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-rw-r--r--users/tazjin/rlox/src/interpreter.rs73
-rw-r--r--users/tazjin/rlox/src/interpreter/tests.rs25
-rw-r--r--users/tazjin/rlox/src/main.rs9
3 files changed, 59 insertions, 48 deletions
diff --git a/users/tazjin/rlox/src/interpreter.rs b/users/tazjin/rlox/src/interpreter.rs
index 6aab389369ea..bd907542fb5e 100644
--- a/users/tazjin/rlox/src/interpreter.rs
+++ b/users/tazjin/rlox/src/interpreter.rs
@@ -16,32 +16,35 @@ mod tests;
 // Representation of all callables, including builtins & user-defined
 // functions.
 #[derive(Clone, Debug)]
-pub enum Callable {
+pub enum Callable<'a> {
     Builtin(&'static dyn builtins::Builtin),
+    Function(Rc<parser::Function<'a>>),
 }
 
-impl Callable {
+impl<'a> Callable<'a> {
     fn arity(&self) -> usize {
         match self {
             Callable::Builtin(builtin) => builtin.arity(),
+            _ => unimplemented!(),
         }
     }
 
-    fn call(&self, args: Vec<Value>) -> Result<Value, Error> {
+    fn call(&self, args: Vec<Value>) -> Result<Value<'a>, Error> {
         match self {
             Callable::Builtin(builtin) => builtin.call(args),
+            _ => unimplemented!(),
         }
     }
 }
 
 // Representation of an in-language value.
 #[derive(Clone, Debug)]
-pub enum Value {
+pub enum Value<'a> {
     Literal(Literal),
-    Callable(Callable),
+    Callable(Callable<'a>),
 }
 
-impl PartialEq for Value {
+impl<'a> PartialEq for Value<'a> {
     fn eq(&self, other: &Self) -> bool {
         match (self, other) {
             (Value::Literal(lhs), Value::Literal(rhs)) => lhs == rhs,
@@ -51,13 +54,13 @@ impl PartialEq for Value {
     }
 }
 
-impl From<Literal> for Value {
-    fn from(lit: Literal) -> Value {
+impl<'a> From<Literal> for Value<'a> {
+    fn from(lit: Literal) -> Value<'a> {
         Value::Literal(lit)
     }
 }
 
-impl Value {
+impl<'a> Value<'a> {
     fn expect_literal(self) -> Result<Literal, Error> {
         match self {
             Value::Literal(lit) => Ok(lit),
@@ -67,19 +70,19 @@ impl Value {
 }
 
 #[derive(Debug, Default)]
-struct Environment {
-    enclosing: Option<Rc<RwLock<Environment>>>,
-    values: HashMap<String, Value>,
+struct Environment<'a> {
+    enclosing: Option<Rc<RwLock<Environment<'a>>>>,
+    values: HashMap<String, Value<'a>>,
 }
 
-impl Environment {
-    fn define(&mut self, name: &scanner::Token, value: Value) -> Result<(), Error> {
+impl<'a> Environment<'a> {
+    fn define(&mut self, name: &scanner::Token, value: Value<'a>) -> Result<(), Error> {
         let ident = identifier_str(name)?;
         self.values.insert(ident.into(), value);
         Ok(())
     }
 
-    fn get(&self, name: &parser::Variable) -> Result<Value, Error> {
+    fn get(&self, name: &parser::Variable) -> Result<Value<'a>, Error> {
         let ident = identifier_str(&name.0)?;
 
         self.values
@@ -98,7 +101,7 @@ impl Environment {
             })
     }
 
-    fn assign(&mut self, name: &scanner::Token, value: Value) -> Result<(), Error> {
+    fn assign(&mut self, name: &scanner::Token, value: Value<'a>) -> Result<(), Error> {
         let ident = identifier_str(name)?;
 
         match self.values.get_mut(ident) {
@@ -132,11 +135,11 @@ fn identifier_str<'a>(name: &'a scanner::Token) -> Result<&'a str, Error> {
 }
 
 #[derive(Debug)]
-pub struct Interpreter {
-    env: Rc<RwLock<Environment>>,
+pub struct Interpreter<'a> {
+    env: Rc<RwLock<Environment<'a>>>,
 }
 
-impl Interpreter {
+impl<'a> Interpreter<'a> {
     /// Create a new interpreter and configure the initial global
     /// variable set.
     pub fn create() -> Self {
@@ -156,28 +159,28 @@ impl Interpreter {
     }
 
     // Environment modification helpers
-    fn define_var(&mut self, name: &scanner::Token, value: Value) -> Result<(), Error> {
+    fn define_var(&mut self, name: &scanner::Token, value: Value<'a>) -> Result<(), Error> {
         self.env
             .write()
             .expect("environment lock is poisoned")
             .define(name, value)
     }
 
