From d3ffe6f9a935888233283962ce077ec25a01bec9 Mon Sep 17 00:00:00 2001
From: Yichen Yan <oraluben@outlook.com>
Date: Wed, 1 Nov 2023 22:08:30 +0800
Subject: Bail out unclosed block (#25)

* Report unclosed block in parsing

* Fix tests

* Resolve comments and rebase onto chapter5

* Test `isEOF` after consume whitespaces
---
 .../src/main/java/com/seaofnodes/simple/Parser.java    | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

(limited to 'chapter03/src/main/java/com/seaofnodes')

diff --git a/chapter03/src/main/java/com/seaofnodes/simple/Parser.java b/chapter03/src/main/java/com/seaofnodes/simple/Parser.java
index 12e156ed..3d06a9c3 100644
--- a/chapter03/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter03/src/main/java/com/seaofnodes/simple/Parser.java
@@ -39,7 +39,7 @@ public class Parser {
     }
 
     public ReturnNode parse() {
-        return (ReturnNode) parseBlock();
+        return (ReturnNode) parseBlock(false);
     }
 
 
@@ -50,14 +50,22 @@ public class Parser {
      *     '{' statements '}'
      * </pre>
      */
-    private Node parseBlock() {
+    private Node parseBlock(boolean requireClosingBracket) {
         // Enter a new scope
         _scope.push();
         Node n = null;
-        while (!match("}") && !_lexer.isEOF()) {
+        do {
+            if (match("}")) {
+                if (requireClosingBracket) break;
+                else throw error("unexpected '}' token");
+            } else if (_lexer.isEOF()) {
+                if (requireClosingBracket) require("}");
+                else break;
+            }
+
             Node n0 = parseStatement();
             if (n0 != null) n = n0; // Allow null returns from eg showGraph
-        }
+        } while (true);
         // Exit scope
         _scope.pop();
         return n;
@@ -73,7 +81,7 @@ public class Parser {
     private Node parseStatement() {
         if (match("return")) return parseReturn();
         else if (match("int")) return parseDecl();
-        else if (match("{")) return parseBlock();
+        else if (match("{")) return parseBlock(true);
         else if (match("#showGraph")) return showGraph();
         else return parseExpressionStatement();
     }
-- 
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