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 +++++++++++++-----
 .../test/java/com/seaofnodes/simple/Chapter05Test.java | 10 ++++++++++
 2 files changed, 23 insertions(+), 5 deletions(-)

(limited to 'chapter05')

diff --git a/chapter05/src/main/java/com/seaofnodes/simple/Parser.java b/chapter05/src/main/java/com/seaofnodes/simple/Parser.java
index 79b50672..a9bec582 100644
--- a/chapter05/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter05/src/main/java/com/seaofnodes/simple/Parser.java
@@ -93,7 +93,7 @@ public class Parser {
         try {
             _scope.define(CTRL , new ProjNode(START, 0, CTRL ).peephole());
             _scope.define("arg", new ProjNode(START, 1, "arg").peephole());
-            parseBlock();
+            parseBlock(false);
             return STOP;
         }
         finally {
@@ -111,14 +111,22 @@ public class Parser {
      * </pre>
      * @return a {@link Node} or {@code null}
      */
-    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;
@@ -135,7 +143,7 @@ public class Parser {
     private Node parseStatement() {
         if (matchx("return")  ) return parseReturn();
         else if (matchx("int")) return parseDecl();
-        else if (match ("{"  )) return parseBlock();
+        else if (match ("{"  )) return parseBlock(true);
         else if (matchx("if" )) return parseIf();
         else if (matchx("#showGraph")) return require(showGraph(),";");
         else return parseExpressionStatement();
diff --git a/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java b/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java
index 5ac309f3..0516fb73 100644
--- a/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java
+++ b/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java
@@ -430,4 +430,14 @@ return c;
         // this test used to fail in chapter 1
         assertEquals("return -100;", new Parser("return -100;").parse().print());
     }
+
+    @Test
+    public void testBad6() {
+        try {
+            new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b;").parse();
+            fail();
+        } catch( RuntimeException e ) {
+            assertEquals("Syntax error, expected }: ",e.getMessage());
+        }
+    }
 }
-- 
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