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fix: validate charset flag conflicts in (?...) groups #45

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fix: validate charset flag conflicts in (?...) groups #45

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9 changes: 9 additions & 0 deletions README
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Expand Up @@ -305,6 +305,15 @@ ERROR HANDLING
RPe_IRANGE (-28)
Invalid [] range "%s-%s"

RPe_DUPLCH (-29)
Regexp modifier "%s" may not appear twice

RPe_EXCLCH (-30)
Regexp modifiers "%s" and "%s" are mutually exclusive

RPe_NEGCHR (-31)
Regexp modifier "%s" may not appear after the "-"

EXTENSIONS
Here are some ideas for extensions (sub-classes) for this module. Some
of them may be absorbed into the core functionality of Regexp::Parser in
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12 changes: 12 additions & 0 deletions lib/Regexp/Parser.pm
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Expand Up @@ -706,6 +706,18 @@ False [] range "%s-%s"

Invalid [] range "%s-%s"

=item RPe_DUPLCH (-29)

Regexp modifier "%s" may not appear twice

=item RPe_EXCLCH (-30)

Regexp modifiers "%s" and "%s" are mutually exclusive

=item RPe_NEGCHR (-31)

Regexp modifier "%s" may not appear after the "-"

=back

=head1 EXTENSIONS
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3 changes: 3 additions & 0 deletions lib/Regexp/Parser/Diagnostics.pm
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Expand Up @@ -34,5 +34,8 @@ use constant RPe_OUTPOS => --$ENUM, 'POSIX syntax [%s %s] belongs inside charact
use constant RPe_EMPTYB => --$ENUM, 'Empty \%s{}';
use constant RPe_FRANGE => --$ENUM, 'False [] range "%s-%s"';
use constant RPe_IRANGE => --$ENUM, 'Invalid [] range "%s-%s"';
use constant RPe_DUPLCH => --$ENUM, 'Regexp modifier "%s" may not appear twice';
use constant RPe_EXCLCH => --$ENUM, 'Regexp modifiers "%s" and "%s" are mutually exclusive';
use constant RPe_NEGCHR => --$ENUM, 'Regexp modifier "%s" may not appear after the "-"';

1;
22 changes: 22 additions & 0 deletions lib/Regexp/Parser/Handlers.pm
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Expand Up @@ -734,10 +734,28 @@ sub init {
&RxPOS -= length($on.$off);
my $old = &RxPOS;

my $charset_seen = ''; # track first charset flag (a/d/l/u)
for (split //, $on) {
&RxPOS++;
if (my $f = $S->can("FLAG_$_")) {
my $v = $S->$f(1) and $r_on .= $_;
# charset flag conflict detection (Perl 5.14+)
if ($v && ($v & 0xF0)) { # this is a charset flag
if ($charset_seen) {
if ($charset_seen eq $_ && $_ eq 'a') {
# aa (strict ASCII) is valid — continue
}
elsif ($charset_seen eq $_) {
# dd, ll, uu — doubled non-a charset flag
$S->error($S->RPe_DUPLCH, $_);
}
else {
# different charset flags — mutually exclusive
$S->error($S->RPe_EXCLCH, $charset_seen, $_);
}
}
$charset_seen = $_;
}
# /xx: if x is already on, set the xx bit (Perl 5.26+)
if ($_ eq 'x' && ($f_on & $v)) {
$f_on |= 0x200; # FLAG_xx
Expand All @@ -756,6 +774,10 @@ sub init {
&RxPOS++;
if (my $f = $S->can("FLAG_$_")) {
my $v = $S->$f(0) and $r_off .= $_;
# charset flags may not appear after - (Perl 5.14+)
if ($v && ($v & 0xF0)) {
$S->error($S->RPe_NEGCHR, $_);
}
# -xx: also turn off the xx bit (Perl 5.26+)
if ($_ eq 'x' && ($f_off & $v)) {
$f_off |= 0x200; # FLAG_xx
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40 changes: 40 additions & 0 deletions t/11errors.t
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Expand Up @@ -263,6 +263,46 @@ warns_regex('(?o)', 'useless (?o) flag warning');
# Negative flag forms too
warns_regex('(?-g)', 'useless (?-g) flag warning');

##
## 9b. CHARSET FLAG CONFLICTS — RPe_DUPLCH, RPe_EXCLCH, RPe_NEGCHR
##

# Doubled non-a charset flags (Perl rejects these)
fails_regex('(?dd:a)', ($r->RPe_DUPLCH)[0], 'doubled d flag');
fails_regex('(?ll:a)', ($r->RPe_DUPLCH)[0], 'doubled l flag');
fails_regex('(?uu:a)', ($r->RPe_DUPLCH)[0], 'doubled u flag');

# Mutually exclusive charset flags
fails_regex('(?al:a)', ($r->RPe_EXCLCH)[0], 'a and l mutually exclusive');
fails_regex('(?ad:a)', ($r->RPe_EXCLCH)[0], 'a and d mutually exclusive');
fails_regex('(?au:a)', ($r->RPe_EXCLCH)[0], 'a and u mutually exclusive');
fails_regex('(?du:a)', ($r->RPe_EXCLCH)[0], 'd and u mutually exclusive');
fails_regex('(?dl:a)', ($r->RPe_EXCLCH)[0], 'd and l mutually exclusive');
fails_regex('(?lu:a)', ($r->RPe_EXCLCH)[0], 'l and u mutually exclusive');

# Charset flags not allowed after - (negation section)
fails_regex('(?-a:a)', ($r->RPe_NEGCHR)[0], 'charset a after -');
fails_regex('(?-d:a)', ($r->RPe_NEGCHR)[0], 'charset d after -');
fails_regex('(?-l:a)', ($r->RPe_NEGCHR)[0], 'charset l after -');
fails_regex('(?-u:a)', ($r->RPe_NEGCHR)[0], 'charset u after -');
fails_regex('(?i-a:a)', ($r->RPe_NEGCHR)[0], 'charset a after - with on-flags');
fails_regex('(?i-al:a)', ($r->RPe_NEGCHR)[0], 'charset a after - mixed');

# Valid charset flag usage
parses_ok('(?aa:a)', 'aa (strict ASCII) is valid');
parses_ok('(?a:a)', 'single a flag valid');
parses_ok('(?d:a)', 'single d flag valid');
parses_ok('(?l:a)', 'single l flag valid');
parses_ok('(?u:a)', 'single u flag valid');
parses_ok('(?ai:a)', 'charset a + modifier i valid');
parses_ok('(?aai:a)', 'strict ASCII + modifier i valid');
parses_ok('(?^a:a)', 'caret + charset a valid');
parses_ok('(?^aa:a)', 'caret + strict ASCII valid');

# Caret with charset conflicts should also fail
fails_regex('(?^al:a)', ($r->RPe_EXCLCH)[0], 'caret + a and l exclusive');
fails_regex('(?^du:a)', ($r->RPe_EXCLCH)[0], 'caret + d and u exclusive');

##
## 10. BAD ESCAPE IN CHARACTER CLASS WARNINGS — RPe_BADESC
##
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