优化等价市值排序的选股路径

crates/fidc-core/src/platform_expr_strategy.rs

@@ -9219,6 +9219,15 @@ impl PlatformExprStrategy {
             .unwrap_or_else(|| self.field_value(candidate)))
     }
 
+    fn rank_reuses_market_cap_order(&self) -> bool {
+        self.config.rank_expr.trim().is_empty()
+            && !self.config.rank_desc
+            && matches!(
+                self.config.rank_by.trim(),
+                "market_cap" | "market_cap_bn"
+            )
+    }
+
     fn can_sell_position(&self, ctx: &StrategyContext<'_>, date: NaiveDate, symbol: &str) -> bool {
         self.can_sell_position_at_time(ctx, date, symbol, None)
     }
@@ -9429,6 +9438,7 @@ impl PlatformExprStrategy {
             }
             candidates.push((candidate, stock, rank_value));
         }
+        if !self.rank_reuses_market_cap_order() {
             candidates.sort_by(|lhs, rhs| {
                 let lhs_value = lhs.2;
                 let rhs_value = rhs.2;
@@ -9447,6 +9457,7 @@ impl PlatformExprStrategy {
                     ordering
                 }
             });
+        }
 
         let mut selected = Vec::new();
         for (candidate, stock, _) in candidates {
@@ -13749,6 +13760,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn market_cap_ascending_rank_reuses_only_equivalent_universe_order() {
+        let mut cfg = PlatformExprStrategyConfig::microcap_rotation();
+        cfg.rank_by = "market_cap".to_string();
+        let strategy = PlatformExprStrategy::new(cfg.clone());
+        assert!(strategy.rank_reuses_market_cap_order());
+
+        cfg.rank_by = "market_cap_bn".to_string();
+        assert!(PlatformExprStrategy::new(cfg.clone()).rank_reuses_market_cap_order());
+
+        cfg.rank_desc = true;
+        assert!(!PlatformExprStrategy::new(cfg.clone()).rank_reuses_market_cap_order());
+
+        cfg.rank_desc = false;
+        cfg.rank_expr = "close".to_string();
+        assert!(!PlatformExprStrategy::new(cfg.clone()).rank_reuses_market_cap_order());
+
+        cfg.rank_expr.clear();
+        cfg.rank_by = "free_float_cap".to_string();
+        assert!(!PlatformExprStrategy::new(cfg).rank_reuses_market_cap_order());
+    }
+
     #[test]
     fn current_rolling_helpers_do_not_load_factor_maps_or_decision_rollings() {
         let mut cfg = PlatformExprStrategyConfig::microcap_rotation();