refactor: 拆分 class 相关编译逻辑

crates/oxide_compiler/src/class/header.rs

@@ -0,0 +1,24 @@
+use crate::compiler::{CompileCtx, Compiler};
+
+impl Compiler {
+    pub(crate) fn count_class_header(&self, class: &oxide_parser::Class, ctx: &mut CompileCtx) {
+        ctx.alloc_reg();
+        ctx.alloc_reg();
+        if let Some(super_class) = &class.super_class {
+            self.count_expression(super_class, ctx);
+        }
+    }
+
+    pub(crate) fn emit_class_header(
+        &self, class: &oxide_parser::Class, ctx: &mut CompileCtx,
+    ) -> Result<(u8, u8, Option<u8>), String> {
+        let ctor_reg = ctx.alloc_reg();
+        let proto_reg = ctx.alloc_reg();
+        let super_reg = if let Some(super_expr) = &class.super_class {
+            Some(self.emit_expression(super_expr, ctx)?)
+        } else {
+            None
+        };
+        Ok((ctor_reg, proto_reg, super_reg))
+    }
+}