Interpreter - Additional errors for variables
* Uninitialized variable usage * Redefining variables
This commit is contained in:
parent
e92628a4eb
commit
81aef09c5b
2 changed files with 25 additions and 10 deletions
|
@ -7,16 +7,19 @@ use super::{InterpreterResult, Value};
|
|||
/// A mutable reference to an environment.
|
||||
pub type EnvironmentRef = Rc<RefCell<Environment>>;
|
||||
|
||||
/// A variable.
|
||||
pub type Variable = Option<Value>;
|
||||
|
||||
/// The execution environment.
|
||||
#[derive(Debug, Default)]
|
||||
pub struct Environment {
|
||||
enclosing: Option<EnvironmentRef>,
|
||||
values: HashMap<String, Value>,
|
||||
values: HashMap<String, Variable>,
|
||||
}
|
||||
|
||||
impl Environment {
|
||||
/// Create an environment enclosed in another.
|
||||
pub fn create_child(parent: &Rc<RefCell<Self>>) -> Rc<RefCell<Self>> {
|
||||
pub fn create_child(parent: &EnvironmentRef) -> EnvironmentRef {
|
||||
Rc::new(RefCell::new(Self {
|
||||
enclosing: Some(parent.clone()),
|
||||
values: HashMap::default(),
|
||||
|
@ -24,8 +27,16 @@ impl Environment {
|
|||
}
|
||||
|
||||
/// Define a new variable.
|
||||
pub fn define(&mut self, name: String, value: Value) {
|
||||
self.values.insert(name, value);
|
||||
pub fn define(&mut self, name: &Token, value: Variable) -> Result<(), InterpreterError> {
|
||||
if self.values.contains_key(&name.lexeme as &str) {
|
||||
Err(InterpreterError::new(
|
||||
name,
|
||||
&format!("variables '{}' already defined in scope", name.lexeme),
|
||||
))
|
||||
} else {
|
||||
self.values.insert(name.lexeme.clone(), value);
|
||||
Ok(())
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the value of a variable.
|
||||
|
@ -38,14 +49,18 @@ impl Environment {
|
|||
)),
|
||||
Some(parent) => parent.borrow().get(name),
|
||||
},
|
||||
Some(value) => Ok(value.clone()),
|
||||
Some(None) => Err(InterpreterError::new(
|
||||
name,
|
||||
&format!("variable '{}' has not been initialized", name.lexeme),
|
||||
)),
|
||||
Some(Some(value)) => Ok(value.clone()),
|
||||
}
|
||||
}
|
||||
|
||||
/// Assign a value to an existing variable.
|
||||
pub fn assign(&mut self, name: &Token, value: Value) -> InterpreterResult {
|
||||
if self.values.contains_key(&name.lexeme as &str) {
|
||||
self.values.insert(name.lexeme.clone(), value);
|
||||
self.values.insert(name.lexeme.clone(), Some(value));
|
||||
Ok(Value::Nil)
|
||||
} else {
|
||||
match &mut self.enclosing {
|
||||
|
|
|
@ -77,11 +77,11 @@ impl ast::StmtNode {
|
|||
name: &Token,
|
||||
initializer: &Option<ast::ExprNode>,
|
||||
) -> InterpreterResult {
|
||||
let value = match initializer {
|
||||
Some(expr) => expr.interprete(environment)?,
|
||||
None => Value::Nil,
|
||||
let variable = match initializer {
|
||||
Some(expr) => Some(expr.interprete(environment)?),
|
||||
None => None,
|
||||
};
|
||||
environment.borrow_mut().define(name.lexeme.clone(), value);
|
||||
environment.borrow_mut().define(name, variable)?;
|
||||
Ok(Value::Nil)
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue