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fix: clean up stale try handlers #61

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Merged
TheUncharted merged 1 commit into from
Aug 29, 2026
Merged

fix: clean up stale try handlers #61

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39 changes: 33 additions & 6 deletions crates/zapcode-core/src/compiler/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,12 +31,14 @@ struct Compiler {
local_indices: HashMap<String, usize>,
functions: Vec<CompiledFunction>,
loop_stack: Vec<LoopInfo>,
try_depth: usize,
external_functions: HashSet<String>,
}

struct LoopInfo {
break_patches: Vec<usize>,
continue_patches: Vec<usize>,
try_depth: usize,
}

impl Compiler {
Expand All @@ -47,6 +49,7 @@ impl Compiler {
local_indices: HashMap::new(),
functions: Vec::new(),
loop_stack: Vec::new(),
try_depth: 0,
external_functions,
}
}
Expand Down Expand Up @@ -222,6 +225,7 @@ impl Compiler {
self.loop_stack.push(LoopInfo {
break_patches: Vec::new(),
continue_patches: Vec::new(),
try_depth: self.try_depth,
});

self.compile_expr(test)?;
Expand All @@ -248,6 +252,7 @@ impl Compiler {
self.loop_stack.push(LoopInfo {
break_patches: Vec::new(),
continue_patches: Vec::new(),
try_depth: self.try_depth,
});

for s in body {
Expand Down Expand Up @@ -282,6 +287,7 @@ impl Compiler {
self.loop_stack.push(LoopInfo {
break_patches: Vec::new(),
continue_patches: Vec::new(),
try_depth: self.try_depth,
});

let exit_jump = if let Some(test) = test {
Expand Down Expand Up @@ -329,6 +335,7 @@ impl Compiler {
self.loop_stack.push(LoopInfo {
break_patches: Vec::new(),
continue_patches: Vec::new(),
try_depth: self.try_depth,
});

self.emit(Instruction::Dup);
Expand Down Expand Up @@ -382,9 +389,11 @@ impl Compiler {
} => {
let setup = self.emit(Instruction::SetupTry(0, None));

self.try_depth += 1;
for s in try_body {
self.compile_statement(s)?;
}
self.try_depth -= 1;
self.emit(Instruction::EndTry);
let jump_past_catch = self.emit(Instruction::Jump(0));

Expand Down Expand Up @@ -413,16 +422,34 @@ impl Compiler {
}
}
Statement::Break { .. } => {
let idx = self.emit(Instruction::Jump(0));
if let Some(loop_info) = self.loop_stack.last_mut() {
loop_info.break_patches.push(idx);
let Some(target_try_depth) = self.loop_stack.last().map(|info| info.try_depth)
else {
return Err(ZapcodeError::CompileError(
"illegal break statement (not inside a loop)".to_string(),
));
};
for _ in target_try_depth..self.try_depth {
self.emit(Instruction::EndTry);
}
let idx = self.emit(Instruction::Jump(0));
self.loop_stack.last_mut().unwrap().break_patches.push(idx);
}
Statement::Continue { .. } => {
let idx = self.emit(Instruction::Jump(0));
if let Some(loop_info) = self.loop_stack.last_mut() {
loop_info.continue_patches.push(idx);
let Some(target_try_depth) = self.loop_stack.last().map(|info| info.try_depth)
else {
return Err(ZapcodeError::CompileError(
"illegal continue statement (not inside a loop)".to_string(),
));
};
for _ in target_try_depth..self.try_depth {
self.emit(Instruction::EndTry);
}
let idx = self.emit(Instruction::Jump(0));
self.loop_stack
.last_mut()
.unwrap()
.continue_patches
.push(idx);
}
Statement::FunctionDecl { func_index, .. } => {
self.emit(Instruction::CreateClosure(*func_index));
Expand Down
155 changes: 100 additions & 55 deletions crates/zapcode-core/src/vm/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,7 @@ pub struct Vm {
last_load_source: Option<ReceiverSource>,
/// Counter for assigning unique generator IDs.
next_generator_id: u64,
generator_try_handlers: HashMap<u64, Vec<SuspendedTryHandler>>,
}

