feat(tazjin/rlox): Implement calling user-defined functions

This slightly jiggles around interpret_block to let callers pass in an
environment.

Change-Id: I03112a38be0e8696242d8eae8d41da8c2cc66b48
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2392
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2021-01-14 18:03:05 +03:00 committed by tazjin
parent fe97398fd9
commit 56d8fa97ed

View file

@ -25,14 +25,23 @@ impl<'a> Callable<'a> {
fn arity(&self) -> usize {
match self {
Callable::Builtin(builtin) => builtin.arity(),
_ => unimplemented!(),
Callable::Function(func) => func.params.len(),
}
}
fn call(&self, args: Vec<Value>) -> Result<Value<'a>, Error> {
fn call(&self, lox: &mut Interpreter<'a>, args: Vec<Value<'a>>) -> Result<Value<'a>, Error> {
match self {
Callable::Builtin(builtin) => builtin.call(args),
_ => unimplemented!(),
Callable::Function(func) => {
let mut fn_env: Environment<'a> = Default::default();
for (param, value) in func.params.iter().zip(args.into_iter()) {
fn_env.define(param, value)?;
}
lox.interpret_block(Rc::new(RwLock::new(fn_env)), &func.body)
},
}
}
}
@ -208,7 +217,7 @@ impl<'a> Interpreter<'a> {
Value::Literal(Literal::String(output))
}
Statement::Var(var) => return self.interpret_var(var),
Statement::Block(block) => return self.interpret_block(block),
Statement::Block(block) => return self.interpret_block(Default::default(), block),
Statement::If(if_stmt) => return self.interpret_if(if_stmt),
Statement::While(while_stmt) => return self.interpret_while(while_stmt),
Statement::Function(_) => unimplemented!(),
@ -227,13 +236,17 @@ impl<'a> Interpreter<'a> {
Ok(value)
}
fn interpret_block(&mut self, block: &parser::Block<'a>) -> Result<Value<'a>, Error> {
fn interpret_block(
&mut self,
env: Rc<RwLock<Environment<'a>>>,
block: &parser::Block<'a>,
) -> Result<Value<'a>, Error> {
// Initialise a new environment and point it at the parent
// (this is a bit tedious because we need to wrap it in and
// out of the Rc).
//
// TODO(tazjin): Refactor this to use Rc on the interpreter itself.
let previous = std::mem::replace(&mut self.env, Default::default());
let previous = std::mem::replace(&mut self.env, env);
self.set_enclosing(previous.clone());
let result = self.interpret(block);
@ -388,7 +401,7 @@ impl<'a> Interpreter<'a> {
});
}
callable.call(args)
callable.call(self, args)
}
}