-    fn assign_var(&mut self, name: &scanner::Token, value: Value) -> Result<(), Error> {
+    fn assign_var(&mut self, name: &scanner::Token, value: Value<'a>) -> Result<(), Error> {
         self.env
             .write()
             .expect("environment lock is poisoned")
             .assign(name, value)
     }
 
-    fn get_var(&mut self, var: &parser::Variable) -> Result<Value, Error> {
+    fn get_var(&mut self, var: &parser::Variable) -> Result<Value<'a>, Error> {
         self.env
             .read()
             .expect("environment lock is poisoned")
             .get(var)
     }
 
-    fn set_enclosing(&mut self, parent: Rc<RwLock<Environment>>) {
+    fn set_enclosing(&mut self, parent: Rc<RwLock<Environment<'a>>>) {
         self.env
             .write()
             .expect("environment lock is poisoned")
@@ -185,7 +188,7 @@ impl Interpreter {
     }
 
     // Interpreter itself
-    pub fn interpret<'a>(&mut self, program: &Block<'a>) -> Result<Value, Error> {
+    pub fn interpret(&mut self, program: &Block<'a>) -> Result<Value<'a>, Error> {
         let mut value = Value::Literal(Literal::Nil);
 
         for stmt in program {
@@ -195,7 +198,7 @@ impl Interpreter {
         Ok(value)
     }
 
-    fn interpret_stmt<'a>(&mut self, stmt: &Statement<'a>) -> Result<Value, Error> {
+    fn interpret_stmt(&mut self, stmt: &Statement<'a>) -> Result<Value<'a>, Error> {
         let value = match stmt {
             Statement::Expr(expr) => self.eval(expr)?,
             Statement::Print(expr) => {
@@ -214,7 +217,7 @@ impl Interpreter {
         Ok(value)
     }
 
-    fn interpret_var<'a>(&mut self, var: &parser::Var<'a>) -> Result<Value, Error> {
+    fn interpret_var(&mut self, var: &parser::Var<'a>) -> Result<Value<'a>, Error> {
         let init = var.initialiser.as_ref().ok_or_else(|| Error {
             line: var.name.line,
             kind: ErrorKind::InternalError("missing variable initialiser".into()),
@@ -224,7 +227,7 @@ impl Interpreter {
         Ok(value)
     }
 
-    fn interpret_block<'a>(&mut self, block: &parser::Block<'a>) -> Result<Value, Error> {
+    fn interpret_block(&mut self, 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).
@@ -241,7 +244,7 @@ impl Interpreter {
         return result;
     }
 
-    fn interpret_if<'a>(&mut self, if_stmt: &parser::If<'a>) -> Result<Value, Error> {
+    fn interpret_if(&mut self, if_stmt: &parser::If<'a>) -> Result<Value<'a>, Error> {
         let condition = self.eval(&if_stmt.condition)?;
 
         if eval_truthy(&condition) {
@@ -253,7 +256,7 @@ impl Interpreter {
         }
     }
 
-    fn interpret_while<'a>(&mut self, stmt: &parser::While<'a>) -> Result<Value, Error> {
+    fn interpret_while(&mut self, stmt: &parser::While<'a>) -> Result<Value<'a>, Error> {
         let mut value = Value::Literal(Literal::Nil);
         while eval_truthy(&self.eval(&stmt.condition)?) {
             value = self.interpret_stmt(&stmt.body)?;
@@ -262,7 +265,7 @@ impl Interpreter {
         Ok(value)
     }
 
-    fn eval<'a>(&mut self, expr: &Expr<'a>) -> Result<Value, Error> {
+    fn eval(&mut self, expr: &Expr<'a>) -> Result<Value<'a>, Error> {
         match expr {
             Expr::Assign(assign) => self.eval_assign(assign),
             Expr::Literal(lit) => Ok(lit.clone().into()),
@@ -275,7 +278,7 @@ impl Interpreter {
         }
     }
 
-    fn eval_unary<'a>(&mut self, expr: &parser::Unary<'a>) -> Result<Value, Error> {
+    fn eval_unary(&mut self, expr: &parser::Unary<'a>) -> Result<Value<'a>, Error> {
         let right = self.eval(&*expr.right)?;
 
         match (&expr.operator.kind, right) {
@@ -294,7 +297,7 @@ impl Interpreter {
         }
     }
 
-    fn eval_binary<'a>(&mut self, expr: &parser::Binary<'a>) -> Result<Value, Error> {
+    fn eval_binary(&mut self, expr: &parser::Binary<'a>) -> Result<Value<'a>, Error> {
         let left = self.eval(&*expr.left)?.expect_literal()?;
         let right = self.eval(&*expr.right)?.expect_literal()?;
 
