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// use rustc_hash::FxHashMap as HashMap;
// use hashbrown::HashMap;
use std::{cell::RefCell, collections::HashMap, rc::Rc, vec};
// use std::println;
use crate::{expression::Ident, value::Value};
pub type Scope = Rc<RefCell<HashMap<usize, Value>>>;
pub struct Environment {
pub variables: Vec<Scope>,
depth: usize, // pub enclosing: Option<&'b mut Environment<'a, 'b>>,
/** Whether undeclared variables should implicitly define up to the top level like normal lua, or start in immediate scope */
implicit_global: bool,
strict: bool,
free_registers: Vec<usize>,
next_register: usize,
map: HashMap<String, usize>,
// local_table: HashMap<usize, usize>,
// meta_table: HashMap<usize, usize>, // key
}
impl Environment {
pub fn new() -> Self {
Environment {
variables: vec![Rc::new(RefCell::new(HashMap::default()))],
depth: 0, // enclosing: None,
implicit_global: true,
strict: false,
free_registers: vec![],
next_register: 0,
map: HashMap::default(),
}
}
pub fn new_with_std() -> Self {
let mut env = Environment::new();
env.load_standard_library();
env
}
pub fn load_standard_library(&mut self) {
// self.register_std("clock", crate::standard::clock);
// self.register_std("print", crate::standard::print);
}
fn register_std(&mut self, name: &str, func: fn(Vec<Value>) -> Value) -> usize {
// let u = self.to_register(name);
// self.declare_global((u, 0), Value::NativeFunction(func));
// u
todo!()
}
pub fn declare_global(&mut self, ident: Ident, value: Value) {
self.set(ident, value, true, false);
}
pub fn declare_local(&mut self, ident: Ident, value: Value) {
self.set(ident, value, true, true);
}
pub fn set_in_scope(&mut self, ident: usize, value: Value) {
self.variables[self.depth].borrow_mut().insert(ident, value);
}
pub fn assign_local(&mut self, ident: Ident, value: Value) {
self.set(ident, value, false, true);
}
/** If we have implicit global then we default implicit declaration to the highest level as lua
* does, otherwise we do something nicer and create in local scope if not shadowing anything*/
pub fn set(&mut self, ident: Ident, value: Value, declare: bool, local: bool) {
// if declare {
// self.variables[if local { self.depth } else { 0 }].insert(ident, value);
// } else {
// // println!(
// // "assign {} to {} (current depth {})",
// // value, ident, self.depth
// // );
// // check if exists
// if self.depth > 0 {
// // for vars in self.variables.iter_mut().rev() {
// // if let Some(val) = vars.get_mut(&ident) {
// // *val = value;
// // return;
// // }
// // }
// for i in (0..=self.depth).rev() {
// if let Some(val) = self.variables[i].get_mut(&ident) {
// *val = value;
// return;
// }
// }
// }
// // implicit declaration as we were unable to find an existing variable
// if self.implicit_global {
// self.variables[0].insert(ident, value);
// } else {
// self.variables[self.depth].insert(ident, value);
// }
// }
self.variables[ident.1].borrow_mut().insert(ident.0, value);
}
pub fn get(&self, ident: &Ident) -> Value {
// match self.variables.get(ident) {
// Some(v) => v.clone(),
// None => match &self.enclosing {
// Some(e) => e.get(ident),
// None => &Value::Nil,
// },
// }
if let Some(val) = self.variables[ident.1].borrow().get(&ident.0) {
val.clone()
} else {
Value::Nil
}
// if self.depth > 0 {
// for vars in self.variables.iter().rev() {
// if let Some(val) = vars.get(ident) {
// return val.clone();
// }
// }
// } else {
// if let Some(val) = self.variables[0].get(ident) {
// // println!("got");
// return val.clone();
// }
// }
// vars.get(ident)
}
// pub fn get_at(&self, ident: &usize, depth: usize) -> Value {
// if let Some(val) = self.variables[depth].borrow().get(ident) {
// return val.clone();
// }
// Value::Nil
// }
pub fn new_scope(&mut self) {
self.variables
.push(Rc::new(RefCell::new(HashMap::default())));
self.depth += 1;
}
pub fn pop_scope(&mut self) {
// self.variables.get_mut(self.depth).unwrap().clear(); // not faster, +2-3% time, despite keeping memory
// self.variables[self.depth].clear(); // about the same as popping +1% time, but keeps memory
self.variables.pop();
self.depth -= 1;
}
fn get_register(&mut self) -> usize {
if let Some(reg) = self.free_registers.pop() {
reg
} else {
let reg = self.next_register;
self.next_register += 1;
reg
}
}
pub fn get_current_scope(&self) -> Vec<Scope> {
self.variables
.iter()
.rev()
.take(self.depth + 1)
.map(|s| s.clone())
.collect()
}
///////////////////////////
pub fn swap_scope(&mut self, scope: &Vec<Scope>) -> Vec<Scope> {
let temp_scope = self.variables.drain(0..=self.depth).collect::<Vec<_>>();
self.variables.extend(scope.iter().rev().cloned());
self.depth = self.variables.len() - 1;
temp_scope
}
pub fn replace_scope(&mut self, scope: Vec<Scope>) {
self.variables = scope;
self.depth = self.variables.len() - 1;
}
///////////////////////////
pub fn resolve_local(&mut self, ident: usize, depth: usize) {
// TODO use the expression as a key? the expr as key should point to a the depth
// self.local_table.insert(ident, depth);
}
fn free_register(&mut self, reg: usize) {
self.free_registers.push(reg);
}
pub fn to_register(&mut self, name: &str) -> usize {
if let Some(reg) = self.map.get(name) {
*reg
} else {
let reg = self.get_register();
// println!("to_register {} @ {}", name, reg);
self.map.insert(name.to_string(), reg);
reg
}
}
pub fn from_register(&self, reg: usize) -> &str {
for (k, v) in self.map.iter() {
if *v == reg {
return k;
}
}
"unknown"
}
pub fn is_strict(&self) -> bool {
self.strict
}
}