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Frame-aware lookups

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greg 2018-03-01 23:13:32 -08:00
parent a105c84943
commit 57c7858c87
1 changed files with 20 additions and 6 deletions
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26
src/schala_lang/eval.rs
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@ -8,6 +8,20 @@ pub struct State<'a> {
values: HashMap<Rc<String>, ValueEntry>, values: HashMap<Rc<String>, ValueEntry>,
} }
impl<'a> State<'a> {
fn insert(&mut self, name: Rc<String>, value: ValueEntry) {
self.values.insert(name, value);
}
fn lookup(&self, name: &Rc<String>) -> Option<&ValueEntry> {
match (self.values.get(name), self.parent_frame) {
(None, None) => None,
(None, Some(parent)) => parent.lookup(name),
(Some(value), _) => Some(value),
}
}
}
#[derive(Debug)] #[derive(Debug)]
enum ValueEntry { enum ValueEntry {
Binding { Binding {
@ -95,12 +109,12 @@ impl<'a> State<'a> {
FuncDecl(signature, statements) => { FuncDecl(signature, statements) => {
let name = signature.name; let name = signature.name;
let param_names: Vec<Rc<String>> = signature.params.iter().map(|fp| fp.0.clone()).collect(); let param_names: Vec<Rc<String>> = signature.params.iter().map(|fp| fp.0.clone()).collect();
self.values.insert(name, ValueEntry::Function { body: statements.clone(), param_names }); self.insert(name, ValueEntry::Function { body: statements.clone(), param_names });
}, },
TypeDecl(_name, body) => { TypeDecl(_name, body) => {
for variant in body.0.iter() { for variant in body.0.iter() {
match variant { match variant {
&UnitStruct(ref name) => self.values.insert(name.clone(), &UnitStruct(ref name) => self.insert(name.clone(),
ValueEntry::Binding { val: FullyEvaluatedExpr::Custom { string_rep: name.clone() } }), ValueEntry::Binding { val: FullyEvaluatedExpr::Custom { string_rep: name.clone() } }),
&TupleStruct(ref _name, ref _args) => unimplemented!(), &TupleStruct(ref _name, ref _args) => unimplemented!(),
&Record(ref _name, ref _fields) => unimplemented!(), &Record(ref _name, ref _fields) => unimplemented!(),
@ -109,7 +123,7 @@ impl<'a> State<'a> {
}, },
Binding { name, constant, expr } => { Binding { name, constant, expr } => {
let val = self.eval_expr(expr)?; let val = self.eval_expr(expr)?;
self.values.insert(name.clone(), ValueEntry::Binding { val }); self.insert(name.clone(), ValueEntry::Binding { val });
}, },
_ => return Err(format!("Declaration evaluation not yet implemented")) _ => return Err(format!("Declaration evaluation not yet implemented"))
} }
@ -154,7 +168,7 @@ impl<'a> State<'a> {
use self::ExpressionType::*; use self::ExpressionType::*;
match f { match f {
Expression(Value(identifier), _) => { Expression(Value(identifier), _) => {
match self.values.get(&identifier) { match self.lookup(&identifier) {
Some(&ValueEntry::Function { ref body, ref param_names }) => { Some(&ValueEntry::Function { ref body, ref param_names }) => {
if arguments.len() != param_names.len() { if arguments.len() != param_names.len() {
return Err(format!("Wrong number of arguments for the function")); return Err(format!("Wrong number of arguments for the function"));
@ -162,7 +176,7 @@ impl<'a> State<'a> {
let mut new_state = State::new_with_parent(self); let mut new_state = State::new_with_parent(self);
let sub_ast = body.clone(); let sub_ast = body.clone();
for (param, val) in param_names.iter().zip(arguments.into_iter()) { for (param, val) in param_names.iter().zip(arguments.into_iter()) {
new_state.values.insert(param.clone(), ValueEntry::Binding { val }); new_state.insert(param.clone(), ValueEntry::Binding { val });
} }
let mut ret: Option<FullyEvaluatedExpr> = None; let mut ret: Option<FullyEvaluatedExpr> = None;
for statement in sub_ast.into_iter() { for statement in sub_ast.into_iter() {
@ -179,7 +193,7 @@ impl<'a> State<'a> {
fn eval_value(&mut self, name: Rc<String>) -> EvalResult<FullyEvaluatedExpr> { fn eval_value(&mut self, name: Rc<String>) -> EvalResult<FullyEvaluatedExpr> {
use self::ValueEntry::*; use self::ValueEntry::*;
match self.values.get(&name) { match self.lookup(&name) {
None => return Err(format!("Value {} not found", *name)), None => return Err(format!("Value {} not found", *name)),
Some(lookup) => match lookup { Some(lookup) => match lookup {
&Binding { ref val } => Ok(val.clone()), &Binding { ref val } => Ok(val.clone()),