From 79b169d9513017b9849696d0d49f78b0b8401076 Mon Sep 17 00:00:00 2001
From: mark <markbaumeister26@gmail.com>
Date: Thu, 11 May 2023 01:56:33 +0200
Subject: [PATCH] fixed bug where all but the first loop iterations would write
 data to the mutable variables from the last iteration(s) even though the
 variables are supposed to be completely local: is_init can be set on
 steatements that have an output_to to force them to always redeclare and
 never reassign the new value.

---
 mers/src/script/code_runnable.rs | 26 ++++++++++++++++----------
 mers/src/script/to_runnable.rs   |  6 +++---
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/mers/src/script/code_runnable.rs b/mers/src/script/code_runnable.rs
index 8a1b220..85dc9a8 100755
--- a/mers/src/script/code_runnable.rs
+++ b/mers/src/script/code_runnable.rs
@@ -81,27 +81,33 @@ impl RFunction {
 
 #[derive(Clone, Debug)]
 pub struct RStatement {
-    pub output_to: Option<(usize, usize)>,
+    // (_, _, is_init)
+    pub output_to: Option<(usize, usize, bool)>,
     statement: Box<RStatementEnum>,
     pub force_output_type: Option<VType>,
 }
 impl RStatement {
     pub fn run(&self, vars: &mut Vec<VData>, info: &GSInfo) -> VData {
         let out = self.statement.run(vars, info);
-        if let Some((v, derefs)) = self.output_to {
-            let mut val = dereference_n(&mut vars[v], derefs);
-            fn dereference_n(d: &mut VData, n: usize) -> VData {
-                if n > 0 {
-                    if let VDataEnum::Reference(v) = &mut d.data.lock().unwrap().0 {
-                        dereference_n(v, n - 1)
+        if let Some((v, derefs, is_init)) = self.output_to {
+            // let mut parent = None;
+            let mut val = &mut vars[v];
+            fn deref(n: usize, val: &mut VData, is_init: bool, out: VData) {
+                if n == 0 {
+                    if is_init {
+                        *val = out.inner().to();
                     } else {
-                        unreachable!("dereferencing something that isn't a reference in assignment")
+                        val.assign(out.inner());
                     }
                 } else {
-                    d.clone_mut()
+                    if let VDataEnum::Reference(r) = &mut val.data().0 {
+                        deref(n - 1, r, is_init, out)
+                    } else {
+                        unreachable!("cannot derefence: not a reference.");
+                    }
                 }
             }
-            val.assign(out.inner());
+            deref(derefs, val, is_init, out);
             VDataEnum::Tuple(vec![]).to()
         } else {
             out
diff --git a/mers/src/script/to_runnable.rs b/mers/src/script/to_runnable.rs
index aeceb96..c2d50aa 100755
--- a/mers/src/script/to_runnable.rs
+++ b/mers/src/script/to_runnable.rs
@@ -652,11 +652,11 @@ fn statement(
                     ));
                 }
                 linfo.vars.insert(opt.clone(), (ginfo.vars, out));
-                statement.output_to = Some((ginfo.vars, 0));
+                statement.output_to = Some((ginfo.vars, 0, true));
                 ginfo.vars += 1;
             } else {
                 // mutate existing variable
-                statement.output_to = Some((*var_id, *derefs));
+                statement.output_to = Some((*var_id, *derefs, false));
             }
         } else {
             let mut out = statement.out(ginfo);
@@ -672,7 +672,7 @@ fn statement(
                 }
             }
             linfo.vars.insert(opt.clone(), (ginfo.vars, out));
-            statement.output_to = Some((ginfo.vars, *derefs));
+            statement.output_to = Some((ginfo.vars, *derefs, true));
             ginfo.vars += 1;
         }
     }