
Shouldn't be hard. Here are patches for perl 5.7.0
=over 4
=item C<\v>
--- toke.c.orig Fri Sep 15 04:14:57 2000
+++ toke.c Tue Sep 26 12:54:30 2000
@@ -469,7 +469,7 @@
for (t = s; !isSPACE(*t); t++) ;
e = t;
}
- while (SPACE_OR_TAB(*e) || *e == '\r' || *e == '\f')
+ while (SPACE_OR_TAB(*e) || *e == '\r' || *e == '\f' || *e == '\v')
e++;
if (*e != '\n' && *e != '\0')
return; /* false alarm */
@@ -1196,7 +1196,7 @@
: UTF;
const char *leaveit = /* set of acceptably-backslashed characters */
PL_lex_inpat
- ? "\\.^$@AGZdDwWsSbBpPXC+*?|()-nrtfeaxcz0123456789[{]} \t\n\r\f\v#"
+ ? "\\.^$@AGZdDwWsSbBpPXC+*?|()-nrtfveaxcz0123456789[{]} \t\n\r\f\v#"
: "";
while (s < send || dorange) {
@@ -1540,6 +1540,9 @@
case 'f':
*d++ = '\f';
break;
+ case 'v':
+ *d++ = '\v';
+ break;
case 't':
*d++ = '\t';
break;
@@ -2700,7 +2703,7 @@
Perl_croak(aTHX_
"\t(Maybe you didn't strip carriage returns after a network transfer?)\n");
#endif
- case ' ': case '\t': case '\f': case 013:
+ case ' ': case '\t': case '\f': case '\v':
#ifdef MACOS_TRADITIONAL
case '\312':
#endif
--- t/op/pat.t.orig Tue Aug 29 13:54:13 2000
+++ t/op/pat.t Tue Sep 26 12:56:36 2000
@@ -469,27 +469,27 @@
print "ok $test\n";
$test++;
-print "not " unless qr/\b\v$/i eq '(?i-xsm:\bv$)';
+print "not " unless qr/\b\y$/i eq '(?i-xsm:\by$)';
print "ok $test\n";
$test++;
-print "not " unless qr/\b\v$/s eq '(?s-xim:\bv$)';
+print "not " unless qr/\b\y$/s eq '(?s-xim:\by$)';
print "ok $test\n";
$test++;
-print "not " unless qr/\b\v$/m eq '(?m-xis:\bv$)';
+print "not " unless qr/\b\y$/m eq '(?m-xis:\by$)';
print "ok $test\n";
$test++;
-print "not " unless qr/\b\v$/x eq '(?x-ism:\bv$)';
+print "not " unless qr/\b\y$/x eq '(?x-ism:\by$)';
print "ok $test\n";
$test++;
-print "not " unless qr/\b\v$/xism eq '(?msix:\bv$)';
+print "not " unless qr/\b\y$/xism eq '(?msix:\by$)';
print "ok $test\n";
$test++;
-print "not " unless qr/\b\v$/ eq '(?-xism:\bv$)';
+print "not " unless qr/\b\y$/ eq '(?-xism:\by$)';
print "ok $test\n";
$test++;
=item C<\S> to C<\s>
--- handy.h.orig Thu Sep 14 15:44:20 2000
+++ handy.h Tue Sep 26 13:04:30 2000
@@ -295,8 +295,9 @@
#define isIDFIRST(c) (isALPHA(c) || (c) == '_')
#define isALPHA(c) (isUPPER(c) || isLOWER(c))
#define isSPACE(c) \
- ((c) == ' ' || (c) == '\t' || (c) == '\n' || (c) =='\r' || (c) == '\f')
-#define isPSXSPC(c) (isSPACE(c) || (c) == '\v')
+ ((c) == ' ' || (c) == '\t' || (c) == '\n' || (c) =='\r' || (c) == '\f' \
+ || (c) == '\v')
+#define isPSXSPC(c) isSPACE(c)
#define isBLANK(c) ((c) == ' ' || (c) == '\t')
#define isDIGIT(c) ((c) >= '0' && (c) <= '9')
#ifdef EBCDIC
--- t/op/pat.t.orig Tue Aug 29 13:54:13 2000
+++ t/op/pat.t Tue Sep 26 14:27:14 2000
@@ -1064,15 +1064,14 @@
cr => "\r",
lf => "\n",
ff => "\f",
-# The vertical tabulator seems miraculously be 12 both in ASCII and EBCDIC.
- vt => chr(11),
+ vt => "\v",
false => "space" );
my @space0 = sort grep { $space{$_} =~ /\s/ } keys %space;
my @space1 = sort grep { $space{$_} =~ /[[:space:]]/ } keys %space;
my @space2 = sort grep { $space{$_} =~ /[[:blank:]]/ } keys %space;
-print "not " unless "@space0" eq "cr ff lf spc tab";
+print "not " unless "@space0" eq "cr ff lf spc tab vt";
print "ok $test\n";
$test++;
=back
To be strict the perl5 to perl6 convertor would need to
=over 4
=item *
replace C<\v> with C<v> in interpolated strings.
=item *
replace C<\s> with C<[\t\n\r\f ]> and C<\S> with C<[^\t\n\r\f ]> in regular
expressions.
=back
It might be considered acceptable to omit either or both conversions if the
number of programs that would break were negligible.
=head1 REFERENCES
perlop manpage for interpolation
perlre manpage for \s and \S
