refactor(symfony-string): extract symfony/string into the shirabe-symfony-string crate

Move `Symfony\Component\String` out of shirabe-external-packages and into
its own crate, so the path is `shirabe_symfony_string::ByteString`
instead of `shirabe_external_packages::symfony::string::ByteString`.

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

1 files changed, 56 insertions, 0 deletions

diff --git a/crates/shirabe-symfony-string/src/unicode_string.rs b/crates/shirabe-symfony-string/src/unicode_string.rs
new file mode 100644
index 00000000..9048f77b
--- /dev/null
+++ b/crates/shirabe-symfony-string/src/unicode_string.rs
@@ -0,0 +1,56 @@
+//! ref: composer/vendor/symfony/string/UnicodeString.php
+
+#[derive(Debug, Clone)]
+pub struct UnicodeString {
+    pub(crate) string: String,
+}
+
+impl UnicodeString {
+    // TODO(phase-c): the real constructor runs `normalizer_normalize` (Unicode NFC normalization),
+    // which has no Rust std equivalent and would need a dedicated normalization implementation.
+    // Normalization is skipped here, which is only correct for already-NFC input such as ASCII.
+    pub fn new(string: &str) -> Self {
+        Self {
+            string: string.to_string(),
+        }
+    }
+
+    // TODO(phase-c): ASCII-only provisional implementation. The faithful `width()` uses `wcswidth`
+    // with the Unicode width tables to treat wide characters as width 2 and skip zero-width /
+    // combining characters; here every character counts as width 1, correct only for ASCII. The
+    // ANSI/control-character stripping driven by `ignore_ansi_decoration` is likewise not handled.
+    pub fn width(&self, _ignore_ansi_decoration: bool) -> i64 {
+        let s = self.string.replace(['\x00', '\x05', '\x07'], "");
+        let s = s.replace("\r\n", "\n").replace('\r', "\n");
+
+        let mut width: i64 = 0;
+        for line in s.split('\n') {
+            let line_width = line.chars().count() as i64;
+            if line_width > width {
+                width = line_width;
+            }
+        }
+
+        width
+    }
+
+    // TODO(phase-c): the faithful `length()` uses `grapheme_strlen` (extended grapheme clusters),
+    // which needs Unicode segmentation tables with no Rust std equivalent and no permitted crate.
+    // Approximated with the code-point count, exact only when no combining/multi-code-point
+    // clusters are present (e.g. ASCII).
+    pub fn length(&self) -> i64 {
+        shirabe_php_shim::mb_strlen(&self.string, "UTF-8")
+    }
+
+    // TODO(phase-c): the faithful `slice()` uses `grapheme_substr` (grapheme-cluster offsets), which
+    // needs Unicode segmentation tables with no std equivalent and no permitted crate. Approximated
+    // with code-point offsets via `mb_substr`, exact only without combining/multi-code-point clusters.
+    pub fn slice(&self, start: i64, length: Option<i64>) -> Self {
+        Self::new(&shirabe_php_shim::mb_substr(
+            &self.string,
+            start,
+            length,
+            Some("UTF-8"),
+        ))
+    }
+}