refactor(preg): report unmatched groups as null throughout

The shim carried two reporting modes for the preg_* $matches maps: PHP's
default (trailing unmatched groups dropped, interior ones ""), and the
PREG_UNMATCHED_AS_NULL form, picked by calling a *_unmatched_as_null()
variant. The regex crate hands out Option<Match>, which maps onto the
null form directly, and no caller distinguished a dropped group from a
null one -- preg_match() and preg_match_all2() already reported nulls
unconditionally. Keep only the null form; the shim API no longer mirrors
PHP's flag set, which is intended.

Preg::is_match_with_indexed_captures() modelled PHP's "unset" as a
truncated Vec<String>, and now returns Vec<Option<String>>. That is what
Composer actually does: Preg::isMatch() always sets
PREG_UNMATCHED_AS_NULL, and its callers test groups with `!== null`.

preg_match_all(), preg_match_all_set_order() and
preg_split_delim_capture() still hand back Vec<String> and keep the ""
form.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/crates/shirabe/src/repository/vcs/svn_driver.rs b/crates/shirabe/src/repository/vcs/svn_driver.rs
index 297e8f33..db8c43f0 100644
--- a/crates/shirabe/src/repository/vcs/svn_driver.rs
+++ b/crates/shirabe/src/repository/vcs/svn_driver.rs
@@ -260,10 +260,10 @@ impl SvnDriver {
         let (path, rev) = if let Some(m) =
             Preg::is_match_with_indexed_captures(php_regex!(r"{^(.+?)(@\d+)?/$}"), &identifier)
         {
-            if m.get(2).is_some() {
+            if m[2].is_some() {
                 (
-                    m.get(1).cloned().unwrap_or_default(),
-                    m.get(2).cloned().unwrap_or_default(),
+                    m[1].clone().unwrap_or_default(),
+                    m[2].clone().unwrap_or_default(),
                 )
             } else {
                 (identifier.clone(), String::new())
@@ -300,10 +300,10 @@ impl SvnDriver {
         let (path, rev) = if let Some(m) =
             Preg::is_match_with_indexed_captures(php_regex!(r"{^(.+?)(@\d+)?/$}"), &identifier)
         {
-            if m.get(2).is_some() {
+            if m[2].is_some() {
                 (
-                    m.get(1).cloned().unwrap_or_default(),
-                    m.get(2).cloned().unwrap_or_default(),
+                    m[1].clone().unwrap_or_default(),
+                    m[2].clone().unwrap_or_default(),
                 )
             } else {
                 (identifier.clone(), String::new())