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Fix interpreter variable persistence bug

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This commit is contained in:
Alex Bethel 2021-06-08 19:21:33 -05:00
parent 39c5709db7
commit 0fe7819e28
1 changed files with 19 additions and 11 deletions
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26
src/interpret.rs
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@ -61,15 +61,16 @@ impl ExecEnv {
/// other information. /// other information.
pub fn new() -> Self { pub fn new() -> Self {
Self { Self {
stack: Default::default(), // We always need at least one stackframe.
stack: vec![Default::default()],
} }
} }
/// Execute a set of Statements in their own stack frame. Return /// Execute a set of Statements in the root stack frame. Return an
/// an error if one or more of the Stmts failed to evaluate, or if /// error if one or more of the Stmts failed to evaluate, or if a
/// a `break` or `hopback` statement occurred at the top level. /// `break` or `hopback` statement occurred at the top level.
pub fn eval_stmts(&mut self, stmts: &[Stmt]) -> Result<(), Error> { pub fn eval_stmts(&mut self, stmts: &[Stmt]) -> Result<(), Error> {
match self.eval_stmts_hs(stmts)? { match self.eval_stmts_hs(stmts, false)? {
HaltStatus::Finished => Ok(()), HaltStatus::Finished => Ok(()),
HaltStatus::Break(span) | HaltStatus::Hopback(span) => Err(Error { HaltStatus::Break(span) | HaltStatus::Hopback(span) => Err(Error {
// It's an error to issue a `break` outside of a // It's an error to issue a `break` outside of a
@ -81,14 +82,18 @@ impl ExecEnv {
} }
/// The same as `eval_stmts`, but report "break" and "hopback" /// The same as `eval_stmts`, but report "break" and "hopback"
/// exit codes as normal conditions in a HaltStatus enum. /// exit codes as normal conditions in a HaltStatus enum, and
/// create a new stack frame if `stackframe` is true.
/// ///
/// `interpret`-internal code should typically prefer this /// `interpret`-internal code should typically prefer this
/// function over `eval_stmts`. /// function over `eval_stmts`.
fn eval_stmts_hs(&mut self, stmts: &[Stmt]) -> Result<HaltStatus, Error> { fn eval_stmts_hs(&mut self, stmts: &[Stmt], stackframe: bool) -> Result<HaltStatus, Error> {
let init_depth = self.stack.len(); let init_depth = self.stack.len();
if stackframe {
self.stack.push(Default::default()); self.stack.push(Default::default());
}
let mut final_result = Ok(HaltStatus::Finished); let mut final_result = Ok(HaltStatus::Finished);
for stmt in stmts { for stmt in stmts {
final_result = self.eval_stmt(stmt); final_result = self.eval_stmt(stmt);
@ -96,7 +101,10 @@ impl ExecEnv {
break; break;
} }
} }
if stackframe {
self.stack.pop(); self.stack.pop();
}
// Invariant: stack size must have net 0 change. // Invariant: stack size must have net 0 change.
debug_assert_eq!(self.stack.len(), init_depth); debug_assert_eq!(self.stack.len(), init_depth);
@ -211,7 +219,7 @@ impl ExecEnv {
// } // }
StmtKind::If { cond, body } => { StmtKind::If { cond, body } => {
if self.eval_expr(cond)?.to_bool() { if self.eval_expr(cond)?.to_bool() {
return self.eval_stmts_hs(&body.block); return self.eval_stmts_hs(&body.block, true);
} }
} }
StmtKind::Call { iden, args } => { StmtKind::Call { iden, args } => {
@ -254,7 +262,7 @@ impl ExecEnv {
} }
} }
StmtKind::Loop { body } => loop { StmtKind::Loop { body } => loop {
let res = self.eval_stmts_hs(&body.block)?; let res = self.eval_stmts_hs(&body.block, true)?;
match res { match res {
HaltStatus::Finished => {} HaltStatus::Finished => {}
HaltStatus::Break(_) => break, HaltStatus::Break(_) => break,