Interpreter - Refactored method handling to prepare for getters/setters

src/interpreter/classes.rs

@@ -1,6 +1,9 @@
 use std::{cell::RefCell, collections::HashMap, fmt::Display, rc::Rc};
 
+use lazy_static::lazy_static;
+
 use crate::{
+    ast::ClassMemberKind,
     errors::{ErrorKind, SloxError, SloxResult},
     tokens::Token,
 };
@@ -14,12 +17,14 @@ pub trait PropertyCarrier {
     fn set(&self, name: &Token, value: Value);
 }
 
+/// The key for the table of class members.
+pub type ClassMemberKey = (ClassMemberKind, bool, String);
+
 /// A Lox class.
 #[derive(Debug, Clone)]
 pub struct Class {
     name: String,
-    methods: HashMap<String, Function>,
-    static_methods: HashMap<String, Function>,
+    members: HashMap<ClassMemberKey, Function>,
     fields: RefCell<HashMap<String, Value>>,
 }
 
@@ -40,6 +45,11 @@ pub type InstanceRef = Rc<RefCell<Instance>>;
  * Class implementation *
  * -------------------- */
 
+lazy_static! {
+    static ref INIT_METHOD_KEY: ClassMemberKey =
+        (ClassMemberKind::Method, false, String::from("init"));
+}
+
 fn bind_method(method: &Function, this_value: Value) -> Function {
     let bm = method.copy_with_child_env();
     bm.env().set("this", this_value);
@@ -48,15 +58,10 @@ fn bind_method(method: &Function, this_value: Value) -> Function {
 
 impl Class {
     /// Create a new class, specifying its name.
-    pub fn new(
-        name: String,
-        methods: HashMap<String, Function>,
-        static_methods: HashMap<String, Function>,
-    ) -> Self {
+    pub fn new(name: String, members: HashMap<ClassMemberKey, Function>) -> Self {
         Self {
             name,
-            methods,
-            static_methods,
+            members,
             fields: RefCell::new(HashMap::default()),
         }
     }
@@ -72,7 +77,7 @@ impl Display for Class {
 
 impl Callable for ClassRef {
     fn arity(&self) -> usize {
-        if let Some(init) = self.borrow().methods.get("init") {
+        if let Some(init) = self.borrow().members.get(&INIT_METHOD_KEY) {
             init.arity()
         } else {
             0
@@ -81,7 +86,7 @@ impl Callable for ClassRef {
 
     fn call(&self, itpr_state: &mut InterpreterState, arguments: Vec<Value>) -> SloxResult<Value> {
         let inst_value = Value::from(Instance::new(self.clone()));
-        if let Some(init) = self.borrow().methods.get("init") {
+        if let Some(init) = self.borrow().members.get(&INIT_METHOD_KEY) {
             inst_value.with_instance(
                 |_| {
                     let bound_init = bind_method(init, inst_value.clone());
@@ -98,10 +103,11 @@ impl Callable for ClassRef {
 impl PropertyCarrier for ClassRef {
     fn get(&self, name: &Token) -> SloxResult<Value> {
         let class = self.borrow();
+        let mut mb_key = (ClassMemberKind::Method, true, name.lexeme.clone());
         if let Some(value) = class.fields.borrow().get(&name.lexeme) {
             return Ok(value.clone());
         }
-        if let Some(method) = class.static_methods.get(&name.lexeme) {
+        if let Some(method) = class.members.get(&mb_key) {
             let bound_method = bind_method(method, Value::from(self.clone()));
             return Ok(Value::from(bound_method));
         }
@@ -141,10 +147,11 @@ impl Display for Instance {
 impl PropertyCarrier for InstanceRef {
     fn get(&self, name: &Token) -> SloxResult<Value> {
         let instance = self.borrow();
+        let mut mb_key = (ClassMemberKind::Method, false, name.lexeme.clone());
         if let Some(value) = instance.fields.borrow().get(&name.lexeme) {
             return Ok(value.clone());
         }
-        if let Some(method) = instance.class.borrow().methods.get(&name.lexeme) {
+        if let Some(method) = instance.class.borrow().members.get(&mb_key) {
             let bound_method = bind_method(method, Value::from(self.clone()));
             return Ok(Value::from(bound_method));
         }

src/interpreter/interpretable.rs

@@ -10,7 +10,11 @@ use crate::{
     tokens::{Token, TokenType},
 };
 
-use super::{classes::Class, functions::Function, Environment, EnvironmentRef, Value};
+use super::{
+    classes::{Class, ClassMemberKey},
+    functions::Function,
+    Environment, EnvironmentRef, Value,
+};
 
 /// Evaluate an interpretable, returning its value.
 pub fn evaluate(ast: &ProgramNode, vars: ResolvedVariables) -> SloxResult<Value> {
@@ -173,6 +177,30 @@ impl Interpretable for StmtNode {
     }
 }
 
+/// Extract members from a class declaration, generating a map of
+/// functions.
+fn extract_members(
+    es: &mut InterpreterState,
+    decl: &ClassDecl,
+) -> HashMap<ClassMemberKey, Function> {
+    decl.members
+        .iter()
+        .map(|member| {
+            let fnd = &member.fun_decl;
+            (
+                (member.kind, member.is_static, fnd.name.lexeme.clone()),
+                Function::new(
+                    Some(&fnd.name),
+                    &fnd.params,
+                    &fnd.body,
+                    es.environment.clone(),
+                    fnd.name.lexeme == "init",
+                ),
+            )
+        })
+        .collect()
+}
+
 impl StmtNode {
     /// Handle the `print` statement.
     fn on_print(&self, es: &mut InterpreterState, expr: &ExprNode) -> InterpreterResult {
@@ -197,53 +225,10 @@ impl StmtNode {
         Ok(InterpreterFlowControl::default())
     }
 
-    /// Extract members from a class declaration, generating a map of
-    /// functions.
-    fn extract_members<F>(
-        &self,
-        es: &mut InterpreterState,
-        decl: &ClassDecl,
-        filter: F,
-    ) -> HashMap<String, Function>
-    where
-        F: FnMut(&ClassMemberDecl) -> Option<(&FunDecl, &[Token])>,
-    {
-        decl.members
-            .iter()
-            .filter_map(filter)
-            .map(|(fdecl, params)| {
-                (
-                    fdecl.name.lexeme.clone(),
-                    Function::new(
-                        Some(&fdecl.name),
-                        &params,
-                        &fdecl.body,
-                        es.environment.clone(),
-                        fdecl.name.lexeme == "init",
-                    ),
-                )
-            })
-            .collect::<HashMap<String, Function>>()
-    }
-
     /// Handle a class declaration
     fn on_class_decl(&self, es: &mut InterpreterState, decl: &ClassDecl) -> InterpreterResult {
         es.environment.borrow_mut().define(&decl.name, None)?;
-        let methods =
-            self.extract_members(es, decl, |member| match (&member.kind, member.is_static) {
-                (ClassMemberKind::Method, false) => {
-                    Some((&member.fun_decl, &member.fun_decl.params))
-                }
-                _ => None,
-            });
-        let static_methods =
-            self.extract_members(es, decl, |member| match (&member.kind, member.is_static) {
-                (ClassMemberKind::Method, true) => {
-                    Some((&member.fun_decl, &member.fun_decl.params))
-                }
-                _ => None,
-            });
-        let class = Class::new(decl.name.lexeme.clone(), methods, static_methods);
+        let class = Class::new(decl.name.lexeme.clone(), extract_members(es, decl));
         es.environment
             .borrow_mut()
             .assign(&decl.name, class.into())?;