Chapter 8: Add variable declarations

1 files changed, 18 insertions, 0 deletions

diff --git a/src/com/craftinginterpreters/lox/Interpreter.java b/src/com/craftinginterpreters/lox/Interpreter.java
index b8ba090..f4e7f99 100644
--- a/src/com/craftinginterpreters/lox/Interpreter.java
+++ b/src/com/craftinginterpreters/lox/Interpreter.java
@@ -3,6 +3,8 @@ package com.craftinginterpreters.lox;
 import java.util.List;
 
 class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
+    private Environment environment = new Environment();
+
     @Override
     public Object visitLiteralExpr(Expr.Literal expr) {
         return expr.value;
@@ -24,6 +26,11 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
         return null;
     }
 
+    @Override
+    public Object visitVariableExpr(Expr.Variable expr) {
+        return environment.get(expr.name);
+    }
+
     private void checkNumberOperand(Token operator, Object operand) {
         if (operand instanceof Double)
             return;
@@ -96,6 +103,17 @@ class Interpreter implements Expr.Visitor<Object>, Stmt.Visitor<Void> {
     }
 
     @Override
+    public Void visitVarStmt(Stmt.Var stmt) {
+        Object value = null;
+        if (stmt.initializer != null) {
+            value = evaluate(stmt.initializer);
+        }
+
+        environment.define(stmt.name.lexeme, value);
+        return null;
+    }
+
+    @Override
     public Object visitBinaryExpr(Expr.Binary expr) {
         Object left = evaluate(expr.left);
         Object right = evaluate(expr.right);