refactor(preg): merge preg_match_all_offset_capture2() into its sibling

The two functions ran the same search and differed only in how they
reported a non-participating group: one as ("", 0) in a bespoke struct,
the other as (null, -1) in a capture-key map. Neither shape covered both
callers, because PHP reaches preg_match_all() with different flags from
each: Preg::matchAllWithOffsets() always ORs in PREG_UNMATCHED_AS_NULL,
while OutputFormatter::formatAndWrap() passes PREG_OFFSET_CAPTURE alone.

Keep the capture-key map, which also exposes named groups, and take the
flags that decide between null and "" for an unmatched group. The offset
is -1 either way, so the ("", 0) approximation is gone.

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

1 files changed, 3 insertions, 2 deletions

diff --git a/crates/shirabe-pcre/src/preg.rs b/crates/shirabe-pcre/src/preg.rs
index 822609a9..8fb0c2e8 100644
--- a/crates/shirabe-pcre/src/preg.rs
+++ b/crates/shirabe-pcre/src/preg.rs
@@ -15,7 +15,7 @@ use indexmap::IndexMap;
 pub use shirabe_php_shim::CaptureKey;
 use shirabe_php_shim::{
     PREG_OFFSET_CAPTURE, PREG_SET_ORDER, PREG_SPLIT_OFFSET_CAPTURE, PREG_UNMATCHED_AS_NULL,
-    PregPattern, preg_grep, preg_match_all_offset_capture2, preg_match_all2, preg_match2,
+    PregPattern, preg_grep, preg_match_all_offset_capture, preg_match_all2, preg_match2,
     preg_replace_callback, preg_replace2, preg_split2,
 };
 
@@ -89,7 +89,8 @@ impl Preg {
         matches: Option<&mut IndexMap<CaptureKey, Vec<(Option<String>, i64)>>>,
     ) -> usize {
         let mut internal: IndexMap<CaptureKey, Vec<(Option<String>, i64)>> = IndexMap::new();
-        let result = preg_match_all_offset_capture2(pattern, subject, &mut internal);
+        let result =
+            preg_match_all_offset_capture(pattern, subject, &mut internal, PREG_UNMATCHED_AS_NULL);
 
         if let Some(out) = matches {
             *out = internal;