@@ -338,13 +341,13 @@ impl Interpreter {
         Ok(result.into())
     }
 
-    fn eval_assign<'a>(&mut self, assign: &parser::Assign<'a>) -> Result<Value, Error> {
+    fn eval_assign(&mut self, assign: &parser::Assign<'a>) -> Result<Value<'a>, Error> {
         let value = self.eval(&assign.value)?;
         self.assign_var(&assign.name, value.clone())?;
         Ok(value)
     }
 
-    fn eval_logical<'a>(&mut self, logical: &parser::Logical<'a>) -> Result<Value, Error> {
+    fn eval_logical(&mut self, logical: &parser::Logical<'a>) -> Result<Value<'a>, Error> {
         let left = eval_truthy(&self.eval(&logical.left)?);
         let right = eval_truthy(&self.eval(&logical.right)?);
 
@@ -358,7 +361,7 @@ impl Interpreter {
         }
     }
 
-    fn eval_call<'a>(&mut self, call: &parser::Call<'a>) -> Result<Value, Error> {
+    fn eval_call(&mut self, call: &parser::Call<'a>) -> Result<Value<'a>, Error> {
         let callable = match self.eval(&call.callee)? {
             Value::Callable(c) => c,
             Value::Literal(v) => {
diff --git a/users/tazjin/rlox/src/interpreter/tests.rs b/users/tazjin/rlox/src/interpreter/tests.rs
index 3aaea707d64b..93a025c5e832 100644
--- a/users/tazjin/rlox/src/interpreter/tests.rs
+++ b/users/tazjin/rlox/src/interpreter/tests.rs
@@ -1,8 +1,11 @@
 use super::*;
 
+fn code(code: &str) -> Vec<char> {
+    code.chars().collect()
+}
+
 /// Evaluate a code snippet, returning a value.
-fn parse_eval(code: &str) -> Value {
-    let chars: Vec<char> = code.chars().collect();
+fn parse_eval<'a>(chars: &'a [char]) -> Value<'a> {
     let tokens = scanner::scan(&chars).expect("could not scan code");
     let program = parser::parse(tokens).expect("could not parse code");
     Interpreter::create()
@@ -12,7 +15,7 @@ fn parse_eval(code: &str) -> Value {
 
 #[test]
 fn test_if() {
-    let result = parse_eval(
+    let code = code(
         r#"
 if (42 > 23)
   "pass";
@@ -21,12 +24,15 @@ else
 "#,
     );
 
-    assert_eq!(Value::Literal(Literal::String("pass".into())), result);
+    assert_eq!(
+        Value::Literal(Literal::String("pass".into())),
+        parse_eval(&code)
+    );
 }
 
 #[test]
 fn test_scope() {
-    let result = parse_eval(
+    let code = code(
         r#"
 var result = "";
 
@@ -48,16 +54,19 @@ var c = "global c";
 
     assert_eq!(
         Value::Literal(Literal::String("inner a, outer b, global c".into())),
-        result
+        parse_eval(&code),
     );
 }
 
 #[test]
 fn test_binary_operators() {
-    assert_eq!(Value::Literal(Literal::Number(42.0)), parse_eval("40 + 2;"));
+    assert_eq!(
+        Value::Literal(Literal::Number(42.0)),
+        parse_eval(&code("40 + 2;"))
+    );
 
     assert_eq!(
         Value::Literal(Literal::String("foobar".into())),
-        parse_eval("\"foo\" + \"bar\";")
+        parse_eval(&code("\"foo\" + \"bar\";"))
     );
 }
diff --git a/users/tazjin/rlox/src/main.rs b/users/tazjin/rlox/src/main.rs
index 8970349bfa69..222eb4cd534f 100644
--- a/users/tazjin/rlox/src/main.rs
+++ b/users/tazjin/rlox/src/main.rs
@@ -25,14 +25,12 @@ fn main() {
 // Run Lox code from a file and print results to stdout
 fn run_file(file: &str) {
     let contents = fs::read_to_string(file).expect("failed to read the input file");
-    let mut lox = interpreter::Interpreter::create();
-    run(&mut lox, &contents);
+    run(&contents);
 }
 
 // Evaluate Lox code interactively in a shitty REPL.
 fn run_prompt() {
     let mut line = String::new();
-    let mut lox = interpreter::Interpreter::create();
 
     loop {
         print!("> ");
@@ -40,13 +38,14 @@ fn run_prompt() {
         io::stdin()
             .read_line(&mut line)
             .expect("failed to read user input");
-        run(&mut lox, &line);
+        run(&line);
         line.clear();
     }
 }
 
-fn run(lox: &mut interpreter::Interpreter, code: &str) {
+fn run(code: &str) {
     let chars: Vec<char> = code.chars().collect();
+    let mut lox = interpreter::Interpreter::create();
 
     match scanner::scan(&chars) {
         Ok(tokens) => match parser::parse(tokens) {