#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
Expand All @@ -108,6 +109,11 @@ pub(crate) struct TryInfo {
pub(crate) stack_depth: usize,
}

struct SuspendedTryHandler {
catch_ip: usize,
stack_offset: usize,
}

impl Vm {
fn new(
program: CompiledProgram,
Expand Down Expand Up @@ -135,6 +141,7 @@ impl Vm {
last_global_name: None,
last_load_source: None,
next_generator_id: 0,
generator_try_handlers: HashMap::new(),
}
}

Expand Down Expand Up @@ -181,6 +188,7 @@ impl Vm {
last_global_name: None,
last_load_source: None,
next_generator_id: 0,
generator_try_handlers: HashMap::new(),
}
}

Expand All @@ -203,6 +211,60 @@ impl Vm {
.ok_or_else(|| ZapcodeError::RuntimeError("stack underflow".to_string()))
}

fn pop_call_frame(&mut self) -> Option<CallFrame> {
let frame = self.frames.pop()?;
self.tracker.pop_frame();
let remaining_depth = self.frames.len();
self.try_stack
.retain(|try_info| try_info.frame_depth <= remaining_depth);
Some(frame)
}

fn take_try_handler(&mut self, min_frame_depth: usize) -> Option<TryInfo> {
while let Some(try_info) = self.try_stack.last() {
if try_info.frame_depth > self.frames.len() {
self.try_stack.pop();
continue;
}
if try_info.frame_depth <= min_frame_depth {
return None;
}
return self.try_stack.pop();
}
None
}

fn try_handle_error(&mut self, err: &ZapcodeError, min_frame_depth: usize) -> Result<bool> {
let Some(try_info) = self.take_try_handler(min_frame_depth) else {
return Ok(false);
};

self.continuations.retain(|continuation| {
let callback_frame_index = match continuation {
Continuation::ArrayMap {
callback_frame_index,
..
}
| Continuation::ArrayForEach {
callback_frame_index,
..
} => *callback_frame_index,
};
callback_frame_index < try_info.frame_depth
});
while self.frames.len() > try_info.frame_depth {
self.pop_call_frame();
}
self.stack.truncate(try_info.stack_depth);
self.push(Value::String(Arc::from(err.to_string())))?;
let frame = self
.frames
.last_mut()
.ok_or_else(|| ZapcodeError::RuntimeError("no active call frame".to_string()))?;
frame.ip = try_info.catch_ip;
Ok(true)
}

fn peek(&self) -> Result<&Value> {
self.stack
.last()
Expand Down Expand Up @@ -364,8 +426,7 @@ impl Vm {
return Ok(VmState::Complete(result));
} else {
// Return from function
let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame = self.pop_call_frame().unwrap();
// If this was a constructor, return `this`
if let Some(this_val) = frame.this_value {
self.stack.truncate(frame.stack_base);
Expand All @@ -392,22 +453,7 @@ impl Vm {
}
}
Err(err) => {
// Try to catch the error
if let Some(try_info) = self.try_stack.pop() {
// Unwind to catch block
while self.frames.len() > try_info.frame_depth {
self.frames.pop();
self.tracker.pop_frame();
}
self.stack.truncate(try_info.stack_depth);

// Push error value
let error_val = Value::String(Arc::from(err.to_string()));
self.push(error_val)?;

