From c18ee2c2266fadd98de20b9f63a75cfa84461695 Mon Sep 17 00:00:00 2001
From: jess <jess@else-if.org>
Date: Sat, 30 May 2026 16:39:53 -0700
Subject: [PATCH] lib

---
 compile/src/lib.rs | 77 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 72 insertions(+), 5 deletions(-)

diff --git a/compile/src/lib.rs b/compile/src/lib.rs
index 1192ddb..a9f882e 100644
--- a/compile/src/lib.rs
+++ b/compile/src/lib.rs
@@ -182,9 +182,13 @@ fn emit_stmt(out: &mut String, stmt: &Stmt, depth: usize, deps: &mut Vec<Depende
             indent(out, depth, &format!("{} = {};", ident(name), rhs));
         }
         Stmt::PathAssign(lhs, expr) => {
-            let lhs_s = emit_expr(lhs, hook)?;
+            let mut steps = Vec::new();
+            let root = collect_lvalue_path(lhs, &mut steps, hook)?;
             let rhs = emit_expr(expr, hook)?;
-            indent(out, depth, &format!("v_path_assign(&mut {}, &{});", lhs_s, rhs));
+            indent(out, depth, &format!(
+                "v_assign_path(&mut {}, &[{}], {});",
+                root, steps.join(", "), rhs
+            ));
         }
         Stmt::Return(expr) => {
             let rhs = emit_expr(expr, hook)?;
@@ -277,6 +281,25 @@ fn emit_stmt(out: &mut String, stmt: &Stmt, depth: usize, deps: &mut Vec<Depende
     Ok(())
 }
 
+/// walks a Field/Index lvalue chain into a root identifier plus emitted Step nodes.
+fn collect_lvalue_path(expr: &Expr, steps: &mut Vec<String>, hook: &dyn DecomposeHook) -> Result<String, String> {
+    match expr {
+        Expr::Ident(name) => Ok(ident(name)),
+        Expr::Field(inner, field) => {
+            let root = collect_lvalue_path(inner, steps, hook)?;
+            steps.push(format!("Step::Field({:?}.into())", field));
+            Ok(root)
+        }
+        Expr::Index(inner, idx) => {
+            let root = collect_lvalue_path(inner, steps, hook)?;
+            let i = emit_expr(idx, hook)?;
+            steps.push(format!("Step::Index(v_num(&{}) as i64)", i));
+            Ok(root)
+        }
+        _ => Err("assignment target must root at a variable".into()),
+    }
+}
+
 fn emit_expr(expr: &Expr, hook: &dyn DecomposeHook) -> Result<String, String> {
     if let Some(custom) = hook.expr(expr) {
         return Ok(custom);
@@ -543,8 +566,31 @@ fn v_field(base: &V, name: &str) -> V {
     }
 }
 
-fn v_field_set(base: &mut V, _val: &V) {
-    let _ = base; // path assignment placeholder
+enum Step { Field(String), Index(i64) }
+
+fn v_assign_path(root: &mut V, steps: &[Step], val: V) {
+    let mut cur = root;
+    for (i, step) in steps.iter().enumerate() {
+        let last = i + 1 == steps.len();
+        match step {
+            Step::Field(k) => match cur {
+                V::Struct(m) => {
+                    if last { m.insert(k.clone(), val); return; }
+                    cur = m.entry(k.clone()).or_insert(V::Void);
+                }
+                _ => return,
+            },
+            Step::Index(idx) => match cur {
+                V::Array(a) => {
+                    let n = if *idx < 0 { (a.len() as i64 + idx) as usize } else { *idx as usize };
+                    if n >= a.len() { return; }
+                    if last { a[n] = val; return; }
+                    cur = &mut a[n];
+                }
+                _ => return,
+            },
+        }
+    }
 }
 
 fn v_iter(val: &V) -> Vec<V> {
@@ -555,7 +601,6 @@ fn v_iter(val: &V) -> Vec<V> {
     }
 }
 
-fn v_path_assign(target: &mut V, val: &V) { *target = val.clone(); }
 fn v_cell_get(_table: &str, _col: u32, _row: u32) -> V { V::Void }
 fn v_cell_range(_table: &str, _c1: u32, _r1: u32, _c2: u32, _r2: u32) -> V { V::Array(Vec::new()) }
 fn v_cell_table(_table: &str) -> V { V::Array(Vec::new()) }
@@ -729,8 +774,17 @@ impl Vec2 {
 let a = Vec2::new(1, 2)
 let b = Vec2::new(3, 4)
 let c = a + b
+let p = {x: 1, y: 2}
+p.x = 10
+let arr = [1, 2, 3]
+arr[1] = 20
+let node = {pose: {pos: {x: 0}}}
+node.pose.pos.x = 5
 ";
         let mut code = dec(src);
+        assert!(code.contains("v_assign_path(&mut p"));
+        assert!(code.contains("v_assign_path(&mut arr"));
+        assert!(code.contains("v_assign_path(&mut node"));
         code.push_str(r#"
 fn main() {
     let a = Vec2__new(V::Num(1.0), V::Num(2.0));
@@ -740,6 +794,19 @@ fn main() {
     assert_eq!(v_field(&c, "y"), V::Num(6.0));
     let l = v_method_call(&a, "len2", &[]);
     assert_eq!(l, V::Num(5.0));
+
+    let mut p = V::Struct([("x".to_string(), V::Num(1.0))].into_iter().collect());
+    v_assign_path(&mut p, &[Step::Field("x".into())], V::Num(10.0));
+    assert_eq!(v_field(&p, "x"), V::Num(10.0));
+
+    let mut arr = V::Array(vec![V::Num(1.0), V::Num(2.0), V::Num(3.0)]);
+    v_assign_path(&mut arr, &[Step::Index(1)], V::Num(20.0));
+    assert_eq!(v_index(&arr, &V::Num(1.0)), V::Num(20.0));
+
+    let mut node = V::Struct([("pose".to_string(), V::Struct([("pos".to_string(), V::Struct([("x".to_string(), V::Num(0.0))].into_iter().collect()))].into_iter().collect()))].into_iter().collect());
+    v_assign_path(&mut node, &[Step::Field("pose".into()), Step::Field("pos".into()), Step::Field("x".into())], V::Num(5.0));
+    assert_eq!(v_field(&v_field(&v_field(&node, "pose"), "pos"), "x"), V::Num(5.0));
+
     let _ = run();
     println!("OK");
 }