Interpretation timeout

kalk/src/interpreter.rs

@@ -12,15 +12,24 @@ pub struct Context<'a> {
     angle_unit: String,
     precision: u32,
     sum_n_value: Option<i128>,
+    timeout: Option<u32>,
+    start_time: std::time::SystemTime,
 }
 
 impl<'a> Context<'a> {
-    pub fn new(symbol_table: &'a mut SymbolTable, angle_unit: &str, precision: u32) -> Self {
+    pub fn new(
+        symbol_table: &'a mut SymbolTable,
+        angle_unit: &str,
+        precision: u32,
+        timeout: Option<u32>,
+    ) -> Self {
         Context {
             angle_unit: angle_unit.into(),
             symbol_table,
             precision,
             sum_n_value: None,
+            timeout: timeout,
+            start_time: std::time::SystemTime::now(),
         }
     }
 
@@ -82,6 +91,12 @@ fn eval_expr_stmt(context: &mut Context, expr: &Expr) -> Result<KalkNum, CalcErr
 }
 
 fn eval_expr(context: &mut Context, expr: &Expr, unit: &str) -> Result<KalkNum, CalcError> {
+    if let (Ok(elapsed), Some(timeout)) = (context.start_time.elapsed(), context.timeout) {
+        if elapsed.as_secs() >= timeout as u64 {
+            return Err(CalcError::TimedOut);
+        }
+    }
+
     match expr {
         Expr::Binary(left, op, right) => eval_binary_expr(context, &left, op, &right, unit),
         Expr::Unary(op, expr) => eval_unary_expr(context, op, expr, unit),
@@ -352,7 +367,7 @@ mod tests {
             .insert(DEG_RAD_UNIT.clone())
             .insert(RAD_DEG_UNIT.clone());
 
-        let mut context = Context::new(&mut symbol_table, "rad", PRECISION);
+        let mut context = Context::new(&mut symbol_table, "rad", PRECISION, None);
         context.interpret(vec![stmt])
     }
 
@@ -428,8 +443,8 @@ mod tests {
         deg_symbol_table
             .insert(DEG_RAD_UNIT.clone())
             .insert(RAD_DEG_UNIT.clone());
-        let mut rad_context = Context::new(&mut rad_symbol_table, "rad", PRECISION);
-        let mut deg_context = Context::new(&mut deg_symbol_table, "deg", PRECISION);
+        let mut rad_context = Context::new(&mut rad_symbol_table, "rad", PRECISION, None);
+        let mut deg_context = Context::new(&mut deg_symbol_table, "deg", PRECISION, None);
 
         assert!(cmp(
             rad_context
@@ -452,7 +467,7 @@ mod tests {
         let mut symbol_table = SymbolTable::new();
         symbol_table.insert(var_decl("x", literal(1f64)));
 
-        let mut context = Context::new(&mut symbol_table, "rad", PRECISION);
+        let mut context = Context::new(&mut symbol_table, "rad", PRECISION, None);
         assert_eq!(
             context.interpret(vec![stmt]).unwrap().unwrap().to_f64(),
             1f64
@@ -473,7 +488,7 @@ mod tests {
     fn test_var_decl() {
         let stmt = var_decl("x", literal(1f64));
         let mut symbol_table = SymbolTable::new();
-        Context::new(&mut symbol_table, "rad", PRECISION)
+        Context::new(&mut symbol_table, "rad", PRECISION, None)
             .interpret(vec![stmt])
             .unwrap();
 
@@ -492,7 +507,7 @@ mod tests {
             binary(var("x"), TokenKind::Plus, literal(2f64)),
         ));
 
-        let mut context = Context::new(&mut symbol_table, "rad", PRECISION);
+        let mut context = Context::new(&mut symbol_table, "rad", PRECISION, None);
         assert_eq!(
             context.interpret(vec![stmt]).unwrap().unwrap().to_f64(),
             3f64

kalk/src/parser.rs

@@ -24,6 +24,7 @@ pub struct Context {
     pos: usize,
     symbol_table: SymbolTable,
     angle_unit: String,
+    timeout: Option<u32>,
     /// This is true whenever the parser is currently parsing a unit declaration.
     /// It is necessary to keep track of this in order to know when to find (figure out) units that haven't been defined yet.
     /// Unit names are instead treated as variables.
@@ -43,6 +44,7 @@ impl Context {
             pos: 0,
             symbol_table: SymbolTable::new(),
             angle_unit: DEFAULT_ANGLE_UNIT.into(),
+            timeout: None,
             parsing_unit_decl: false,
             unit_decl_base_unit: None,
             parsing_identifier_stmt: false,
@@ -60,6 +62,12 @@ impl Context {
 
         self
     }
+
+    pub fn set_timeout(mut self, timeout: Option<u32>) -> Self {
+        self.timeout = timeout;
+
+        self
+    }
 }
 
 impl Default for Context {
@@ -75,6 +83,7 @@ pub enum CalcError {
     InvalidNumberLiteral(String),
     InvalidOperator,
     InvalidUnit,
+    TimedOut,
     UnexpectedToken(TokenKind, TokenKind),
     UndefinedFn(String),
     UndefinedVar(String),
@@ -95,8 +104,12 @@ pub fn eval(
     context.contains_equal_sign = input.contains("=");
     let statements = parse(context, input)?;
 
-    let mut interpreter =
-        interpreter::Context::new(&mut context.symbol_table, &context.angle_unit, precision);
+    let mut interpreter = interpreter::Context::new(
+        &mut context.symbol_table,
+        &context.angle_unit,
+        precision,
+        context.timeout,
+    );
     interpreter.interpret(statements)
 }
 

kalk_cli/src/main.rs

@@ -50,7 +50,9 @@ fn default_action(context: &Context) {
     } else {
         get_env_angle_unit()
     };
-    let mut parser_context = parser::Context::new().set_angle_unit(&angle_unit);
+    let mut parser_context = parser::Context::new()
+        .set_angle_unit(&angle_unit)
+        .set_timeout(Some(5));
     let precision = context.int_flag("precision").unwrap_or(53isize) as u32;
 
     if let Ok(input_file_path) = context.string_flag("input-file") {

kalk_cli/src/output.rs

@@ -35,6 +35,7 @@ fn print_calc_err(err: CalcError) {
         InvalidNumberLiteral(x) => format!("Invalid number literal: '{}'.", x),
         InvalidOperator => format!("Invalid operator."),
         InvalidUnit => format!("Invalid unit."),
+        TimedOut => format!("Operation took too long."),
         UnexpectedToken(got, expected) => {
             format!("Unexpected token: '{:?}', expected '{:?}'.", got, expected)
         }