From 5712221cd68b286f98c34f606b141cc6ba38ce52 Mon Sep 17 00:00:00 2001
From: Andrew Morris <voltrevo@gmail.com>
Date: Thu, 1 Jun 2023 11:53:36 +1000
Subject: [PATCH] Generators now work

---
 inputs/passing/range.ts                    | 23 ++++++++++++++++++++++
 valuescript_vm/src/bytecode_stack_frame.rs |  5 ++++-
 valuescript_vm/src/generator.rs            | 10 +++++++++-
 valuescript_vm/src/stack_frame.rs          |  1 +
 valuescript_vm/src/virtual_machine.rs      |  2 ++
 5 files changed, 39 insertions(+), 2 deletions(-)
 create mode 100644 inputs/passing/range.ts

diff --git a/inputs/passing/range.ts b/inputs/passing/range.ts
new file mode 100644
index 0000000..159803b
--- /dev/null
+++ b/inputs/passing/range.ts
@@ -0,0 +1,23 @@
+//! test_output({"iter":[4,5,6,7,8,9],"iterSnapshot":[2,3,4,5,6,7,8,9]})
+
+export default function main() {
+  let iter = range(10);
+  iter.next();
+  iter.next();
+
+  let iterSnapshot = iter;
+
+  iter.next();
+  iter.next();
+
+  return {
+    iter: [...iter],
+    iterSnapshot: [...iterSnapshot],
+  };
+}
+
+function* range(n: number) {
+  for (let i = 0; i < n; i++) {
+    yield i;
+  }
+}
diff --git a/valuescript_vm/src/bytecode_stack_frame.rs b/valuescript_vm/src/bytecode_stack_frame.rs
index c1f7a49..6c28007 100644
--- a/valuescript_vm/src/bytecode_stack_frame.rs
+++ b/valuescript_vm/src/bytecode_stack_frame.rs
@@ -553,7 +553,10 @@ impl StackFrameTrait for BytecodeStackFrame {
       }
 
       Yield => {
-        panic!("TODO: yield");
+        let val = self.decoder.decode_val(&self.registers);
+        self.decoder.decode_register_index(); // TODO: Use this
+
+        return Ok(FrameStepOk::Yield(val));
       }
 
       YieldStar => {
diff --git a/valuescript_vm/src/generator.rs b/valuescript_vm/src/generator.rs
index 38f4449..7da2de5 100644
--- a/valuescript_vm/src/generator.rs
+++ b/valuescript_vm/src/generator.rs
@@ -154,7 +154,7 @@ impl StackFrameTrait for GeneratorFrame {
     let fsr = self.generator.frame.step();
 
     match fsr {
-      Err(_) => Err("TODO: exceptions inside generators".to_error()),
+      Err(_) => fsr, // TODO: Stack unwind internal stack first
       Ok(FrameStepOk::Continue) | Ok(FrameStepOk::Push(_)) => fsr,
       Ok(FrameStepOk::Pop(call_result)) => Ok(FrameStepOk::Pop(CallResult {
         return_: IterationResult {
@@ -164,6 +164,14 @@ impl StackFrameTrait for GeneratorFrame {
         .to_dynamic_val(),
         this: take(&mut self.generator).to_dynamic_val(),
       })),
+      Ok(FrameStepOk::Yield(val)) => Ok(FrameStepOk::Pop(CallResult {
+        return_: IterationResult {
+          value: val,
+          done: false,
+        }
+        .to_dynamic_val(),
+        this: take(&mut self.generator).to_dynamic_val(),
+      })),
     }
   }
 
diff --git a/valuescript_vm/src/stack_frame.rs b/valuescript_vm/src/stack_frame.rs
index 85070aa..80d66f9 100644
--- a/valuescript_vm/src/stack_frame.rs
+++ b/valuescript_vm/src/stack_frame.rs
@@ -12,6 +12,7 @@ pub enum FrameStepOk {
   Continue,
   Pop(CallResult),
   Push(StackFrame),
+  Yield(Val),
 }
 
 pub type FrameStepResult = Result<FrameStepOk, Val>;
diff --git a/valuescript_vm/src/virtual_machine.rs b/valuescript_vm/src/virtual_machine.rs
index ffd8b69..ac49a13 100644
--- a/valuescript_vm/src/virtual_machine.rs
+++ b/valuescript_vm/src/virtual_machine.rs
@@ -86,6 +86,8 @@ impl VirtualMachine {
       FrameStepOk::Push(new_frame) => {
         self.push(new_frame);
       }
+      // TODO: Internal errors
+      FrameStepOk::Yield(_) => return self.handle_exception("Unexpected yield".to_error()),
     }
 
     Ok(())