From b74ddcfd6176d31e89cf9c8a5e9dc458504e4c92 Mon Sep 17 00:00:00 2001
From: Michael Schimmel <schimmel@mycelium.de>
Date: Sun, 1 Mar 2026 21:24:42 +0100
Subject: [PATCH] Introduce unified Series trait

This commit introduces the `Series` trait to provide a unified interface
for accessing indexed data across different series types (RecordSeries,
SeriesView, and future SharedSeries). This simplifies the VM's indexer
logic and lays the groundwork for the dual series architecture.
---
 src/ast/rtl/series.rs | 19 +++++++++++++++++++
 src/ast/types.rs      | 12 ++++++++++++
 src/ast/vm.rs         | 31 +++++++------------------------
 3 files changed, 38 insertions(+), 24 deletions(-)

diff --git a/src/ast/rtl/series.rs b/src/ast/rtl/series.rs
index efe5ece..8b4d9d8 100644
--- a/src/ast/rtl/series.rs
+++ b/src/ast/rtl/series.rs
@@ -285,6 +285,15 @@ impl Object for RecordSeries {
     fn as_any(&self) -> &dyn Any {
         self
     }
+    fn as_series(&self) -> Option<&dyn crate::ast::types::Series> {
+        Some(self)
+    }
+}
+
+impl crate::ast::types::Series for RecordSeries {
+    fn get_item(&self, index: usize) -> Option<Value> {
+        self.get_record(index)
+    }
 }
 
 // ============================================================================
@@ -328,6 +337,16 @@ impl Object for SeriesView {
     fn as_any(&self) -> &dyn Any {
         self
     }
+
+    fn as_series(&self) -> Option<&dyn crate::ast::types::Series> {
+        Some(self)
+    }
+}
+
+impl crate::ast::types::Series for SeriesView {
+    fn get_item(&self, index: usize) -> Option<Value> {
+        self.inner.borrow().get_value(index)
+    }
 }
 
 // ============================================================================
diff --git a/src/ast/types.rs b/src/ast/types.rs
index d810b7b..4eb49ce 100644
--- a/src/ast/types.rs
+++ b/src/ast/types.rs
@@ -180,6 +180,18 @@ impl RecordLayout {
 pub trait Object: fmt::Debug {
     fn type_name(&self) -> &'static str;
     fn as_any(&self) -> &dyn Any;
+    
+    /// Optional optimization: If this object behaves like a time series (indexable lookbacks),
+    /// it can return a reference to its Series trait implementation.
+    fn as_series(&self) -> Option<&dyn Series> {
+        None
+    }
+}
+
+/// Unified interface for all series types (Local RecordSeries, SeriesViews, and future SharedSeries).
+pub trait Series {
+    /// Gets the value at the specified lookback index (0 = newest).
+    fn get_item(&self, index: usize) -> Option<Value>;
 }
 
 /// A shared sequence of values, used by both Tuples and Records.
diff --git a/src/ast/vm.rs b/src/ast/vm.rs
index 0b242c8..4f8bc3c 100644
--- a/src/ast/vm.rs
+++ b/src/ast/vm.rs
@@ -529,41 +529,24 @@ impl VM {
                                     }
                                     res => break res,
                                 }
-                            } else if let Some(view) = obj.as_any().downcast_ref::<crate::ast::rtl::series::SeriesView>() {
-                                // Support for `(prices 0)` or `prices[0]` - reading from the 0-copy view!
+                            } else if let Some(series) = obj.as_series() {
+                                // Unified Series Access (Step 1 of Dual Series Architecture)
+                                // This handles RecordSeries, SeriesView, and future SharedSeries polymorphically.
                                 if arg_vals.len() != 1 {
-                                    break Err("Series indexer expects exactly 1 argument (the lookback index)".to_string());
+                                    break Err(format!("{} indexer expects exactly 1 argument (the lookback index)", obj.type_name()));
                                 }
                                 if let Value::Int(idx) = arg_vals[0] {
                                     if idx < 0 {
-                                        break Err("Series lookback index cannot be negative".to_string());
+                                        break Err(format!("{} lookback index cannot be negative", obj.type_name()));
                                     }
-                                    if let Some(val) = view.inner.borrow().get_value(idx as usize) {
+                                    if let Some(val) = series.get_item(idx as usize) {
                                         break Ok(val);
                                     } else {
                                         // Out of bounds / not enough data yet
                                         break Ok(Value::Void);
                                     }
                                 } else {
-                                    break Err("Series index must be an integer".to_string());
-                                }
-                            } else if let Some(rs) = obj.as_any().downcast_ref::<crate::ast::rtl::series::RecordSeries>() {
-                                // Support for `(my_ticks 0)` - reconstructs the full Record from SoA!
-                                if arg_vals.len() != 1 {
-                                    break Err("RecordSeries indexer expects exactly 1 argument (the lookback index)".to_string());
-                                }
-                                if let Value::Int(idx) = arg_vals[0] {
-                                    if idx < 0 {
-                                        break Err("RecordSeries lookback index cannot be negative".to_string());
-                                    }
-                                    if let Some(rec) = rs.get_record(idx as usize) {
-                                        break Ok(rec);
-                                    } else {
-                                        // Out of bounds / not enough data yet
-                                        break Ok(Value::Void);
-                                    }
-                                } else {
-                                    break Err("RecordSeries index must be an integer".to_string());
+                                    break Err(format!("{} index must be an integer", obj.type_name()));
                                 }
                             } else {
                                 break Err(format!("Object is not callable: {}", obj.type_name()));