deps/vm: vendor regress 0.11.1 补 Script/Script_Extensions 的 Unknown(Zzzz) 取值——上游表缺未分配码点集取值，规范合法模式 \p{Script=Unknown} 编译期 SyntaxError；fork 纯增量（0 行改动上游行，仅补区间表与解析臂），回归钉四则（未分配匹配/已分配不匹配/sc·scx·Zzzz 别名/既有取值不扰动）

third_party/regress/src/cursor.rs

@@ -0,0 +1,77 @@
+use crate::indexing::InputIndexer;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Forward;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Backward;
+
+pub trait Direction: core::fmt::Debug + Copy + Clone {
+    const FORWARD: bool;
+    fn new() -> Self;
+}
+
+impl Direction for Forward {
+    const FORWARD: bool = true;
+    #[inline(always)]
+    fn new() -> Self {
+        Forward {}
+    }
+}
+
+impl Direction for Backward {
+    const FORWARD: bool = false;
+    #[inline(always)]
+    fn new() -> Self {
+        Backward {}
+    }
+}
+
+/// \return whether we match some literal bytes.
+/// If so, update the position. If not, the position is unspecified.
+#[inline(always)]
+pub fn try_match_lit<const N: usize, Input: InputIndexer, Dir: Direction>(
+    input: &Input,
+    dir: Dir,
+    pos: &mut Input::Position,
+    bytes: &[u8; N],
+) -> bool {
+    input.match_bytes(dir, pos, bytes)
+}
+
+/// \return the next character, updating the position.
+#[inline(always)]
+pub fn next<Input: InputIndexer, Dir: Direction>(
+    input: &Input,
+    _dir: Dir,
+    pos: &mut Input::Position,
+) -> Option<Input::Element> {
+    if Dir::FORWARD {
+        input.next_right(pos)
+    } else {
+        input.next_left(pos)
+    }
+}
+
+/// \return the next *byte*, or None if at the end, updating the position.
+/// Note this may break UTF8 sequences.
+#[inline(always)]
+pub fn next_byte<Input: InputIndexer, Dir: Direction>(
+    input: &Input,
+    _dir: Dir,
+    pos: &mut Input::Position,
+) -> Option<u8> {
+    assert!(
+        Input::CODE_UNITS_ARE_BYTES,
+        "Not implemented for non-byte input"
+    );
+    let res;
+    if Dir::FORWARD {
+        res = input.peek_byte_right(*pos);
+        *pos += if res.is_some() { 1 } else { 0 };
+    } else {
+        res = input.peek_byte_left(*pos);
+        *pos -= if res.is_some() { 1 } else { 0 };
+    }
+    res
+}