12.4 Methods on Classes

src/com/craftinginterpreters/lox/Interpreter.java

@@ -177,7 +177,14 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
     @Override
     public Void visitClassStmt(Stmt.Class stmt) {
         environment.define(stmt.name.lexeme, null);
-        LoxClass klass = new LoxClass(stmt.name.lexeme);
+
+        Map<String, LoxFunction> methods = new HashMap<>();
+        for (Stmt.Function method : stmt.methods) {
+            LoxFunction function = new LoxFunction(method, environment);
+            methods.put(method.name.lexeme, function);
+        }
+
+        LoxClass klass = new LoxClass(stmt.name.lexeme, methods);
         environment.assign(stmt.name, klass);
         return null;
     }

src/com/craftinginterpreters/lox/LoxClass.java

@@ -1,12 +1,23 @@
 package com.craftinginterpreters.lox;
 
 import java.util.List;
+import java.util.Map;
 
 class LoxClass implements LoxCallable {
     final String name;
+    private final Map<String, LoxFunction> methods;
 
-    LoxClass(String name) {
+    LoxClass(String name, Map<String, LoxFunction> methods) {
         this.name = name;
+        this.methods = methods;
+    }
+
+    LoxFunction findMethod(String name) {
+        if (methods.containsKey(name)) {
+            return methods.get(name);
+        }
+
+        return null;
     }
 
     @Override

src/com/craftinginterpreters/lox/LoxInstance.java

@@ -16,6 +16,10 @@ class LoxInstance {
             return fields.get(name.lexeme);
         }
 
+        LoxFunction method = klass.findMethod(name.lexeme);
+        if (method != null)
+            return method;
+
         throw new RuntimeError(name, "Undefined proprety '" + name.lexeme + "'.");
     }
 

src/com/craftinginterpreters/lox/Resolver.java

@@ -15,7 +15,7 @@ class Resolver implements Expr.Visitor<Void>, Stmt.Visitor<Void> {
     }
 
     private enum FunctionType {
-        NONE, FUNCTION
+        NONE, FUNCTION, METHOD
     }
 
     public void resolve(List<Stmt> statements) {
@@ -36,6 +36,12 @@ class Resolver implements Expr.Visitor<Void>, Stmt.Visitor<Void> {
     public Void visitClassStmt(Stmt.Class stmt) {
         declare(stmt.name);
         define(stmt.name);
+
+        for (Stmt.Function method : stmt.methods) {
+            FunctionType declaration = FunctionType.METHOD;
+            resolveFunction(method, declaration);
+        }
+
         return null;
     }