refactor(preg): split PregMatches reads into get() and name()

PregMatches keyed both forms of a capture group through CaptureKey, so
every read built one: a usize wrapped in an enum, or worse, a String
allocated to name a group that regex::Captures can look up from a &str.
It now mirrors regex::Captures instead -- get() takes the group number,
name() the group name -- and the enum drops out of the type entirely.

That is 285 call sites across 59 files, and the named ones carry most of
the win: `matches.get(&CaptureKey::ByName("host".to_string()))` reads as
`matches.name("host")`. ProcessExecutor loses a `user_key` binding that
existed only to build the key once.

CaptureKey stays as the key type of PregMatchesAll and
PregMatchesAllWithOffsets, where numbered and named entries share one
IndexMap and a key type is the point. Five files still name it.

Also retargets the two preg_match_all comments that described the
occurrence count through `matches[&CaptureKey::ByIndex(0)].len()`, an
Index impl these types no longer carry.

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

1 files changed, 8 insertions, 29 deletions

diff --git a/crates/shirabe/src/platform/version.rs b/crates/shirabe/src/platform/version.rs
index 204bdccd..00ff3097 100644
--- a/crates/shirabe/src/platform/version.rs
+++ b/crates/shirabe/src/platform/version.rs
@@ -1,6 +1,6 @@
 //! ref: composer/src/Composer/Platform/Version.php
 
-use shirabe_pcre::{CaptureKey, Preg};
+use shirabe_pcre::Preg;
 use shirabe_php_shim::{CmpOp, php_regex, version_compare};
 
 pub struct Version;
@@ -16,18 +16,9 @@ impl Version {
             openssl_version,
         )?;
 
-        let version = matches
-            .get(&CaptureKey::ByName("version".to_string()))
-            .unwrap_or_default()
-            .to_string();
-        let patch_str = matches
-            .get(&CaptureKey::ByName("patch".to_string()))
-            .unwrap_or_default()
-            .to_string();
-        let suffix_str = matches
-            .get(&CaptureKey::ByName("suffix".to_string()))
-            .unwrap_or_default()
-            .to_string();
+        let version = matches.name("version").unwrap_or_default().to_string();
+        let patch_str = matches.name("patch").unwrap_or_default().to_string();
+        let suffix_str = matches.name("suffix").unwrap_or_default().to_string();
 
         let patch = if version_compare(&version, "3.0.0", CmpOp::Lt) {
             format!(
@@ -56,14 +47,8 @@ impl Version {
             libjpeg_version,
         )?;
 
-        let major = matches
-            .get(&CaptureKey::ByName("major".to_string()))
-            .unwrap_or_default()
-            .to_string();
-        let minor = matches
-            .get(&CaptureKey::ByName("minor".to_string()))
-            .unwrap_or_default()
-            .to_string();
+        let major = matches.name("major").unwrap_or_default().to_string();
+        let minor = matches.name("minor").unwrap_or_default().to_string();
         Some(format!(
             "{}.{}",
             major,
@@ -77,14 +62,8 @@ impl Version {
             zoneinfo_version,
         )?;
 
-        let year = matches
-            .get(&CaptureKey::ByName("year".to_string()))
-            .unwrap_or_default()
-            .to_string();
-        let revision = matches
-            .get(&CaptureKey::ByName("revision".to_string()))
-            .unwrap_or_default()
-            .to_string();
+        let year = matches.name("year").unwrap_or_default().to_string();
+        let revision = matches.name("revision").unwrap_or_default().to_string();
         Some(format!(
             "{}.{}",
             year,