Finish chapter 6

java/com/craftinginterpreters/lox/Lox.java

@@ -46,11 +46,14 @@ public class Lox {
   private static void run(String source) {
     Scanner scanner = new Scanner(source);
     List<Token> tokens = scanner.scanTokens();
+    Parser parser = new Parser(tokens);
+    Expr expression = parser.parse();
 
-    // For now, just print the tokens.
-    for (Token token : tokens) {
-      System.out.println(token);
-    }
+    // Stop if there was a syntax error.
+    if (hadError)
+      return;
+
+    System.out.println(new AstPrinter().print(expression));
   }
 
   static void error(int line, String message) {
@@ -63,4 +66,11 @@ public class Lox {
     hadError = true;
   }
 
+  static void error(Token token, String message) {
+    if (token.type == TokenType.EOF) {
+      report(token.line, " at end", message);
+    } else {
+      report(token.line, " at '" + token.lexeme + "'", message);
+    }
+  }
 }