use crate::obj::prelude::*;
use std::collections::BTreeMap;

#[derive(Default)]
pub struct Frame {
    stack: Vec<DynRef>,
    ip: usize,
    return_value: Option<DynRef>,
    locals: BTreeMap<Sym, DynRef>,
}

impl Frame {
    pub fn new() -> Self {
        Default::default()
    }

    pub fn push(&mut self, obj_ref: DynRef) {
        self.stack.push(obj_ref)
    }
    
    pub fn pop(&mut self) -> Option<DynRef> {
        self.stack.pop()
    }

    pub fn ip(&self) -> usize {
        self.ip
    }

    pub fn set_ip(&mut self, ip: usize) {
        self.ip = ip;
    }

    pub fn return_value(&self) -> Option<DynRef> {
        self.return_value
    }

    pub fn set_return_value(&mut self, obj_ref: DynRef) {
        self.return_value = Some(obj_ref);
    }

    pub fn get_local(&self, sym: Sym) -> Option<DynRef> {
        self.locals.get(&sym).copied()
    }

    pub fn set_local(&mut self, sym: Sym, obj_ref: DynRef) -> Option<DynRef> {
        self.locals.insert(sym, obj_ref)
    }
}