// Jump to catch
self.current_frame_mut().ip = try_info.catch_ip;
} else {
if !self.try_handle_error(&err, 0)? {
return Err(err);
}
}
Expand Down Expand Up @@ -590,14 +636,12 @@ impl Vm {
// End of function without explicit return
if self.frames.len() > target_frame_depth + 1 {
// Inner function ended, pop and continue
self.frames.pop();
self.tracker.pop_frame();
self.pop_call_frame();
self.push(Value::Undefined)?;
continue;
} else {
// Our target function ended
self.frames.pop();
self.tracker.pop_frame();
self.pop_call_frame();
return Ok(Value::Undefined);
}
}
Expand All @@ -624,17 +668,7 @@ impl Vm {
}
}
Err(err) => {
// Try to catch the error within the callback
if let Some(try_info) = self.try_stack.pop() {
while self.frames.len() > try_info.frame_depth {
self.frames.pop();
self.tracker.pop_frame();
}
self.stack.truncate(try_info.stack_depth);
let error_val = Value::String(Arc::from(err.to_string()));
self.push(error_val)?;
self.current_frame_mut().ip = try_info.catch_ip;
} else {
if !self.try_handle_error(&err, target_frame_depth)? {
return Err(err);
}
}
Expand Down Expand Up @@ -1033,6 +1067,15 @@ impl Vm {
this_value: None,
receiver_source: None,
});
let frame_depth = self.frames.len();
if let Some(handlers) = self.generator_try_handlers.remove(&gen_obj.id) {
self.try_stack
.extend(handlers.into_iter().map(|handler| TryInfo {
catch_ip: handler.catch_ip,
frame_depth,
stack_depth: stack_base + handler.stack_offset,
}));
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}
self.run_generator_until_yield_or_return(gen_obj)
}
}
Expand All @@ -1044,6 +1087,7 @@ impl Vm {
let gen_key = format!("__gen_{}", gen_obj.id);
if gen_obj.done {
self.globals.remove(&gen_key);
self.generator_try_handlers.remove(&gen_obj.id);
} else {
self.globals.insert(gen_key, Value::Generator(gen_obj));
}
Expand Down Expand Up @@ -1074,8 +1118,7 @@ impl Vm {
};
if frame.ip >= instructions.len() {
if self.frames.len() > target_frame_depth + 1 {
let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame = self.pop_call_frame().unwrap();
if let Some(this_val) = frame.this_value {
self.stack.truncate(frame.stack_base);
self.push(this_val)?;
Expand All @@ -1084,8 +1127,7 @@ impl Vm {
}
continue;
}
let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame = self.pop_call_frame().unwrap();
self.stack.truncate(frame.stack_base);
let result = self.finish_generator(gen_obj, Value::Undefined);
return Ok(result);
Expand All @@ -1094,9 +1136,24 @@ impl Vm {
if matches!(instr, Instruction::Yield) {
self.current_frame_mut().ip += 1;
let yielded_value = self.pop()?;
let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame_depth = self.frames.len();
let frame_stack_base = self.current_frame().stack_base;
let try_handlers: Vec<SuspendedTryHandler> = self
.try_stack
.iter()
.filter(|try_info| try_info.frame_depth == frame_depth)
.map(|try_info| SuspendedTryHandler {
catch_ip: try_info.catch_ip,
stack_offset: try_info.stack_depth.saturating_sub(frame_stack_base),
})
.collect();
let frame = self.pop_call_frame().unwrap();
let frame_stack: Vec<Value> = self.stack.drain(frame.stack_base..).collect();
if try_handlers.is_empty() {
self.generator_try_handlers.remove(&gen_obj.id);
} else {
self.generator_try_handlers.insert(gen_obj.id, try_handlers);
}
gen_obj.suspended = Some(SuspendedFrame {
ip: frame.ip,
locals: frame.locals,
Expand All @@ -1110,14 +1167,12 @@ impl Vm {
self.current_frame_mut().ip += 1;
let return_val = self.pop().unwrap_or(Value::Undefined);
if self.frames.len() > target_frame_depth + 1 {
let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame = self.pop_call_frame().unwrap();
self.stack.truncate(frame.stack_base);
self.push(return_val)?;
continue;
}
let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame = self.pop_call_frame().unwrap();
self.stack.truncate(frame.stack_base);
let result = self.finish_generator(gen_obj, return_val);
return Ok(result);
Expand All @@ -1138,16 +1193,7 @@ impl Vm {
}
}
Err(err) => {
if let Some(try_info) = self.try_stack.pop() {
while self.frames.len() > try_info.frame_depth {
self.frames.pop();
self.tracker.pop_frame();
}
self.stack.truncate(try_info.stack_depth);
let error_val = Value::String(Arc::from(err.to_string()));
self.push(error_val)?;
self.current_frame_mut().ip = try_info.catch_ip;
} else {
if !self.try_handle_error(&err, target_frame_depth)? {
return Err(err);
}
}
Expand Down Expand Up @@ -1783,8 +1829,7 @@ impl Vm {
return Ok(Some(VmState::Complete(return_val)));
}

let frame = self.frames.pop().unwrap();
self.tracker.pop_frame();
let frame = self.pop_call_frame().unwrap();

// If this was a constructor frame (has this_value), return the
// updated `this` instead of the explicit return value (unless
Expand Down
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