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use std::rc::Rc;
use std::cell::RefCell;
use std::collections::HashMap;
use types::{MalVal, MalRet, _nil, list, err_string};
use types::MalType::{Sym, List, Vector};
struct EnvType {
data: HashMap<String,MalVal>,
outer: Option<Env>,
}
pub type Env = Rc<RefCell<EnvType>>;
pub fn env_new(outer: Option<Env>) -> Env {
Rc::new(RefCell::new(EnvType{data: HashMap::new(), outer: outer}))
}
pub fn env_bind(env: &Env,
mbinds: MalVal,
mexprs: MalVal) -> Result<Env,String> {
let mut variadic = false;
match *mbinds {
List(ref binds,_) | Vector(ref binds,_) => {
match *mexprs {
List(ref exprs,_) | Vector(ref exprs,_) => {
let mut it = binds.iter().enumerate();
for (i, b) in it.by_ref() {
match **b {
Sym(ref strn) => {
if *strn == "&" {
variadic = true;
break;
} else {
env_set(env, b.clone(), exprs[i].clone());
}
}
_ => return Err("non-symbol bind".to_string()),
}
}
if variadic {
let (i, sym) = it.next().unwrap();
match **sym {
Sym(_) => {
let rest = exprs[i-1..].to_vec();
env_set(env, sym.clone(), list(rest));
}
_ => return Err("& bind to non-symbol".to_string()),
}
}
Ok(env.clone())
},
_ => Err("exprs must be a list".to_string()),
}
},
_ => Err("binds must be a list".to_string()),
}
}
pub fn env_find(env: &Env, key: &MalVal) -> Option<Env> {
match **key {
Sym(ref k) => {
let map = env.borrow();
if map.data.contains_key(k) {
Some(env.clone())
} else {
match map.outer {
Some(ref e) => env_find(e, key),
None => None,
}
}
},
_ => None
}
}
pub fn env_root(env: &Env) -> Env {
match env.borrow().outer {
Some(ref ei) => env_root(ei),
None => env.clone(),
}
}
pub fn env_set(env: &Env, key: MalVal, val: MalVal) {
match *key {
Sym(ref k) => { env.borrow_mut().data.insert(k.to_string(), val); }
_ => {},
}
}
pub fn env_get(env: &Env, key: &MalVal) -> MalRet {
match **key {
Sym(ref k) => {
match env_find(env, key) {
Some(e) => {
match e.borrow().data.get(k) {
Some(v) => Ok(v.clone()),
None => Ok(_nil()),
}
},
None => err_string(format!("'{}' not found", k)),
}
}
_ => err_string("env_get called with non-symbol key".to_string()),
}
}
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